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href="/www/command-line-options.html#resize">‑resize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#respect-parentheses">‑respect‑parentheses</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#reverse">‑reverse</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#roll">‑roll</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#rotate">‑rotate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sample">‑sample</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sampling-factor">‑sampling‑factor</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#scale">‑scale</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#scene">‑scene</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#screen">‑screen</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#seed">‑seed</a> <span 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href="/www/command-line-options.html#shear">‑shear</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#silent">‑silent</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#size">‑size</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sketch">‑sketch</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#smush">‑smush</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#snaps">‑snaps</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#solarize">‑solarize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sparse-color">‑sparse‑color</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#splice">‑splice</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#spread">‑spread</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#statistic">‑statistic</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#stegano">‑stegano</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#stereo">‑stereo</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#stretch">‑stretch</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#strip">‑strip</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#stroke">‑stroke</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#strokewidth">‑strokewidth</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#style">‑style</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#subimage-search">‑subimage‑search</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#swap">‑swap</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#swirl">‑swirl</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#synchronize">‑synchronize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#taint">‑taint</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#text-font">‑text‑font</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#texture">‑texture</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#threshold">‑threshold</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#thumbnail">‑thumbnail</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#tile">‑tile</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#tile-offset">‑tile‑offset</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#tint">‑tint</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#title">‑title</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#transform">‑transform</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#transparent">‑transparent</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#transparent-color">‑transparent‑color</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#transpose">‑transpose</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#transverse">‑transverse</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#treedepth">‑treedepth</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#trim">‑trim</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#type">‑type</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#undercolor">‑undercolor</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#unique-colors">‑unique‑colors</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#units">‑units</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#unsharp">‑unsharp</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#update">‑update</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#verbose">‑verbose</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#version">‑version</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#view">‑view</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#vignette">‑vignette</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#virtual-pixel">‑virtual‑pixel</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#visual">‑visual</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#watermark">‑watermark</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#wave">‑wave</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#weight">‑weight</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#white-point">‑white‑point</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#white-threshold">‑white‑threshold</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#window">‑window</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#window-group">‑window‑group</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#write">‑write</a> ] </p> 206 207<div class="doc-section"> 208 209<p>Below is list of command-line options recognized by the ImageMagick <a 210href="/www/command-line-tools.html">command-line 211tools</a>. If you want a description of a particular option, click on the 212option name in the navigation bar above and you will go right to it. Unless 213otherwise noted, each option is recognized by the commands <a href="/www/convert.html">convert</a>, <a href="/www/mogrify.html">mogrify</a>.</p> 214 215<div style="margin: auto;"> 216 <h4><a id="adaptive-blur"></a>-adaptive-blur <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4> 217</div> 218 219<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively blur pixels, with decreasing effect near edges.</td><td style='text-align:right;'></td></tr></table> 220<p>A Gaussian operator of the given radius and standard deviation (<em class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it defaults to 1.</p> 221 222<div style="margin: auto;"> 223 <h4><a id="adaptive-resize"></a>-adaptive-resize <em class="arg">geometry</em></h4> 224</div> 225 226<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize the image using data-dependent triangulation.</td><td style='text-align:right;'></td></tr></table> 227 228<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="#adaptive-resize">-adaptive-resize</a> option defaults to data-dependent triangulation. Use the <a href="#filter">-filter</a> to choose a different resampling algorithm. Offsets, if present in the geometry string, are ignored, and the <a href="#gravity">-gravity</a> option has no effect.</p> 229 230<div style="margin: auto;"> 231 <h4><a id="adaptive-sharpen"></a>-adaptive-sharpen <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4> 232</div> 233 234<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively sharpen pixels, with increasing effect near edges.</td><td style='text-align:right;'></td></tr></table> 235 236<p>A Gaussian operator of the given radius and standard deviation (<em class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it defaults to 1.</p> 237 238<div style="margin: auto;"> 239 <h4><a id="adjoin"></a>-adjoin</h4> 240</div> 241 242<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join images into a single multi-image file.</td><td style='text-align:right;'></td></tr></table> 243 244<p>This option is enabled by default. An attempt is made to save all images of 245an image sequence into the given output file. However, some formats, such as 246JPEG and PNG, do not support more than one image per file, and in that case 247ImageMagick is forced to write each image as a separate file. As such, if 248more than one image needs to be written, the filename given is modified by 249adding a <a href="#scene">-scene</a> number before the suffix, in order to 250make distinct names for each image. </p> 251 252<p>Use <a href="#adjoin">+adjoin</a> to force each image to be written to 253separate files, whether or not the file format allows multiple images per file 254(for example, GIF, MIFF, and TIFF). </p> 255 256<p>Including a C-style integer format string in the output filename will 257automagically enable <a href="#adjoin">+adjoin</a> and are used to specify 258where the <a href="#scene">-scene</a> number is placed in the filenames. These 259strings, such as '<kbd>%d</kbd>' or '<kbd>%03d</kbd>', are familiar to those 260who have used the standard <kbd>printf()</kbd>' C-library function. As an 261example, the command</p> 262 263<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: rose: -morph 15 my%02dmorph.jpg</span></p> 264<p>will create a sequence of 17 images (the two given plus 15 more created by 265<a href="#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg, 266my02morph.jpg, ..., my16morph.jpg. </p> 267 268<p>In summary, ImageMagick tries to write all images to one file, but will 269save to multiple files, if any of the following conditions exist... 270<ol> 271<li>the output image's file format does not allow multi-image files, 272<li>the <a href="#adjoin">+adjoin</a> option is given, or 273<li>a printf() integer format string (eg: "%d") is present in the output 274 filename. 275</ol></p> 276 277 278<div style="margin: auto;"> 279 <h4><a id="affine"></a>-affine 280 <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em 281 class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em>[,<em 282 class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>]</h4> 283</div> 284 285<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the drawing transformation matrix for combined rotating and scaling.</td><td style='text-align:right;'></td></tr></table> 286 287<p>This option sets a transformation matrix, for use by subsequent <a 288href="#draw">-draw</a> or <a href="#transform">-transform</a> options. </p> 289 290<p>The matrix entries are entered as comma-separated numeric values either in 291quotes or without spaces. </p> 292 293<p>Internally, the transformation matrix has 3x3 elements, but three of them 294are omitted from the input because they are constant. The new (transformed) 295coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at 296position (<em class="arg">x</em>, <em class="arg">y</em>) in the original 297image are calculated using the following matrix equation.</p> 298 299<div class="eqn"> 300<img alt="affine transformation" src="/images/affine.png"/> 301</div> 302 303<p> The size of the resulting image is that of the smallest rectangle that 304contains the transformed source image. The parameters <em 305class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> 306subsequently shift the image pixels so that those that are moved out of the 307image area are cut off.</p> 308 309<p>The transformation matrix complies with the left-handed pixel coordinate 310system: positive <em class="arg">x</em> and <em class="arg">y</em> directions 311are rightward and downward, resp.; positive rotation is clockwise.</p> 312 313<p> If the translation coefficients <em class="arg">t<sub>x</sub></em> and <em 314class="arg">t<sub>y</sub></em> are omotted they default to 0,0. Therefore, 315four parameters suffice for rotation and scaling without translation.</p> 316 317<p>Scaling by the factors <em class="arg">s<sub>x</sub></em> and <em 318class="arg">s<sub>y</sub></em> in the <em>x</em> and <em>y</em> directions, 319respectively, is accomplished with the following.</p> 320 321<p>See <a href="#transform">-transform</a>, and the <a 322href="#distort">-distort</a> method '<kbd>Affineprojection</kbd> for more 323information </p> 324 325 326<p class="crtsnip"> 327 -affine <em class="arg">s<sub>x</sub></em>,0,0,<em class="arg">s<sub>y</sub></em> 328</p> 329 330<p>Translation by a displacement (<em class="arg">t<sub>x</sub></em>, <em class="arg">t<sub>y</sub></em>) is accomplished like so:</p> 331 332<p class="crtsnip"> 333 -affine 1,0,0,1,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em> 334</p> 335 336<p>Rotate clockwise about the origin (the upper left-hand corner) by an angle <em>a</em> by letting 337<em>c</em> = cos(<em>a</em>), <em>s</em> = sin(<em>a</em>), and using the following.</p> 338 339<p class="crtsnip"> 340 -affine <em>c</em>,<em>s</em>,-<em>s</em>,<em>c</em> 341</p> 342 343<p>The cumulative effect of a sequence of <a href="#affine" >-affine</a> transformations can be accomplished by instead by a single <a href="#affine" >-affine</a> operation using the matrix equal to the product of the matrices of the individual transformations.</p> 344 345<p>An attempt is made to detect near-singular transformation matrices. If the matrix determinant has a sufficiently small absolute value it is rejected.</p> 346 347<div style="margin: auto;"> 348 <h4><a id="alpha"></a>-alpha <em class="arg">type</em></h4> 349</div> 350 351<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Gives control of the alpha/matte channel of an image.</td><td style='text-align:right;'></td></tr></table> 352 353<p>Used to set a flag on an image indicating whether or not to use existing alpha 354channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument <em class="arg">type</em> from the list below.</p> 355 356 357<table class="doc"> 358 <tbody> 359 <tr valign="top"> 360 <th align="left" style="width: 8%">type</th> 361 <th align="left">Description</th> 362 </tr> 363 364 <tr valign="top"> 365 <td valign="top"><kbd>Activate</kbd> or <kbd>On</kbd></td> 366 <td valign="top"> 367 Enable the image's transparency channel. Note normally <kbd>Set</kbd> 368 should be used instead of this, unless you specifically need to 369 preserve existing (but specifically turned <kbd>Off</kbd>) transparency 370 channel. </td></tr> 371 372 <tr valign="top"> 373 <td valign="top"><kbd>Deactivate</kbd> or <kbd>Off</kbd></td> 374 <td valign="top"> 375 Disables the image's transparency channel. Does not delete or change the 376 existing data, just turns off the use of that data.</td></tr> 377 378 <tr valign="top"> 379 <td valign="top"><kbd>Set</kbd></td> 380 <td valign="top"> 381 Activates the alpha/matte channel. If it was previously turned off 382 then it also resets the channel to opaque. If the image already had 383 the alpha channel turned on, it will have no effect.</td></tr> 384 385 <tr valign="top"> 386 <td valign="top"><kbd>Opaque</kbd></td> 387 <td valign="top"> 388 Enables the alpha/matte channel and forces it to be fully opaque. 389 </td></tr> 390 391 <tr valign="top"> 392 <td valign="top"><kbd>Transparent</kbd></td> 393 <td valign="top"> 394 Activates the alpha/matte channel and forces it to be fully 395 transparent. This effectively creates a fully transparent image the 396 same size as the original and with all its original RGB data still 397 intact, but fully transparent. </td></tr> 398 399 <tr valign="top"> 400 <td valign="top"><kbd>Extract</kbd></td> 401 <td valign="top"> 402 Copies the alpha channel values into all the color channels and turns 403 '<kbd>Off</kbd>' the the image's transparency, so as to generate 404 a gray-scale mask of the image's shape. The alpha channel data is left 405 intact just deactivated. This is the inverse of '<kbd>Copy</kbd>'. 406 </td></tr> 407 408 <tr valign="top"> 409 <td valign="top"><kbd>Copy</kbd></td> 410 <td valign="top"> 411 Turns '<kbd>On</kbd>' the alpha/matte channel, then copies the 412 gray-scale intensity of the image, into the alpha channel, converting 413 a gray-scale mask into a transparent shaped mask ready to be colored 414 appropriately. The color channels are not modified. </td></tr> 415 416 <tr valign="top"> 417 <td valign="top"><kbd>Shape</kbd></td> 418 <td valign="top"> 419 As per '<kbd>Copy</kbd>' but also colors the resulting shape mask with 420 the current background color. That is the RGB color channels is 421 replaced, with appropriate alpha shape. 422 </td></tr> 423 424 <tr valign="top"> 425 <td valign="top"><kbd>Background</kbd></td> 426 <td valign="top"> 427 Set any fully-transparent pixel to the background color, while leaving 428 it fully-transparent. This can make some image file formats, such as 429 PNG, smaller as the RGB values of transparent pixels are more uniform, 430 and thus can compress better. 431 </td></tr> 432 </tbody> 433</table> 434 435<p>Note that while the <a href="#matte" >+matte</a> operation is the same as 436"<kbd><a href="#alpha" >-alpha</a> Off</kbd>", the <a href="#matte" 437>-matte</a> operation is the same as "<kbd><a href="#alpha" >-alpha</a> 438Set</kbd>" and not "<kbd><a href="#alpha" >-alpha</a> On</kbd>". </p> 439 440 441<div style="margin: auto;"> 442 <h4><a id="annotate"></a> 443 -annotate <em class="arg">degrees</em> <em class="arg">text</em><br /> 444 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> <em class="arg">text</em><br /> 445 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> {+-}<em class="arg">t<sub>x</sub></em>{+-}<em class="arg">t<sub>y</sub></em> <em class="arg">text</em></h4> 446</div> 447 448<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with text.</td><td style='text-align:right;'></td></tr></table> 449 450<p>This is a convenience for annotating an image with text. For more precise control over text annotations, use <a href="#draw">-draw</a>.</p> 451 452 453<p>The values <em class="arg">Xdegrees</em> and <em class="arg">Ydegrees</em> control the shears with respect to the , respectively, applied to the text, while <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are offsets that give the location of the text relative to the upper left corner of the image.</p> 454 455<p>Using <a href="#annotate">-annotate</a> <em class="arg">degrees</em> or <a href="#annotate">-annotate</a> <em class="arg">degrees</em>x<em class="arg">degrees</em> produces an unsheared rotation of the text. The direction of the rotation is positive, which means a clockwise rotation if <em class="arg">degrees</em> is positive. (This conforms to the usual mathematical convention once it is realized that the positive <em>y</em>–direction is conventionally considered to be <em>downward</em> for images.)</p> 456 457<p>The new (transformed) coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at position (<em class="arg">x</em>, <em class="arg">y</em>) in the image are calculated using the following matrix equation.</p> 458<div class="eqn"><img alt="annotate transformation" src="/images/annotate.png"/></div> 459 460<p>If <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are omitted, they default to 0. This makes the bottom-left of the text becomes the upper-left corner of the image, which is probably undesirable. Adding a <a href="#gravity" >-gravity</a> option in this case leads to nice results.</p> 461 462<p>Text is any UTF-8 encoded character sequence. If <em class="arg">text</em> is of the form '@mytext.txt', the text is read from the file <kbd>mytext.txt</kbd>. Text in a file is taken literally; no embedded formatting characters are recognized.</p> 463 464<div style="margin: auto;"> 465 <h4><a id="antialias"></a>-antialias</h4> 466</div> 467 468<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enable/Disable of the rendering of anti-aliasing pixels when 469drawing fonts and lines.</td><td style='text-align:right;'></td></tr></table> 470 471<p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when 472drawn. Use <a href="#antialias">+antialias</a> to disable the addition of 473antialiasing edge pixels. This will then reduce the number of colors added to 474an image to just the colors being directly drawn. That is, no mixed colors 475are added when drawing such objects. </p> 476 477<div style="margin: auto;"> 478 <h4><a id="append"></a>-append</h4> 479</div> 480 481<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join current images vertically or horizontally.</td><td style='text-align:right;'></td></tr></table> 482 483<p>This option creates a single longer image image, by joining all the current 484images in sequence top-to-bottom. Use <a href="#append">+append</a> to 485stack images left-to-right. </p> 486 487<p>If they are not of the same width, narrower images are padded with the 488current <a href="#background">-background</a> color setting, and their 489position relative to each other can be controlled by the current <a 490href="#gravity">-gravity</a> setting. </p> 491 492 493<div style="margin: auto;"> 494 <h4><a id="attenuate"></a>-attenuate <em class="arg">value</em></h4> 495</div> 496 497<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lessen (or intensify) when adding noise to an image.</td><td style='text-align:right;'></td></tr></table> 498 499 500<div style="margin: auto;"> 501 <h4><a id="authenticate"></a>-authenticate <em class="arg">password</em></h4> 502</div> 503 504<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decrypt a PDF with a password.</td><td style='text-align:right;'></td></tr></table> 505 506<p>Use this option to supply a <em class="arg">password</em> for decrypting a PDF that has been encrypted using Microsoft Crypto API (MSC API). The encrypting using the MSC API is not supported.</p> 507 508<p>For a different encryption method, see <a href="#encipher">-encipher</a> and <a href="#decipher">-decipher</a>. </p> 509 510 511 512<div style="margin: auto;"> 513 <h4><a id="auto-gamma"></a>-auto-gamma</h4> 514</div> 515 516<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust gamma level of image.</td><td style='text-align:right;'></td></tr></table> 517 518<p>This calculates the mean values of an image, then applies a calculated <a 519href="#gamma" >-gamma</a> adjustment so that is the mean color exists in the 520image it will get a have a value of 50%. </p> 521 522<p>This means that any solid 'gray' image becomes 50% gray. </p> 523 524<p>This works well for real-life images with little or no extreme dark and 525light areas, but tend to fail for images with large amounts of bright sky or 526dark shadows. It also does not work well for diagrams or cartoon like images. 527</p> 528 529<p>It uses the <a href="#channel" >-channel</a> setting, (including the 530'<em>sync</em>' flag for channel syncronization), to determine which color 531values is used and modified. As the default <a href="#channel" 532>-channel</a> setting is '<em>RGB,sync</em>', channels are modified 533together by the same gamma value, preserving colors. </p> 534 535 536 537<div style="margin: auto;"> 538 <h4><a id="auto-level"></a>-auto-level</h4> 539</div> 540 541<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust color levels of image.</td><td style='text-align:right;'></td></tr></table> 542 543<p>This is a 'perfect' image normalization operator. It finds the exact 544minimum and maximum color values in the image and then applies a <a 545href="#level" >-level</a> operator to stretch the values to the full range of 546values. </p> 547 548<p>The operator is not typically used for real-life images, image scans, or 549JPEG format images, as a single 'out-rider' pixel can set a bad min/max values 550for the <a href="#level" >-level</a> operation. On the other hand it is the 551right operator to use for color stretching gradient images being used to 552generate Color lookup tables, distortion maps, or other 'mathematically' 553defined images. </p> 554 555<p>The operator is very similar to the <a href="#normalize">-normalize</a>, <a 556href="#contrast-stretch" >-contrast-stretch</a>, and <a href="#linear-stretch" 557>-linear-stretch</a> operators, but without 'histogram binning' or 'clipping' 558problems that these operators may have. That is <a href="#auto-level" 559>-auto-level</a> is the perfect or ideal version these operators. </p> 560 561<p>It uses the <a href="#channel" >-channel</a> setting, (including the 562special '<em>sync</em>' flag for channel syncronization), to determine 563which color values are used and modified. As the default <a 564href="#channel" >+channel</a> setting is '<em>RGB,sync</em>', the 565'<em>sync</em>' ensures that the color channels will are modified 566together by the same gamma value, preserving colors, and ignoring 567transparency. </p> 568 569 570<div style="margin: auto;"> 571 <h4><a id="auto-orient"></a>-auto-orient</h4> 572</div> 573 574<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically orient (rotate) an image created by a digital camera.</td><td style='text-align:right;'></td></tr></table> 575 576<p>This operator reads and resets the EXIF image profile setting 'Orientation' 577and then performs the appropriate 90 degree rotation on the image to orient 578the image, for correct viewing. </p> 579 580<p>This EXIF profile setting is usually set using a gravity sensor in digital 581camara, however photos taken directly downward or upward may not have an 582appropriate value. Also images that have been orientation 'corrected' without 583reseting this setting, may be 'corrected' again resulting in a incorrect 584result. If the he EXIF profile was previously stripped, the <a 585href="#auto-orient" >-auto-orient</a> operator will do nothing. </p> 586 587 588<div style="margin: auto;"> 589 <h4><a id="average"></a>-average</h4> 590</div> 591 592<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Average a set of images.</td><td style='text-align:right;'></td></tr></table> 593 594<p>An error results if the images are not identically sized.</p> 595 596 597<div style="margin: auto;"> 598 <h4><a id="backdrop"></a>-backdrop</h4> 599</div> 600 601<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display the image centered on a backdrop.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 602 603<p>This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the background color. The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 604 605<div style="margin: auto;"> 606 <h4><a id="background"></a>-background <em class="arg">color</em></h4> 607</div> 608 609<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the background color.</td><td style='text-align:right;'></td></tr></table> 610 611<p>The color is specified using the format described under the <a href="#fill">-fill</a> option. The default background color (if none is specified or found in the image) is white.</p> 612 613<div style="margin: auto;"> 614 <h4><a id="bench"></a>-bench <em class="arg">iterations</em></h4> 615</div> 616 617<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Measure performance.</td><td style='text-align:right;'></td></tr></table> 618 619<p>Repeat the entire command for the given number of <em class="arg">iterations</em> and report the user-time and elapsed time. For instance, consider the following command and its output. Modify the benchmark with the -duration to run the benchmark for a fixed number of seconds and -concurrent to run the benchmark in parallel (requires the OpenMP feature).</p> 620 621<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize 1000% -bench 5 logo.png</span><span class='crtout'>Performance: 5i 0.875657ips 6.880u 0:05.710</span></p> 622<p>In this example, 5 iterations were completed at 0.875657 iterations per second, using 6.88 seconds of the user's allotted time, for a total elapsed time of 5.71 seconds.</p> 623 624<div style="margin: auto;"> 625 <h4><a id="bias"></a>-bias <em class="arg">value</em>{<em class="arg">%</em>}</h4> 626</div> 627 628<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add bias when convolving an image.</td><td style='text-align:right;'></td></tr></table> 629 630<p>This option shifts the output of <a href="/www/command-line-options.html#convolve">‑convolve</a> so that positive and negative results are relative to the specified bias value. </p> 631 632<p>This is important for non-HDRI compilations of ImageMagick when dealing with convolutions that contain negative as well as positive values. This is especially the case with convolutions involving high pass filters or edge detection. Without an output bias, the negative values are clipped at zero.</p> 633 634<p>When using an ImageMagick with the HDRI compile-time setting, <a href="/www/command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any 635negative results without clipping to the color value range 636(0..QuantumRange).</p> 637 638<p>See the discussion on HDRI implementations of ImageMagick on the page 639<a href="/www/high-dynamic-range.html">High Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> entry. 640</p> 641 642<div style="margin: auto;"> 643 <h4><a id="black-point-compensation"></a>-black-point-compensation</h4> 644</div> 645 646<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use black point compensation.</td><td style='text-align:right;'></td></tr></table> 647 648<div style="margin: auto;"> 649 <h4><a id="black-threshold"></a>-black-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 650</div> 651 652<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</td><td style='text-align:right;'></td></tr></table> 653 654<p> The threshold value can be given as a percentage or as an absolute integer value within [0, <em class="QR">QuantumRange</em>] corresponding to the desired <a href="/www/command-line-options.html#channel">‑channel</a> value. See <a href="/www/command-line-options.html#threshold">‑threshold</a> for more details on thresholds and resulting values. 655</p> 656 657 658<div style="margin: auto;"> 659 <h4><a id="blend"></a>-blend <em class="arg">geometry</em></h4> 660</div> 661 662<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>blend an image into another by the given absolute value or percent.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 663 664<p>Blend will average the images together ('plus') according to the 665percentages given and each pixels transparency. If only a single percentage 666value is given it sets the weight of the composite or 'source' image, while 667the background image is weighted by the exact opposite amount. That is a 668<kbd>-blend 30%</kbd> merges 30% of the 'source' image with 70% of the 669'destination' image. Thus it is equivalent to <kbd>-blend 30x70%</kbd>.</p> 670 671 672<div style="margin: auto;"> 673 <h4><a id="blue-primary"></a>-blue-primary <em class="arg">x</em>,<em class="arg">y</em></h4> 674</div> 675 676<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the blue chromaticity primary point.</td><td style='text-align:right;'></td></tr></table> 677 678<div style="margin: auto;"> 679 <h4><a id="blue-shift"></a>-blue-shift <em class="arg">factor</em></h4> 680</div> 681 682<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</td><td style='text-align:right;'></td></tr></table> 683 684<div style="margin: auto;"> 685 686<div style="margin: auto;"> 687 <h4><a id="blur"></a>-blur <em class="arg">radius</em><br />-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4> 688</div> 689 690<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce image noise and reduce detail levels.</td><td style='text-align:right;'></td></tr></table> 691 692<p>Convolve the image with a Gaussian or normal distribution using the given 693<em class="arg" >Sigma</em> value. The formula is:</p> 694 695<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="/images/gaussian-blur.png"/> 696</div> 697 698<p>The <em class="arg" >Sigma</em> value is the important argument, and 699determines the actual amount of blurring that will take place. </p> 700 701<p>The <em class="arg" >Radius</em> is only used to determine the size of the 702array which will hold the calculated Gaussian distribution. It should be an 703integer. If not given, or set to zero, IM will calculate the largest possible 704radius that will provide meaningful results for the Gaussian distribution. 705</p> 706 707<p>The larger the <em class="arg" >Radius</em> the radius the slower the 708operation is. However too small a <em class="arg" >Radius</em>, and sever 709aliasing effects may result. As a guideline, <em class="arg" >Radius</em> 710should be at least twice the <em class="arg" >Sigma</em> value, though three 711times will produce a more accurite result. </p> 712 713<p>This option differs from <a href="#gaussian-blur">-gaussian-blur</a> simply 714by taking advantage of the separability properties of the distribution. Here 715we apply a single-dimensional Gaussian matrix in the horizontal direction, 716then repeat the process in the vertical direction.</p> 717 718<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 719pixels which are outside the image proper are blurred into the final result. 720</p> 721 722 723<div style="margin: auto;"> 724 <h4>-blur <em class="arg">Width</em>[x<em class="arg">Height</em>[+<em class="arg">Angle</em>]]</h4> 725</div> 726 727<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Variably blur and image according to the overlay mapping.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 728 729<p>Each pixel in the overlaid region is replaced with an Elliptical Weighted 730Average (EWA) of the source image, scaled according to the grayscale 731mapping. </p> 732 733<p>The ellipse is weighted with sigma set to the given <em class="arg" 734>Width</em> and <em class="arg" >Height</em>. The <em class="arg" >Height</em> 735defaults to the <em class="arg" >Width</em> for a normal circular Guassian 736weighting. The <em class="arg" >Angle</em> will rotate the ellipse from 737horizontal clock-wise. </p> 738 739<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 740pixels which are outside the image proper are blurred into the final result. 741</p> 742 743 744<div style="margin: auto;"> 745 <h4><a id="border"></a>-border <em class="arg">geometry</em></h4> 746</div> 747 748<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border of color. </td><td style='text-align:right;'></td></tr></table> 749 750<p>Set the width and height using the <em class="arg">size</em> portion of the 751<em class="arg">gravity</em> argument. See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are 752ignored. </p> 753 754<p>Set the border color by preceding with the <a 755href="#bordercolor">-bordercolor</a> setting.</p> 756 757<p>The <a href="#border">-border</a> operation is affected by the current <a 758href="#compose">-compose</a> setting and assumes that this is using the default 759'<kbd>Over</kbd>' composition method. It generates a image of the appropriate 760size colors by the current <a href="#bordercolor">-bordercolor</a> before 761overlaying the original image in the center of this net image. This means that 762with the default compose method of '<kbd>Over</kbd>' any transparent parts may 763be replaced by the current <a href="#bordercolor">-bordercolor</a> setting.</p> 764<p>See also the <a href="#frame">-frame</a> option, which has more 765functionality.</p> 766 767<div style="margin: auto;"> 768 <h4><a id="bordercolor"></a>-bordercolor <em class="arg">color</em></h4> 769</div> 770 771<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border color.</td><td style='text-align:right;'></td></tr></table> 772 773<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 774 775<p>The default border color is <kbd>#DFDFDF</kbd>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p> 776 777<div style="margin: auto;"> 778 <h4><a id="borderwidth"></a>-borderwidth <em class="arg">geometry</em> </h4> 779</div> 780 781<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border width.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 782 783<div style="margin: auto;"> 784 <h4><a id="brightness-contrast"></a>-brightness-contrast <em class="arg">brightness</em><br />-brightness-contrast <em class="arg">brightness</em>{x<em class="arg">contrast</em>}{<em class="arg">%</em>}}</h4> 785</div> 786 787<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the brightness and/or contrast of the image.</td><td style='text-align:right;'></td></tr></table> 788 789<p>Brightness and Contrast values apply changes to the input image. They are 790not absolute settings. A brightness or contrast value of zero means no change. 791The range of values is -100 to +100 on each. Positive values increase the 792brightness or contrast and negative values decrease the brightness or contrast. 793To control only contrast, set the brightness=0. To control only brightness, 794set contrast=0 or just leave it off.</p> 795 796<p>You may also use <a href="#fill">-channel</a> to control which channels to 797apply the brightness and/or contrast change. The default is to apply the same 798transformation to all channels.</p> 799 800<p>Brightness and Contrast arguments are converted to offset and slope of a 801linear transform and applied 802using <a href="#fill">-function polynomial "slope,offset"</a>.</p> 803 804<p>The slope varies from 0 at contrast=-100 to almost vertical at 805contrast=+100. For brightness=0 and contrast=-100, the result are totally 806midgray. For brightness=0 and contrast=+100, the result will approach but 807not quite reach a threshold at midgray; that is the linear transformation 808is a very steep vertical line at mid gray.</p> 809 810<p>Negative slopes, i.e. negating the image, are not possible with this 811function. All achievable slopes are zero or positive.</p> 812 813<p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5 814at brightness=+100. Thus, when contrast=0 and brightness=100, the result is 815totally white. Similarly, when contrast=0 and brightness=-100, the result is 816totally black.</p> 817 818<p>As the range of values for the arguments are -100 to +100, adding the '%' 819symbol is no different than leaving it off.</p> 820 821<div style="margin: auto;"> 822 <h4><a id="cache"></a>-cache <em class="arg">threshold</em></h4> 823</div> 824 825<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>(This option has been replaced by the <a href='#limit'>-limit</a> option.)</td><td style='text-align:right;'></td></tr></table> 826 827<div style="margin: auto;"> 828 <h4><a id="caption"></a>-caption <em class="arg">string</em></h4> 829</div> 830 831<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a caption to an image.</td><td style='text-align:right;'></td></tr></table> 832 833<p>This option sets the caption meta-data of an image read in after this 834option has been given. To modify a caption of images already in memory use 835"<kbd><a href="#set">-set</a> caption</kbd>". </p> 836 837<p>The caption can contain special format characters listed in the <a 838href="/www/escape.html">Format and 839Print Image Properties</a>. These attributes are expanded when the caption 840is finally assigned to the individual images. </p> 841 842<p>If the first character of <em class="arg">string</em> is <em 843class="arg">@</em>, the image caption is read from a file titled by the 844remaining characters in the string. Comments read in from a file are literal; 845no embedded formatting characters are recognized.</p> 846 847<p>Caption meta-data ais not visible on the image itself. To do that use the 848<a href="#annotate">-annotate</a> or <a href="#draw">-draw</a> options 849instead.</p> 850 851<p>For example,</p> 852 853<p class="crtsnip"> 854 -caption "%m:%f %wx%h" bird.miff 855</p> 856 857<p>produces an image caption of <kbd>MIFF:bird.miff 512x480</kbd> (assuming 858that the image <kbd>bird.miff</kbd> has a width of 512 and a height of 859480.</p> 860 861 862<div style="margin: auto;"> 863 <h4><a id="cdl"></a>-cdl <em class="arg">filename</em></h4> 864</div> 865 866<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color correct with a color decision list.</td><td style='text-align:right;'></td></tr></table> 867 868<p>Here is an example color correction collection:</p> 869 870<pre class="text"> 871<?xml version="1.0" encoding="UTF-8"?> 872<ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"> 873 <ColorCorrection id="cc06668"> 874 <SOPNode> 875 <Slope> 0.9 1.2 0.5 </Slope> 876 <Offset> 0.4 -0.5 0.6 </Offset> 877 <Power> 1.0 0.8 1.5 </Power> 878 </SOPNode> 879 <SATNode> 880 <Saturation> 0.85 </Saturation> 881 </SATNode> 882 </ColorCorrection> 883</ColorCorrectionCollection> 884</pre> 885 886<div style="margin: auto;"> 887 <h4><a id="channel"></a>-channel <em class="arg">type</em></h4> 888</div> 889 890<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify those image color channels to which subsequent operators are limited.</td><td style='text-align:right;'></td></tr></table> 891 892<p>Choose from: <kbd>Red</kbd>, <kbd>Green</kbd>, <kbd>Blue</kbd>, 893<kbd>Alpha</kbd>, <kbd>Cyan</kbd>, <kbd>Magenta</kbd>, <kbd>Yellow</kbd>, 894<kbd>Black</kbd>, <kbd>Opacity</kbd>, <kbd>Index</kbd>, <kbd>RGB</kbd>, 895<kbd>RGBA</kbd>, <kbd>CMYK</kbd>, or <kbd>CMYKA</kbd>.</p> 896 897<p>The channels above can also be specified as a comma-separated list or can be 898abbreviated as a concatenation of the letters '<kbd>R</kbd>', '<kbd>G</kbd>', 899'<kbd>B</kbd>', '<kbd>A</kbd>', '<kbd>O</kbd>', '<kbd>C</kbd>', 900'<kbd>M</kbd>', '<kbd>Y</kbd>', '<kbd>K</kbd>'. 901 902For example, to only select the <kbd>Red</kbd> and <kbd>Blue</kbd> channels 903you can either use </p> 904<p class="crtsnip"> 905 -channel Red,Blue 906</p> 907<p>or you can use the short hand form</p> 908<p class="crtsnip"> 909 -channel RB 910</p> 911 912<p>All the channels that is present in an image can be specified using the 913special channel type <kbd>All</kbd>. Not all operators are 'channel capable', 914but generally any operators that are generally 'grey-scale' image operators, 915will understand this setting. See individual operator documentation. </p> 916 917<br /> 918 919<p>On top of the normal channel selection a extra flag can be specified, 920'<kbd>Sync</kbd>'. This is turned on by default and if set means that 921operators that understand this flag should perform: cross-channel 922syncronization of the channels. If not specified, then most grey-scale 923operators will apply their image processing operations to each individual 924channel (as specified by the rest of the <a href="#channel">-channel</a> 925setting) completely independently from each other. </p> 926 927<p>For example for operators such as <a href="#auto-level">-auto-level</a> and 928<a href="#auto-gamma">-auto-gamma</a> the color channels are modified 929together in exactly the same way so that colors will remain in-sync. Without 930it being set, then each channel is modified separately and 931independently, which may produce color distortion. </p> 932 933<p>The <a href="#morphology">-morphology</a> '<kbd>Convolve</kbd>' method 934and the <a href="#compose">-compose</a> mathematical methods, also understands 935the '<kbd>Sync</kbd>' flag to modify the behaviour of pixel colors according 936to the alpha channel (if present). That is to say it will modify the image 937processing with the understanding that fully-transparent colors should not 938contribute to the final result. </p> 939 940<p>Basically, by default, operators work with color channels in syncronous, and 941treats transparency as special, unless the <a href="#channel">-channel</a> 942setting is modified so as to remove the effect of the '<kbd>Sync</kbd>' flag. 943How each operator does this depends on that operators current implementation. 944Not all operators understands this flag at this time, but that is changing. 945</p> 946 947<p>To print a complete list of channel types, use <a href="#list">-list 948channel</a>.</p> 949 950<br /> 951 952<p>By default, ImageMagick sets <a href="#channel">-channel</a> to the value 953'<kbd>RGBK,sync</kbd>', which specifies that operators act on all color 954channels except the transparency channel, and that all the color channels are 955to be modified in exactly the same way, with a understanding of transprancy 956(depending on the operation being applied). The 'plus' form <a 957href="#channel" >+channel</a> will reset the value back to this default. </p> 958 959<p>Options that are affected by the <a href="#channel" >-channel</a> setting 960include the following. 961 962<a href="#auto-gamma">-auto-gamma</a>, 963<a href="#auto-level">-auto-level</a>, 964<a href="#black-threshold">-black-threshold</a>, 965<a href="#blur">-blur</a>, 966<a href="#clamp">-clamp</a>, 967<a href="#clut">-clut</a>, 968<a href="#combine">-combine</a>, 969<a href="#composite">-composite</a> (Mathematical compose methods only), 970<a href="#convolve">-convolve</a>, 971<a href="#contrast-stretch">-contrast-stretch</a>, 972<a href="#evaluate">-evaluate</a>, 973<a href="#function">-function</a>, 974<a href="#fx">-fx</a>, 975<a href="#gaussian-blur">-gaussian-blur</a>, 976<a href="#hald-clut">-hald-clut</a>, 977<a href="#motion-blur">-motion-blur</a>, 978<a href="#morphology">-morphology</a>, 979<a href="#negate">-negate</a>, 980<a href="#normalize">-normalize</a>, 981<a href="#ordered-dither">-ordered-dither</a>, 982<a href="#radial-blur">-radial-blur</a>, 983<a href="#random-threshold">-random-threshold</a>, 984<a href="#separate">-separate</a>, 985<a href="#threshold">-threshold</a>, and 986<a href="#white-threshold">-white-threshold</a>. 987</p> 988 989<p>Warning, some operators behave differently when the <a href="#channel" 990>+channel</a> default setting is in effect, verses ANY user defined <a 991href="#channel" >-channel</a> setting (including the equivalent of the 992default). These operators have yet to be made to understand the newer 'Sync' 993flag. </p> 994 995<p>For example <a href="#threshold">-threshold</a> will by default gray-scale 996the image before thresholding, if no <a href="#channel" >-channel</a> setting 997has been defined. This is not 'Sync flag controlled, yet. </p> 998 999<p>Also some operators such as <a href="#blur">-blur</a>, <a 1000href="#gaussian-blur">-gaussian-blur</a>, will modify their handling of the 1001color channels if the '<kbd>alpha</kbd>' channel is also enabled by <a 1002href="#channel" >-channel</a>. Generally this done to ensure that 1003fully-transparent colors are treated as being fully-transparent, and thus any 1004underlying 'hidden' color has no effect on the final results. Typically 1005resulting in 'halo' effects. The newer <a href="#morphology">-morphology</a> 1006convolution equivalents however does have a understanding of the 'Sync' flag 1007and will thus handle transparency correctly by default. </p> 1008 1009<p>As a alpha channel is optional within images, some operators will read the 1010color channels of an image as a greyscale alpha mask, when the image has no 1011alpha channel present, and the <a href="#channel" >-channel</a> setting tells 1012the operator to apply the operation using alpha channels. The <a 1013href="#clut">-clut</a> operator is a good example of this. </p> 1014 1015 1016<div style="margin: auto;"> 1017 <h4><a id="clamp"></a>-clamp</h4> 1018</div> 1019 1020<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Restrict image colors from 0 to the quantum depth.</td><td style='text-align:right;'></td></tr></table> 1021 1022<div style="margin: auto;"> 1023 <h4><a id="charcoal"></a>-charcoal <em class="arg">factor</em></h4> 1024</div> 1025 1026<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Simulate a charcoal drawing.</td><td style='text-align:right;'></td></tr></table> 1027 1028<div style="margin: auto;"> 1029 <h4><a id="chop"></a>-chop <em class="arg">geometry</em></h4> 1030</div> 1031 1032<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Remove pixels from the interior of an image.</td><td style='text-align:right;'></td></tr></table> 1033 1034<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">width</em> 1035and <em class="arg">height</em> given in the of the <em class="arg">size</em> 1036portion of the <em class="arg">geometry</em> argument give the number of 1037columns and rows to remove. The <em class="arg">offset</em> portion of 1038the <em class="arg">geometry</em> argument is influenced by 1039a <a href="#gravity">-gravity</a> setting, if present.</p> 1040 1041<p>The <a href="#chop">-chop</a> option removes entire rows and columns, 1042and moves the remaining corner blocks leftward and upward to close the gaps.</p> 1043 1044<p>While it can remove internal rows and columns of pixels, it is more 1045typically used with as <a href="#gravity">-gravity</a> setting and zero 1046offsets so as to remove a single edge from an image. Compare this to <a 1047href="#shave" >-shave</a> which removes equal numbers of pixels from oppisite 1048sides of the image. </p> 1049 1050<p>Using <a href="#chop">-chop</a> will effectivally undo the results of a <a 1051href="#splice">-splice</a> that was given the same <em 1052class="arg">geometry</em> and <a href="#gravity">-gravity</a> settings. </p> 1053 1054 1055<div style="margin: auto;"> 1056 <h4><a id="clip"></a>-clip</h4> 1057</div> 1058 1059<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply the clipping path if one is present.</td><td style='text-align:right;'></td></tr></table> 1060 1061<p>If a clipping path is present, it is applied to subsequent operations.</p> 1062 1063<p>For example, in the command</p> 1064 1065<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -clip -negate cockatoo.tif negated.tif</span></p> 1066<p>only the pixels within the clipping path are negated.</p> 1067 1068<p>The <a href="#clip">-clip</a> feature requires the XML library. If the XML library is not present, the option is ignored.</p> 1069 1070<div style="margin: auto;"> 1071 <h4><a id="clip-mask"></a>-clip-mask</h4> 1072</div> 1073 1074<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip the image as defined by this mask.</td><td style='text-align:right;'></td></tr></table> 1075 1076<p>Use the given image as a 'do-not-modify' mask of the current images in the 1077current image sequence. Assuming the clipmask is a greyscale image the same 1078size at the one already in memory, any areas that is white will not be 1079modified by any of the 'image processing operators' that follow, until the 1080mask is removed. Pixels in the black areas of the clip mask will be modified 1081as normal. </p> 1082 1083<p>In some ways this is similar to (though not the same) as defining 1084a rectangular <a href="#region" >-region</a>, or using the negative of the 1085mask (thrid) image in a three image <a href="#composite" >-composite</a>, 1086operation. </p> 1087 1088 1089<div style="margin: auto;"> 1090 <h4><a id="clip-path"></a>-clip-path <em class="arg">id</em></h4> 1091</div> 1092 1093<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip along a named path from the 8BImageMagick profile.</td><td style='text-align:right;'></td></tr></table> 1094 1095<p>This is almost identical to <a href="#clip">-clip</a>. </p> 1096 1097 1098<div style="margin: auto;"> 1099 <h4><a id="clone"></a>-clone <em class="arg">index(s)</em></h4> 1100</div> 1101 1102<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make a clone of an image (or images).</td><td style='text-align:right;'></td></tr></table> 1103 1104<p>Inside parenthesis (where the operator is normally used) it will make a 1105clone of the images from the last 'pushed' image sequence, and adds them to 1106the end of the current image sequence. Outside parenthesis 1107(not recommended) it clones the images from the current image sequence. </p> 1108 1109<p>Specify the image by its index in the sequence. The first image is index 11100. Negative indexes are relative to the end of the sequence; for 1111example, <kbd>−1</kbd> 1112represents the last image of the sequence. Specify a range of images with a 1113dash (e.g. <kbd>0−4</kbd>). Separate multiple indexes with commas but no 1114spaces (e.g. <kbd>0,2,5</kbd>). A value of '<kbd>0−−1</kbd> will 1115effectively clone all the images. </p> 1116 1117<p>The <a href="#clone">+clone</a> will simply make a copy of the last image 1118in the image sequence, and is thus equivalent to using a argument of 1119'<kbd>−1</kbd>'. </p> 1120 1121<div style="margin: auto;"> 1122 <h4><a id="clut"></a>-clut</h4> 1123</div> 1124 1125<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Replace the channel values in the first image using each 1126corresponding channel in the second image as a <b>c</b>olor 1127<b>l</b>ook<b>u</b>p <b>t</b>able.</td><td style='text-align:right;'></td></tr></table> 1128 1129<p>The second (LUT) image is ordinarily a gradient image containing the 1130histogram mapping of how each channel should be modified. Typically it is a 1131either a single row or column image of replacement color values. If larger 1132than a single row or column, values are taken from a diagonal line from 1133top-left to bottom-right corners.</p> 1134 1135<p>The lookup is further controlled by the <a 1136href="#interpolate">-interpolate</a> setting, which is especially handy for an 1137LUT which is not the full length needed by the ImageMagick installed Quality 1138(Q) level. Good settings for this are the '<kbd>bilinear</kbd>' and 1139'<kbd>bicubic</kbd>' interpolation settings, which give smooth color 1140gradients, and the '<kbd>integer</kbd>' setting for a direct, unsmoothed 1141lookup of color values. </p> 1142 1143<p>This operator is especially suited to replacing a grayscale image with a 1144specific color gradient from the CLUT image. </p> 1145 1146<p>Only the channel values defined by the <a href="#channel">-channel</a> 1147setting will have their values replaced. In particular, since the default <a 1148href="#channel">-channel</a> setting is <kbd>RGB</kbd>, this means that 1149transparency (alpha/matte channel) is not affected, unless the <a 1150href="#channel">-channel</a> setting is modified. When the alpha channel is 1151set, it is treated by the <a href="#clut" >-clut</a> operator in the same way 1152as the other channels, implying that alpha/matte values are replaced using the 1153alpha/matte values of the original image. </p> 1154 1155<p>If either the image being modified, or the lookup image, contains no 1156transparency (i.e. <a href="#alpha" >-alpha</a> is turned 'off') but the <a 1157href="#channel">-channel</a> setting includes alpha replacement, then it is 1158assumed that image represents a gray-scale gradient which is used for the 1159replacement alpha values. That is you can use a gray-scale CLUT image to 1160adjust a existing images alpha channel, or you can color a gray-scale image 1161using colors form CLUT containing the desired colors, including transparency. 1162</p> 1163 1164<p>See also <a href="#hald-clut" >-hald-clut</a> which replaces colors 1165according to the lookup of the full color RGB value from a 2D representation 1166of a 3D color cube. </p> 1167 1168 1169<div style="margin: auto;"> 1170 <h4><a id="coalesce"></a>-coalesce</h4> 1171</div> 1172 1173<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</td><td style='text-align:right;'></td></tr></table> 1174 1175<p>Overlay each image in an image sequence according to 1176its <a href="#dispose">-dispose</a> meta-data, to reproduce the look of 1177an animation at each point in the animation sequence. All images should be 1178the same size, and are assigned appropriate GIF disposal settings for the 1179animation to continue working as expected as a GIF animation. Such frames 1180are more easily viewed and processed than the highly optimized GIF overlay 1181images. </p> 1182 1183<p>The animation can be re-optimized after processing using 1184the <a href="#layers">-layers</a> method '<kbd>optimize</kbd>', although 1185there is no guarantee that the restored GIF animation optimization is 1186better than the original. </p> 1187 1188 1189<div style="margin: auto;"> 1190 <h4><a id="colorize"></a>-colorize <em class="arg">value</em></h4> 1191</div> 1192 1193<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colorize the image by an amount specified by <em class="arg">value</em> using the color specified by the most recent <a href="#fill" >-fill</a> setting.</td><td style='text-align:right;'></td></tr></table> 1194 1195<p>Specify the amount of colorization as a percentage. Separate colorization 1196values can be applied to the red, green, and blue channels of the image with 1197a comma-delimited list of colorization 1198values (e.g., <kbd>-colorize 0,0,50</kbd>).</p> 1199 1200<div style="margin: auto;"> 1201 <h4><a id="colormap"></a>-colormap <em class="arg">type</em></h4> 1202</div> 1203 1204<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the colormap type.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 1205 1206<p>The <em class="arg">type</em> can be <kbd>shared</kbd> or <kbd>private</kbd>.</p> 1207 1208<p>This option only applies when the default X server visual 1209is <kbd>PseudoColor</kbd> or <kbd>GrayScale</kbd>. Refer 1210to <a href="#visual">-visual</a> for more details. By default, 1211a shared colormap is allocated. The image shares colors with 1212other X clients. Some image colors could be approximated, 1213therefore your image may look very different than intended. 1214If <kbd>private</kbd> is chosen, the image colors appear exactly 1215as they are defined. However, other clients may go <em>technicolor</em> 1216when the image colormap is installed.</p> 1217 1218<div style="margin: auto;"> 1219 <h4><a id="colors"></a>-colors <em class="arg">value</em></h4> 1220</div> 1221 1222<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred number of colors in the image.</td><td style='text-align:right;'></td></tr></table> 1223 1224<p>The actual number of colors in the image may be less than your request, 1225but never more. Note that this a color reduction option. Images with fewer 1226unique colors than specified by <em class="arg">value</em> will have any 1227duplicate or unused colors removed. The ordering of an existing color 1228palette may be altered. When converting an image from color to grayscale, 1229it is more efficient to convert the image to the gray colorspace before 1230reducing the number of colors. Refer to 1231the <a href="/www/quantize.html"> 1232color reduction algorithm</a> for more details.</p> 1233 1234<div style="margin: auto;"> 1235 <h4><a id="color-matrix"></a>-color-matrix <em class="arg">matrix</em></h4> 1236</div> 1237 1238<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply color correction to the image.</td><td style='text-align:right;'></td></tr></table> 1239 1240<p>This option permits saturation changes, hue rotation, luminance to alpha, 1241and various other effects. Although variable-sized transformation matrices 1242can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6 1243for CMYKA (or RGBA with offsets). The matrix is similar to those used by 1244Adobe Flash except offsets are in column 6 rather than 5 (in support of 1245CMYKA images) and offsets are normalized (divide Flash offset by 255).</p> 1246 1247<p>As an example, to add contrast to an image with offsets, try this command:</p> 1248 1249<pre class="text"> 1250 convert kittens.jpg -color-matrix \ 1251 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \ 1252 0.0 1.5 0.0 0.0, 0.0, -0.157 \ 1253 0.0 0.0 1.5 0.0, 0.0, -0.157 \ 1254 0.0 0.0 0.0 1.0, 0.0, 0.0 \ 1255 0.0 0.0 0.0 0.0, 1.0, 0.0 \ 1256 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png 1257</pre> 1258<div style="margin: auto;"> 1259 <h4><a id="colorspace"></a>-colorspace <em class="arg">value</em></h4> 1260</div> 1261 1262<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image colorspace.</td><td style='text-align:right;'></td></tr></table> 1263 1264<p>Choices are:</p> 1265 1266<pre class="text"> 1267 CMY CMYK Gray HSB 1268 HSL HWB Lab Log 1269 OHTA Rec601Luma Rec601YCbCr Rec709Luma 1270 Rec709YCbCr RGB sRGB Transparent 1271 XYZ YCbCr YCC YIQ 1272 YPbPr YUV 1273</pre> 1274 1275<p>To print a complete list of colorspaces, use <a href="#list">-list colorspace</a>.</p> 1276 1277<p>For a more accurate color conversion to or from the RGB, CMYK, or grayscale colorspaces, use the <a href="#profile">-profile</a> option.</p> 1278 1279<table class="doc"> 1280 <caption>Conversion Of RGB To Other Color Spaces</caption> 1281 <tr><th align="left" valign="middle">CMY</th></tr> 1282 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>−R</td></tr> 1283 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>−G</td></tr> 1284 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>−B</td></tr> 1285 <tr><th align="left" valign="middle">CMYK — starts with CMY from above</th></tr> 1286 <tr><td align="left" valign="middle">K=min(C,Y,M)</td></tr> 1287 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>*(C−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1288 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>*(M−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1289 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>*(Y−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1290 1291 <tr><th align="left" valign="middle">Gray</th></tr> 1292 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr> 1293 1294 <tr><th align="left" valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr> 1295 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr> 1296 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr> 1297 <tr><td align="left" valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <em>intensity-like</em></td></tr> 1298 1299 <tr><th align="left" valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr> 1300 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr> 1301 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr> 1302 <tr><td align="left" valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <em>intensity-like</em></td></tr> 1303 1304 <tr><th align="left" valign="middle">HWB — Hue, Whiteness, Blackness</th></tr> 1305 <tr><td align="left" valign="middle">Hue (complicated equation)</td></tr> 1306 <tr><td align="left" valign="middle">Whiteness (complicated equation)</td></tr> 1307 <tr><td align="left" valign="middle">Blackness (complicated equation)</td></tr> 1308 1309 <tr><th align="left" valign="middle">LAB</th></tr> 1310 <tr><td align="left" valign="middle">L (complicated equation relating X,Y,Z)</td></tr> 1311 <tr><td align="left" valign="middle">A (complicated equation relating X,Y,Z)</td></tr> 1312 <tr><td align="left" valign="middle">B (complicated equation relating X,Y,Z)</td></tr> 1313 1314 <tr><th align="left" valign="middle">LOG</th></tr> 1315 <tr><td align="left" valign="middle">I1 (complicated equation involving logarithm of R)</td></tr> 1316 <tr><td align="left" valign="middle">I2 (complicated equation involving logarithm of G)</td></tr> 1317 <tr><td align="left" valign="middle">I3 (complicated equation involving logarithm of B)</td></tr> 1318 1319 <tr><th align="left" valign="middle">OHTA — approximates principal components transformation</th></tr> 1320 <tr><td align="left" valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <em>intensity-like</em></td></tr> 1321 <tr><td align="left" valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1322 <tr><td align="left" valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1323 1324 <tr><th align="left" valign="middle">Rec601Luma</th></tr> 1325 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr> 1326 1327 <tr><th align="left" valign="middle">Rec601YCbCr</th></tr> 1328 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1329 <tr><td align="left" valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1330 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1331 1332 <tr><th align="left" valign="middle">Rec709Luma</th></tr> 1333 <tr><td align="left" valign="middle">Gray=0.21260*R+0.71520*G+0.07220*B</td></tr> 1334 1335 <tr><th align="left" valign="middle">Rec709YCbCr</th></tr> 1336 <tr><td align="left" valign="middle">Y=0.212600*R+0.715200*G+0.072200*B; <em>intensity-like</em></td></tr> 1337 <tr><td align="left" valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1338 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1339 1340 <tr><th align="left" valign="middle">sRGB</th></tr> 1341 <tr><td align="left" valign="middle">if Rs ≤ .04045 then Rs=R/12.92 else Rs=((R+.055)/1.055)^2.4</td></tr> 1342 <tr><td align="left" valign="middle">if Gs ≤ .04045 then Gs=B/12.92 else Gs=((G+.055)/1.055)^2.4</td></tr> 1343 <tr><td align="left" valign="middle">if Bs ≤ .04045 then Bs=B/12.92 else Bs=((B+.055)/1.055)^2.4</td></tr> 1344 1345 <tr><th align="left" valign="middle">XYZ</th></tr> 1346 <tr><td align="left" valign="middle">X=0.4124240*R+0.3575790*G+0.1804640*B</td></tr> 1347 <tr><td align="left" valign="middle">Y=0.2126560*R+0.7151580*G+0.0721856*B</td></tr> 1348 <tr><td align="left" valign="middle">Z=0.0193324*R+0.1191930*G+0.9504440*B</td></tr> 1349 1350 <tr><th align="left" valign="middle">YCC</th></tr> 1351 <tr><td align="left" valign="middle">Y=(0.29900*R+0.58700*G+0.11400*B) (with complicated scaling); <em>intensity-like</em></td></tr> 1352 <tr><td align="left" valign="middle">C1=(−0.29900*R−0.58700*G+0.88600*B) (with complicated scaling)</td></tr> 1353 <tr><td align="left" valign="middle">C2=(0.70100*R−0.58700*G−0.11400*B) (with complicated scaling)</td></tr> 1354 1355 <tr><th align="left" valign="middle">YCbCr</th></tr> 1356 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1357 <tr><td align="left" valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1358 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1359 1360 <tr><th align="left" valign="middle">YIQ</th></tr> 1361 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr> 1362 <tr><td align="left" valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1363 <tr><td align="left" valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1364 1365 <tr><th align="left" valign="middle">YPbPr</th></tr> 1366 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1367 <tr><td align="left" valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1368 <tr><td align="left" valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1369 1370 <tr><th align="left" valign="middle">YUV</th></tr> 1371 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr> 1372 <tr><td align="left" valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1373 <tr><td align="left" valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr> 1374</table> 1375 1376<div style="margin: auto;"> 1377 <h4><a id="combine"></a>-combine</h4> 1378</div> 1379 1380<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Combine one or more images into a single image.</td><td style='text-align:right;'></td></tr></table> 1381 1382<p>The channels (previously set by <a href="#channel">-channel</a>) of the combined image are taken from the grayscale values of each image in the sequence, in order. For the default -channel setting of <kbd>RGB</kbd>, this means the first image is assigned to the <kbd>Red</kbd> channel, the second to the <kbd>Green</kbd> channel, the third to the <kbd>Blue</kbd>.</p> 1383 1384<p>This option can be thought of as the inverse to <a href="#separate">-separate</a>, so long as the channel settings are the same. Thus, in the following example, the final image should be a copy of the original. 1385</p> 1386 1387<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert original.png -channel RGB -separate sepimage.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \ <br/> -combine imagecopy.png</span></p> 1388<div style="margin: auto;"> 1389 <h4><a id="comment"></a>-comment <em class="arg">string</em></h4> 1390</div> 1391 1392<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Embed a comment in an image.</td><td style='text-align:right;'></td></tr></table> 1393 1394<p>This option sets the comment meta-data of an image read in after this 1395option has been given. To modify a comment of images already in memory use 1396"<kbd><a href="#set">-set</a> comment</kbd>". </p> 1397 1398<p>The comment can contain special format characters listed in the <a 1399href="/www/escape.html">Format and 1400Print Image Properties</a>. These attributes are expanded when the comment 1401is finally assigned to the individual images. </p> 1402 1403<p>If the first character of <em class="arg">string</em> is <em 1404class="arg">@</em>, the image comment is read from a file titled by the 1405remaining characters in the string. Comments read in from a file are literal; 1406no embedded formatting characters are recognized.</p> 1407 1408<p>Comment meta-data are not visible on the image itself. To do that use the 1409<a href="#annotate">-annotate</a> or <a href="#draw">-draw</a> options 1410instead.</p> 1411 1412<p>For example,</p> 1413 1414<p class="crtsnip"> 1415 -comment "%m:%f %wx%h" bird.miff 1416</p> 1417 1418<p>produces an image comment of <kbd>MIFF:bird.miff 512x480</kbd> (assuming 1419that the image <kbd>bird.miff</kbd> has a width of 512 and a height of 1420480.</p> 1421 1422<div style="margin: auto;"> 1423 <h4><a id="compose"></a>-compose <em class="arg">operator</em></h4> 1424</div> 1425 1426<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the type of image composition.</td><td style='text-align:right;'></td></tr></table> 1427 1428<p>See <a href="/www/compose.html">Alpha Compositing</a> for 1429a detailed discussion of alpha compositing.</p> 1430 1431<p>This setting effects image processing operators that merge two (or more) 1432images together in some way. This includes the operators, 1433<a href="#composite">-composite</a>, 1434<a href="#layers">-layers</a> composite, 1435<a href="#flatten">-flatten</a>, 1436<a href="#mosaic">-mosaic</a>, 1437<a href="#layers">-layers</a> merge, 1438<a href="#border">-border</a>, 1439<a href="#frame">-frame</a>, 1440and <a href="#extent">-extent</a>. </p> 1441 1442<p>It is also one of the primary options for the "<kbd>composite</kbd>" 1443command. </p> 1444 1445 1446<div style="margin: auto;"> 1447 <h4><a id="composite"></a>-composite</h4> 1448</div> 1449 1450<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Perform alpha composition on two images and an optional mask</td><td style='text-align:right;'></td></tr></table> 1451 1452<p>Take the first image 'destination' and overlay the second 'source' image 1453according to the current <a href="#compose">-compose</a> setting. The location 1454of the 'source' or 'overlay' image is controlled according to <a 1455href="#geometry" >-geometry</a>, and <a href="#geometry" >-geometry</a> 1456settings. </p> 1457 1458<p>If a third image is given this is treated as a gray-scale 'mask' image 1459relative to the first 'destination' image. This mask will limit what parts of 1460the destination can be modified by the image composition. However for the 1461'<kbd>displace</kbd>' compose method, the mask is used to provide a separate 1462Y-displacement image instead. </p> 1463 1464<p>If a <a href="#compose">-compose</a> method requires extra numerical 1465arguments or flags these can be provided by setting the <a 1466href="#set">-set</a> '<kbd class="arg">option:compose:args</kbd>' 1467appropriately for the compose method. </p> 1468 1469<p>Some <a href="#compose">-compose</a> methods can modify the 'destination' 1470image outside the overlay area. You can disable this by setting the special <a 1471href="#set">-set</a> '<kbd class="arg">option:compose:outside-overlay</kbd>' 1472to '<kbd>false</kbd>'. </p> 1473 1474 1475<div style="margin: auto;"> 1476 <h4><a id="compress"></a>-compress <em class="arg">type</em></h4> 1477</div> 1478 1479<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use pixel compression specified by <em class="arg">type</em> when writing the image.</td><td style='text-align:right;'></td></tr></table> 1480 1481<p>Choices are: <kbd class="arg">None</kbd>, <kbd class="arg">BZip</kbd>, <kbd class="arg">Fax</kbd>, <kbd class="arg">Group4</kbd>, <kbd class="arg">JPEG</kbd>, <kbd class="arg">JPEG2000</kbd>, <kbd class="arg">Lossless</kbd>, <kbd class="arg">LZW</kbd>, <kbd class="arg">RLE</kbd> or <kbd class="arg">Zip</kbd>.</p> 1482 1483<p>To print a complete list of compression types, use <a href="#list">-list compress</a>.</p> 1484 1485<p>Specify <a href="#compress">+compress</a> to store the binary image in an uncompressed format. The default is the compression type of the specified image file.</p> 1486 1487<p>If <kbd>LZW</kbd> compression is specified but LZW compression has not been enabled, the image data is written in an uncompressed LZW format that can be read by LZW decoders. This may result in larger-than-expected GIF files.</p> 1488 1489<p><kbd>Lossless</kbd> refers to lossless JPEG, which is only available if the JPEG library has been patched to support it. Use of lossless JPEG is generally not recommended.</p> 1490 1491<p>Use the <a href="#quality">-quality</a> option to set the compression level to be used by JPEG, PNG, MIFF, and MPEG encoders. Use the <a href="#sampling-factor">-sampling-factor</a> option to set the sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling the chroma channels.</p> 1492 1493<div style="margin: auto;"> 1494 <h4><a id="contrast"></a>-contrast</h4> 1495</div> 1496 1497<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enhance or reduce the image contrast.</td><td style='text-align:right;'></td></tr></table> 1498 1499<p>This option enhances the intensity differences between the lighter and darker elements of the image. Use <a href="#contrast">-contrast</a> to enhance the image or <a href="#contrast">+contrast</a> to reduce the image contrast.</p> 1500 1501<p>For a more pronounced effect you can repeat the option:</p> 1502 1503<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -contrast -contrast rose_c2.png</span></p> 1504<div style="margin: auto;"> 1505 <h4><a id="contrast-stretch"></a>-contrast-stretch <em class="arg">black-point</em><br />-contrast-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4> 1506</div> 1507 1508<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table> 1509 1510<p>While performing the stretch, black-out at most <em 1511class="arg" >black-point</em> pixels and white-out at most <em 1512class="arg" >white-point</em> pixels. Or, if percent is used, black-out at most 1513<em class="arg" >black-point %</em> pixels and white-out at most <em 1514class="arg" >white-point %</em> pixels.</p> 1515 1516<p>Prior to ImageMagick 6.4.7-0, <a href="#contrast-stretch" 1517>-contrast-stretch</a> will black-out at most <em class="arg" 1518>black-point</em> pixels and white-out at most <em class="arg" >total pixels 1519minus white-point</em> pixels. Or, if percent is used, black-out at most <em 1520class="arg">black-point %</em> pixels and white-out at most <em class="arg" 1521>100% minus white-point %</em> pixels.</p> 1522 1523<p>Note that <kbd>-contrast-stretch 0</kbd> will modify the image such that 1524the image's min and max values are stretched to 0 and <em class="QR" 1525>QuantumRange</em>, respectively, without any loss of data due to burn-out or 1526clipping at either end. This is not the same as <a href="#normalize" 1527>-normalize</a>, which is equivalent to <kbd>-contrast-stretch 0.15x0.05%</kbd> (or 1528prior to ImageMagick 6.4.7-0, <kbd>-contrast-stretch 2%x99%</kbd>).</p> 1529 1530<p>Internally operator works by creating a histogram bin, and then uses that 1531bin to modify the image. As such some colors may be merged together when they 1532originally fell into the same 'bin'. </p> 1533 1534<p>All the channels are normalized in concert by the came amount so as to 1535preserve color integrity, when the default <a href="#channel" >+channel</a> 1536setting is in use. Specifying any other <a href="#channel" >-channel</a> 1537setting will normalize the RGB channels independently.</p> 1538 1539<p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect' 1540normalization of mathematical images. </p> 1541 1542<p>This operator is under review for re-development. </p> 1543 1544 1545<div style="margin: auto;"> 1546 <h4><a id="convolve"></a>-convolve <em class="arg">kernel</em></h4> 1547</div> 1548 1549<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Convolve an image with a user-supplied convolution kernel.</td><td style='text-align:right;'></td></tr></table> 1550 1551<p>The <em class="arg">kernel</em> is a matrix specified as 1552a comma-separated list of integers (with no spaces), ordered left-to right, 1553starting with the top row. Presently, only odd-dimensioned kernels are 1554supported, and therefore the number of entries in the specified <em 1555class="arg">kernel</em> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25, 15567<sup>2</sup>=49, etc. </p> 1557 1558<p>Note that the <a href="/www/command-line-options.html#convolve">‑convolve</a> operator supports the <a href="/www/command-line-options.html#bias">‑bias</a> setting. This option shifts the convolution so that 1559positive and negative results are relative to a user-specified bias value. 1560This is important for non-HDRI compilations of ImageMagick when dealing with 1561convolutions that contain negative as well as positive values. This is 1562especially the case with convolutions involving high pass filters or edge 1563detection. Without an output bias, the negative values is clipped at zero. 1564</p> 1565 1566<p>When using an ImageMagick with the HDRI compile-time setting, <a href="/www/command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any 1567negative results without clipping to the color value range (0..QuantumRange). 1568See the discussion on HDRI implementations of ImageMagick on the page <a 1569href="/www/high-dynamic-range.html">High 1570Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a 1571href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this 1572<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> 1573entry. </p> 1574 1575 1576<div style="margin: auto;"> 1577 <h4><a id="crop"></a>-crop <em class="arg">geometry</em></h4> 1578</div> 1579 1580<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Cut out one or more rectangular regions of the image.</td><td style='text-align:right;'></td></tr></table> 1581 1582<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 1583 1584<p>The <em class="arg">width</em> and <em class="arg">height</em> of the <em class="arg">geometry</em> argument give the size of the image that remains after cropping, and <em class="arg">x</em> and <em class="arg">y</em> in the <em class="arg">offset</em> (if present) gives the location of the top left corner of the cropped image with respect to the original image. To specify the amount to be removed, use <a href="#shave">-shave</a> instead.</p> 1585 1586<p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are present, a single image is generated, consisting of the pixels from the cropping region. The offsets specify the location of the upper left corner of the cropping region measured downward and rightward with respect to the upper left corner of the image. If the <a href="#gravity">-gravity</a> option is present with <kbd>NorthEast</kbd>, <kbd>East</kbd>, or <kbd>SouthEast</kbd> gravity, it gives the distance leftward from the right edge of the image to the right edge of the cropping region. Similarly, if the <a href="#gravity">-gravity</a> option is present with <kbd>SouthWest</kbd>, <kbd>South</kbd>, or <kbd>SouthEast</kbd> gravity, the distance is measured upward between the bottom edges.</p> 1587 1588<p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are omitted, a set of tiles of the specified geometry, covering the entire input image, is generated. The rightmost tiles and the bottom tiles are smaller if the specified geometry extends beyond the dimensions of the input image.</p> 1589 1590<p>By adding a exclamation character flag to the geometry argument, the 1591cropped images virtual canvas page size and offset is set as if the 1592geometry argument was a viewport or window. This means the canvas page size 1593is set to exactly the same size you specified, the image offset set 1594relative top left corner of the region cropped. </p> 1595 1596<p>If the cropped image 'missed' the actual image on its virtual canvas, a 1597special single pixel transparent 'missed' image is returned, and a 'crop 1598missed' warning given. </p> 1599 1600<p>It might be necessary to <a href="#repage" >+repage</a> the image prior to cropping the image to ensure the crop coordinate frame is relocated to the upper-left corner of the visible image.</p> 1601 1602<div style="margin: auto;"> 1603 <h4><a id="cycle"></a>-cycle <em class="arg">amount</em></h4> 1604</div> 1605 1606<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image colormap by amount.</td><td style='text-align:right;'></td></tr></table> 1607 1608<p><em class="arg">Amount</em> defines the number of positions each 1609colormap entry is shifted.</p> 1610 1611 1612<div style="margin: auto;"> 1613 <h4><a id="debug"></a>-debug <em class="arg">events</em></h4> 1614</div> 1615 1616<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>enable debug printout.</td><td style='text-align:right;'></td></tr></table> 1617 1618<p>The <kbd>events</kbd> parameter specifies which events are to be logged. It can be either <kbd>None</kbd>, <kbd>All</kbd>, <kbd>Trace</kbd>, or a comma-separated list consisting of one or more of the following domains: <kbd>Annotate</kbd>, <kbd>Blob</kbd>, <kbd>Cache</kbd>, <kbd>Coder</kbd>, <kbd>Configure</kbd>, <kbd>Deprecate</kbd>, <kbd>Exception</kbd>, <kbd>Locale</kbd>, <kbd>Render</kbd>, <kbd>Resource</kbd>, <kbd>Security</kbd>, <kbd>TemporaryFile</kbd>, <kbd>Transform</kbd>, <kbd>X11</kbd>, or <kbd>User</kbd>. </p> 1619 1620 1621<p>For example, to log cache and blob events, use.</p> 1622 1623<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -debug "Cache,Blob" rose: rose.png</span></p> 1624<p>The <kbd>User</kbd> domain is normally empty, but developers can log user events in their private copy of ImageMagick.</p> 1625 1626<p>To print the complete list of debug methods, use <a href="#list">-list debug</a>.</p> 1627 1628<p>Use the <a href="#log">-log</a> option to specify the format for debugging output.</p> 1629 1630<p>Use <a href="#debug">+debug</a> to turn off all logging.</p> 1631 1632<p>Debugging may also be set using the <kbd>MAGICK_DEBUG</kbd> <a href="/www/resources.html#environment">environment variable</a>. The allowed values for the <kbd>MAGICK_DEBUG</kbd> environment variable are the same as for the <a href="#debug">-debug</a> option.</p> 1633 1634 1635<div style="margin: auto;"> 1636 <h4><a id="decipher"></a>-decipher <em class="arg">filename</em></h4> 1637</div> 1638 1639<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decipher and restore pixels that were previously transformed by <a href="#encipher">-encipher</a>.</td><td style='text-align:right;'></td></tr></table> 1640 1641<p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p> 1642 1643<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p> 1644 1645 1646<div style="margin: auto;"> 1647 <h4><a id="deconstruct"></a>-deconstruct</h4> 1648</div> 1649 1650<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>find areas that has changed between images </td><td style='text-align:right;'></td></tr></table> 1651 1652<p>Given a sequence of images all the same size, such as produced by <a href="#coalesce">-coalesce</a>, replace the second and later images, with a smaller image of just the area that changed relative to the previous image. </p> 1653 1654<p>The resulting sequence of images can be used to optimize an animation sequence, though will not work correctly for GIF animations when parts of the animation can go from opaque to transparent. </p> 1655 1656<p>This option is actually equivalent to the <a href="#layers">-layers</a> method '<kbd>compare-any</kbd>'. </p> 1657 1658 1659<div style="margin: auto;"> 1660 <h4><a id="define"></a>-define <em class="arg">key</em>{<em class="arg">=value</em>}<em class="arg">...</em></h4> 1661</div> 1662 1663<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add specific global settings generally used to control 1664coders and image processing operations.</td><td style='text-align:right;'></td></tr></table> 1665 1666<p>This option creates one or more definitions for coders and decoders to use 1667while reading and writing image data. Definitions are generally used to 1668control image file format coder modules, and image processing operations, 1669beyond what is provided by normal means. Defined settings are listed in <a 1670href="#verbose" >-verbose</a> information ("<kbd>info:</kbd>" output format) 1671as "Artifacts". </p> 1672 1673<p>If <em class="arg">value</em> is missing for a definition, an empty-valued 1674definition of a flag is created with that name. This used to control on/off 1675options. Use <a href="#define">+define key</a> to remove definitions 1676previously created. Use <a href="#define">+define "*"</a> to remove all 1677existing definitions.</p> 1678 1679<p>The same 'artifact' settings can also be defined using the <a 1680href="#set" >-set "option:<em class="arg">key</em>" "<em class="arg" 1681>value</em>"</a> option, which also allows the use of <a href="/www/escape.html" >Format and Print Image 1682Properties</a> in the defined value. </p> 1683 1684<p>The <em>option</em> and <em>key</em> are case-independent (they are 1685converted to lowercase for use within the decoders) while the <em>value</em> 1686is case-dependent.</p> 1687 1688<p>Such settings are global in scope, and effect all images and operations. </p> 1689 1690<p>The following definitions are just some of the artifacts that are 1691available:</p> 1692 1693<dl> 1694<dt>dcm:display-range=reset</dt> 1695<dd>Set the display range to the minimum and maximum pixel values for the 1696 DCM image format.</dd> 1697 1698<dt>dot:layout-engine=<em class="arg">value</em></dt> 1699<dd>Set the specify the layout engine for the DOT image format (e.g. 1700 <kbd>neato</kbd>).</dd> 1701 1702<dt>jpeg:extent=<em class="arg">value</em></dt> 1703<dd>Restrict the maximum JPEG file size, for example <kbd>-define 1704 jpeg:extent=400kb</kbd>.</dd> 1705 1706<dt>jpeg:size=<em class="arg">geometry</em></dt> 1707<dd>Set the size hint of a JPEG image, for example, -define jpeg:size=128x128. 1708 It is most useful for increasing performance and reducing the memory 1709 requirements when reducing the size of a large JPEG image.</dd> 1710 1711<dt>jp2:rate=<em class="arg">value</em></dt> 1712<dd>Specify the compression factor to use while writing JPEG-2000 files. The 1713 compression factor is the reciprocal of the compression ratio. The valid 1714 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined, 1715 this value overrides the -quality setting. A quality setting of 75 1716 results in a rate value of 0.06641.</dd> 1717 1718<dt>mng:need-cacheoff</dt> 1719 <dd>turn playback caching off for streaming MNG.</dd> 1720 1721<dt>png:bit-depth=<em class="arg">value</em></dt> 1722<dt>png:color-type=<em class="arg">value</em></dt> 1723<dd>desired bit-depth and color-type for PNG output. You can force the PNG 1724 encoder to use a different bit-depth and color-type than it would have 1725 normally selected, but only if this does not cause any loss of image 1726 quality. Any attempt to reduce image quality is treated as an error and no 1727 PNG file is written. E.g., if you have a 1-bit black-and-white image, you 1728 can use these "defines" to cause it to be written as an 8-bit grayscale, 1729 indexed, or even a 64-bit RGBA. But if you have a 16-million color image, 1730 you cannot force it to be written as a grayscale or indexed PNG. If you 1731 wish to do this, you must use the appropriate <a href="#depth">-depth</a>, 1732 <a href="#colors">-colors</a>, or <a href="#type">-type</a> directives to 1733 reduce the image quality prior to using the PNG encoder. Note that in 1734 indexed PNG files, "bit-depth" refers to the number of bits per index, 1735 which can be 1, 2, 4, or 8. In such files, the color samples always have 1736 8-bit depth.</dd> 1737 1738<dt>png:exclude-chunk=<em class="arg">value</em></dt> 1739<dt>png:include-chunk=<em class="arg">value</em></dt> 1740<dd>ancillary chunks to be excluded from or included in PNG output. 1741 1742 <p>The<em class="arg">value</em> can be the name of a PNG chunk-type such 1743 as <em class="arg">bKGD</em>, a comma-separated list of chunk-types, 1744 or the word <em class="arg">all</em> or 1745 the word <em class="arg">none</em>. There must be no spaces in the 1746 list. Although PNG chunk-names are case-dependent, you can use 1747 all lowercase names if you prefer.</p> 1748 1749 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior 1750 of the PNG encoder and have no effect on the PNG decoder.</p> 1751 1752 <p>As a special case, if the <kbd>sRGB</kbd> chunk is excluded and 1753 the <kbd>gAMA</kbd> chunk is included, the <kbd>gAMA</kbd> chunk will 1754 only be written if gamma is not 1/2.2, since most decoders assume 1755 sRGB and gamma=1/2.2 when no colorspace information is included in 1756 the PNG file. Because the list is processed from left to right, you 1757 can achieve this with a single define:</p> 1758 1759<pre class="text"> 1760 -define png:include-chunk=none,gAMA 1761</pre> 1762 1763 <p>The critical PNG chunks <kbd>IHDR</kbd>, <kbd>PLTE</kbd>, 1764 <kbd>IDAT</kbd>, and <kbd>IEND</kbd> cannot be excluded. Any of 1765 these entries appearing in the list will be ignored.</p> 1766 1767 <p>If the ancillary PNG <kbd>tRNS</kbd> chunk is excluded and the 1768 image has transparency, the PNG colortype is forced to be 4 or 6 1769 (GRAY_ALPHA or RGBA). If the image is not transparent, then the 1770 <kbd>tRNS</kbd> chunk isn't written anyhow, and there is no effect 1771 on the PNG colortype of the output image.</p> 1772 1773 <p>The <a href="#strip">-strip</a> option does the equivalent of the 1774 following for PNG output:</p> 1775 1776<pre class="text"> 1777 -define png:include-chunk=none,gama 1778</pre> 1779 1780 <p>The default behavior is to include all known PNG ancillary chunks 1781 plus ImageMagick's private <kbd>vpAg</kbd> ("virtual page") chunk, 1782 and to exclude all PNG chunks that are unknown to ImageMagick, 1783 regardless of their PNG "copy-safe" status as described in the 1784 PNG specification.</p> 1785 1786 <p>Any chunk names that are not known to ImageMagick are ignored 1787 if they appear in either the "include-chunk" or "exclude-chunk" list. 1788 The ancillary chunks currently known to ImageMagick are 1789 <kbd>bKGD</kbd>, <kbd>cHRM</kbd>, <kbd>gAMA</kbd>, <kbd>iCCP</kbd>, 1790 <kbd>oFFs</kbd>, <kbd>pHYs</kbd>, <kbd>sRGB</kbd>, <kbd>tEXt</kbd>, 1791 <kbd>tRNS</kbd>, <kbd>vpAg</kbd>, and <kbd>zTXt</kbd>.</p> 1792 1793 <p>You can also put <kbd>date</kbd> in the list to include or exclude 1794 the "Date:create" and "Date:modify" text chunks that ImageMagick normally 1795 inserts in the output PNG.</p> 1796 1797</dd> 1798 1799<dt>png:preserve-colormap</dt> 1800 <dd>Use the existing image->colormap. Normally the PNG encoder will 1801 try to optimize the palette, eliminating unused entries and putting 1802 the transparent colors first. If this flag is set, that behavior 1803 is suppressed.</dd> 1804 1805<dt>ps:imagemask</dt> 1806<dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create 1807 Postscript files that render bilevel images with the Postscript imagemask 1808 operator instead of the image operator.</dd> 1809 1810<dt>quantum:format=<em class="arg">type</em></dt> 1811<dd>Set the type to <kbd>floating-point</kbd> to specify a floating-point 1812 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode 1813 to preserve negative values. If <a href="#depth">-depth</a> 16 is 1814 included, the result is a single precision floating point format. 1815 If <a href="#depth">-depth</a> 32 is included, the result is 1816 double precision floating point format.</dd> 1817 1818</dl> 1819 1820<p>For example, to create a postscript file that will render only the black 1821pixels of a bilevel image, use:</p> 1822 1823<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bilevel.tif -define ps:imagemask eps3:stencil.ps</span></p> 1824<p>Set attributes of the image registry by prefixing the value with 1825<kbd>registry:</kbd>. For example, to set a temporary path to put work files, 1826use:</p> 1827 1828<p class="crtsnip"> 1829-define registry:temporary-path=/data/tmp 1830</p> 1831 1832 1833 1834<div style="margin: auto;"> 1835 <h4><a id="delay"></a>-delay <em class="arg">ticks</em> <br />-delay <em class="arg">ticks</em>x<em class="arg">ticks-per-second</em> {<em class="arg"><</em>} {<em class="arg">></em>}</h4> 1836</div> 1837 1838<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display the next image after pausing.</td><td style='text-align:right;'></td></tr></table> 1839 1840<p>This option is useful for regulating the animation of image sequences <em>ticks/ticks-per-second</em> seconds must expire before the display of the next image. The default is no delay between each showing of the image sequence. The default ticks-per-second is 100.</p> 1841 1842<p>Use <kbd>></kbd> to change the image delay <em>only</em> if its current value exceeds the given delay. <kbd><</kbd> changes the image delay <em>only</em> if current value is less than the given delay. For example, if you specify <kbd>30></kbd> and the image delay is 20, the image delay does not change. However, if the image delay is 40 or 50, the delay it is changed to 30. Enclose the given delay in quotation marks to prevent the <kbd><</kbd> or <kbd>></kbd> from being interpreted by your shell as a file redirection.</p> 1843 1844 1845<div style="margin: auto;"> 1846 <h4><a id="delete"></a>-delete <em class="arg">indexes</em></h4> 1847</div> 1848 1849<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>delete the image, specified by its index, from the image sequence.</td><td style='text-align:right;'></td></tr></table> 1850 1851<p>Specify the image by its index in the sequence. The first image is index 0. Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Specify a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use <kbd>+delete</kbd> to delete the last image in the current image sequence.</p> 1852 1853 1854<div style="margin: auto;"> 1855 <h4><a id="density"></a>-density <em class="arg">width</em><br />-density <em class="arg">width</em>x<em class="arg">height</em></h4> 1856</div> 1857 1858<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the horizontal and vertical resolution of an image for rendering to devices.</td><td style='text-align:right;'></td></tr></table> 1859 1860<p>This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering (reading) vector formats such as Postscript, PDF, WMF, and SVG into a raster image. Image resolution provides the unit of measure to apply when rendering to an output device or raster image. The default unit of measure is in dots per inch (DPI). The <a href="#units">-units</a> option may be used to select dots per centimeter instead.</p> 1861 1862<p>The default resolution is 72 dots per inch, which is equivalent to one point per pixel (Macintosh and Postscript standard). Computer screens are normally 72 or 96 dots per inch, while printers typically support 150, 300, 600, or 1200 dots per inch. To determine the resolution of your display, use a ruler to measure the width of your screen in inches, and divide by the number of horizontal pixels (1024 on a 1024x768 display).</p> 1863 1864<p>If the file format supports it, this option may be used to update the stored image resolution. Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile is not stripped from the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.</p> 1865 1866<p>The <a href="#density">-density</a> option sets an <em>attribute</em> and does not alter the underlying raster image. It may be used to adjust the rendered size for desktop publishing purposes by adjusting the scale applied to the pixels. To resize the image so that it is the same size at a different resolution, use the <a href="#resample">-resample</a> option.</p> 1867 1868<div style="margin: auto;"> 1869 <h4><a id="depth"></a>-depth <em class="arg">value</em></h4> 1870</div> 1871 1872<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>depth of the image.</td><td style='text-align:right;'></td></tr></table> 1873 1874<p>This the number of bits in a color sample within a pixel. Use this option to specify the depth of raw images whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.</p> 1875 1876<div style="margin: auto;"> 1877 <h4><a id="descend"></a>-descend</h4> 1878</div> 1879 1880<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>obtain image by descending window hierarchy.</td><td style='text-align:right;'></td></tr></table> 1881 1882<div style="margin: auto;"> 1883 <h4><a id="deskew"></a>-deskew <em class="arg">threshold</em></h4> 1884</div> 1885 1886<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>straighten an image. A threshold of 40% works for most images.</td><td style='text-align:right;'></td></tr></table> 1887 1888<p>Use <a href="#set">-set</a> <kbd>option:deskew:auto-crop <em>width</em></kbd> to auto crop the image. The set argument is the pixel width of the image background (e.g 40).</p> 1889 1890<div style="margin: auto;"> 1891 <h4><a id="despeckle"></a>-despeckle</h4> 1892</div> 1893 1894<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the speckles within an image.</td><td style='text-align:right;'></td></tr></table> 1895 1896<div style="margin: auto;"> 1897 <h4><a id="direction"></a>-direction <em class="arg">type</em></h4> 1898</div> 1899 1900<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render text right-to-left or left-to-right.</td><td style='text-align:right;'></td></tr></table> 1901 1902<div style="margin: auto;"> 1903 <h4><a id="displace"></a>-displace <em class="arg">horizontal-scale</em><br />-displace <em class="arg">horizontal-scale</em>x<em class="arg">vertical-scale</em></h4> 1904</div> 1905 1906<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shift image pixels as defined by a displacement map.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 1907 1908<p>With this option, the 'overlay' image, and optionally the 'mask' image, 1909is used as a displacement map, which is used to displace the lookup of 1910what part of the 'background' image is seen at each point of the overlaid 1911area. Much like the displacement map is a 'lens' that redirects light shining 1912through it so as to present a distorted view the original 'background' image 1913behind it. </p> 1914 1915<p>Any perfect grey areas of the displacement map produce a zero 1916displacement of the image. Black areas produce the given maximum negative 1917displacement of the lookup point, while white produce a maximum positive 1918displacement of the lookup. </p> 1919 1920<p>Note that it is the lookup of the 'background' that is displaced, not a 1921displacement of the image itself. As such an area of the displacement map 1922containing 'white' will have the lookup point 'shifted' by a positive amount, 1923and thus generating a copy of the destination image to the right/downward from 1924the correct position. That is the image will look like it may have been 1925'shifted' in a negative left/upward direction. Understanding this is a very 1926important in understanding how displacement maps work. </p> 1927 1928<p>The given arguments define the maximum amount of displacement in pixels 1929that a particular map can produce. If the displacement scale is large enough 1930it is also possible to lookup parts of the 'background' image that lie well 1931outside the bounds of the displacement map itself. That is you could very 1932easily copy a section of the original image from outside the overlay area 1933into the overlay area. </p> 1934 1935<p>The '%' flag makes the displacement scale relative to the size of the 1936overlay image (100% = half width/height of image). Using '!' switches 1937percentage arguments to refer to the destination image size instead. 1938these flags were added as of IM v6.5.3-5.</p> 1939 1940<p>Normally a single grayscale displacement map is provided, which with the 1941given scaling values will determine a single direction (vector) in which 1942displacements can occur (positively or negatively). However, if you also 1943specify a third image which is normally used as a <em class="arg">mask</em>, 1944the <em class="arg">composite image</em> is used for horizontal X 1945displacement, while the <em class="arg">mask image</em> is used for vertical Y 1946displacement. This allows you to define completely different displacement 1947values for the X and Y directions, and allowing you to lookup any point within 1948the <em class="arg">scale</em> bounds. In other words each pixel can lookup 1949any other nearby pixel, producing complex 2 dimensional displacements, rather 1950than a simple 1 dimensional vector displacements. </p> 1951 1952<p>Alteratively rather than suppling two separate images, as of IM v6.4.4-0, 1953you can use the 'red' channel of the overlay image to specify the horizontal 1954or X displacement, and the 'green' channel for the vertical or Y displacement. 1955</p> 1956 1957<p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a 1958mask the transparency of the destination image. However areas outside the 1959overlaid areas will not be effected. </p> 1960 1961 1962<div style="margin: auto;"> 1963 <h4><a id="display"></a>-display <em class="arg">host:display[.screen]</em></h4> 1964</div> 1965 1966<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies the X server to contact.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 1967 1968<p>This option is used with convert for obtaining image or font from this X server. See <em class="arg">X(1)</em>.</p> 1969 1970<div style="margin: auto;"> 1971 <h4><a id="dispose"></a>-dispose <em class="arg">method</em></h4> 1972</div> 1973 1974<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>define the GIF disposal image setting for images that are being created or read in. </td><td style='text-align:right;'></td></tr></table> 1975 1976<p>The layer disposal method defines the way each the displayed image is to be 1977modified after the current 'frame' of an animation has finished being 1978displayed (after its 'delay' period), but before the next frame on an 1979animation is to be overlaid onto the display. </p> 1980 1981<p>Here are the valid methods:</p> 1982 1983<pre class="text"> 1984 Undefined 0 No disposal specified (equivalent to '<kbd>none</kbd>'). 1985 None 1 Do not dispose, just overlay next frame image. 1986 Background 2 Clear the frame area with the background color. 1987 Previous 3 Clear to the image prior to this frames overlay. 1988</pre> 1989 1990<p>You can also use the numbers given above, which is what the GIF format 1991uses internally to represent the above settings. </p> 1992 1993<p>To print a complete list of dispose methods, use <a href="#list">-list dispose</a>.</p> 1994 1995<p>Use <a href="#dispose" >+dispose</a>, turn off the setting and prevent 1996resetting the layer disposal methods of images being read in. </p> 1997 1998<p>Use <a href="#set">-set</a> '<kbd>dispose</kbd>' method to set the image 1999disposal method for images already in memory.</p> 2000 2001<div style="margin: auto;"> 2002 <h4><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <em class="arg">value</em></h4> 2003</div> 2004 2005<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>maximum RMSE for subimage match (default 0.2).</td><td style='text-align:right;'>[<a href="/www/compare.html">compare</a>]</td></tr></table> 2006 2007 2008<div style="margin: auto;"> 2009 <h4><a id="dissolve"></a>-dissolve <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]</h4> 2010</div> 2011 2012<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dissolve an image into another by the given percent.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 2013 2014<p>The opacity of the composite image is multiplied by the given percent, then 2015it is composited 'over' the main image. If <em class="arg">src_percent</em> 2016is greater than 100, start dissolving the main image so it becomes 2017transparent at a value of '<kbd class="arg">200</kbd>'. If both percentages 2018are given, each image are dissolved to the percentages given. </p> 2019 2020<p>Note that dissolve percentages do not add, two opaque images dissolved 2021'50,50', produce a 75% transparency. For a 50% + 50% blending of the two 2022images, you would need to use dissolve values of '50,100'. </p> 2023 2024<div style="margin: auto;"> 2025 <h4><a id="distort"></a>-distort <em class="arg">method arguments</em></h4> 2026</div> 2027 2028<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>distort an image, using the given <em class="arg">method</em> and its required <em class="arg">arguments</em>.</td><td style='text-align:right;'></td></tr></table> 2029 2030<p>The <em class="arg">arguments</em> is a single string containing a list 2031of floating point numbers separated by commas or spaces. The number of 2032and meaning of the floating point values depends on the distortion <em 2033class="arg">method</em> being used. </p> 2034 2035<p>Choose from these distortion types:</p> 2036 2037<table class="doc"> 2038 <tr valign="top"> 2039 <th align="left" style="width: 8%">Method</th> 2040 <th align="left">Description</th> 2041 </tr> 2042 2043 <tr valign="top"> 2044 <td valign="top"><kbd>ScaleRotateTranslate</kbd> 2045 <br/>or <kbd>SRT</kbd></td> 2046 <td valign="top"> 2047 Distort image by first scaling and rotating about a given 'center', 2048 before translating that 'center' to the new location, in that order. It 2049 is an alternative method of specifying a '<kbd>Affine</kbd>' type of 2050 distortion, but without shearing effects. It also provides a good way 2051 of rotating and displacing a smaller image for tiling onto a larger 2052 background (IE 2-dimensional animations). <br/> 2053 2054 The number of arguments determine the specific meaning of each 2055 argument for the scales, rotation, and translation operations. <br/> 2056 2057 <table style="margin-left:auto; margin-right:auto;"> 2058 <tr><td># </td><td>arguments meaning</td></tr> 2059 <tr><td>1:</td><td><em>Angle_of_Rotation</em></td></tr> 2060 <tr><td>2:</td><td><em>Scale Angle</em></td></tr> 2061 <tr><td>3:</td><td><em>X,Y Angle</em></td></tr> 2062 <tr><td>4:</td><td><em>X,Y Scale Angle</em></td></tr> 2063 <tr><td>5:</td> 2064 <td><em>X,Y ScaleX,ScaleY Angle</em></td></tr> 2065 <tr><td>6:</td> 2066 <td><em>X,Y Scale Angle NewX,NewY</em></td></tr> 2067 <tr><td>7:</td> 2068 <td><em>X,Y ScaleX,ScaleY Angle 2069 NewX,NewY</em></td></tr> 2070 </table> 2071 2072 This is actually an alternative way of specifying a 2 dimensional linear 2073 '<kbd>Affine</kbd>' or '<kbd>AffineProjection</kbd>' distortion. </td> </tr> 2074 2075 <tr valign="top"> 2076 <td valign="top"><kbd>Affine</kbd></td> 2077 <td valign="top"> 2078 Distort the image linearly by moving a list of at least 3 or more sets 2079 of control points (as defined below). Ideally 3 sets or 12 floating 2080 point values are given allowing the image to be linearly scaled, 2081 rotated, sheared, and translated, according to those three points. See 2082 also the related '<kbd>AffineProjection</kbd>' and '<kbd>SRT</kbd>' 2083 distortions. <br/> 2084 2085 More than 3 sets given control point pairs (12 numbers) is least 2086 squares fitted to best match a lineary affine distortion. If only 2 2087 control point pairs (8 numbers) are given a two point image translation 2088 rotation and scaling is performed, without any possible shearing, 2089 flipping or changes in aspect ratio to the resulting image. If only one 2090 control point pair is provides the image is only translated, (which may 2091 be a floating point non-integer translation). <br/> 2092 2093 This distortion does not include any form of perspective distortion. 2094 </td> 2095 2096 </tr> 2097 2098 <tr valign="top"> 2099 <td valign="top"><kbd>AffineProjection</kbd></td> 2100 <td valign="top"> 2101 Linearly distort an image using the given Affine Matrix of 6 2102 pre-calculated coefficients forming a set of Affine Equations to map 2103 the source image to the destination image. 2104 2105 <div style="text-align: center"><em> 2106 s<sub>x</sub>, r<sub>x</sub>, 2107 r<sub>y</sub>, s<sub>y</sub>, 2108 t<sub>x</sub>, t<sub>y</sub> 2109 </em></div> 2110 2111 See <a href="#affine" >-affine</a> setting for more detail, and 2112 meanings of these coefficients. <br/> 2113 2114 The distortions '<kbd>Affine</kbd>' and '<kbd>SRT</kbd>' provide 2115 alternative methods of defining this distortion, with ImageMagick doing 2116 the calculations needed to generate the required coefficients. You can 2117 see the internally generated coefficients, by using a <a 2118 href="#verbose" >-verbose</a> setting with those other varients. </td> 2119 2120 </tr> 2121 2122 <tr valign="top"> 2123 <td valign="top"><kbd>BilinearForward</kbd><br/> 2124 <kbd>BilinearReverse</kbd></td> 2125 <td valign="top"> 2126 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or 2127 16 values (see below). Not that lines may not appear straight after 2128 distortion, though the distance between coordinates will remain 2129 consistent. <br/> 2130 2131 The '<kbd>BilinearForward</kbd>' is used to map rectangles to any 2132 quadrilateral, while the '<kbd>BilinearReverse</kbd>' form maps any 2133 quadrilateral to a rectangle, while preserving the straigth line edges 2134 in each case. <br/> 2135 2136 Note that '<kbd>BilinearForward</kbd>' can generate invalid pixels 2137 which will be colored using the <a href="#mattecolor" >-mattecolor</a> 2138 color setting. Also if the quadraterial becomes 'flipped' the image 2139 may dissappear. <br/> 2140 2141 There are future plans to produce a true Bilinear distortion that will 2142 attempt to map any quadrilateral to any other quadrilateral, while 2143 preserving edges (and edge distance ratios). 2144 2145 </td> 2146 </tr> 2147 2148 <tr valign="top"> 2149 <td valign="top"><kbd>Perspective</kbd></td> 2150 <td valign="top"> 2151 Perspective distort the images, using a list of 4 or more sets of 2152 control points (as defined below). More that 4 sets (16 numbers) of 2153 control points provide least squares fitting for more accurate 2154 distortions (for the purposes of image registration and panarama 2155 effects). Less than 4 sets will fall back to a '<kbd>Affine</kbd>' 2156 linear distortion. <br/> 2157 2158 Perspective Distorted images ensures that straight lines remain 2159 straight, but the scale of the distorted image will vary. The horizon 2160 is anti-aliased, and the 'sky' color may be set using the 2161 <a href="#mattecolor" >-mattecolor</a> setting. </td> 2162 </tr> 2163 2164 <tr valign="top"> 2165 <td valign="top"><kbd>PerspectiveProjection</kbd> </td> 2166 <td valign="top"> 2167 Do a '<kbd>Perspective</kbd>' distortion biased on a set of 8 2168 pre-calculated coefficients. You can get these coefficients by looking 2169 at the <a href="#verbose" >-verbose</a> output of a 2170 '<kbd>Prespective</kbd>' distortion, or by calculating them yourself. 2171 If the last two perspective scaling coefficients are zero, the 2172 remaining 6 represents a transposed 'Affine Matrix'. </td> 2173 2174 </tr> 2175 2176 <tr valign="top"> 2177 <td valign="top"><kbd>Arc</kbd></td> 2178 <td valign="top"> 2179 Arc the image (variation of polar mapping) over the angle given around 2180 a circle. <br/> 2181 <table width="90%" style = "margin-left: auto; margin-right: auto;"> 2182 <tr valign="top"><td>Argument</td> 2183 <td>Meaning</td></tr> 2184 <tr valign="top"><td><em>arc_angle</em></td> 2185 <td>The angle over which to arc the image side-to-side</td></tr> 2186 <tr valign="top"><td><em>rotate_angle</em></td> 2187 <td>Angle to rotate resulting image from vertical center</td></tr> 2188 <tr valign="top"><td><em>top_radius</em></td> 2189 <td>Set top edge of source image at this radius</td></tr> 2190 <tr valign="top"><td><em>bottom_radius</em> </td> 2191 <td>Set bottom edge to this radius (radial scaling)</td></tr> 2192 </table> 2193 2194 The resulting image is always resized to best fit the resulting image, 2195 (as if using <a href="#distort" >+distort</a>) while attempting to 2196 preserve scale and aspect ratio of the original image as much as 2197 possible with the arguments given by the user. All four arguments will 2198 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/> 2199 2200 This a variation of a polar distortion designed to try to preserve the 2201 aspect ratio of the image rather than direct Cartesian to Polar 2202 conversion. </td> 2203 </tr> 2204 2205 <tr valign="top"> 2206 <td valign="top"><kbd>Polar</kbd></td> 2207 <td valign="top"> 2208 Like '<kbd>Arc</kbd>' but do a complete Cartesian to Polar mapping of 2209 the image. that is the height of the input image is mapped to the 2210 radius limits, while the width is wrapped around between the 2211 angle limits. <br/> 2212 2213 Arguments: <em>Rmax,Rmin CenterX,CenterY, start,end_angle</em> <br/> 2214 2215 All arguments are optional. With <em>Rmin</em> defaulting to zero, the 2216 center to the center of the image, and the angles going from -180 (top) 2217 to +180 (top). If <em>Rmax</em> is given the special value of 2218 '<code>0</code>', the the distance from the center to the nearest edge 2219 is used for the radius of the output image, which will ensure the whole 2220 image is visible (though scaled smaller). However a special value of 2221 '<code>-1</code>' will use the distance from the center to the furthest 2222 corner, This may 'clip' the corners from the input rectangular image, 2223 but will generate the exact reverse of a '<kbd>DePolar</kbd>' with 2224 the same arguments. <br/> 2225 2226 If the plus form of distort (<a href="#distort" >+distort</a>) is used 2227 output image center will default to <code>0,0</code> of the virtual 2228 canvas, and the image size adjusted to ensure the whole input image is 2229 made visible in the output image on the virtual canvas. </td> 2230 2231 </tr> 2232 2233 <tr valign="top"> 2234 <td valign="top"><kbd>DePolar</kbd></td> 2235 <td valign="top"> 2236 Uses the same arguments and meanings as a '<kbd>Polar</kbd>' distortion 2237 but generates the reverse Polar to Cartesian distortion. <br/> 2238 2239 The special <em>Rmax</em> setting of '<code>0</code>' may however clip 2240 the corners of the input image. However using the special 2241 <em>Rmax</em> setting of '<code>-1</code>' (maximum center to corner 2242 distance) will ensure the whole distorted image is preserved in the 2243 generated result, so that the same argument to '<kbd>Polar</kbd>' will 2244 reverse the distortion re-producing the original. 2245 2246 Note that as this distortion requires the area resampling of a circular 2247 arc, which can not be handled by the builtin EWA resampling function. 2248 As such the normal EWA filters are turned off. It is recommended some 2249 form of 'super-sampling' image processing technique be used to produce 2250 a high quality result. </td> 2251 2252 </tr> 2253 2254 <tr valign="top"> 2255 <td valign="top"><kbd>Barrel</kbd></td> 2256 <td valign="top"> 2257 Given the four coefficients (A,B,C,D) as defined by <a 2258 href="http://wiki.panotools.org/Lens_correction_model" >Helmut 2259 Dersch</a>, perform a barrell or pin-cushion distortion appropriate to 2260 correct radial lens distortions. That is in photographs, make straight 2261 lines straight again. <br/> 2262 2263 Arguments: <em>A B C</em> [ <em>D</em> [ 2264 <em>X</em> , <em>Y</em> ] ] <br/> 2265 or <em>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub> 2266 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></em> 2267 [ <em>X</em> , <em>Y</em> ] <br/> 2268 So that it forms the function <br/> 2269 Rsrc = r * ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> + 2270 <em>C</em>*r + <em>D</em> )<br/> 2271 2272 Where <em>X</em>,<em>Y</em> is the optional center of the distortion 2273 (defaulting to the center of the image). <br/> 2274 The second form is typically used to distort images, rather than 2275 correct lens distortions. <br/> 2276 </td> 2277 2278 </tr> 2279 2280 <tr valign="top"> 2281 <td valign="top"><kbd>BarrelInverse</kbd></td> 2282 <td valign="top"> 2283 This is very simular to '<kbd>Barrel</kbd>' with the same set of 2284 arguments, and argument handling. However it uses the inverse 2285 of the radial polynomial, 2286 so that it forms the function <br/> 2287 Rsrc = r / ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> + 2288 <em>C</em>*r + <em>D</em> )<br/> 2289 Note that this is not the reverse of the '<kbd>Barrel</kbd>' 2290 distortion, just a different barrel-like radial distortion method. 2291 2292 </td> 2293 </tr> 2294 2295 <tr valign="top"> 2296 <td valign="top"><kbd>Shepards</kbd></td> 2297 <td valign="top"> 2298 Distort the given list control points (any number) using an Inverse 2299 Squared Distance Interpolation Method (<a 2300 href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards 2301 Method</a>). The control points in effect do 'localized' displacement 2302 of the image around the given control point (preserving the look and 2303 the rotation of the area near the control points. For best results 2304 extra control points should be added to 'lock' the positions of the 2305 corners, edges and other unchanging parts of the image, to prevent 2306 their movement. <br/> 2307 2308 The distortion has been likened to 'taffy pulling' using nails, or 2309 pins' stuck in a block of 'jelly' which is then moved to the new 2310 position, distorting te surface of the jelly. <br/> 2311 2312 Internally it is equivalent to generating a displacement map (see <a 2313 href="#displace" >-displace</a>) for source image color look-up using 2314 the <a href="#sparse-color" >-sparse-color</a> method of the same name. 2315 2316 </td> 2317 </tr> 2318 2319</table> 2320 2321<p>To print a complete list of distortion methods, use <a href="#list">-list 2322distort</a>.</p> 2323 2324<p>Many of the above distortion methods such as '<kbd>Affine</kbd>', 2325'<kbd>Perspective</kbd>', and '<kbd>Shepards</kbd>' use a list control points 2326defining how these points in the given image should be distorted in the 2327destination image. Each set of four floating point values represent a source 2328image coordinate, followed immediately by the destination image coordinate. 2329This produces a list of values such as...</p> 2330<div style="text-align: center"><em> 2331 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub> 2332 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub> 2333 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub> 2334 ... 2335 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub> 2336</em></div> 2337<p>where <em>U,V</em> on the source image is mapped to <em>X,Y</em> on the 2338destination image. </p> 2339 2340<p>For example, to warp an image using '<kbd>perspective</kbd>' distortion, 2341needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the 2342perspective distortion of the built-in "rose:" image. Note how spaces were 2343used to group the 4 sets of coordinate pairs, to make it easier to read and 2344understand.</p> 2345 2346<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'> 2347convert rose: -virtual-pixel black \<br/> 2348 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \<br/> 2349 rose_3d_rotated.gif</span></p> 2350<p>If more that the required number of coordinate pairs are given for 2351a distortion, the distortion method is 'least squares' fitted to produce the 2352best result for all the coordinate pairs given. If less than the ideal number 2353of points are given, the distort will generally fall back to a simpler form of 2354distortion that can handles the smaller number of coordinates (usally a linear 2355'<kbd>Affine</kbd>' distortion). </p> 2356 2357<p>By using more coordinates you can make use of image registration tool to 2358find matching coordinate pairs in overlapping images, so as to improve the 2359'fit' of the distortion. Of course a bad coordinate pair can also make the 2360'fit' worse. Caution is always advised. </p> 2361 2362<p>Colors are acquired from the source image according to the <a 2363href="#interpolate" >-interpolate</a> color lookup setting, when the image is 2364magnified. However if the viewed image is minified (image becomes smaller), 2365a special area resampling function (added ImageMagick v6.3.5-9), is used to 2366produce a higher quality image. For example you can use 2367a '<kbd>perspective</kbd>' distortion to view a infinitely tiled 'plane' all 2368the way to the horizon. </p> 2369 2370<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'> 2371convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \<br/> 2372 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \<br/> 2373 checks_tiled.jpg</span></p> 2374<p>Note that a infinitely tiled perspective images involving the horizon can 2375be very slow to generate due to the use of the high quality 'area resampling' 2376function (added ImageMagick v6.3.5-9). You can turn off 'area resampling' 2377using a <a href="#filter" >-filter</a> setting of '<kbd>point</kbd>' 2378(recommended if you plan to use super-sampling instead). </p> 2379 2380<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last 2381'<kbd>perspective</kbd>' distortion example, <a href="#distort" >-distort</a> 2382will use the current <a href="#mattecolor" >-mattecolor</a> setting for these 2383pixels. If you do not what these pixels to be visible, set the color to match 2384the rest of the ground. </p> 2385 2386<p>The output image size will by default be the same as the input image. This 2387means that if the part of the distorted image falls outside the viewed area of 2388the 'distorted space', those parts is clipped and lost. However if you use 2389the plus form of the operator (<a href="#distort" >+distort</a>) the operator 2390will attempt (if possible) to show the whole of the distorted image, while 2391retaining a correct 'virtual canvas' offset, for image layering. This offset 2392may need to be removed using <a href="#repage" >+repage</a>, to remove if it 2393is unwanted. </p> 2394 2395<p>You can alternatively specify a special "<kbd><a href="#set" >-set</a> 2396option:distort:viewport {geometry_string}</kbd>" setting which will specify 2397the size and the offset of the generated 'viewport' image of the distorted 2398image space.</p> 2399 2400<p>Adding a "<kbd><a href="#set" >-set</a> option:distort:scale 2401{scale_factor}</kbd>" will scale the output image (viewport or otherwise) by 2402that factor without changing the viewed contents of the distorted image. This 2403can be used either for 'super-sampling' the image for a higher quality result, 2404or for panning and zooming around the image (with appropriate viewport 2405changes, or post-distort cropping and resizing). </p> 2406 2407<p>Setting <a href="#verbose" >-verbose</a> setting, will cause <a 2408href="#distort" >-distort</a> to attempt to output the internal coefficients, 2409and the <a href="#fx" >-fx</a> equivalent to the distortion, for expert study, 2410and debugging purposes. This many not be available for all distorts. </p> 2411 2412<p>Affine rotations and shears (such as '<kbd>SRT</kbd>' distortion), tend to 2413produce a cleaner result that the equivalent <a href="#rotate" >-rotate</a> 2414and/or <a href="#shear" >-shear</a> operation, with more control of due to the 2415above settings. It is algorithmically slower however, though that may not be 2416the case in ImageMagick's implementation. </p> 2417 2418 2419<div style="margin: auto;"> 2420 <h4><a id="dither"></a>-dither <em class="arg">method</em></h4> 2421</div> 2422 2423<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a Riemersma or Floyd-Steinberg error diffusion dither to images when general color reduction is applied via an option, or automagically when saving to specific formats. This enabled by default. </td><td style='text-align:right;'></td></tr></table> 2424 2425<p>Dithering places two or more colors in neighboring pixels so that to the eye a closer approximation of the images original color is reproduced. This reduces the number of colors needed to reproduce the image but at the cost of a lower level pattern of colors. Error diffusion dithers can use any set of colors (generated or user defined) to an image. </p> 2426 2427<p>Dithering is turned on by default, to turn it off use the plus form of the 2428setting, <a href="#dither">+dither</a>. This will also also render PostScript 2429without text or graphic aliasing. Disabling dithering often (but not always) 2430leads to faster process, a smaller number of colors, but more cartoon like 2431image coloring. Generally resulting in 'color banding' effects in areas with 2432color gradients. </p> 2433 2434<p>The color reduction operators <a href="#colors">-colors</a>, <a 2435href="#monochrome">-monochrome</a>, <a href="#remap ">-remap</a>, and <a href="#posterize">-posterize</a>, apply dithering to images using the reduced color set they created. These operators are also used as part of automatic color reduction when saving images to formats with limited color support, such as <kbd>GIF:</kbd>, <kbd>XBM:</kbd>, and others, so dithering may also be used in these cases. </p> 2436 2437<p>Alternatively you can use <a href="#random-threshold">-random-threshold</a> to generate purely random dither. Or use <a href="#ordered-dither">-ordered-dither</a> to apply threshold mapped dither patterns, using uniform color maps, rather than specific color maps. </p> 2438 2439 2440<div style="margin: auto;"> 2441 <h4><a id="draw"></a>-draw <em class="arg">string</em></h4> 2442</div> 2443 2444<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with one or more graphic primitives.</td><td style='text-align:right;'></td></tr></table> 2445 2446<p>Use this option to annotate or decorate an image with one or more graphic primitives. The primitives include shapes, text, transformations, and pixel operations.</p> 2447 2448<p>The shape primitives:</p> 2449 2450<pre class="text"> 2451 point x,y 2452 line x0,y0 x1,y1 2453 rectangle x0,y0 x1,y1 2454 roundRectangle x0,y0 x1,y1 wc,hc 2455 arc x0,y0 x1,y1 a0,a1 2456 ellipse x0,y0 rx,ry a0,a1 2457 circle x0,y0 x1,y1 2458 polyline x0,y0 ... xn,yn 2459 polygon x0,y0 ... xn,yn 2460 bezier x0,y0 ... xn,yn 2461 path path specification 2462 image operator x0,y0 w,h filename 2463</pre> 2464 2465<p>The text primitive:</p> 2466 2467<pre class="text"> 2468 text x0,y0 string 2469</pre> 2470<p>The text gravity primitive:</p> 2471 2472<pre class="text"> 2473 gravity NorthWest, North, NorthEast, West, Center, 2474 East, SouthWest, South, or SouthEast 2475</pre> 2476 2477<p>The text gravity primitive only affects the placement of text and does not interact with the other primitives. It is equivalent to using the <a href="#gravity">-gravity</a> command-line option, except that it is limited in scope to the <a href="#draw">-draw</a> option in which it appears.</p> 2478 2479<p>The transformation primitives:</p> 2480 2481<pre class="text"> 2482 rotate degrees 2483 translate dx,dy 2484 scale sx,sy 2485 skewX degrees 2486 skewY degrees 2487</pre> 2488 2489<p>The pixel operation primitives:</p> 2490 2491<pre class="text"> 2492 color x0,y0 method 2493 matte x0,y0 method 2494</pre> 2495 2496<p>The shape primitives are drawn in the color specified by the preceding <a href="#fill">-fill</a> setting. For unfilled shapes, use <a href="#fill">-fill none</a>. You can optionally control the stroke (the "outline" of a shape) with the <a href="#stroke">-stroke</a> and <a href="#strokewidth">-strokewidth</a> settings.</p> 2497 2498<p>A <kbd>point</kbd> primitive is specified by a single <em>point</em> in the pixel plane, that is, by an ordered pair of integer coordinates, <em>x</em>,<em>y</em>. (As it involves only a single pixel, a <kbd>point</kbd> primitive is not affected by <a href="#stroke">-stroke</a> or <a href="#strokewidth">-strokewidth</a>.)</p> 2499 2500<p>A <kbd>line</kbd> primitive requires a start point and end point.</p> 2501 2502<p>A <kbd>rectangle</kbd> primitive is specified by the pair of points at the upper left and lower right corners.</p> 2503 2504<p>A <kbd>roundRectangle</kbd> primitive takes the same corner points as a <kbd>rectangle</kbd> followed by the width and height of the rounded corners to be removed.</p> 2505 2506<p>The <kbd>circle</kbd> primitive makes a disk (filled) or circle (unfilled). Give the center and any point on the perimeter (boundary).</p> 2507 2508<p>The <kbd>arc</kbd> primitive is used to inscribe an elliptical segment in to a given rectangle. An <kbd>arc</kbd> requires the two corners used for <kbd>rectangle</kbd> (see above) followed by the start and end angles of the arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end points produced are then joined with a line segment and the resulting segment of an ellipse is filled.</p> 2509 2510<p>Use <kbd>ellipse</kbd> to draw a partial (or whole) ellipse. Give the center point, the horizontal and vertical "radii" (the <em>semi-axes</em> of the ellipse) and start and end angles in degrees (e.g. 100,100 100,150 0,360).</p> 2511 2512<p>The <kbd>polyline</kbd> and <kbd>polygon</kbd> primitives require three or more points to define their perimeters. A <kbd>polyline</kbd> is simply a <kbd>polygon</kbd> in which the final point is not stroked to the start point. When unfilled, this is a <em>polygonal line</em>. If the <a href="#stroke">-stroke</a> setting is <kbd>none</kbd> (the default), then a <kbd>polyline</kbd> is identical to a <kbd>polygon</kbd>. 2513</p> 2514 2515<p>A <em>coordinate</em> is a pair of integers separated by a space or optional comma. </p> 2516 2517<p>As an example, to define a circle centered at 100,100 that extends to 150,150 use:</p> 2518 2519<p class="crtsnip"> 2520 -draw 'circle 100,100 150,150' 2521</p> 2522 2523<p>The <kbd>Bezier</kbd> primitive creates a spline curve and requires three or points to define its shape. The first and last points are the <em>knots</em> and these points are attained by the curve, while any intermediate coordinates are <em>control points</em>. If two control points are specified, the line between each end knot and its sequentially respective control point determines the tangent direction of the curve at that end. If one control point is specified, the lines from the end knots to the one control point determines the tangent directions of the curve at each end. If more than two control points are specified, then the additional control points act in combination to determine the intermediate shape of the curve. In order to 2524draw complex curves, it is highly recommended either to use the <kbd>path</kbd> primitive or to draw multiple four-point bezier segments with the start and end knots of each successive segment repeated. For example:</p> 2525 2526<p class="crtsnip"> 2527 -draw 'bezier 20,50 45,100 45,0 70,50' 2528</p> 2529<p class="crtsnip"> 2530 -draw 'bezier 70,50 95,100 95,0 120,50' 2531</p> 2532 2533 2534<p>A <kbd>path</kbd> represents an outline of an object, defined in terms of moveto (set a new current point), lineto (draw a straight line), curveto (draw a Bezier curve), arc (elliptical or circular arc) and closepath (close the current shape by drawing a line to the last moveto) elements. Compound paths (i.e., a path with subpaths, each consisting of a single moveto followed by one or more line or curve operations) are possible to allow effects such as <em>donut holes</em> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p> 2535 2536<p>Use <kbd>image</kbd> to composite an image with another image. Follow the image keyword with the composite operator, image location, image size, and filename:</p> 2537 2538<p class="crtsnip"> 2539 -draw 'image SrcOver 100,100 225,225 image.jpg' 2540</p> 2541 2542<p>You can use 0,0 for the image size, which means to use the actual 2543dimensions found in the image header. Otherwise, it is scaled to the given 2544dimensions. See <a href="/www/compose.html">Alpha Compositing</a> for 2545a detailed discussion of alpha composition methods that are available. </p> 2546 2547<p>Use <kbd>text</kbd> to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in single or double quotes.</p> 2548 2549<p>For example, the following annotates the image with <kbd>Works like magick!</kbd> for an image titled <kbd>bird.miff</kbd>. </p> 2550 2551<p class="crtsnip"> 2552 -draw 'text 100,100 "Works like magick!"' 2553</p> 2554 2555<p>See the <a href="#annotate">-annotate</a> option for another convenient way to annotate an image with text.</p> 2556 2557<p>The <kbd>rotate</kbd> primitive rotates subsequent shape primitives and text primitives about the origin of the main image. If the <a href="#region">-region</a> option precedes the <a href="#draw">-draw</a> option, the origin for transformations is the upper left corner of the region.</p> 2558 2559<p>The <kbd>translate</kbd> primitive translates subsequent shape and text primitives.</p> 2560 2561<p>The <kbd>scale</kbd> primitive scales them.</p> 2562 2563<p>The <kbd>skewX</kbd> and <kbd>skewY</kbd> primitives skew them with respect to the origin of the main image or the region.</p> 2564 2565<p>The transformations modify the current affine matrix, which is initialized from the initial affine matrix defined by the <a href="#affine">-affine</a> option. Transformations are cumulative within the <a href="#draw">-draw</a> option. The initial affine matrix is not affected; that matrix is only changed by the appearance of another <a href="#affine">-affine</a> option. If another <a href="#draw">-draw</a> option appears, the current affine matrix is reinitialized from the initial affine 2566matrix.</p> 2567 2568<p>Use the <kbd>color</kbd> primitive to change the color of a pixel to the fill color (see <a href="#fill">-fill</a>). Follow the pixel coordinate with a method:</p> 2569 2570<pre class="text"> 2571 point 2572 replace 2573 floodfill 2574 filltoborder 2575 reset 2576</pre> 2577 2578<p>Consider the target pixel as that specified by your coordinate. The <kbd>point</kbd> method recolors the target pixel. The <kbd>replace</kbd> method recolors any pixel that matches the color of the target pixel. <kbd>Floodfill</kbd> recolors any pixel that matches the color of the target pixel and is a neighbor, whereas <kbd>filltoborder</kbd> recolors any neighbor pixel that is not the border color. Finally, <kbd>reset</kbd> recolors all pixels.</p> 2579 2580<p>Use <kbd>matte</kbd> to the change the pixel matte value to transparent. Follow the pixel coordinate with a method (see the <kbd>color</kbd> primitive for a description of methods). The <kbd>point</kbd> method changes the matte value of the target pixel. The <kbd>replace</kbd> method changes the matte value of any pixel that matches the color of the target pixel. <kbd>Floodfill</kbd> changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas <kbd>filltoborder</kbd> changes the matte value of any neighbor pixel that is not the border color (<a href="#bordercolor">-bordercolor</a>). Finally <kbd>reset</kbd> changes the matte value of all pixels.</p> 2581 2582<p>You can set the primitive color, font, and font bounding box color with <a href="#fill">-fill</a>, <a href="#font">-font</a>, and <a href="#box">-box</a> respectively. Options are processed in command line order so be sure to use these options <em>before</em> the <a href="#draw">-draw</a> option.</p> 2583 2584<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather than 1.png).</p> 2585 2586<p>Drawing primitives conform to the <a href="/www/magick-vector-graphics.html">Magick Vector Graphics</a> format.</p> 2587 2588<div style="margin: auto;"> 2589 <h4><a id="duplicate"></a>-duplicate <em class="arg">count,indexes</em></h4> 2590</div> 2591 2592<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>duplicate an image one or more times.</td><td style='text-align:right;'></td></tr></table> 2593 2594<p>Specify the count and the image to duplicate by its index in the sequence. The first image is index 0. Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Specify a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use <kbd>+duplicate</kbd> to duplicate the last image in the current image sequence.</p> 2595 2596<div style="margin: auto;"> 2597 <h4><a id="edge"></a>-edge <em class="arg">radius</em></h4> 2598</div> 2599 2600<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect edges within an image.</td><td style='text-align:right;'></td></tr></table> 2601 2602<div style="margin: auto;"> 2603 <h4><a id="emboss"></a>-emboss <em class="arg">radius</em></h4> 2604</div> 2605 2606<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>emboss an image.</td><td style='text-align:right;'></td></tr></table> 2607 2608<div style="margin: auto;"> 2609 <h4><a id="encipher"></a>-encipher <em class="arg">filename</em></h4> 2610</div> 2611 2612<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Encipher pixels for later deciphering by <a href="#decipher">-decipher</a>.</td><td style='text-align:right;'></td></tr></table> 2613 2614<p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p> 2615 2616<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p> 2617 2618 2619 2620<div style="margin: auto;"> 2621 <h4><a id="encoding"></a>-encoding <em class="arg">type</em></h4> 2622</div> 2623 2624<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the text encoding.</td><td style='text-align:right;'></td></tr></table> 2625 2626<p>Choose from <kbd>AdobeCustom</kbd>, <kbd>AdobeExpert</kbd>, <kbd>AdobeStandard</kbd>, <kbd>AppleRoman</kbd>, <kbd>BIG5</kbd>, <kbd>GB2312</kbd>, <kbd>Latin 2</kbd>, <kbd>None</kbd>, <kbd>SJIScode</kbd>, <kbd>Symbol</kbd>, <kbd>Unicode</kbd>, <kbd>Wansung</kbd>.</p> 2627 2628<div style="margin: auto;"> 2629 <h4><a id="endian"></a>-endian <em class="arg">type</em></h4> 2630</div> 2631 2632<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify endianness (<kbd>MSB</kbd> or <kbd>LSB</kbd>) of the image.</td><td style='text-align:right;'></td></tr></table> 2633 2634<p>To print a complete list of endian types, use the <a href="#list">-list endian</a> option.</p> 2635 2636<p>Use <a href="#endian">+endian</a> to revert to unspecified endianness.</p> 2637 2638 2639<div style="margin: auto;"> 2640 <h4><a id="enhance"></a>-enhance</h4> 2641</div> 2642 2643<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a digital filter to enhance a noisy image.</td><td style='text-align:right;'></td></tr></table> 2644 2645 2646<div style="margin: auto;"> 2647 <h4><a id="equalize"></a>-equalize</h4> 2648</div> 2649 2650<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform histogram equalization on the image channel-by-channel.</td><td style='text-align:right;'></td></tr></table> 2651 2652<p>To perform histogram equalization on all channels in concert, transform the image into some other color space, such as HSL, OHTA, YIQ or YUV, then equalize the appropriate intensity-like channel, then convert back to RGB.</p> 2653 2654<p>For example using HSL, we have: ... <kbd>-colorspace HSL -channel lightness -equalize -colorspace RGB</kbd> ...</p> 2655 2656<p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal components transformation that puts most of the information in the first channel. Here we have ... <kbd>-colorspace OHTA -channel red -equalize -colorspace RGB</kbd> ...</p> 2657 2658<div style="margin: auto;"> 2659 <h4><a id="evaluate"></a>-evaluate <em class="arg">operator value</em></h4> 2660</div> 2661 2662<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</td><td style='text-align:right;'></td></tr></table> 2663 2664<p>(See the <a href="#function" >-function</a> operator for some multi-parameter functions. See the <a href="#fx" >-fx</a> operator if more elaborate calculations are needed.)</p> 2665 2666<p>The behaviors of each <em class="arg">operator</em> are summarized in the following list. For brevity, the numerical value of a "pixel" referred to below is the value of the corresponding channel of that pixel, while a "normalized pixel" is that number divided by the maximum (installation-dependent) value <em class="QR">QuantumRange</em>. (If normalized pixels are used, they are restored, following the other calculations, to the full range by multiplying by <em class="QR">QuantumRange</em>.)</p> 2667 2668<table class="doc"> 2669 <col width="25%" /> 2670 <col width="75%" /> 2671 <thead> 2672 <tr> 2673 <th><em class="arg">operator</em></th> 2674 <th>Summary (see further below for details)</th> 2675 </tr> 2676 </thead> 2677 <tbody> 2678 2679 <tr><td>Abs </td> <td>Add <em class="arg">value</em> to pixels and return absolute value. </td></tr> 2680 <tr><td>Add </td> <td>Add <em class="arg">value</em> to pixels. </td></tr> 2681 <tr><td>AddModulus </td> <td>Add <em class="arg">value</em> to pixels modulo <em class="QR">QuantumRange</em>.</td></tr> 2682 <tr><td>And </td> <td>Binary AND of pixels with <em class="arg">value</em>.</td></tr> 2683 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr> 2684 <tr><td>Divide </td> <td>Divide pixels by <em class="arg">value</em>.</td></tr> 2685 <tr><td>Exp </td> <td>base-e exponential function</td></tr> 2686 <tr><td>Exponential </td> <td>base-e exponential function</td></tr> 2687 <tr><td>LeftShift </td> <td>Shift the pixel values left by <em class="arg">value</em> bits (i.e., multiply pixels by 2<sup><em class="arg">value</em></sup>).</td></tr> 2688 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr> 2689 <tr><td>Max </td> <td>Clip pixels at lower bound <em class="arg">value</em>.</td></tr> 2690 <tr><td>Mean </td> <td>Add the <em class="arg">value</em> and divide by 2.</td></tr> 2691 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr> 2692 <tr><td>Min </td> <td>Clip pixels at upper bound <em class="arg">value</em>.</td></tr> 2693 <tr><td>Multiply </td> <td>Multiply pixels by <em class="arg">value</em>.</td></tr> 2694 <tr><td>Or </td> <td>Binary OR of pixels with <em class="arg">value</em>.</td></tr> 2695 <tr><td>Pow </td> <td>Raise normalized pixels to the power <em class="arg">value</em>.</td></tr> 2696 <tr><td>RightShift </td> <td>Shift the pixel values right by <em class="arg">value</em> bits (i.e., divide pixels by 2<sup><em class="arg">value</em></sup>).</td></tr> 2697 <tr><td>Set </td> <td>Set pixel equal to <em class="arg">value</em>.</td></tr> 2698 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr> 2699 <tr><td>Subtract </td> <td>Subtract <em class="arg">value</em> from pixels.</td></tr> 2700 <tr><td>Xor </td> <td>Binary XOR of pixels with <em class="arg">value.</em></td></tr> 2701 2702 <tr><td> </td></tr> 2703 2704 <tr><td>Gaussian-noise</td></tr> 2705 <tr><td>Impulse-noise</td></tr> 2706 <tr><td>Laplacian-noise</td></tr> 2707 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="#noise" >-noise</a> operators.)</td></tr> 2708 <tr><td>PoissonNoise</td></tr> 2709 <tr><td>Uniform-noise</td></tr> 2710 2711 <tr><td> </td></tr> 2712 2713 <tr><td>Threshold </td> <td>Threshold pixels larger than <em class="arg">value</em>.</td></tr> 2714 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <em class="arg">value</em>.</td></tr> 2715 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <em class="arg">value</em>. </td></tr> 2716 </tbody> 2717 </table> 2718 2719<p>The specified functions are applied only to each previously set <a 2720href="#channel" >-channel</a> in the image. If necessary, the results of the 2721calculations are truncated (clipped) to fit in the interval [0, <em 2722class="QR">QuantumRange</em>]. The transparency channel of the image is 2723represented as a 'alpha' values (0 = fully transparent), so, for example, a 2724<kbd>Divide</kbd> by 2 of the alpha channel will make the image 2725semi-transparent. Append the percent symbol '<kbd>%</kbd>' to specify a value 2726as a percentage of the <em class="QR">QuantumRange</em>.</p> 2727 2728<p>To print a complete list of <a href="#evaluate">-evaluate</a> operators, use 2729<a href="#list">-list evaluate</a>.</p> 2730 2731<p>The results of the <kbd>Add</kbd>, <kbd>Subtract</kbd> and 2732<kbd>Multiply</kbd> methods can also be achieved using either the <a 2733href="#level" >-level</a> or the <a href="#level" >+level</a> operator, with 2734appropriate argument, to linearly modify the overall range of color values. 2735Please note, however, that <a href="#level" >-level</a> treats transparency as 2736'matte' values (0 = opaque), while <a href="#level" >-evaluate</a> works with 2737'alpha' values.</p> 2738 2739<p><kbd>AddModulus</kbd> has been added as of ImageMagick 6.4.8-4 and provides addition modulo the <em class="QR">QuantumRange</em>. It is therefore equivalent to <kbd>Add</kbd> unless the resulting pixel value is outside the interval [0, <em class="QR">QuantumRange</em>]. </p> 2740 2741<p><kbd>Exp or Exponential</kbd> has been added as of ImageMagick 6.6.5-1 and works on normalized pixel values. The <em class="arg">value</em> used with <kbd>Exp</kbd> should be negative so as to produce a decaying exponential function. Non-negative values will always produce results larger unity and thus outside the interval [0, <em class="QR">QuantumRange</em>]. The formula is expressed below. </p> 2742 2743 <div style="text-align:center;"> 2744 exp(<em class="arg">value</em> × <b><em>u</em></b>) 2745 </div> 2746 2747<p> If the input image is squared, for example, using <a 2748href="#-function" >-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be the result.</p> 2749 2750<p><kbd>Log</kbd> has been added as of ImageMagick 6.4.2-1 and works on normalized pixel values. This a <em>scaled</em> log function. The <em class="arg">value</em> used with <kbd>Log</kbd> provides a <em>scaling factor</em> that adjusts the curvature in the graph of the log function. The formula applied to a normalized value <b><em>u</em></b> is below. </p> 2751 2752 <div style="text-align:center;"> 2753 log(<em class="arg">value</em> × <b><em>u</em></b> + 1) / log(<em class="arg">value</em> + 1) 2754 </div> 2755 2756<p><kbd>Pow</kbd> has been added as of ImageMagick 6.4.1-9, and works on 2757normalized pixel values. Note that <kbd>Pow</kbd> is related to the <a 2758href="#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent 2759to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used 2760with <a href="#gamma" >-gamma</a> is simply the reciprocal of the value used 2761with <kbd>Pow</kbd>.</p> 2762 2763<p><kbd>Cosine</kbd> and <kbd>Sine</kbd> was added as of IM v6.4.8-8 and 2764converts the image values into a value according to a (co)sine wave function. 2765The synonyms <kbd>Cos</kbd> and <kbd>Sin</kbd> may also be used. The output 2766is biased 50% and normalized by 50% so as to fit in the respective color value 2767range. The <em class="arg">value</em> scaling of the <em>period</em> of the 2768function (its frequency), and thus determines the number of 'waves' that will 2769be generated over the input color range. For example, if the <em 2770class="arg">value</em> is 1, the effective period is simply the <em 2771class="QR">QuantumRange</em>; but if the <em class="arg">value</em> is 2, 2772then the effective period is the <em>half</em> the <em 2773class="QR">QuantumRange</em>.</p> 2774 2775 <div style="text-align:center;"> 2776 0.5 + 0.5 × cos(2 π <b><em>u</em></b> × <em class="arg">value</em>). 2777 </div> 2778 2779<p>See also the <a href="#function" >-function</a> operator, which is a 2780multi-value version of evaluate. </p> 2781 2782<div style="margin: auto;"> 2783 <h4><a id="evaluate-sequence"></a>-evaluate-sequence <em class="arg">operator</em></h4> 2784</div> 2785 2786<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or logical expression over a sequence of images.</td><td style='text-align:right;'></td></tr></table> 2787 2788<div style="margin: auto;"> 2789 <h4><a id="extent"></a>-extent <em class="arg">geometry</em></h4> 2790</div> 2791 2792<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image size and offset.</td><td style='text-align:right;'></td></tr></table> 2793 2794<p>If the image is enlarged, unfilled areas are set to the background color. To position the image, use offsets in the <em class="arg">geometry</em> specification or precede with a <a href="#gravity">-gravity</a> setting. To specify how to compose the image with the background, use <a href="#compose" >-compose</a>.</p> 2795<p>This command reduces or expands a JPEG image to fit on an 800x600 2796display. If the aspect ratio of the input image isn't exactly 4:3, then the 2797image is centered on an 800x600 black canvas: </p> 2798 2799<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert input.jpg -resize 800x600 -background black -compose Copy \ <br /> -gravity center -extent 800x600 -quality 92 output.jpg</span></p> 2800 2801 2802<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 2803 2804<div style="margin: auto;"> 2805 <h4><a id="extract"></a>-extract <em class="arg">geometry</em></h4> 2806</div> 2807 2808<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Extract the specified area from image.</td><td style='text-align:right;'></td></tr></table> 2809 2810<p>This option is most useful for extracting a subregion of a very large raw image. Note that these two commands are equivalent:</p> 2811 2812<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \ <br/> image.rgb image.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \ <br/> image.rgb image.png</span></p><p>If you omit the offsets, as in</p> 2813 2814<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480 \ <br/> image.rgb image.png</span></p> 2815<p>the image is <em>resized</em> to the specified dimensions instead, 2816equivalent to:</p> 2817 2818<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png</span></p> 2819<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 2820 2821<div style="margin: auto;"> 2822 <h4><a id="family"></a>-family <em class="arg">fontFamily</em></h4> 2823</div> 2824 2825<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font family for text.</td><td style='text-align:right;'></td></tr></table> 2826 2827<p>This setting suggests a font family that ImageMagick should try to use for rendering text. If the family can be found it is used; if not, a default font (e.g., "Arial") or a family known to be similar is substituted (e.g., "Courier" might be used if "System" is requested but not found). 2828</p> 2829 2830<p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#stretch">-stretch</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>. 2831</p> 2832 2833<div style="margin: auto;"> 2834 <h4><a id="features"></a>-features <em class="arg">distance</em></h4> 2835</div> 2836 2837<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</td><td style='text-align:right;'></td></tr></table> 2838 2839<div style="margin: auto;"> 2840 <h4><a id="fft"></a>-fft</h4> 2841</div> 2842 2843<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the forward discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table> 2844 2845<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms an image from the normal (spatial) domain to the frequency domain. In the frequency domain, an image is represented as a superposition of complex sinusoidal waves of varying amplitudes. The image x and y coordinates are the possible frequencies along the x and y directions, respectively, and the pixel intensity values are complex numbers that correspond to the sinusoidal wave amplitudes. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p> 2846 2847<p>A single image name is provided as output for this option. However, the output result will have two components. It is either a two-frame image or two separate images, depending upon whether the image format specified supports multi-frame images. The reason that we get a dual output result is because the frequency domain represents an image using complex numbers, which cannot be visualized directly. Therefore, the complex values are automagically separated into a two-component image representation. The first component is the magnitude of the complex number and the second is the phase of the complex number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p> 2848 2849<p>The magnitude and phase component images must be specified using image formats that do not limit the color or compress the image. Thus, MIFF, TIF, PFM, EXR and PNG are the recommended image formats to use. All of these formats, except PNG support multi-frame images. So for example,</p> 2850 2851<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.miff</span></p> 2852<p>generates a magnitude image as <kbd>fft_image.miff[0]</kbd> and a phase image as <kbd>fft_image.miff[1]</kbd>. Similarly,</p> 2853 2854<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.png</span></p> 2855<p>generates a magnitude image as <kbd>fft_image-0.png</kbd> and a phase image as <kbd>fft_image-1.png</kbd>. If you prefer this representation, then you can force any of the other formats to produce two output images by including <a href="#adjoin">+adjoin</a> following -fft in the command line.</p> 2856 2857<p>The input image can be any size, but if not square and even-dimensioned, it is padded automagically to the larger of the width or height of the input image and to an even number of pixels. The padding will occur at the bottom and/or right sides of the input image. The resulting output magnitude and phase images is square at this size. The kind of padding relies on the <a href="#virtual-pixel">-virtual-pixel</a> setting.</p> 2858 2859<p>Both output components will have dynamic ranges that fit within [0, <em class="QR">QuantumRange</em>], so that HDRI need not be enabled. Phase values nominally range from 0 to 2*π, but for non-HDRI compilations of ImageMagick, the phase image is scaled to span the full dynamic range. The magnitude image is not scaled and thus generally will contain very small values. As such, the image normally will appear totally black. In order to view any detail, the magnitude image typically is enhanced with a log function into what is usually called the spectrum. A log function is used to enhance the darker values more in comparison to the lighter values. This can be done, for example, as follows:</p> 2860 2861<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff[0] -contrast-stretch 0 \ <br /> 2862 -evaluate log 1000 fft_image_spectrum.png</span></p> 2863<p>where the <a href="#contrast-stretch">-contrast-stretch</a> 0 is used to scale the image to full dynamic range, first. The argument to the <a href="#evaluate">-evaluate</a> log typically is specified between 100 and 10,000, depending upon the amount of detail that one wants to bring out in the spectrum. Larger values produce more visible detail. Too much detail, however, may hide the important features.</p> 2864 2865<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to use <a href="#fft">-fft</a>.</p> 2866 2867<p>Use <a href="#fft">+fft</a> to produce two output images that are the real and imaginary components of the complex valued Fourier transform.</p> 2868 2869<p>However, as the real and imaginary components can contain negative values, this requires that IM be configured with HDRI enabled. In this case, you must use either MIFF, TIF or PFM formats for the real and imaginary component results, since they are formats that preserve both negative and fractional values without clipping them or truncating the fractional part.</p> 2870 2871<p>The real and imaginary component images resulting from <a href="#fft">+fft</a> is also square, even dimensioned images due to the same padding that was discussed above for the magnitude and phase component images.</p> 2872 2873<p>See the discussion on HDRI implementations of ImageMagick on the page 2874<a href="/www/high-dynamic-range.html">High Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> entry. 2875</p> 2876 2877 2878<div style="margin: auto;"> 2879 <h4><a id="fill"></a>-fill <em class="arg">color</em></h4> 2880</div> 2881 2882<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when filling a graphic primitive.</td><td style='text-align:right;'></td></tr></table> 2883 2884<p>This option accepts a color name, a hex color, or a numerical RGB, RGBA, HSL, HSLA, CMYK, or CMYKA specification. See <a href="/www/color.html">Color Names</a> for a description of how to properly specify the color argument.</p> 2885 2886<p>Enclose the color specification in quotation marks to prevent the "#" or the parentheses from being interpreted by your shell.</p> 2887 2888<p>For example,</p> 2889 2890<p class="crtsnip"> 2891 -fill blue 2892</p> 2893<p class="crtsnip"> 2894 -fill "#ddddff" 2895</p> 2896<p class="crtsnip"> 2897 -fill "rgb(255,255,255)" 2898</p> 2899 2900<p>See <a href="#draw">-draw</a> for further details.</p> 2901 2902<p>To print a complete list of color names, use the <a href="#list">-list color</a> option.</p> 2903 2904<div style="margin: auto;"> 2905 <h4><a id="filter"></a>-filter <em class="arg">type</em></h4> 2906</div> 2907 2908<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use this <em class="arg">type</em> of filter when resizing or 2909distorting an image.</td><td style='text-align:right;'></td></tr></table> 2910 2911<p>Use this option to affect the resizing operation of an image during 2912operations such as <a href="#resize">-resize</a> and <a href="#distort" 2913>-distort</a>. For example you can use a simple resize filter such as:</p> 2914 2915<pre class="text"> 2916 Point Hermite Cubic 2917 Box Gaussian Catrom 2918 Triangle Quadratic Mitchell 2919</pre> 2920 2921<p>The <kbd>Bessel</kbd> and <kbd>Sinc</kbd> filter is also provided (as well 2922as a faster <kbd>SincFast</kbd> equivalent form). However these filters are 2923generally useless on their own as they are infinite filters that are being 2924clipped to the filters support size. Their direct use is not recommended 2925except via expert settings (see below). </p> 2926 2927<p>Instead these special filter functions are typically windowed by a windowing 2928function that the <a href="#filter" >-filter</a> setting defines. That is 2929using these functions will define a 'Windowed' filter, appropriate to the 2930operator involved. Windowed filters include: </p> 2931 2932<pre class="text"> 2933 Lanczos Hamming Parzen 2934 Blackman Kaiser Welsh 2935 Hanning Bartlett Bohman 2936</pre> 2937 2938<p>Also one special self-windowing filter is also provided 2939<kbd>Lagrange</kbd>, which will automagically re-adjust its function depending 2940on the current 'support' or 'lobes' expert settings (see below).</p> 2941 2942<p>If you do not select a filter with this option, the filter defaults to 2943<kbd>Mitchell</kbd> for a colormapped image, a image with a matte channel, or 2944if the image is enlarged. Otherwise the filter default to 2945<kbd>Lanczos</kbd>.</p> 2946 2947<p>To print a complete list of resize filters, use the <a href="#list">-list 2948filter</a> option.</p> 2949 2950<p>You can modify how the filter behaves as it scales your image through the 2951use of these expert settings (see also <a href="#define" >-define</a> and <a 2952href="#set" >-set</a>):-</p> 2953 2954<dl class="doc"> 2955<dt>-define filter:blur=<em>factor</em></dt> 2956<dd>Scale the X axis of the filter (and its window). Use > 1.0 for 2957 blurry or < 1.0 for sharp. This should only be used with Gaussian and 2958 Gaussian-like filters simple filters, or you may not get the expected 2959 results. </dd> 2960 2961<dt>-define filter:support=<em>radius</em></dt> 2962<dd>Set the filter support radius. Defines how large the filter should be and 2963 thus directly defines how slow the filtered resampling process is. All 2964 filters have a default 'prefered' support size. Some filters like 2965 <kbd>Lagrange</kbd> and windowed filters adjust themselves depending on 2966 this value. With simple filters this value either does nothing (but slow 2967 the resampling), or will clip the filter function in a detrimental way. 2968 </dd> 2969 2970<dt>-define filter:lobes=<em>count</em></dt> 2971<dd>Set the number of lobes to use for the Sinc/Bessel filter. This an 2972 alternative way of specifying the 'support' range of the filter, that is 2973 designed to be more suited to windowed filters, especially when used for 2974 image distorts.</dd> 2975 2976<dt>-define filter:b=<em>b-spline_factor</em></dt> 2977<dt>-define filter:c=<em>keys_alpha_factor</em></dt> 2978<dd>Redefine the values used for cubic filters such as <kbd>Cubic</kbd>, 2979 <kbd>Catrom</kbd>, <kbd>Mitchel</kbd>, and <kbd>Hermite</kbd>, as well as 2980 the <kbd>Parzen</kbd> Sinc windowing function. If only one of the values 2981 are defined, the other is set so as to generate a 'Keys' type cubic 2982 filter. Values meaning was defined by a research paper by 2983 Mitchell-Netravali.</dd> 2984 2985<dt>-define filter:filter=<em>filter_function</em></dt> 2986<dd>Use this function directly as the scaling filter. This will allow 2987 you to directly use a windowing filter such as <kbd>Blackman</kbd>, 2988 rather than as its normal usage as a windowing function for 'Sinc' or 2989 'Bessel' functions. If defined, no windowing function is used, unless the 2990 following expert setting is also defined.</dd> 2991 2992<dt>-define filter:window=<em>filter_function</em></dt> 2993<dd>The IIR (infinite impulse response) filters <kbd>Bessel</kbd> and 2994 <kbd>Sinc</kbd> are windowed (brought down to zero over the defined 2995 support range) with the given filter. This allows you to specify a filter 2996 function that is not normally used as a windowing function, such as 2997 <kbd>Box</kbd>, (which effectively turns off the windowing function), 2998 to window a <kbd>Sinc</kbd>, or the function the previous setting defined. 2999 </dd> 3000 3001<dt>-define filter:verbose=<em>1</em></dt> 3002<dd>This causes IM to print information on the final internal filter 3003 selection to standard output. This includes a commented header on the 3004 filter settings being used, and data allowing the filter weights to be 3005 easily graphed. </dd> 3006 3007<dd>Note however that some filters are internally defined in terms of other 3008 filters. The <kbd>Lanczos</kbd> filter for example is defined in terms of 3009 a <kbd>SincFast</kbd> windowed <kbd>SincFast</kbd> filter, while 3010 <kbd>Mitchell</kbd> is defined as a <kbd>Cubic</kbd> filter with specific 3011 'B' and 'C' settings. </dd> 3012 3013</dl> 3014 3015<p>For example, to get a 8 lobe Bessel windowed Bessel filter:</p> 3016 3017<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -filter bessel \ <br/> 3018 -set filter:window=bessel -set filter:lobes=8 \ <br/> 3019 -resize 150% image.jpg</span></p> 3020<p>Or a raw un-windowed Sinc filter with 4 lobes:</p> 3021 3022<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -set filter:filter=sinc -set filter:lobes=4 \ <br/> 3023 -resize 150% image.jpg</span></p> 3024<p>Note that the use of expert options (except for 'blur' with simple resize 3025filters, and 'verbose' for viewing the internal filter selection), are 3026provided for image processing experts who have studied and understood how 3027resize filters work. Without this knowledge, and an understanding of the 3028definition of the actual filters involved, using expert settings are more 3029likely to be detrimental to your image resizing.</p> 3030 3031 3032<div style="margin: auto;"> 3033 <h4><a id="flatten"></a>-flatten</h4> 3034</div> 3035 3036<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>This is a simple alias for the <a href="#layers" >-layers</a> method "flatten".</td><td style='text-align:right;'></td></tr></table> 3037 3038 3039<div style="margin: auto;"> 3040 <h4><a id="flip"></a>-flip</h4> 3041</div> 3042 3043<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table> 3044 3045<p>reflect the scanlines in the vertical direction.</p> 3046 3047<div style="margin: auto;"> 3048 <h4><a id="floodfill"></a>-floodfill {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em> <em class="arg">color</em></h4> 3049</div> 3050 3051<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>floodfill the image with color at the specified offset. Using <a href="#fuzz" >-fuzz</a> to floodfill pixels which only change by a small amount.</td><td style='text-align:right;'></td></tr></table> 3052 3053<div style="margin: auto;"> 3054 <h4><a id="flop"></a>-flop</h4> 3055</div> 3056 3057<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table> 3058 3059<p>reflect the scanlines in the horizontal direction.</p> 3060 3061 3062<div style="margin: auto;"> 3063 <h4><a id="font"></a>-font <em class="arg">name</em></h4> 3064</div> 3065 3066<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the font to use when annotating images with text, or creating labels.</td><td style='text-align:right;'></td></tr></table> 3067 3068<p>To print a complete list of fonts, use the <a href="#list">-list font</a> option (for versions prior to 6.3.6, use 'type' instead of 'font').</p> 3069 3070<p>In addition to the fonts specified by the above pre-defined list, you can 3071also specify a font from a specific source. For example <kbd>Arial.ttf</kbd> 3072is a TrueType font file, <kbd>ps:helvetica</kbd> is PostScript font, and 3073<kbd>x:fixed</kbd> is X11 font.</p> 3074 3075<p>For other settings that affect fonts, see the options <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>. </p> 3076 3077 3078<div style="margin: auto;"> 3079 <h4><a id="foreground"></a>-foreground <em class="arg">color</em></h4> 3080</div> 3081 3082<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the foreground color.</td><td style='text-align:right;'></td></tr></table> 3083 3084<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 3085 3086<p>The default foreground color is black.</p> 3087 3088<div style="margin: auto;"> 3089 <h4><a id="format"></a>-format <em class="arg">type</em></h4> 3090</div> 3091 3092<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image format type.</td><td style='text-align:right;'></td></tr></table> 3093 3094<p>When used with the <kbd>mogrify</kbd> utility, this option converts any image to the image <a href="/www/formats.html">format</a> you specify. For a list of image format types supported by ImageMagick, use <a href="#list">-list format</a>.</p> 3095 3096<p>By default the file is written to its original name. However, if the filename extension matches a supported format, the extension is replaced with the image format type specified with <a href="#format">-format</a>. For example, if you specify <em class="arg">tiff</em> as the format type and the input image filename is <em class="arg">image.gif</em>, the output image filename becomes <em class="arg">image.tiff</em>.</p> 3097 3098<div style="margin: auto;"> 3099 <h4><a id="format_identify_"></a>-format <em class="arg">string</em></h4> 3100</div> 3101 3102<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>output formatted image characteristics.</td><td style='text-align:right;'>[<a href="/www/identify.html">identify</a>]</td></tr></table> 3103 3104<p>See <a href="/www/escape.html">Format and Print Image Properties</a> for an explanation on how to specify the argument to this option.</p> 3105 3106<div style="margin: auto;"> 3107 <h4><a id="frame"></a>-frame <em class="arg">geometry</em></h4> 3108</div> 3109 3110<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border or beveled frame.</td><td style='text-align:right;'></td></tr></table> 3111 3112<p>The color of the border is specified with the <a href="#mattecolor" 3113>-mattecolor</a> command line option. </p> 3114 3115<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">size</em> portion of the <em 3116class="arg">geometry</em> argument indicates the amount of extra width and 3117height that is added to the dimensions of the image. If no offsets are given 3118in the <em class="arg">geometry</em> argument, then the border added is 3119a solid color. Offsets <em>x</em> and <em>y</em>, if present, specify that 3120the width and height of the border is partitioned to form an outer bevel of 3121thickness <em>x</em> pixels and an inner bevel of thickness 3122<em>y</em> pixels. Negative offsets make no sense as frame arguments. 3123</p> 3124 3125<p>The <a href="#frame">-frame</a> option is affected by the current <a 3126href="#compose">-compose</a> setting and assumes that this is using the default 3127'<kbd>Over</kbd>' composition method. It generates a image of the appropriate 3128size with the current <a href="#bordercolor">-bordercolor</a> setting, and then 3129draws the frame of four distinct colors close to the current <a 3130href="#mattecolor">-mattecolor</a>. The original image is then overlaid onto 3131center of this image. This means that with the default compose method of 3132'<kbd>Over</kbd>' any transparent parts may be replaced by the current <a 3133href="#bordercolor">-bordercolor</a> setting.</p> 3134 3135<p>The image composition is not 3136affected by the <a href="#gravity">-gravity</a> option.</p> 3137 3138 3139<div style="margin: auto;"> 3140 <h4><a id="frame_import_"></a>-frame</h4> 3141</div> 3142 3143<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>include the X window frame in the imported image.</td><td style='text-align:right;'>[<a href="/www/import.html">import</a>]</td></tr></table> 3144 3145<div style="margin: auto;"> 3146 <h4><a id="function"></a>-function <em class="arg">function</em> <em class="arg">parameters</em></h4> 3147</div> 3148 3149<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a function to channel values.</td><td style='text-align:right;'></td></tr></table> 3150 3151<p>This operator performs calculations based on the given arguments to modify each of the color values for each previously set <a href="#channel">-channel</a> in the image. See <a href="#evaluate">-evaluate</a> for details concerning how the results of the calculations are handled.</p> 3152 3153<p>This is can be considered a multi-argument version of the <a href="#evaluate">-evaluate</a> operator. (Added in ImageMagick 6.4.8−8.)</p> 3154 3155<p>Here, <em class="arg">parameters</em> is a comma-separated list of numerical values. The number of values varies depending on which <em class="arg">function</em> is selected. Choose the <em class="arg">function</em> from:</p> 3156 3157<pre class="text"> 3158 Polynomial 3159 Sinusoid 3160 Arcsin 3161 Arctan 3162</pre> 3163 3164<p>To print a complete list of <a href="#function">-function</a> operators, use <a href="#list">-list function</a>. Descriptions follow.</p> 3165 3166<dl class="doc"> 3167<dt><kbd>Polynomial</kbd></dt> 3168<dd> 3169<p>The <kbd>Polynomial</kbd> function takes an arbitrary number of parameters, these being the coefficients of a polynomial, in decreasing order of degree. That is, entering</p> 3170 3171<div style="text-align: center"> 3172 -function Polynomial <em>a</em><sub><em>n</em></sub>,<em>a</em><sub><em>n</em>-1</sub>,...<em>a</em><sub>1</sub>,<em>a</em><sub>0</sub> 3173</div> 3174 3175<p>will invoke a polynomial function given by</p> 3176 3177<div style="text-align: center"> 3178 <em>a</em><sub><em>n</em></sub> <b><em>u</em></b><sup><em>n</em></sup> + 3179 <em>a</em><sub><em>n</em>-1</sub> <b><em>u</em></b><sup><em>n</em>-1</sup> + 3180 ··· <em>a</em><sub>1</sub> <b><em>u</em></b> + <em>a</em><sub>0</sub>, 3181</div> 3182 3183<p>where <b><em>u</em></b> is pixel's original normalized channel value.</p> 3184 3185<p>The <kbd>Polynomial</kbd> function can be used in place of <kbd>Set</kbd> (the <em>constant</em> polynomial) and <kbd>Add</kbd>, <kbd>Divide</kbd>, <kbd>Multiply</kbd>, and <kbd>Subtract</kbd> (some <em>linear</em> polynomials) of the <a href="#evaluate">-evaluate</a> operator. The <a href="#level">-level</a> operator also affects channels linearly. Some correspondences follow.</p> 3186 3187<table class="doc"> 3188 <col width="35%" /> 3189 <col width="35%" /> 3190 <col width="30%" /> 3191 <tr> 3192 <td>-evaluate Set <em class="arg">value</em> </td> 3193 <td>-function Polynomial <em class="arg">value</em></td> 3194 <td>(Constant functions; set <em class="arg">value</em>×100% gray when channels are RGB.)</td> 3195 </tr> 3196 <tr> 3197 <td>-evaluate Add <em class="arg">value</em> </td> 3198 <td>-function Polynomial 1,<em class="arg">value</em></td> 3199 </tr> 3200 <tr> 3201 <td>-evaluate Subtract <em class="arg">value</em> </td> 3202 <td>-function Polynomial 1,−<em class="arg">value</em></td> 3203 </tr> 3204 <tr> 3205 <td>-evaluate Multiply <em class="arg">value</em> </td> 3206 <td>-function Polynomial <em class="arg">value</em>,0</td> 3207 </tr> 3208 <tr> 3209 <td>+level black% x white%</td> 3210 <td>-function Polynomial A,B</td> 3211 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td> 3212 </tr> 3213</table> 3214 3215<p>The <kbd>Polynomial</kbd> function gives great versatility, since polynomials can be used to fit any continuous curve to any degree of accuracy desired.</p> 3216</dd> 3217 3218<dt><kbd>Sinusoid</kbd></dt> 3219<dd> 3220<p>The <kbd>Sinusoid</kbd> function can be used to vary the channel values sinusoidally by setting frequency, phase shift, amplitude, and a bias. These values are given as one to four parameters, as follows,</p> 3221 3222<div style="text-align: center"> 3223 -function <kbd>Sinusoid</kbd> <em class="arg">freq</em>,[<em class="arg">phase</em>,[<em class="arg">amp</em>,[<em class="arg">bias</em>]]] 3224</div> 3225 3226<p>where <em>phase</em> is in degrees. (The domain [0,1] of the function corresponds to 0 through <em class="arg">freq</em>×360 degrees.) The result is that if a pixel's normalized channel value is originally <b><em>u</em></b>, its resulting normalized value is given by </p> 3227 3228<div style="text-align: center"> 3229<em class="arg">amp</em> * sin(2*π* (<em class="arg">freq</em> * <b><em>u</em></b> + <em class="arg">phase</em> / 360)) + <em class="arg">bias</em> 3230</div> 3231 3232<p> For example, the following generates a curve that starts and ends at 0.9 (when <b><em>u</em></b>=0 and 1, resp.), oscillating three times between .7−.2=.5 and .7+.2=.9. </p> 3233 3234<p class="crtsnip"> 3235 -function Sinusoid 3,-90,.2,.7 3236</p> 3237 3238<p>The default values of <em class="arg">amp</em> and <em class="arg">bias</em> are both .5. The default for <em class="arg">phase</em> is 0.</p> 3239 3240<p>The <kbd>Sinusoid</kbd> function generalizes <kbd>Sin</kbd> and <kbd>Cos</kbd> of the <a href="#evaluate">-evaluate</a> operator by allowing varying amplitude, phase and bias. The correspondence is as follows.</p> 3241 3242<table class="doc"> 3243 <tr> 3244 <td>-evaluate Sin <em class="arg">freq</em> </td> 3245 <td>-function Sinusoid <em class="arg">freq</em>,0 </td> 3246 </tr> 3247 <tr> 3248 <td>-evaluate Cos <em class="arg">freq</em> </td> 3249 <td>-function Sinusoid <em class="arg">freq</em>,90 </td> 3250 </tr> 3251</table> 3252</dd> 3253 3254<dt><kbd>ArcSin</kbd></dt> 3255<dd> 3256<p>The <kbd>ArcSin</kbd> function generates the inverse curve of a Sinusoid, 3257and can be used to generate cylindrical distortion and displacement maps. 3258The curve can be adjusted relative to both the input values and output range 3259of values.</p> 3260 3261<p style="text-align: center"> 3262 -function <kbd>ArcSin</kbd> <em class="arg">width</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]] 3263</p> 3264 3265<p>with all values given in terms of noramlize color values (0.0 for black, 32661.0 for white). Defaulting to values covering the full range from 0.0 to 1.0 3267for bout input (<em class="arg">width</em>), and output (<em 3268class="arg">width</em>) values. '<code>1.0,0.5,1.0,0.5</code>' </p> 3269 3270<p style="text-align: center"> 3271<em class="arg">range</em>/π * asin( 2/<em class="arg">width</em> * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em> 3272</p> 3273 3274</dd> 3275 3276<dt><kbd>ArcTan</kbd></dt> 3277<dd> 3278<p>The <kbd>ArcTan</kbd> function generates a curve that smooth crosses from 3279limit values at infinities, though a center using the given slope value. 3280All these values can be adjusted via the arguments.</p> 3281 3282<p style="text-align: center"> 3283 -function <kbd>ArcTan</kbd> <em class="arg">slope</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]] 3284</p> 3285 3286<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'. 3287</p> 3288 3289<p style="text-align: center"> 3290<em class="arg">range</em>/π * atan( <em class="arg">slope</em>*π * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em> 3291</p> 3292 3293</dd> 3294 3295</dl> 3296 3297 3298<div style="margin: auto;"> 3299 <h4><a id="fuzz"></a>-fuzz <em class="arg">distance</em>{<em class="arg">%</em>}</h4> 3300</div> 3301 3302<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colors within this <em class="arg">distance</em> are considered equal.</td><td style='text-align:right;'></td></tr></table> 3303 3304<p>A number of algorithms search for a target color. By default the color must be exact. Use this option to match colors that are close to the target color in RGB space. For example, if you want to automagically trim the edges of an image with <a href="#trim">-trim</a> but the image was scanned and the target background color may differ by a small amount. This option can account for these differences.</p> 3305 3306<p>The <em class="arg">distance</em> can be in absolute intensity units or, by appending <kbd>%</kbd> as a percentage of the maximum possible intensity (255, 65535, or 4294967295).</p> 3307 3308 3309<div style="margin: auto;"> 3310 <h4><a id="fx"></a>-fx <em class="arg">expression</em></h4> 3311</div> 3312 3313<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a mathematical expression to an image or image channels.</td><td style='text-align:right;'></td></tr></table> 3314 3315<p>If the first character of <em class="arg">expression</em> is <kbd>@</kbd>, the expression is read from a file titled by the remaining characters in the string.</p> 3316 3317<p>See <a href="/www/fx.html">FX, The Special Effects Image Operator</a> for a detailed discussion of this option.</p> 3318 3319 3320<div style="margin: auto;"> 3321 <h4><a id="gamma"></a>-gamma <em class="arg">value</em></h4> 3322</div> 3323 3324<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>level of gamma correction.</td><td style='text-align:right;'></td></tr></table> 3325 3326<p>The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference. Reasonable values extend from <kbd>0.8</kbd> to <kbd>2.3</kbd>. Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it. Large adjustments to image gamma may result in the loss of some image information if the pixel quantum size is only eight bits (quantum range 0 to 255).</p> 3327 3328<p>Gamma adjusts the image's channel values pixel-by-pixel according to a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the normalized or 0 to 1 color value. For example, using a value of gamma=2 is the same as taking the square root of the image.</p> 3329 3330<p>You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delimited with commas (e.g., <kbd>1.7,2.3,1.2</kbd>).</p> 3331 3332<p>Use <a href="#gamma">+gamma <em class="arg">value</em></a> to set the image gamma level without actually adjusting the image pixels. This option is useful if the image is of a known gamma but not set as an image attribute (e.g. PNG images).</p> 3333 3334<p>Note that gamma adjustments are also available via the <a href="#level">-level</a> operator.</p> 3335 3336<div style="margin: auto;"> 3337 <h4><a id="gaussian-blur"></a>-gaussian-blur <em class="arg">radius</em><br />-gaussian-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4> 3338</div> 3339 3340<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur the image with a Gaussian operator.</td><td style='text-align:right;'></td></tr></table> 3341 3342<p>Convolve the image with a Gaussian or normal distribution using the given 3343<em class="arg" >Sigma</em> value. The formula is:</p> 3344 3345<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="/images/gaussian-blur.png"/> 3346</div> 3347 3348<p>The <em class="arg" >Sigma</em> value is the important argument, and 3349determines the actual amount of blurring that will take place. </p> 3350 3351<p>The <em class="arg" >Radius</em> is only used to determine the size of the 3352array which will hold the calculated Gaussian distribution. It should be an 3353integer. If not given, or set to zero, IM will calculate the largest possible 3354radius that will provide meaningful results for the Gaussian distribution. 3355</p> 3356 3357<p>The larger the <em class="arg" >Radius</em> the radius the slower the 3358operation is. However too small a <em class="arg" >Radius</em>, and sever 3359aliasing effects may result. As a guideline, <em class="arg" >Radius</em> 3360should be at least twice the <em class="arg" >Sigma</em> value, though three 3361times will produce a more accurite result. </p> 3362 3363<p>This differs from the faster <a href="#blur">-blur</a> operator in that a 3364full 2-dimensional convolution is used to generate the weighted average of the 3365neighboring pixels. </p> 3366 3367<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 3368pixels which are outside the image proper are blurred into the final result. 3369</p> 3370 3371 3372<div style="margin: auto;"> 3373 <h4><a id="geometry"></a>-geometry <em class="arg">geometry</em></h4> 3374</div> 3375 3376<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred size and location of the image.</td><td style='text-align:right;'></td></tr></table> 3377 3378<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 3379 3380<div style="margin: auto;"> 3381 <h4><a id="gravity"></a>-gravity <em class="arg">type</em></h4> 3382</div> 3383 3384<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Sets the current gravity suggestion for various other settings and options.</td><td style='text-align:right;'></td></tr></table> 3385 3386<p>Choices include: <kbd>NorthWest</kbd>, <kbd>North</kbd>, <kbd>NorthEast</kbd>, 3387<kbd>West</kbd>, <kbd>Center</kbd>, <kbd>East</kbd>, <kbd>SouthWest</kbd>, 3388<kbd>South</kbd>, <kbd>SouthEast</kbd>. Use <a href="#list">-list gravity</a> to get a complete 3389list of <a href="#gravity">-gravity</a> settings available in your ImageMagick 3390installation.</p> 3391 3392<p>The direction you choose specifies where to position text or subimages. For example, a gravity of <kbd>Center</kbd> forces the text to be centered within the image. By default, the image gravity is <kbd>NorthWest</kbd>. See <a href="#draw">-draw</a> for more details about graphic primitives. Only the text primitive of <a href="#draw">-draw</a> affected by the <a href="#gravity">-gravity</a> option.</p> 3393 3394<p>The <a href="#gravity">-gravity</a> option is also used in concert with the <a href="#geometry">-geometry</a> setting and other settings or options that take <em class="arg">geometry</em> as an argument, such as the <a href="#crop">-crop</a> option. </p> 3395 3396<p>If a <a href="#gravity">-gravity</a> setting occurs before another option or setting having a <em class="arg">geometry</em> argument that specifies an offset, the offset is usually applied to the point within the image suggested by the <a href="#gravity">-gravity</a> argument. Thus, in the following command, for example, suppose the file <kbd>image.png</kbd> has dimensions 200x100. The offset specified by the argument to <a href="#region">-region</a> is (−40,+20). The argument to <a href="#gravity">-gravity</a> is <kbd>Center</kbd>, which suggests the midpoint of the image, at the point (100,50). The offset (−40,20) is applied to that point, giving (100−40,50+20)=(60,70), so the specified 10x10 region is located at that point. (In addition, the <a href="#gravity">-gravity</a> affects the region itself, which is <em>centered</em> at the pixel coordinate (60,70). (See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p> 3397 3398<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -gravity Center -region 10x10-40+20 \ <br/> -negate output.png</span></p> 3399<p>When used as an option to <a href="/www/composite.html">composite</a>, <a href="#gravity">-gravity</a> gives the direction that the image gravitates within the composite.</p> 3400 3401<p>When used as an option to <a href="/www/montage.html">montage</a>, <a href="#gravity">-gravity</a> gives the direction that an image gravitates within a tile. The default gravity is <kbd>Center</kbd> for this purpose.</p> 3402 3403 3404<div style="margin: auto;"> 3405 <h4><a id="green-primary"></a>-green-primary <em class="arg">x,y</em></h4> 3406</div> 3407 3408<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>green chromaticity primary point.</td><td style='text-align:right;'></td></tr></table> 3409 3410 3411<div style="margin: auto;"> 3412 <h4><a id="hald-clut"></a>-hald-clut</h4> 3413</div> 3414 3415<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a Hald color lookup table to the image.</td><td style='text-align:right;'></td></tr></table> 3416 3417<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2 3418dimensions. Create it with the <kbd>HALD:</kbd> prefix (e.g. HALD:8). You 3419can apply any color transformation to the Hald image and then use this option 3420to apply the transform to the image. </p> 3421 3422<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png hald.png -hald-clut transform.png</span></p> 3423<p>This option provides a convenient method for you to use Gimp or Photoshop 3424to make color corrections to the Hald CLUT image and subsequently apply them 3425to multiple images using an ImageMagick script. </p> 3426 3427<p>Note that the representation is only of the normal RGB color space and that 3428the whole color value triplet is used for the interpolated lookup of the 3429represented Hald color cube image. Because of this the operation is not <a 3430href="#channel" >-channel</a> setting effected, nor can it adjust or modify an 3431images transparency or alpha/matte channel.</p> 3432 3433<p>See also <a href="#clut" >-clut</a> which provides color value replacement 3434of the individual color channels, usally involving a simplier gray-scale 3435image. E.g: gray-scale to color replacement, or modification by a histogram 3436mapping. </p> 3437 3438 3439<div style="margin: auto;"> 3440 <h4><a id="help"></a>-help</h4> 3441</div> 3442 3443<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print usage instructions.</td><td style='text-align:right;'></td></tr></table> 3444 3445<div style="margin: auto;"> 3446 <h4><a id="highlight-color"></a>-highlight-color <em class="arg">color</em></h4> 3447</div> 3448 3449<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table> 3450 3451<div style="margin: auto;"> 3452 <h4><a id="iconGeometry"></a>-iconGeometry <em class="arg">geometry</em></h4> 3453</div> 3454 3455<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the icon geometry.</td><td style='text-align:right;'></td></tr></table> 3456 3457<p>Offsets, if present in the geometry specification, are handled in the same manner as the <a href="#geometry">-geometry</a> option, using X11 style to handle negative offsets.</p> 3458 3459<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 3460 3461<div style="margin: auto;"> 3462 <h4><a id="iconic"></a>-iconic</h4> 3463</div> 3464 3465<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>iconic animation.</td><td style='text-align:right;'></td></tr></table> 3466 3467<div style="margin: auto;"> 3468 <h4><a id="identify"></a>-identify</h4> 3469</div> 3470 3471<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>identify the format and characteristics of the image.</td><td style='text-align:right;'></td></tr></table> 3472 3473<p>This information is printed: image scene number; image name; image size; the image class (<em class="arg">DirectClass</em> or <em class="arg">PseudoClass</em>); the total number of unique colors; and the number of seconds to read and transform the image. Refer to <a href="/www/miff.html">MIFF</a> for a description of the image class.</p> 3474 3475<p>If <a href="#colors">-colors</a> is also specified, the total unique colors in the image and color reduction error values are printed. Refer to <a href="/www/quantize.html">color reduction algorithm</a> for a description of these values.</p> 3476 3477<p>If <a href="#verbose">-verbose</a> precedes this option, copious 3478amounts of image properties are displayed including image statistics, profiles, 3479image histogram, and others.</p> 3480 3481<div style="margin: auto;"> 3482 <h4><a id="ift"></a>-ift</h4> 3483</div> 3484 3485<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the inverse discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table> 3486 3487<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase images from the frequency domain to a single image in the normal or spatial domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p> 3488 3489<p>For example, depending upon the image format used to store the result of the <a href="#fft">-fft</a>, one would use either</p> 3490 3491<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff -ift fft_image_ift.png</span></p> 3492<p>or</p> 3493 3494<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png</span></p> 3495 3496<p>The resulting image may need to be cropped due to padding introduced when the original image, prior to the <a href="#fft">-fft</a> or <a href="#fft">+fft</a>, was not square or even dimensioned. Any padding is at the right and/or bottom sides of the image.</p> 3497 3498<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to use <a href="#ift">-ift</a>.</p> 3499 3500<p>Use <a href="#ift">+ift</a> (with HDRI enabled) to transform a pair of real and imaginary images from the frequency domain to a single image in the normal (spatial) domain.</p> 3501 3502<div style="margin: auto;"> 3503 <h4><a id="immutable"></a>-immutable</h4> 3504</div> 3505 3506<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make image immutable.</td><td style='text-align:right;'></td></tr></table> 3507 3508<div style="margin: auto;"> 3509 <h4><a id="implode"></a>-implode <em class="arg">factor</em></h4> 3510</div> 3511 3512<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implode image pixels about the center.</td><td style='text-align:right;'></td></tr></table> 3513 3514<div style="margin: auto;"> 3515 <h4><a id="insert"></a>-insert <em class="arg">index</em></h4> 3516</div> 3517 3518<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>insert the last image into the image sequence.</td><td style='text-align:right;'></td></tr></table> 3519 3520<p>This option takes last image in the current image sequence and inserts it at the given index. If a negative index is used, the insert position is calculated before the last image is removed from the sequence. As such <kbd>-insert -1</kbd> will result in no change to the image sequence.</p> 3521 3522<p>The <kbd>+insert</kbd> option is equivalent to <kbd>-insert -1</kbd>. In other words, insert the last image, at the end of the current image sequence. Consequently this has no effect on the image sequence order.</p> 3523 3524<div style="margin: auto;"> 3525 <h4><a id="intent"></a>-intent <em class="arg">type</em></h4> 3526</div> 3527 3528<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use this type of rendering intent when managing the image color.</td><td style='text-align:right;'></td></tr></table> 3529 3530<p>Use this option to affect the color management operation of an image (see <a href="#profile">-profile</a>). Choose from these intents: <kbd>Absolute, Perceptual, Relative, Saturation</kbd>.</p> 3531 3532<p>The default intent is undefined.</p> 3533 3534<p>To print a complete list of rendering intents, use <a href="#list">-list intent</a>.</p> 3535 3536<div style="margin: auto;"> 3537 <h4><a id="interlace"></a>-interlace <em class="arg">type</em></h4> 3538</div> 3539 3540<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the type of interlacing scheme.</td><td style='text-align:right;'></td></tr></table> 3541 3542<p>Choose from:</p> 3543 3544<pre class="text"> 3545 none 3546 line 3547 plane 3548 partition 3549 JPEG 3550 GIF 3551 PNG 3552</pre> 3553 3554<p>This option is used to specify the type of interlacing scheme for raw image formats such as <kbd>RGB</kbd> or <kbd>YUV</kbd>.</p> 3555 3556<p><kbd>None</kbd> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p> 3557 3558<p><kbd>Line</kbd> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p> 3559 3560<p><kbd>Plane</kbd> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p> 3561 3562<p><kbd>Partition</kbd> is like plane except the different planes are saved to individual files (e.g. image.R, 3563image.G, and image.B).</p> 3564 3565<p>Use <kbd>Line</kbd> or <kbd>Plane</kbd> to create an <kbd>interlaced PNG</kbd> or <kbd>GIF</kbd> or <kbd>progressive JPEG</kbd> 3566image.</p> 3567 3568<p>To print a complete list of interlacing schemes, use <a href="#list">-list interlace</a>.</p> 3569 3570<div style="margin: auto;"> 3571 <h4><a id="interpolate"></a>-interpolate <em class="arg">type</em></h4> 3572</div> 3573 3574<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</td><td style='text-align:right;'></td></tr></table> 3575 3576<p>When looking up the color of a pixel using a non-integer floating point 3577value, you typically fall in between the pixel colors defined by the source 3578image. This setting determines how the color is determined from the colors of 3579the pixels surrounding that point. That is how to determine the color of a 3580point that falls between two, or even four different colored pixels. </p> 3581 3582<pre class="text"> 3583 integer The color of the top-left pixel (floor function) 3584 nearest-neighbor The nearest pixel to the lookup point (rounded function) 3585 average The average color of the surrounding four pixels 3586 bilinear A double linear interpolation of pixels (the default) 3587 mesh Divide area into two flat triangular interpolations 3588 bicubic Fitted bicubic-spines of surrounding 16 pixels 3589 spline Direct spline curves (colors are blurred) 3590 filter Use resize <a href="#filter">-filter</a> settings 3591</pre> 3592 3593<p>This most important for distortion operators such as <a href="#distort" 3594>-distort</a>, <a href="#implode" >-implode</a>, <a href="#transform" 3595>-transform</a> and <a href="#fx" >-fx</a>. </p> 3596 3597<p>To print a complete list of interpolation methods, use <a href="#list">-list interpolate</a>.</p> 3598 3599<p>See also <a href="#virtual-pixel" >-virtual-pixel</a>, for control of the 3600lookup for positions outside the boundaries of the image. </p> 3601 3602 3603<div style="margin: auto;"> 3604 <h4><a id="interline-spacing"></a>-interline-spacing <em class="arg">value</em></h4> 3605</div> 3606 3607<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two text lines.</td><td style='text-align:right;'></td></tr></table> 3608 3609<div style="margin: auto;"> 3610 <h4><a id="interword-spacing"></a>-interword-spacing <em class="arg">value</em></h4> 3611</div> 3612 3613<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two words.</td><td style='text-align:right;'></td></tr></table> 3614 3615<div style="margin: auto;"> 3616 <h4><a id="kerning"></a>-kerning <em class="arg">value</em></h4> 3617</div> 3618 3619<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two letters.</td><td style='text-align:right;'></td></tr></table> 3620 3621<div style="margin: auto;"> 3622 <h4><a id="label"></a>-label <em class="arg">name</em></h4> 3623</div> 3624 3625<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>assign a label to an image.</td><td style='text-align:right;'></td></tr></table> 3626 3627<p>Use this option to assign a specific label to the image, as it is read in 3628or created. You can use the <a href="#set" >-set</a> operation to re-assign 3629a the labels of images already read in. Image formats such as TIFF, PNG, 3630MIFF, supports saving the label information with the image.</p> 3631 3632<p>When saving an image to a <em class="arg">PostScript</em> file, any label 3633assigned to an image is used as a header string to print above the postscript 3634image. </p> 3635 3636<p>You can include the image filename, type, width, height, or other image 3637attribute by embedding special format character. See <a href="/www/escape.html">Format and Print Image 3638Properties</a> for details of the percent escape codes.</p> 3639 3640<p>For example,</p> 3641 3642<p class="crtsnip"> 3643 -label "%m:%f %wx%h" bird.miff 3644</p> 3645 3646<p>assigns an image label of <kbd>MIFF:bird.miff 512x480</kbd> to the 3647"<kbd>bird.miff</kbd>" image and whose width is 512 and height is 480, as it 3648is read in. If a <a href="#label">+label</a> option was used instead, any 3649existing label present in the image would be used. You can remove all labels 3650from an image by assigning the empty string. </p> 3651 3652<p>A label is not drawn on the image, but is embedded in the image datastream 3653via <em>Label</em> tag or similar mechanism. If you want the label to be 3654visible on the image itself, use the <a href="#draw">-draw</a> option, or 3655during the final processing in the creation of a image montage.</p> 3656 3657<p>If the first character of <em class="arg">string</em> is <em 3658class="arg">@</em>, the image label is read from a file titled by the 3659remaining characters in the string. Labels in a file are literal, no embedded 3660formatting characters are recognized.</p> 3661 3662 3663<div style="margin: auto;"> 3664 <h4><a id="lat"></a>-lat <em class="arg">width</em><br />-lat <em class="arg">width</em>x<em class="arg">height</em>{<em class="arg">+-</em>}<em class="arg">offset</em>{<em class="arg">%</em>}</h4> 3665</div> 3666 3667<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform local adaptive threshold.</td><td style='text-align:right;'></td></tr></table> 3668 3669<p>Adaptively threshold each pixel based on the value of pixels in a 3670surrounding window. If the current pixel is lighter than this average plus 3671the optional <kbd>offset</kbd>, then it is made white, otherwise it is made 3672black. Small variations in pixel values such as found in scanned documents 3673can be ignored if offset is positive. A negative offset will make it more 3674sensitive to those small variations. </p> 3675 3676<p>This is commonly used to threshold images with an uneven background. It is 3677based on the assumption that average color of the small window is the 3678the local background color, from which to separate the forground color. </p> 3679 3680 3681<div style="margin: auto;"> 3682 <h4><a id="layers"></a>-layers <em class="arg">method</em></h4> 3683</div> 3684 3685<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>handle multiple images forming a set of image layers or animation frames.</td><td style='text-align:right;'></td></tr></table> 3686 3687<p>Perform various image operation methods to a ordered sequence of images 3688which may represent either a set of overlaid 'image layers', a GIF disposal 3689animation, or a fully-'coalesced' animation sequence. </p> 3690 3691<table class="doc"> 3692 <tbody> 3693 <tr valign="top"> 3694 <th align="left" style="width: 8%">Method</th> 3695 <th align="left">Description</th> 3696 </tr> 3697 3698 <tr valign="top"> 3699 <td valign="top">compare-any</td> 3700 <td valign="top">Crop the second and later frames to the smallest rectangle 3701 that contains all the differences between the two images. No GIF <a 3702 href="#dispose" >-dispose</a> methods are taken into account. </td> 3703 </tr> 3704 3705 <tr><td></td><td>This exactly the same as the <a href="#deconstruct" 3706 >-deconstruct</a> operator, and does not preserve animations normal 3707 working, especially when animation used layer disposal methods such as 3708 '<kbd>Previous</kbd>' or '<kbd>Background</kbd>'. </td> 3709 </tr> 3710 3711 <tr valign="top"> 3712 <td valign="top">compare-clear</td> 3713 <td valign="top">As '<kbd>compare-any</kbd>' but crop to the bounds of any 3714 opaque pixels which become transparent in the second frame. That is the 3715 smallest image needed to mask or erase pixels for the next frame. </td> 3716 </tr> 3717 3718 <tr valign="top"> 3719 <td valign="top">compare-overlay</td> 3720 <td valign="top">As '<kbd>compare-any</kbd>' but crop to pixels that add 3721 extra color to the next image, as a result of overlaying color pixels. 3722 That is the smallest single overlaid image to add or change colors. </td> 3723 </tr> 3724 3725 <tr><td></td><td>This can be used with the <a href="#compose" >-compose</a> alpha 3726 composition method '<kbd>change-mask</kbd>', to reduce the image to 3727 just the pixels that need to be overlaid. </td> 3728 </tr> 3729 3730 <tr valign="top"> 3731 <td valign="top">coalesce</td> 3732 <td valign="top">Equivalent to a call to the <a href="#coalesce" 3733 >-coalesce</a> operator. Apply the layer disposal methods set in the 3734 current image sequence to form a fully defined animation sequence, as 3735 it should be displayed. Effectively converting a GIF animation into a 3736 'film strip'-like animation. </td> 3737 </tr> 3738 3739 <tr valign="top"> 3740 <td valign="top">composite</td> 3741 <td valign="top">Alpha Composition of two image lists, separated by a 3742 "<kbd>null:</kbd>" image, with the destination image list first, and 3743 the source images last. An image from each list are composited 3744 together until one list is finished. The separator image and source 3745 image lists are removed. </td> 3746 </tr> 3747 3748 3749 <tr><td></td> 3750 <td>The <a href="#geometry" >-geometry</a> offset is adjusted according 3751 to <a href="#gravity" >-gravity</a> in accordance of the virtual 3752 canvas size of the first image in each list. Unlike a normal <a 3753 href="#composite" >-composite</a> operation, the canvas offset is also 3754 added to the final composite positioning of each image. </td> </tr> 3755 3756 <tr><td></td> 3757 <td>If one of the image lists only contains one image, that image is 3758 applied to all the images in the other image list, regardless of which 3759 list it is. In this case it is the image meta-data of the list which 3760 preserved. </td> 3761 </tr> 3762 3763 3764 <tr valign="top"> 3765 <td valign="top">dispose</td> 3766 <td valign="top">This like '<kbd>coalesce</kbd>' but shows the look of 3767 the animation after the layer disposal method has been applied, before 3768 the next sub-frame image is overlaid. That is the 'dispose' image that 3769 results from the application of the GIF <a href="#dispose" 3770 >-dispose</a> method. This allows you to check what 3771 is going wrong with a particular animation you may be developing. 3772 </td> 3773 </tr> 3774 3775 <tr valign="top"> 3776 <td valign="top">flatten</td> 3777 <td valign="top">Create a canvas the size of the first images virtual 3778 canvas using the current <a href="#background" >-background</a> color, 3779 and <a href="#compose" >-compose</a> each image in turn onto that 3780 canvas. Images falling outside that canvas is clipped. Final 3781 image will have a zero virtual canvas offset. </td> 3782 </tr> 3783 3784 <tr><td></td> 3785 <td>This usally used as one of the final 'image layering' operations 3786 overlaying all the prepared image layers into a final image. </td> 3787 </tr> 3788 3789 <tr><td></td> 3790 <td>For a single image this method can also be used to fillout a virtual 3791 canvas with real pixels, or to underlay a opaque color to remove 3792 transparency from an image.</td> 3793 </tr> 3794 3795 3796 <tr valign="top"> 3797 <td valign="top">merge</td> 3798 <td valign="top">As 'flatten' method but merging all the given image 3799 layers into a new layer image just large enough to hold all the image 3800 without clipping or extra space. The new images virtual offset will 3801 prevere the position of the new layer, even if this offset is 3802 negative. the virtual canvas size of the first image is preserved. 3803 </td> 3804 </tr> 3805 3806 <tr><td></td><td>Caution is advised when handling image layers with negative offsets 3807 as few image file formats handle them correctly. </td> 3808 </tr> 3809 3810 <tr valign="top"> 3811 <td valign="top">mosaic</td> 3812 <td valign="top">As 'flatten' method but expanding the initial canvas size 3813 of the first image so as to hold all the image layers. However as a 3814 virtual canvas is 'locked' to the origin, by definition, image layers 3815 with a negative offsets will still be clipped by the top and left 3816 edges.</td> 3817 </tr> 3818 3819 <tr><td></td><td>This method is commonly used to layout individual image using various 3820 offset but without knowing the final canvas size. The resulting image 3821 will, like 'flatten' not have any virtual offset, so can be saved to 3822 any image file format. </td> 3823 </tr> 3824 3825 3826 <tr valign="top"> 3827 <td valign="top">optimize</td> 3828 <td valign="top">Optimize a coalesced animation, into GIF animation using 3829 a number of general techniques. This currently a short cut to 3830 apply both the '<kbd>optimize-frame</kbd>', and 3831 '<kbd>optimize-transparency</kbd>' methods but may be expanded to 3832 include other optimization methods as they are developed. </td> 3833 </tr> 3834 3835 <tr valign="top"> 3836 <td valign="top">optimize-frame</td> 3837 <td valign="top">Optimize a coalesced animation, into GIF animation by 3838 reducing the number of pixels per frame as much as possible by 3839 attempting to pick the best layer disposal method to use, while ensuring 3840 the result will continue to animate properly. </td> 3841 </tr> 3842 3843 <tr><td></td><td> There is no guarantee that the best optimization is found. But 3844 then no reasonably fast GIF optimization algorithm can do this. 3845 However this does seem to do better than most other GIF frame 3846 optimizers seen. </td> 3847 </tr> 3848 3849 <tr valign="top"> 3850 <td valign="top">optimize-plus</td> 3851 <td valign="top">As '<kbd>optimize-frame</kbd>' but attempt to improve the 3852 overall optimization by adding extra frames to the animation, without 3853 changing the final look or timing of the animation. The frames are 3854 added to attempt to separate the clearing of pixels from the 3855 overlaying of new additional pixels from one animation frame to the 3856 next. If this does not improve the optimization (for the next frame 3857 only), it will fall back to the results of the previous normal 3858 '<kbd>optimize-frame</kbd>' technique. </td> 3859 </tr> 3860 3861 <tr><td></td><td>There is the possibility that the change in the disposal style will 3862 result in a worsening in the optimization of later frames, though this 3863 is unlikely. In other words there no guarantee that it is better than 3864 the normal '<kbd>optimize-frame</kbd>' technique. For some animations 3865 however you can get a vast improvement in the final animation size. </td> 3866 </tr> 3867 3868 <tr valign="top"> 3869 <td valign="top">optimize-transparency</td> 3870 <td valign="top">Given a GIF animation, replace any pixel in the sub-frame 3871 overlay images with transparency, if it does not change the resulting 3872 animation by more than the current <a href="#fuzz" >-fuzz</a> factor. 3873 </td> 3874 </tr> 3875 3876 <tr><td></td><td>This should allow a existing frame optimized GIF animation to compress 3877 into a smaller file size due to larger areas of one (transparent) 3878 color rather than a pattern of multiple colors repeating the current 3879 disposed image of the last frame. </td> 3880 </tr> 3881 3882 <tr valign="top"> 3883 <td valign="top">remove-dups</td> 3884 <td valign="top">Remove (and merge time delays) of duplicate consecutive 3885 images, so as to simplify layer overlays of coalesced animations. 3886 </td> 3887 </tr> 3888 3889 <tr><td></td><td>Usually this a result of using a constant time delay across the 3890 whole animation, or after a larger animation was split into smaller 3891 sub-animations. The duplicate frames could also have been used as 3892 part of some frame optimization methods. </td> 3893 </tr> 3894 3895 <tr valign="top"> 3896 <td valign="top">remove-zero</td> 3897 <td valign="top">Remove any image with a zero time delay, unless ALL the 3898 images have a zero time delay (and is not a proper timed animation, a 3899 warning is then issued). </td> 3900 </tr> 3901 3902 <tr><td></td><td>In a GIF animation, such images are usually frames which provide 3903 partial intermediary updates between the frames that are actually 3904 displayed to users. These frames are usally added for improved frame 3905 optimization in GIF animations. </td> 3906 </tr> 3907 3908 <tr valign="top"> 3909 <td valign="top">trim-bounds</td> 3910 <td valign="top">Find the bounds of all the images in the current 3911 image sequence, then adjust the offsets so all images are contained on 3912 a minimal positive canvas. None of the image data is modified, only 3913 there virtual canvas size and offset. The all the image is given 3914 the same canvas size, and and will have a positive offset, but will 3915 remain in the same position relative to each other. As a result of the 3916 minimal canvas size at least one image will touch every edge of that 3917 canvas. The image data however may be transparent. 3918 </td> 3919 </tr> 3920 3921 </tbody> 3922</table> 3923 3924<p>To print a complete list of layer types, use <a href="#list">-list layers</a>.</p> 3925 3926<p>The operators <a href="#coalesce" >-coalesce</a>, <a href="#deconstruct" 3927>-deconstruct</a>, <a href="#flatten" >-flatten</a>, and <a href="#mosaic" 3928>-mosaic</a> are only aliases for the above methods. Also see <a 3929href="#page" >-page</a>, <a href="#repage" >-repage</a> operators, the <a 3930href="#compose" >-compose</a> setting, and the GIF <a href="#dispose" 3931>-dispose</a> and <a href="#delay" >-delay</a> settings. </p> 3932 3933 3934<div style="margin: auto;"> 3935 <h4><a id="level"></a>-level <em class="arg">black_point</em>{,<em class="arg">white_point</em>}{<em class="arg">%</em>}{,<em class="arg">gamma</em>}</h4> 3936</div> 3937 3938<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of image channels.</td><td style='text-align:right;'></td></tr></table> 3939 3940<p>Given one, two or three values delimited with commas: black-point, 3941white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and 3942white points range from 0 to <em class="QR">QuantumRange</em>, or from 0 to 100%; if the white 3943point is omitted it is set to (<em class="QR">QuantumRange</em> - black_point), so as to center 3944contrast changes. If a <kbd>%</kbd> sign is present anywhere in the string, 3945both black and white points are percentages of the full color range. Gamma 3946will do a <a href="#gamma">-gamma</a> adjustment of the values. If it is 3947omitted, the default of 1.0 (no gamma correction) is assumed.</p> 3948 3949<p>In normal usage (<kbd>-level</kbd>) the image values are stretched so that 3950the given '<kbd>black_point</kbd>' value in the original image is set to 3951zero (or black), while the given '<kbd>white_point</kbd>' value is set to 3952<em class="QR">QuantumRange</em> (or white). This provides you with direct contrast adjustments 3953to the image. The '<kbd>gamma</kbd>' of the resulting image will then be 3954adjusted. </p> 3955 3956<p>From ImageMagick v6.4.1-9 using the plus form of the operator (<kbd>+level</kbd>) or 3957adding the special '!' flag anywhere in the argument list, will cause the 3958operator to do the reverse of the level adjustment. That is a zero, or 3959<em class="QR">QuantumRange</em> value (black, and white, resp.) in the original image, is 3960adjusted to the given level values, allowing you to de-contrast, or compress 3961the channel values within the image. The '<kbd>gamma</kbd>' is adjusted before the level adjustment to de-contrast the image is made. </p> 3962 3963<p>Only the channels defined by the current <a href="#channel">-channel</a> 3964setting are adjusted (defaults to RGB color channels only), allowing you to 3965limit the effect of this operator. </p> 3966 3967<p>Please note that the transparency channel is treated as 'matte' 3968values (0 is opaque) and not as 'alpha' values (0 is transparent).</p> 3969 3970 3971<div style="margin: auto;"> 3972 <h4><a id="level-colors"></a>-level-colors {<em 3973 class="arg">black_color</em>}{,}{<em class="arg">white_color</em>}</h4> 3974</div> 3975 3976<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of an image using the provided dash separated colors.</td><td style='text-align:right;'></td></tr></table> 3977 3978<p>This function is exactly like <a href="#level">-level</a>, except that the 3979value value for each color channel is determined by the 3980'<kbd>black_color</kbd>' and '<kbd>white_color</kbd>' colors given (as 3981described under the <a href="#fill">-fill</a> option). </p> 3982 3983<p>This effectually means the colors provided to <kbd>-level-colors</kbd> 3984is mapped to become 'black' and 'white' respectively, with all the other 3985colors linearly adjusted (or clipped) to match that change. Each channel is 3986adjusted separately using the channel values of the colors specified. </p> 3987 3988<p>On the other hand the plus form of the operator (<kbd>+level-colors</kbd>) 3989will map the image color 'black' and 'white' to the given colors 3990respectively, resulting in a gradient (de-contrasting) tint of the image to 3991those colors. This can also be used to convert a plain gray-scale image into a 3992one using the gradient of colors specified. </p> 3993 3994<p>By supplying a single color with a comma separator either before or after 3995that color, will just replace the respective 'black' or 'white' point 3996respectively. But if no comma separator is provided, the given color is 3997used for both the black and white color points, making the operator either 3998threshold the images around that color (- form) or set all colors to that 3999color (+ form). </p> 4000 4001 4002<div style="margin: auto;"> 4003 <h4><a id="limit"></a>-limit <em class="arg">type value</em></h4> 4004</div> 4005 4006<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel cache resource limit.</td><td style='text-align:right;'></td></tr></table> 4007 4008<p>Choose from: <kbd>area</kbd>, <kbd>disk</kbd>, <kbd>file</kbd>, <kbd>map</kbd>, <kbd>memory</kbd>, <kbd>threads</kbd>, or <kbd>time</kbd>.</p> 4009 4010<p>The value for <kbd>file</kbd> is in number of files. The other limits are in bytes. By default the limits are 768 files, 2GB of image area, 1.5GiB memory, 8GiB memory map, and 18.45EB of disk. These limits are adjusted relative to the available resources on your computer if this information is available. When any limit is reached, ImageMagick fails in some fashion but attempts to take compensating actions, if possible. For example, the following limits memory:</p> 4011 4012<p class="crtsnip"> 4013 -limit memory 32MiB -limit map 64MiB 4014</p> 4015 4016<p>Use <a href="#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p> 4017 4018<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list resource</span><span class='crtout'></span></p><pre class="text"> 4019 File Area Memory Map Disk Thread Time 4020 ------------------------------------------------------------------------------ 4021 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited 4022</pre> 4023 4024<p>Requests for pixel storage to keep intermediate images are satisfied by one of three resource categories: in-memory pool, memory-mapped files pool, and disk pool (in that order) depending on the <a href="/www/command-line-options.html#limit">‑limit</a> settings and whether the system honors a resource request. If the total size of allocated pixel storage in the given pool reaches the corresponding limit, the request is passed to the next pool. Additionally, requests that exceed the <kbd>area</kbd> limit automagically are allocated on disk.</p> 4025 4026<p>To illustrate how ImageMagick utilizes resource limits, consider a typical image resource request. First, ImageMagick tries to allocate the pixels in memory. The request might be denied if the resource request exceeds the <kbd>memory</kbd> limit or if the system does not honor the request. If a memory request is not honored, the pixels are allocated to disk and the file is memory-mapped. However, if the allocation request exceeds the <kbd>map</kbd> limit, the resource allocation goes to disk. In all cases, if the resource request exceeds the <kbd>area</kbd> limit, the pixels are automagically cached to disk. If the disk has a hard limit, the program fails.</p> 4027 4028<p>In most cases you simply do not need to concern yourself with resource limits. ImageMagick chooses reasonable defaults and most images do not tax your computer resources. Where limits do come in handy is when you process images that are large or on shared systems where ImageMagick can consume all or most of the available memory. In this case, the ImageMagick workflow slows other processes or, in extreme cases, brings the system to a halt. Under these circumstances, setting limits give some assurances that the ImageMagick workflow will not interfere with other concurrent uses of the computer. For example, assume you have a web interface that processes images uploaded from the Internet. To assure ImageMagick does not exceed 10mb of memory you can simply set the area limit to 10mb:</p> 4029 4030<p class="crtsnip"> 4031-limit area 10mb 4032</p> 4033 4034<p>Now whenever a large image is processed, the pixels are automagically cached to disk instead of memory. This of course implies that large images typically process very slowly, simply because pixel processing in memory can be an order of magnitude faster than on disk. Because your web site users might inadvertently upload a huge image to process, you should set a disk limit as well:</p> 4035 4036<p class="crtsnip"> 4037-limit area 10mb -limit disk 500mb 4038</p> 4039 4040<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p> 4041 4042<p>In addition to command-line resource limit option, resources can be set with <a href="/www/resources.html#environment">environment variables</a>. Set the environment variables <kbd>MAGICK_AREA_LIMIT</kbd>, <kbd>MAGICK_DISK_LIMIT</kbd>, <kbd>MAGICK_FILE_LIMIT</kbd>, <kbd>MAGICK_MEMORY_LIMIT</kbd>, <kbd>MAGICK_MAP_LIMIT</kbd>, <kbd>MAGICK_THREAD_LIMIT</kbd>, <kbd>MAGICK_TIME_LIMIT</kbd> for limits of image area, disk space, open files, heap memory, memory map, number of threads of execution, and maximum elapsed time in seconds respectively.</p> 4043 4044<p> Inquisitive users can try adding <a href="#debug">-debug cache</a> to their commands and then scouring the generated output for references to the pixel cache, in order to determine how the pixel cache was allocated and how resources were consumed. Advanced Unix/Linux users can pipe that output through <kbd>grep memory|open|destroy|disk</kbd> for more readable sifting. 4045</p> 4046 4047<p>For more about ImageMagick's use of resources, see the section <b>Cache Storage and Resource Requirements</b> on the <a href="/www/architecture.html#cache">Architecture</a> page. 4048</p> 4049 4050<div style="margin: auto;"> 4051 <h4><a id="linear-stretch"></a>-linear-stretch <em class="arg">black-point</em><br />-linear-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4> 4052</div> 4053 4054<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Linear with saturation stretch.</td><td style='text-align:right;'></td></tr></table> 4055 4056<p>This is very similar to <a href="#contrast-stretch" >-contrast-stretch</a>, 4057and uses a 'histogram bin' to determine the range of color values that needs to 4058be stretched. However it then stretchs those colors using the <a 4059href="#level" >-level</a> operator.</p> 4060 4061<p>As such while the initial determination may have 'binning' round off 4062effects, the image colors are stretched mathematically, rather than using the 4063histogram bins. This makes the operator more accurate. </p> 4064 4065<p>note however that a <a href="#linear-stretch" >-linear-stretch</a> of 4066'<kbd>0</kbd>' does nothing, while a value of '<kbd>1</kbd>' does a near 4067perfect stretch of the color range. </p> 4068 4069<p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect' 4070normalization of mathematical images. </p> 4071 4072<p>This operator is under review for re-development. </p> 4073 4074 4075<div style="margin: auto;"> 4076 <h4><a id="linewidth"></a>-linewidth</h4> 4077</div> 4078 4079<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the line width for subsequent draw operations.</td><td style='text-align:right;'></td></tr></table> 4080 4081<div style="margin: auto;"> 4082 <h4><a id="liquid-rescale"></a>-liquid-rescale <em class="arg">geometry</em></h4> 4083</div> 4084 4085<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>rescale image with seam-carving.</td><td style='text-align:right;'></td></tr></table> 4086 4087<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 4088 4089<div style="margin: auto;"> 4090 <h4><a id="list"></a>-list <em class="arg">type</em></h4> 4091</div> 4092 4093<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Print a list of supported arguments for various options or settings. Choose from these list types:</td><td style='text-align:right;'></td></tr></table> 4094 4095<pre class="text"> 4096 Align Alpha Boolean Channel 4097 Class ClipPath Coder Color 4098 Colorspace Command Compose Compress 4099 Configure DataType Debug Decoration 4100 Delegate Direction Dispose Distort 4101 Dither Endian Evaluate FillRule 4102 Filter Font Format Function 4103 Gravity ImageList Intent Interlace 4104 Interpolate Kernel Layers LineCap 4105 LineJoin List Locale LogEvent 4106 Log Magic Method Metric 4107 Mime Mode Morphology Module 4108 Noise Orientation Policy PolicyDomain 4109 PolicyRights Preview Primitive QuantumFormat 4110 Resource SparseColor Storage Stretch 4111 Style Threshold Type Units 4112 Validate VirtualPixel 4113</pre> 4114 4115<p>These lists vary depending on your version of ImageMagick. Use "<kbd>-list 4116list</kbd>" to get a complete listing of all the "<kbd>-list</kbd>" arguments 4117available:</p> 4118 4119<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list list</span></p> 4120<div style="margin: auto;"> 4121 <h4><a id="log"></a>-log <em class="arg">string</em></h4> 4122</div> 4123 4124<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify format for debug log.</td><td style='text-align:right;'></td></tr></table> 4125 4126<p>This option specifies the format for the log printed when the <a 4127href="#debug">-debug</a> option is active.</p> 4128 4129<p>You can display the following components by embedding special format 4130characters:</p> 4131 4132<pre class="text"> 4133 %d domain 4134 %e event 4135 %f function 4136 %l line 4137 %m module 4138 %p process ID 4139 %r real CPU time 4140 %t wall clock time 4141 %u user CPU time 4142 %% percent sign 4143 \n newline 4144 \r carriage return 4145</pre> 4146 4147<p>For example:</p> 4148 4149<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -debug coders -log "%u %m:%l %e" in.gif out.png</span></p> 4150<p>The default behavior is to print all of the components.</p> 4151 4152<div style="margin: auto;"> 4153 <h4><a id="loop"></a>-loop <em class="arg">iterations</em></h4> 4154</div> 4155 4156<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add Netscape loop extension to your GIF animation.</td><td style='text-align:right;'></td></tr></table> 4157 4158<p>Set iterations to zero to repeat the animation an infinite number of times, 4159otherwise the animation repeats itself up to <em class="arg">iterations</em> 4160times.</p> 4161 4162<div style="margin: auto;"> 4163 <h4><a id="lowlight-color"></a>-lowlight-color <em class="arg">color</em></h4> 4164</div> 4165 4166<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, de-emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table> 4167 4168<div style="margin: auto;"> 4169 <h4><a id="magnify"></a>-magnify <em class="arg">factor</em></h4> 4170</div> 4171 4172<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>magnify the image.</td><td style='text-align:right;'></td></tr></table> 4173 4174 4175<div style="margin: auto;"> 4176 <h4><a id="map"></a>-map <em class="arg">type</em></h4> 4177</div> 4178 4179<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display image using this <em class="arg">type</em>.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 4180 4181<p>Choose from these <em class="arg">Standard Colormap</em> types:</p> 4182 4183<pre class="text"> 4184 best 4185 default 4186 gray 4187 red 4188 green 4189 blue 4190</pre> 4191 4192<p>The <em class="arg">X server</em> must support the <em class="arg">Standard 4193Colormap</em> you choose, otherwise an error occurs. Use <kbd>list</kbd> as 4194the type and <kbd>display</kbd> searches the list of colormap types in 4195<kbd>top-to-bottom</kbd> order until one is located. See <em 4196class="arg">xstdcmap(1)</em> for one way of creating Standard Colormaps.</p> 4197 4198 4199<div style="margin: auto;"> 4200 <h4><a id="map_stream_"></a>-map <em class="arg">components</em></h4> 4201</div> 4202 4203<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel map.</td><td style='text-align:right;'>[<a href="/www/stream.html">stream</a>]</td></tr></table> 4204 4205<p>Here are the valid components of a map:</p> 4206 4207<pre class="text"> 4208 r red pixel component 4209 g green pixel component 4210 b blue pixel component 4211 a alpha pixel component (0 is transparent) 4212 o opacity pixel component (0 is opaque) 4213 i grayscale intensity pixel component 4214 c cyan pixel component 4215 m magenta pixel component 4216 y yellow pixel component 4217 k black pixel component 4218 p pad component (always 0) 4219</pre> 4220 4221<p>You can specify as many of these components as needed in any order (e.g. 4222bgr). The components can repeat as well (e.g. rgbr).</p> 4223 4224 4225<div style="margin: auto;"> 4226 <h4><a id="mask"></a>-mask 4227<em class="arg">filename</em></h4> 4228</div> 4229 4230<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Prevent updates to image pixels specified by the mask.</td><td style='text-align:right;'></td></tr></table> 4231 4232<p>This the same as using a mask used for composite masking operations, with 4233grayscale values causing blended updates of the image the mask is attached to. 4234</P> 4235 4236<p>Use <a href="#mask">+mask</a> to remove the mask from images.</p> 4237 4238<p>Also see <a href="#clip-mask">-clip-mask</a> which work in the same way, 4239but with strict boolean masking. </p> 4240 4241<div style="margin: auto;"> 4242 <h4><a id="mattecolor"></a>-mattecolor <em class="arg">color</em></h4> 4243</div> 4244 4245<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the color to be used with the <a href="#frame">-frame</a> option.</td><td style='text-align:right;'></td></tr></table> 4246 4247<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 4248 4249<p>The default matte color is <kbd>#BDBDBD</kbd>, <span 4250style="background-color: #bdbdbd;">this shade of gray</span>.</p> 4251 4252<div style="margin: auto;"> 4253 <h4><a id="maximum"></a>-maximum</h4> 4254</div> 4255 4256<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the maximum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table> 4257 4258<p>Select the 'maximum' value from all the surrounding pixels. </p> 4259 4260<p>This is legacy option from the <a href="#statistic" >method</A> of the same 4261name. </p> 4262 4263<div style="margin: auto;"> 4264 <h4><a id="median"></a>-median <em class="arg">geometry</em></h4> 4265</div> 4266 4267<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a median filter to the image.</td><td style='text-align:right;'></td></tr></table> 4268 4269<p>Select the 'middle' value from all the surrounding pixels. </p> 4270 4271<p>This is legacy option from the <a href="#statistic" >method</A> of the same 4272name. </p> 4273 4274<div style="margin: auto;"> 4275 <h4><a id="metric"></a>-metric <em class="arg">type</em></h4> 4276</div> 4277 4278<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Output to STDERR a measure of the differences between images according to the <em class="arg">type</em> given metric.</td><td style='text-align:right;'></td></tr></table> 4279 4280<p>Choose from:</p> 4281 4282<pre class="text"> 4283 AE absolute error count, number of different pixels (-fuzz effected) 4284 FUZZ mean color distance 4285 MAE mean absolute error (normalized), average channel error distance 4286 MEPP mean error per pixel (normalized mean error, normalized peak error) 4287 MSE mean error squared, average of the channel error squared 4288 NCC normalized cross correlation 4289 PAE peak absolute (normalize peak absolute) 4290 PSNR peak signal to noise ratio 4291 RMSE root mean squared (normalized root mean squared) 4292</pre> 4293 4294<p>Control the '<kbd>AE</kbd>', or absolute count of pixels that are different, 4295with the <a href="#fuzz" >-fuzz</a> factor (ignore pixels which 4296only changed by a small amount). Use '<kbd>PAE</kbd>' to find the 4297size of the <a href="#fuzz" >-fuzz</a> factor needed to make all pixels 4298'similar', while '<kbd>MAE</kbd>' dtermines the factor needed 4299for about half the pixels to be similar. </p> 4300 4301<p>The '<kbd>MEPP</kbd>' metric returns three different metrics 4302('<kbd>MAE</kbd>', '<kbd>MAE</kbd>' normalized, and '<kbd>PAE</kbd>' 4303normalized) from a single comparison run. </p> 4304 4305<p>To print a complete list of metrics, use the <a href="#list">-list 4306metrics</a> option.</p> 4307 4308 4309<div style="margin: auto;"> 4310 <h4><a id="minimum"></a>-minimum</h4> 4311</div> 4312 4313<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the minimum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table> 4314 4315<p>Select the 'minimal' value from all the surrounding pixels. </p> 4316 4317<p>This is legacy option from the <a href="#statistic" >method</A> of the same 4318name. </p> 4319 4320 4321 4322<div style="margin: auto;"> 4323 <h4><a id="mode"></a>-mode <em class="arg">geometry</em></h4> 4324</div> 4325 4326<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make each pixel the 'predominate color' of the neighborhood.</td><td style='text-align:right;'>[<a href="/www/convert.html">convert</a>, <a href="/www/mogrify.html">mogrify</a>]</td></tr></table> 4327 4328<div style="margin: auto;"> 4329 <h4>-mode <em class="arg">value</em></h4> 4330</div> 4331 4332<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mode of operation.</td><td style='text-align:right;'>[<a href="/www/montage.html">montage</a>]</td></tr></table> 4333 4334<p>Choose the <em class="arg">value</em> from these styles: <kbd>Frame, 4335Unframe, or Concatenate</kbd></p> 4336 4337<p>Use the <a href="#list" >-list</a> option with a '<kbd>Mode</kbd>' argument 4338for a list of <a href="#mode" >-mode</a> arguments available in your 4339ImageMagick installation.</p> 4340 4341 4342<div style="margin: auto;"> 4343 <h4><a id="modulate"></a>-modulate <em class="arg">brightness</em>[,<em class="arg">saturation</em>,<em class="arg">hue</em>]</h4> 4344</div> 4345 4346<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Vary the <em class="arg">brightness</em>, <em 4347class="arg">saturation</em>, and <em class="arg">hue</em> of an image.</td><td style='text-align:right;'></td></tr></table> 4348 4349<p>The arguments are given as a percentages of variation. A value of 100 means 4350no change, and any missing values are taken to mean 100.</p> 4351 4352<p>The <em class="arg">brightness</em> is a multiplier of the overall 4353brightness of the image, so 0 means pure black, 50 is half as bright, 200 is 4354twice as bright. To invert its meaning <a href="#negate">-negate</a> the image 4355before and after. </p> 4356 4357<p>The <em class="arg">saturation</em> controls the amount of color in an 4358image. For example, 0 produce a grayscale image, while a large value such as 4359200 produce a very colorful, 'cartoonish' color.</p> 4360 4361<p>The <em class="arg">hue</em> argument causes a "rotation" of the colors 4362within the image by the amount specified. For example, 50 results in 4363a counter-clockwise rotation of 90, mapping red shades to purple, and so on. 4364A value of either 0 or 200 results in a complete 180 degree rotation of the 4365image. Using a value of 300 is a 360 degree rotation resulting in no change to 4366the original image. </p> 4367 4368<p>For example, to increase the color brightness by 20% and decrease the color 4369saturation by 10% and leave the hue unchanged, use <a 4370href="#modulate">-modulate 120,90</a>.</p> 4371 4372<p>Use <a href="#set">-set</a> attribute of '<kbd 4373class="arg">option:modulate:colorspace</kbd>' to specify which colorspace to 4374modulate. Choose from <kbd>HSB</kbd>, <kbd>HSL</kbd> (the default), or 4375<kbd>HWB</kbd>. For example,</p> 4376 4377<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png</span></p> 4378 4379<div style="margin: auto;"> 4380 <h4><a id="monitor"></a>-monitor</h4> 4381</div> 4382 4383<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>monitor progress.</td><td style='text-align:right;'></td></tr></table> 4384 4385 4386<div style="margin: auto;"> 4387 <h4><a id="monochrome"></a>-monochrome</h4> 4388</div> 4389 4390<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image to black and white.</td><td style='text-align:right;'></td></tr></table> 4391 4392 4393<div style="margin: auto;"> 4394 <h4><a id="morph"></a>-morph <em class="arg">frames</em></h4> 4395</div> 4396 4397<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>morphs an image sequence.</td><td style='text-align:right;'></td></tr></table> 4398 4399<p>Both the image pixels and size are linearly interpolated to give the 4400appearance of a meta-morphosis from one image to the next, over all the images 4401in the current image list. The added images are the equivalent of a <a 4402href="#blend">-blend</a> composition. The <em class="arg">frames</em> 4403argument determine how many images to interpolate between each image. </p> 4404 4405 4406<div style="margin: auto;"> 4407 <h4><a id="morphology"></a>-morphology</h4> 4408 <h4>-morphology <em class="arg">method</em> <em class="arg">kernel</em></h4> 4409</div> 4410 4411<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a morphology method to the image.</td><td style='text-align:right;'></td></tr></table> 4412 4413<p>Until I get around to writing a option summary for this, see <a 4414href="http://www.imagemagick.org/Usage/morphology/" >IM Usage Examples, 4415Morphology</a>. </p> 4416 4417 4418<div style="margin: auto;"> 4419 <h4><a id="mosaic"></a>-mosaic</h4> 4420</div> 4421 4422<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>an simple alias for the <a href="#layers" >-layers</a> method "mosaic"</td><td style='text-align:right;'></td></tr></table> 4423 4424 4425<div style="margin: auto;"> 4426 <h4><a id="motion-blur"></a>-motion-blur <em class="arg">radius</em><br />-motion-blur <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em></h4> 4427</div> 4428 4429<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate motion blur.</td><td style='text-align:right;'></td></tr></table> 4430 4431<p>Blur with the given radius, standard deviation (sigma), and angle. The 4432angle given is the angle toward which the image is blurred. That is the 4433direction people would consider the object is coming from. </p> 4434 4435<p>Note that the blur is not uniform distribution, giving the motion a 4436definite sense of direction of movement. </p> 4437 4438<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 4439pixels which are outside the image proper are blurred into the final result. 4440</p> 4441 4442<div style="margin: auto;"> 4443 <h4><a id="name"></a>-name</h4> 4444</div> 4445 4446<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name an image.</td><td style='text-align:right;'></td></tr></table> 4447<div style="margin: auto;"> 4448 <h4><a id="negate"></a>-negate</h4> 4449</div> 4450 4451<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with its complementary color.</td><td style='text-align:right;'></td></tr></table> 4452 4453<p>The red, green, and blue intensities of an image are negated. White becomes black, yellow becomes blue, etc. Use <a href="#negate">+negate</a> to only negate the grayscale pixels of the image.</p> 4454 4455<div style="margin: auto;"> 4456 <h4><a id="noise"></a>-noise <em class="arg">geometry</em><br/> 4457 +noise <em class="arg">type</em></h4> 4458</div> 4459 4460<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add or reduce noise in an image.</td><td style='text-align:right;'></td></tr></table> 4461 4462<p>The principal function of noise peak elimination filter is to smooth the objects within an image without losing edge information and without creating undesired structures. The central idea of the algorithm is to replace a pixel with its next neighbor in value within a pixel window, if this pixel has been found to be noise. A pixel is defined as noise if and only if this pixel is a maximum or minimum within the pixel window.</p> 4463 4464<p>Use <kbd><a href="#noise">-noise</a> <em class="arg">radius</em></kbd> to specify the width of the neighborhood when reducing noise.</p> 4465 4466<p>Use <a href="#noise">+noise</a> followed by a noise <em class="arg">type</em> to add noise to an image. Choose from these noise types:</p> 4467 4468<pre class="text"> 4469 Gaussian 4470 Impulse 4471 Laplacian 4472 Multiplicative 4473 Poisson 4474 Random 4475 Uniform 4476</pre> 4477 4478<p>To print a complete list of noises, use the <a href="#list">-list noise</a> option.</p> 4479 4480<p>Also see the <a href="#evaluate">-evaluate</a> noise functions that allos 4481the use of a controlling value to specify teh amount of noise that should be 4482added to an image. </p> 4483 4484 4485<div style="margin: auto;"> 4486 <h4><a id="normalize"></a>-normalize</h4> 4487</div> 4488 4489<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table> 4490 4491<p>The intensity values are stretched to cover the entire range of possible 4492values. While doing so, black-out at most <em>2%</em> of the pixels and 4493white-out at most <em>1%</em> of the pixels.</p> 4494 4495<p>Note that as of ImageMagick 6.4.7-0, <a href="#normalize" >-normalize</a> 4496is equivalent to <a href="#contrast-stretch" >-contrast-stretch 2%x1%</a>. 4497(Before this version, it was equivalent to <a href="#contrast-stretch" 4498>-contrast-stretch 2%x99%</a>).</p> 4499 4500<p>All the channels are normalized in concert by the came amount so as to 4501preserve color integrity, when the default <a href="#channel" >+channel</a> 4502setting is in use. Specifying any other <a href="#channel" >-channel</a> 4503setting will normalize the RGB channels independently.</p> 4504 4505<p>See <a href="#contrast-stretch" >-contrast-stretch</a> for more details. 4506Also see <a href="#auto-level" >-auto-level</a> for a 'perfect' normalization 4507that is better suited to mathematically generated images. </p> 4508 4509<p>This operator is under review for re-development. </p> 4510 4511 4512<div style="margin: auto;"> 4513 <h4><a id="ordered-dither"></a>-ordered-dither <em class="arg">threshold_map</em>{,<em class="arg">level</em>...}</h4> 4514</div> 4515 4516<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dither the image using a pre-defined ordered dither <em 4517class="arg">threshold map</em> specified, and a uniform color map with the 4518given number of <em class="arg">levels</em> per color channel . </td><td style='text-align:right;'></td></tr></table> 4519 4520<p>You can choose from these standard threshold maps:</p> 4521 4522<pre class="text"> 4523 threshold 1x1 Threshold 1x1 (non-dither) 4524 checks 2x1 Checkerboard 2x1 (dither) 4525 o2x2 2x2 Ordered 2x2 (dispersed) 4526 o3x3 3x3 Ordered 3x3 (dispersed) 4527 o4x4 4x4 Ordered 4x4 (dispersed) 4528 o8x8 8x8 Ordered 8x8 (dispersed) 4529 h4x4a 4x1 Halftone 4x4 (angled) 4530 h6x6a 6x1 Halftone 6x6 (angled) 4531 h8x8a 8x1 Halftone 8x8 (angled) 4532 h4x4o Halftone 4x4 (orthogonal) 4533 h6x6o Halftone 6x6 (orthogonal) 4534 h8x8o Halftone 8x8 (orthogonal) 4535 h16x16o Halftone 16x16 (orthogonal) 4536 c5x5b c5x5 Circles 5x5 (black) 4537 c5x5w Circles 5x5 (white) 4538 c6x6b c6x6 Circles 6x6 (black) 4539 c6x6w Circles 6x6 (white) 4540 c7x7b c7x7 Circles 7x7 (black) 4541 c7x7w Circles 7x7 (white) 4542</pre> 4543 4544<p> The <kbd>threshold</kbd> generated a simple 50% threshold of the image. 4545This could be used with <em class="arg" >level</em> to do the equivalent of <a 4546href="#posterize" >-posterize</a> to reduce an image to basic primary colors. 4547</p> 4548 4549<p>The <kbd>checks</kbd> pattern produces a 3 level checkerbord dither 4550pattern. That is a grayscale will become a pattern of solid black, solid 4551white, and mid-tone colors into a checkerboard pattern of black and white. 4552</p> 4553 4554<p>You can define your own <em class="arg" >threshold map</em> for ordered 4555dithering and halftoning your images, in either personal or system 4556<kbd>thresholds.xml</kbd> XML file. See <a href="resources.html" >Resources</A> 4557for more details of configuration files. </p> 4558 4559<p>To print a complete list of the thresholds that have been defined, use the 4560<a href="#list" >-list threshold</a> option.</p> 4561 4562<p>Note that at this time the same threshold dithering map is used for all 4563color channels, no attempt is made to offset or rotate the map for different 4564channels is made, to create an offset printing effect. Also as the maps are 4565simple threshold levels, the halftone and circle maps will create incomplete 4566circles along the edges of a colored area. Also all the effects are purely 4567on/off boolean effects, without anti-aliasing to make the circles smooth 4568looking. Large dots can be made to look better with a small amount of blurring 4569after being created. </p> 4570 4571 4572<div style="margin: auto;"> 4573 <h4><a id="opaque"></a>-opaque <em class="arg">color</em></h4> 4574</div> 4575 4576<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>change this color to the fill color within the image.</td><td style='text-align:right;'></td></tr></table> 4577 4578<p>The <em class="arg">color</em> argument is defined using the format 4579described under the <a href="#fill" >-fill</a> option. The <a href="#fuzz" 4580>-fuzz</a> setting can be used to match and replace colors similar to the one 4581given.</p> 4582 4583<p>Use <a href="#opaque">+opaque</a> to paint any pixel that does not match 4584the target color. </p> 4585 4586<p>The <a href="#transparent">-transparent</a> operator is exactly the same 4587as <a href="#opaque" >-opaque</a> but replaces the matching color with 4588transparency rather than the current <a href="#fill">-fill</a> color setting. 4589To ensure that it can do this it also ensures that the image has an alpha 4590channel enabled, as per "<kbd><a href="#alpha" >-alpha</a> set</kbd>", for 4591the new transparent colors, and does not require you to modify the <a 4592href="#channel">-channel</a> to enable alpha channel handling. </p> 4593 4594 4595<div style="margin: auto;"> 4596 <h4><a id="orient"></a>-orient <em class="arg">image orientation</em></h4> 4597</div> 4598 4599<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify orientation of a digital camera image.</td><td style='text-align:right;'></td></tr></table> 4600 4601<p>Choose from these orientations:</p> 4602 4603<pre class="text"> 4604 bottom-left 4605 bottom-right 4606 left-bottom 4607 left-top 4608 right-bottom 4609 right-top 4610 top-left 4611 top-right 4612 undefined 4613</pre> 4614 4615<p>To print a complete list of orientations, use the <a href="#list" >-list 4616orientation</a> option.</p> 4617 4618 4619<div style="margin: auto;"> 4620 <h4><a id="page"></a>-page <em class="arg">geometry</em><br/> 4621 -page <em class="arg">media</em>[<em class="arg">offset</em>][{<em class="arg">^!<></em>}]<br/> 4622 +page 4623 </h4> 4624</div> 4625 4626<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the size and location of an image on the larger virtual canvas.</td><td style='text-align:right;'></td></tr></table> 4627 4628<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 4629 4630<p>For convenience you can specify the page size using <em class="arg">media</em> (see below). Offsets can then be added as with other <em class="arg">geometry</em> arguments (e.g. <a href="#page">-page</a> <kbd>Letter+43+43</kbd>).</p> 4631 4632<p>Use <em class="arg">media</em> as shorthand to specify the dimensions (<em class="arg">width</em>x<em class="arg">height</em>) of the <em class="arg">PostScript</em> page in dots per inch or a TEXT page in pixels. The choices for a PostScript page are:</p> 4633<table id="geometryTable" cellpadding="2" cellspacing="0" border="1" width="50%" style="margin-left: auto; margin-right: auto;"> 4634<thead> 4635 <tr valign="top"> 4636 <th align="center"><em class="arg">media</em></th> 4637 <th align="center"><em class="arg">width</em></th> 4638 <th align="center"><em class="arg">height</em></th> 4639 </tr> 4640</thead> 4641<tbody> 4642<tr><td align="left"> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr> 4643<tr><td align="left"> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr> 4644<tr><td align="left"> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr> 4645<tr><td align="left"> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr> 4646<tr><td align="left"> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr> 4647<tr><td align="left"> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr> 4648<tr><td align="left"> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr> 4649<tr><td align="left"> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr> 4650<tr><td align="left"> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr> 4651<tr><td align="left"> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr> 4652<tr><td align="left"> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr> 4653<tr><td align="left"> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr> 4654<tr><td align="left"> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr> 4655<tr><td align="left"> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr> 4656<tr><td align="left"> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr> 4657<tr><td align="left"> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr> 4658<tr><td align="left"> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr> 4659<tr><td align="left"> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr> 4660<tr><td align="left"> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr> 4661<tr><td align="left"> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr> 4662<tr><td align="left"> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr> 4663<tr><td align="left"> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr> 4664<tr><td align="left"> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr> 4665<tr><td align="left"> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr> 4666<tr><td align="left"> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr> 4667<tr><td align="left"> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr> 4668<tr><td align="left"> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr> 4669<tr><td align="left"> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr> 4670<tr><td align="left"> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr> 4671<tr><td align="left"> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr> 4672<tr><td align="left"> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr> 4673<tr><td align="left"> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr> 4674<tr><td align="left"> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr> 4675<tr><td align="left"> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr> 4676<tr><td align="left"> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr> 4677<tr><td align="left"> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr> 4678<tr><td align="left"> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr> 4679<tr><td align="left"> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr> 4680</tbody> 4681</table> 4682 4683 4684 4685 4686<p>This option is also used to place subimages when writing to a multi-image format that supports offsets, such as GIF89 and MNG. When used for this purpose the offsets are always measured from the top left corner of the canvas and are not affected by the <a href="#gravity">-gravity</a> option. To position a GIF or MNG image, use <a href="#page">-page</a><em class="arg">{+-}x{+-}y</em> (e.g. -page +100+200). When writing to a MNG file, a <a href="#page">-page</a> option appearing ahead of the first image in the sequence with nonzero width and height defines the width and height values that are written in the <kbd>MHDR</kbd> chunk. Otherwise, the MNG width and height are computed from the bounding box that contains all images in the sequence. When writing a GIF89 file, only the bounding box method is used to determine its dimensions.</p> 4687 4688<p>For a PostScript page, the image is sized as in <a href="#geometry">-geometry</a> but positioned relative to the <em>lower left-hand corner</em> of the page by {+-}<kbd>x</kbd><em class="arg">offset</em>{+-}<kbd>y</kbd> <em class="arg">offset</em>. Use <a href="#page">-page 612x792</a>, for example, to center the image within the page. If the image size exceeds the PostScript page, it is reduced to fit the page. The default gravity for the <a href="#page">-page</a> option is <em class="arg">NorthWest</em>, i.e., positive <kbd>x</kbd> and <kbd>y</kbd> <em class="arg">offset</em> are measured rightward and downward from the top left corner of the page, unless the <a href="#gravity">-gravity</a> option is present with a value other than <em class="arg">NorthWest</em>.</p> 4689 4690<p>The default page dimensions for a TEXT image is 612x792.</p> 4691 4692<p>This option is used in concert with <a href="#density">-density</a>.</p> 4693 4694<p>Use <a href="#page">+page</a> to remove the page settings for an image.</p> 4695 4696<div style="margin: auto;"> 4697 <h4><a id="paint"></a>-paint <em class="arg">radius</em></h4> 4698</div> 4699 4700<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an oil painting.</td><td style='text-align:right;'></td></tr></table> 4701 4702<p>Each pixel is replaced by the most frequent color in a circular neighborhood whose width is specified with <em class="arg">radius</em>.</p> 4703 4704<div style="margin: auto;"> 4705 <h4><a id="path"></a>-path <em class="arg">path</em></h4></div> 4706 4707<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write images to this path on disk.</td><td style='text-align:right;'></td></tr></table> 4708 4709<div style="margin: auto;"> 4710 <h4><a id="pause_animate_"></a>-pause <em class="arg">seconds</em></h4> 4711</div> 4712 4713<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between animation loops.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>]</td></tr></table> 4714 4715<p>Pause for the specified number of seconds before repeating the animation.</p> 4716 4717<div style="margin: auto;"> 4718 <h4><a id="pause_import_"></a>-pause <em class="arg">seconds</em></h4> 4719</div> 4720 4721<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between snapshots.</td><td style='text-align:right;'>[<a href="/www/import.html">import</a>]</td></tr></table> 4722 4723<p>Pause for the specified number of seconds before taking the next snapshot.</p> 4724 4725<div style="margin: auto;"> 4726 <h4><a id="ping"></a>-ping</h4> 4727</div> 4728 4729<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>efficiently determine image characteristics.</td><td style='text-align:right;'></td></tr></table> 4730 4731<div style="margin: auto;"> 4732 <h4><a id="pointsize"></a>-pointsize <em class="arg">value</em></h4> 4733</div> 4734 4735<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pointsize of the PostScript, OPTION1, or TrueType font.</td><td style='text-align:right;'></td></tr></table> 4736 4737<div style="margin: auto;"> 4738 <h4><a id="polaroid"></a>-polaroid <em class="arg">angle</em></h4> 4739</div> 4740 4741<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a Polaroid picture.</td><td style='text-align:right;'></td></tr></table> 4742 4743<p>Use <kbd>+polaroid</kbd> to rotate the image at a random angle between -15 and +15 degrees.</p> 4744 4745<div style="margin: auto;"> 4746 <h4><a id="posterize"></a>-posterize <em class="arg">levels</em></h4> 4747</div> 4748 4749<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the image to a limited number of color levels.</td><td style='text-align:right;'></td></tr></table> 4750 4751<div style="margin: auto;"> 4752 <h4><a id="precision"></a>-precision <em class="arg">value</em></h4> 4753</div> 4754 4755<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the maximum number of significant digits to be printed.</td><td style='text-align:right;'></td></tr></table> 4756 4757<div style="margin: auto;"> 4758 <h4><a id="preview"></a>-preview <em class="arg">type</em></h4> 4759</div> 4760 4761<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>image preview type.</td><td style='text-align:right;'></td></tr></table> 4762 4763<p>Use this option to affect the preview operation of an image (e.g. <kbd>convert file.png -preview Gamma Preview:gamma.png</kbd>). Choose from these previews:</p> 4764 4765<pre class="text"> 4766 Rotate Shear Roll Hue 4767 Saturation Brightness Gamma Spiff 4768 Dull Grayscale Quantize Despeckle 4769 ReduceNoise Add Noise Sharpen Blur 4770 Threshold EdgeDetect Spread Shade 4771 Raise Segment Solarize Swirl 4772 Implode Wave OilPaint CharcoalDrawing 4773 JPEG 4774</pre> 4775 4776<p>To print a complete list of previews, use the <a href="#list">-list preview</a> option.</p> 4777 4778<p>The default preview is <kbd>JPEG</kbd>.</p> 4779 4780<div style="margin: auto;"> 4781 <h4><a id="print"></a>-print <em class="arg">string</em></h4> 4782</div> 4783 4784<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>interpret string and print to console.</td><td style='text-align:right;'></td></tr></table> 4785 4786<div style="margin: auto;"> 4787 <h4><a id="process"></a>-process <em class="arg">command</em></h4> 4788</div> 4789 4790<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>process the image with a custom image filter.</td><td style='text-align:right;'></td></tr></table> 4791 4792<p>The command arguments has the form <kbd>"module arg1 arg2 arg3 ... argN"</kbd> where <kbd>module</kbd> is the name of the module to invoke (e.g. "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to pass to the process module.</p> 4793 4794<div style="margin: auto;"> 4795 <h4><a id="profile"></a>-profile <em class="arg">filename</em><br/> 4796 +profile <em class="arg">profile_name</em></h4> 4797</div> 4798 4799<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Manage ICM, IPTC, or generic profiles in an image.</td><td style='text-align:right;'></td></tr></table> 4800 4801<p>Using <a href="#profile">-profile</a> <em class="arg">filename</em> adds an ICM (ICC color management), IPTC (newswire information), or a generic profile to the image.</p> 4802 4803<p>Use <a href="#profile">+profile <em class="arg">profile_name</em></a> to remove the indicated profile. ImageMagick uses standard filename globbing, so wildcard expressions may be used to remove more than one profile. Here we remove all profiles from the image except for the XMP profile: <kbd>+profile "!xmp,*"</kbd>. </p> 4804 4805<p>Use <kbd>identify -verbose</kbd> to find out which profiles are in the image file. Use <a href="#strip">-strip</a> to remove all profiles (and comments).</p> 4806 4807<p>To extract a profile, the <a href="#profile">-profile</a> option is not used. Instead, simply write the file to an image format such as <em class="arg">APP1, 8BImageMagick, ICM,</em> or <em class="arg">IPTC</em>.</p> 4808 4809<p>For example, to extract the Exif data (which is stored in JPEG files in the <em class="arg">APP1</em> profile), use.</p> 4810 4811<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert cockatoo.jpg profile.exif</span></p> 4812<p>It is important to note that results may depend on whether or not the original image already has an included profile. Also, keep in mind that <a href="#profile">-profile</a> is an "operator" (as opposed to a "setting") and therefore a conversion is made each time it is encountered, in order, in the command-line. For instance, in the following example, if the original image is CMYK with profile, a CMYK-CMYK-RGB conversion results.</p> 4813 4814<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff</span></p> 4815<p>Furthermore, since ICC profiles are not necessarily symmetric, extra conversion steps can yield unwanted results. 4816CMYK profiles are often very asymmetric since they involve 3−>4 and 4−>3 channel mapping. 4817</p> 4818 4819<p>The <a href="#profile">-profile</a> option can also be used to inject 4820previously-formatted ancillary chunks into the output PNG file, using 4821the commandline option as shown below or by setting the profile via a 4822programming interface:</p> 4823 4824<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>-profile PNG-chunk-x:<filename></span></p> 4825<p>where <em>x</em> is a location flag and 4826<em class="arg">filename</em> is a file containing the chunk 4827name in the first 4 bytes, then a colon (":"), followed by the chunk data. 4828This encoder will compute the chunk length and CRC, so those must not 4829be included in the file.</p> 4830 4831<p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT), 4832or "e" (end, i.e., after IDAT). If you want to write multiple chunks 4833of the same type, then add a short unique string after the "x" to prevent 4834subsequent profiles from overwriting the preceding ones, e.g.,</p> 4835 4836 4837<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>-profile PNG-chunk-b01:file01 -profile PNG-chunk-b02:file02</span></p> 4838<div style="margin: auto;"> 4839 <h4><a id="quality"></a>-quality <em class="arg">value</em></h4> 4840</div> 4841 4842<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>JPEG/MIFF/PNG compression level.</td><td style='text-align:right;'></td></tr></table> 4843 4844<p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and highest compression) to 100 (best quality but least effective compression). The default is to use the estimate quality of your input image otherwise 92. Use the <a href="#sampling-factor">-sampling-factor</a> option to specify the factors for chroma downsampling.</p> 4845 4846<p>For the MIFF image format, quality/10 is the zlib compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.</p> 4847 4848<p>For the JPEG-2000 image format, quality is mapped using a non-linear equation to the compression ratio required by the Jasper library. This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. The default quality value 100, a request for non-lossy compression. A quality of 75 results in a request for 16:1 compression.</p> 4849 4850<p>For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression. The default PNG compression is 75.</p> 4851 4852<p>If filter-type is 4 or less, the specified filter-type is used for all scanlines:</p> 4853 4854<pre class="text"> 4855 0: none 4856 1: sub 4857 2: up 4858 3: average 4859 4: Paeth 4860</pre> 4861 4862<p>If filter-type is 5, adaptive filtering is used when quality is greater than 50 and the image does not have a color map, otherwise no filtering is used.</p> 4863 4864<p>If filter-type is 6, adaptive filtering with <em class="arg">minimum-sum-of-absolute-values</em> is used.</p> 4865 4866<p>Only if the output is MNG, if filter-type is 7, the LOCO color transformation and adaptive filtering with <em class="arg">minimum-sum-of-absolute-values</em> are used.</p> 4867 4868<p>The quality setting has no effect on the appearance of PNG and MNG images, since the compression is always lossless.</p> 4869 4870<p>For further information, see the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p> 4871 4872<div style="margin: auto;"> 4873 <h4><a id="quantize"></a>-quantize <em class="arg">colorspace</em></h4> 4874</div> 4875 4876<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce colors using this colorspace.</td><td style='text-align:right;'></td></tr></table> 4877 4878<p>This setting defines the colorspace used to sort out and reduce the number 4879of colors needed by an image (for later dithering) by operators such as <a 4880href="#colors" >-colors</a>, Note that color reducion also happens 4881automatically when saving images to color-limited image file formats, such as 4882GIF, and PNG8.</p> 4883 4884 4885<div style="margin: auto;"> 4886 <h4><a id="quiet"></a>-quiet</h4> 4887</div> 4888 4889<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>suppress all warning messages. Error messages are still reported.</td><td style='text-align:right;'></td></tr></table> 4890 4891<div style="margin: auto;"> 4892 <h4><a id="radial-blur"></a>-radial-blur <em class="arg">angle</em></h4> 4893</div> 4894 4895<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur around the center of the image.</td><td style='text-align:right;'></td></tr></table> 4896 4897<p>Note that this is actually a rotational blur rather than a radial and as 4898such actually mis-named. </p> 4899 4900<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 4901pixels which are outside the image proper are blurred into the final result. 4902</p> 4903 4904 4905<div style="margin: auto;"> 4906 <h4><a id="raise"></a>-raise <em class="arg">thickness</em></h4> 4907</div> 4908 4909<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lighten or darken image edges.</td><td style='text-align:right;'></td></tr></table> 4910 4911<p>This will create a 3-D effect. Use <a href="#raise">-raise</a> to create a raised effect, otherwise use <a href="#raise">+raise</a>. 4912</p> 4913 4914<p>Unlike the similar <a href="#frame">-frame</a> option, <a href="#raise">-raise</a> does not alter the dimensions of the image.</p> 4915 4916<div style="margin: auto;"> 4917 <h4><a id="random-threshold"></a>-random-threshold <em class="arg">low</em>x<em class="arg">high</em></h4> 4918</div> 4919 4920<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a random threshold to the image.</td><td style='text-align:right;'></td></tr></table> 4921 4922<div style="margin: auto;"> 4923 <h4><a id="red-primary"></a>-red-primary <em class="arg">x,y</em></h4> 4924</div> 4925 4926<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the red chromaticity primary point.</td><td style='text-align:right;'></td></tr></table> 4927 4928<div style="margin: auto;"> 4929 <h4><a id="regard-warnings"></a>-regard-warnings</h4> 4930</div> 4931 4932<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pay attention to warning messages.</td><td style='text-align:right;'></td></tr></table> 4933 4934<div style="margin: auto;"> 4935 <h4><a id="remap"></a>-remap <em class="arg">filename</em></h4> 4936</div> 4937 4938<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce the number of colors in an image to the colors used by this image.</td><td style='text-align:right;'></td></tr></table> 4939 4940<p>If the <a href="#dither">-dither</a> setting is enabled (the default) then 4941the given colors are dithered over the image as necessary, otherwise the closest 4942color (in RGB colorspace) is selected to replace that pixel in the image. </p> 4943 4944<p>As a side effect of applying a <a href="#remap">-remap</a> of colors across all 4945images in the current image sequence, all the images will have the same color 4946table. That means that when saved to a file format such as GIF, it will use 4947that color table as a single common or global color table, for all the images, 4948without requiring extra local color tables. </p> 4949 4950<p>Use <a href="#remap">+remap</a> to reduce all images in the current image 4951sequence to use a common color map over all the images. This equivalent to 4952appending all the images together (without extra background colors) and color 4953reducing those images using <a href="#colors">-colors</a> with a 256 color 4954limit, then <a href="#remap">-remap</a> those colors over the original list of 4955images. This ensures all the images follow a single color map. </p> 4956 4957<p>If the number of colors over all the images is less than 256, then <a 4958href="#remap">+remap</a> should not perform any color reduction or dithering, as 4959no color changes are needed. In that case, its only effect is to force the use 4960of a global color table. This recommended after using either <a 4961href="#colors">-colors</a> or <a href="#ordered-dither">-ordered-dither</a> to 4962reduce the number of colors in an animated image sequence. </p> 4963 4964<div style="margin: auto;"> 4965 <h4><a id="region"></a>-region <em class="arg">geometry</em></h4> 4966</div> 4967 4968<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a region in which subsequent operations apply.</td><td style='text-align:right;'></td></tr></table> 4969 4970<p>The <em class="arg">x</em> and <em class="arg">y</em> offsets are treated in the same manner as in <a href="#crop">-crop</a>.</p> 4971 4972<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 4973 4974<div style="margin: auto;"> 4975 <h4><a id="remote"></a>-remote</h4> 4976</div> 4977 4978<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform a remote operation.</td><td style='text-align:right;'></td></tr></table> 4979 4980<p>The only command recognized is the name of an image file to load.</p> 4981 4982<p>If you have more than one <a href="/www/display.html">display</a> application running simultaneously, use the <a href="#window"> window</a> option to specify which application to control.</p> 4983 4984<div style="margin: auto;"> 4985 <h4><a id="render"></a>-render</h4> 4986</div> 4987 4988<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render vector operations.</td><td style='text-align:right;'></td></tr></table> 4989 4990<p>Use <a href="#render">+render</a> to turn off rendering vector operations. This useful when saving the result to vector formats such as MVG or SVG.</p> 4991 4992<div style="margin: auto;"> 4993<h4><a id="repage"></a>-repage <em class="arg">geometry</em></h4> 4994</div> 4995 4996<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the canvas and offset information of the image.</td><td style='text-align:right;'></td></tr></table> 4997 4998<p>This option is like <a href="#page">-page</a> but acts as an image operator 4999rather than a setting. You can separately set the canvas size or the offset 5000of the image on that canvas by only providing those components. </p> 5001 5002<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 5003 5004<p>If a <kbd>!</kbd> flag is given the offset given is added to the existing 5005offset to move the image relative to its previous position. This useful for 5006animation sequences. </p> 5007 5008<p>A given a canvas size of zero such as '<kbd>0x0</kbd>' forces it to 5009recalculate the canvas size so the image (at its current offset) will appear 5010completely on that canvas (unless it has a negative offset).</p> 5011 5012<p>Use <a href="#repage">+repage</a> to completely remove/reset the virtual 5013canvas meta-data from the images. </p> 5014 5015<p>The <a href="#set">-set</a> '<kbd>page</kbd>' option can be used to 5016directly assign virtual canvas meta-data. </p> 5017 5018 5019<div style="margin: auto;"> 5020 <h4><a id="resample"></a>-resample <em class="arg">horizontal</em>x<em class="arg">vertical</em></h4> 5021</div> 5022 5023<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resample image to specified horizontal and vertical resolution.</td><td style='text-align:right;'></td></tr></table> 5024 5025<p>Resize the image so that its rendered size remains the same as the original at the specified target resolution. For example, if a 300 DPI image renders at 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of storing the image resolution. For formats which do not support an image resolution, the original resolution of the image must be specified via <a href="#density">-density</a> on the command line prior to specifying the resample resolution.</p> 5026 5027<p>Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile exists in the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.</p> 5028 5029<div style="margin: auto;"> 5030 <h4><a id="resize"></a>-resize <em class="arg">geometry</em></h4> 5031</div> 5032 5033<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize an image.</td><td style='text-align:right;'></td></tr></table> 5034 5035<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are ignored, and the <a href="#gravity">-gravity</a> option has no effect.</p> 5036 5037<p>If the <a href="#filter">-filter</a> option precedes the <a href="#resize">-resize</a> option, the image is resized with the specified filter.</p> 5038 5039<p>Many image processing algorithms assume your image is in a linear-light coding. If your image is gamma-corrected, you can remove the nonlinear gamma correction, apply the transform, then restore it like this:</p> 5040 5041<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \ <br/> -quality 92 passport.jpg</span></p> 5042<div style="margin: auto;"> 5043 <h4><a id="respect-parentheses"></a>-respect-parentheses</h4> 5044</div> 5045 5046<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>settings remain in effect until parenthesis boundary.</td><td style='text-align:right;'></td></tr></table> 5047 5048<div style="margin: auto;"> 5049 <h4><a id="reverse"></a>-reverse</h4> 5050</div> 5051 5052<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reverse the order of images in the current image list.</td><td style='text-align:right;'></td></tr></table> 5053 5054 5055<div style="margin: auto;"> 5056 <h4><a id="roll"></a>-roll {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4> 5057</div> 5058 5059<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>roll an image vertically or horizontally by the amount given.</td><td style='text-align:right;'></td></tr></table> 5060 5061<p>A negative <em class="arg">x</em> offset rolls the image left-to-right. A negative <em class="arg">y</em> offset rolls the image top-to-bottom.</p> 5062 5063 5064<div style="margin: auto;"> 5065 <h4><a id="rotate"></a>-rotate <em class="arg">degrees</em>{<em class="arg"><</em>}{<em class="arg">></em>}</h4> 5066</div> 5067 5068<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply Paeth image rotation (using shear operations) to the image.</td><td style='text-align:right;'></td></tr></table> 5069 5070<p>Use <kbd>></kbd> to rotate the image only if its width exceeds the height. <kbd><</kbd> rotates the image <em>only</em> if its width is less than the height. For example, if you specify <kbd>-rotate "-90>"</kbd> and the image size is 480x640, the image is not rotated. However, if the image is 640x480, it is rotated by -90 degrees. If you use <kbd>></kbd> or <kbd><</kbd>, enclose it in quotation marks to prevent it from being misinterpreted as a file redirection.</p> 5071 5072<p>Empty triangles in the corners, left over from rotating the image, are 5073filled with the <kbd>background</kbd> color. </p> 5074 5075<p>See also the <a href="#distort">-distort</a> operator and specifically the 5076'<kbd>ScaleRotateTranslate</kbd>' distort method. </p> 5077 5078 5079<div style="margin: auto;"> 5080 <h4><a id="sample"></a>-sample <em class="arg">geometry</em></h4> 5081</div> 5082 5083<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel subsampling and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table> 5084 5085<p>Change the image size simply by directly sampling the pixels original 5086image. When magnifying, pixels are replicated in blocks. When minifying, 5087pixels are sub-sampled (i.e., some rows and columns are skipped over). </p> 5088 5089<p>The results are thus equivalent to using <a href="#resize">-resize</a> with 5090a <a href="#filter">-filter</a> setting of <kbd>point</kbd> (nearest 5091neighbour), though <a href="#sample">-sample</a> is a lot faster, as it 5092avoids all the filter processing of the image. As such it completely ignores 5093the current <a href="#filter">-filter</a> setting. </p> 5094 5095<p>The key feature of the <a href="#sample">-sample</a> is that no new colors 5096will be added to the resulting image, though some colors may disappear. </p> 5097 5098<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are 5099ignored, unlike <a href="#resize">-resize</a>. </p> 5100 5101 5102<div style="margin: auto;"> 5103 <h4><a id="sampling-factor"></a>-sampling-factor <em class="arg">horizontal-factor</em>x<em class="arg">vertical-factor</em></h4> 5104</div> 5105 5106<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</td><td style='text-align:right;'></td></tr></table> 5107 5108<p>This option specifies the sampling factors to be used by the JPEG encoder for chroma downsampling. If this option is omitted, the JPEG library will use its own default values. When reading or writing the YUV format and when writing the M2V (MPEG-2) format, use <a href="#sampling-factor">-sampling-factor 2x1</a> or <a href="#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2 downsampling method.</p> 5109 5110<div style="margin: auto;"> 5111 <h4><a id="scale"></a>-scale <em class="arg">geometry</em></h4> 5112</div> 5113 5114<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel block averaging and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table> 5115 5116<p>Change the image size simply by replacing pixels by averaging pixels 5117together when minifying, or replacing pixels when magnifing. </p> 5118 5119<p>The results are thus equivalent to using <a href="#resize">-resize</a> with 5120a <a href="#filter">-filter</a> setting of <kbd>box</kbd>. Though it is a lot 5121faster, as it avoids all the filter processing of the image. As such it 5122completely ignores the current <a href="#filter">-filter</a> setting. </p> 5123 5124<p>If when shrinking (minifying) images the original image is some integer 5125multiple of the new image size, the number of pixels avergaed together to 5126produce the new pixel color is the same across the whole image. This is 5127a special case known as 'binning' and is often used as a method of reducing 5128noise in image such as those generated by digital cameras, especially in low 5129light conditions. </p> 5130 5131 5132<div style="margin: auto;"> 5133 <h4><a id="scene"></a>-scene <em class="arg">value</em></h4> 5134</div> 5135 5136<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set scene number.</td><td style='text-align:right;'></td></tr></table> 5137 5138<p>This option sets the scene number of an image or the first image in an image sequence.</p> 5139 5140<div style="margin: auto;"> 5141 <h4><a id="screen"></a>-screen</h4> 5142</div> 5143 5144<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the screen to capture.</td><td style='text-align:right;'></td></tr></table> 5145 5146<p>This option indicates that the GetImage request used to obtain the image should be done on the root window, rather than directly on the specified window. In this way, you can obtain pieces of other windows that overlap the specified window, and more importantly, you can capture menus or other popups that are independent windows but appear over the specified window.</p> 5147 5148<div style="margin: auto;"> 5149 <h4><a id="seed"></a>-seed</h4> 5150</div> 5151 5152<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>seed a new sequence of pseudo-random numbers</td><td style='text-align:right;'></td></tr></table> 5153 5154<div style="margin: auto;"> 5155 <h4><a id="segment"></a>-segment <em class="arg">cluster-threshold</em>x<em class="arg">smoothing-threshold</em></h4> 5156</div> 5157 5158<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>segment the colors of an image.</td><td style='text-align:right;'></td></tr></table> 5159 5160<p>Segment an image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. This is part of the ImageMagick color quantization routines. </p> 5161 5162<p>Specify <em class="arg">cluster threshold</em> as the number of pixels in each cluster that must exceed the cluster threshold to be considered valid. <em class="arg">Smoothing threshold</em> eliminates noise in the second derivative of the histogram. As the value is increased, you can expect a smoother second derivative. The default is 1.5.</p> 5163 5164<p>If the <a href="#verbose">-verbose</a> setting is defined, a detailed report 5165of the color clusters is returned.</p> 5166 5167 5168<div style="margin: auto;"> 5169 <h4><a id="selective-blur"></a>-selective-blur <em class="arg">radius</em><br />-selective-blur <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+threshold</em>}</h4> 5170</div> 5171 5172<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Selectively blur pixels within a contrast threshold.</td><td style='text-align:right;'></td></tr></table> 5173 5174<p>Blurs those pixels that are less than or equal to the threshold in contrast. The threshold may be expressed as a fraction of <em class="QR">QuantumRange</em> or as a percentage.</p> 5175 5176<div style="margin: auto;"> 5177 <h4><a id="separate"></a>-separate</h4> 5178</div> 5179 5180<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>separate an image channel into a grayscale image. Specify the channel with <a href="#channel">-channel</a>.</td><td style='text-align:right;'></td></tr></table> 5181 5182<div style="margin: auto;"> 5183 <h4><a id="sepia-tone"></a>-sepia-tone <em class="arg">threshold</em></h4> 5184</div> 5185 5186<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a sepia-toned photo.</td><td style='text-align:right;'></td></tr></table> 5187 5188<p>Specify <em class="arg">threshold</em> as the percent threshold of the intensity (0 - 99.9%).</p> 5189 5190<p>This option applies a special effect to the image, similar to the effect achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <em class="QR">QuantumRange</em> and is a measure of the extent of the sepia toning. A threshold of 80% is a good starting point for a reasonable tone.</p> 5191 5192 5193 5194<div style="margin: auto;"> 5195 <h4><a id="set"></a>-set <em class="arg">key value</em></h4> 5196 <h4>+set <em class="arg">key</em></h4> 5197</div> 5198 5199<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sets image attributes and properties for images in the current 5200image sequence.</td><td style='text-align:right;'></td></tr></table> 5201 5202<p>This will assign (or modify) specific settings attached to all the images 5203in the current image sequence. Using the <a href="#set">+set</a> form of the 5204option will either remove, or reset that setting to a default state, as 5205appropriate. </p> 5206 5207<p>For example, it will modify specific well known image meta-data 5208'attributes' such as those normally overridden by: the options <a 5209href="#delay" >-delay</a>, <a href="#dispose" >-dispose</a>, and <a 5210href="#page" >-page</a>, <a href="#colorspace" >-colorspace</a>; generally 5211assigned before the image is read in, by using a <em class="arg">key</em> of 5212the same name. </p> 5213 5214<p>If the given <em class="arg">key</em> does not match a specific known 5215'attribute ', such as shown above, the setting is stored as a a free form 5216'property' string. Such settings are listed in <a href="#verbose" 5217>-verbose</a> information ("<kbd>info:</kbd>" output format) as "Properties". 5218</p> 5219 5220<p>This includes string 'properities' that are set by and assigned to images 5221using the options <a href="#comment" >-comment</a>, <a href="#label" 5222>-label</a>, <a href="#caption" >-caption</a>. These options actually assign 5223a global 'artifact' which are automatically assigned (and any <a href="/www/escape.html" >Format Percent 5224Escapes</a> expanded) to images as they are read in. For example:</p> 5225 5226<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png</span><span class='crtout'>identify -format %c rose.png</span><span class="crtprompt"> $magick> </span><span class='crtin'>Rose is a rose is a rose is a rose</span></p> 5227<p>The set value can also make use of <a href="/www/escape.html" >Format and Print Image 5228Properties</a> in the defined value. For example:</p> 5229 5230<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set origsize '%wx%h' -resize 50% \</span><span class='crtout'> -format 'Old size = %[origsize] New size = %wx%h' info:</span><span class="crtprompt"> $magick> </span><span class='crtin'>Old size = 70x46 New size = 35x23</span></p> 5231<p>Other well known 'properities' that can be include: 5232'<kbd>date:create</kbd>' and '<kbd>date:modify</kbd>' and 5233'<kbd>signature</kbd>'. </p> 5234 5235<p>The <a href="#repage">-repage</a> operator will also allow you to modify 5236the '<kbd>page</kbd>' attribute of an image for images already in memory (also 5237see <a href="#repage">-page</a>). However it is designed to provide a finer 5238control of the sub-parts of this 'attribute'. The <a href="#set">-set page</a> 5239option will only provide a direct, unmodified assignment of '<kbd>page</kbd>' 5240attribute. </p> 5241 5242<p>This option can also associate a colorspace or profile with your image. 5243For example,</p> 5244 5245<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd</span></p> 5246<p>Some 'properties' must be defined in a specific way to be used. For 5247example only 'properties' prefixed with "<kbd>filename:</kbd>" can be used to 5248modify the output filename of an image. For example</p> 5249 5250<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'</span></p> 5251<p>If the setting value is prefixed with "<kbd>option:</kbd>" the setting will 5252be saved as a global "Artifact" exactly as if it was set using the <a 5253href="#define" >-define</a> option. As such settings are global in scope, they 5254can be used to pass 'attributes' and 'properities' of one specific image, 5255in a way that allows you to use them in a completely different image, even if 5256the original image has long since been modified or destroyed. For example: </p> 5257 5258<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set option:rosesize '%wx%h' -delete 0 \</span><span class='crtout'> label:'%[rosesize]' label_size_of_rose.gif</span></p> 5259<p>Note that <a href="/www/escape.html" >Format Percent Escapes</a> will only match 5260a 'artifact' if the given <em class="arg">key</em> does not match an existing 5261'attribute' or 'property'. </p> 5262 5263<p>You can set the attributes of the image registry by prefixing the value 5264with <kbd>registry:</kbd>.</p> 5265 5266 5267 5268<div style="margin: auto;"> 5269 <h4><a id="shade"></a>-shade <em class="arg">azimuth</em>x<em class="arg">elevation</em></h4> 5270</div> 5271 5272<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shade the image using a distant light source.</td><td style='text-align:right;'></td></tr></table> 5273 5274<p>Specify <em class="arg">azimuth</em> and <em class="arg">elevation</em> as the position of the light source. Use <a href="#shade">+shade</a> to return the shading results as a grayscale image.</p> 5275 5276<div style="margin: auto;"> 5277 <h4><a id="shadow"></a>-shadow <em class="arg">percent-opacity</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4> 5278</div> 5279 5280<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an image shadow.</td><td style='text-align:right;'></td></tr></table> 5281 5282<div style="margin: auto;"> 5283 <h4><a 5284id="shared-memory"></a>-shared-memory</h4> 5285</div> 5286 5287<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use shared memory.</td><td style='text-align:right;'></td></tr></table> 5288 5289<p>This option specifies whether the utility should attempt to use shared memory for pixmaps. ImageMagick must be compiled with shared memory support, and the display must support the <em class="arg">MIT-SHM</em> extension. Otherwise, this option is ignored. The default is <kbd>True</kbd>.</p> 5290 5291<div style="margin: auto;"> 5292 <h4><a id="sharpen"></a>-sharpen <em class="arg">radius</em>{x<em class="arg">sigma</em>}</h4> 5293</div> 5294 5295<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image.</td><td style='text-align:right;'></td></tr></table> 5296 5297<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p> 5298 5299<div style="margin: auto;"> 5300 <h4><a id="shave"></a>-shave <em class="arg">geometry</em></h4> 5301</div> 5302 5303<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shave pixels from the image edges.</td><td style='text-align:right;'></td></tr></table> 5304 5305<p>The <em class="arg">size</em> portion of the <em class="arg">geometry</em> argument specifies the width of the region to be removed from both sides of the image and the height of the regions to be removed from top and bottom. Offsets are ignored.</p> 5306 5307<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 5308 5309<div style="margin: auto;"> 5310 <h4><a id="shear"></a>-shear <em class="arg">Xdegrees</em>[x<em class="arg">Ydegrees</em>]</h4> 5311</div> 5312 5313<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the image along the x-axis and/or y-axis.</td><td style='text-align:right;'></td></tr></table> 5314 5315<p>The shear angles may be positive, negative, or zero. When <em class="arg">Ydegrees</em> is omitted it defaults to 0. When both angles are given, the horizontal component of the shear is performed before the vertical component.</p> 5316 5317<p>Shearing slides one edge of an image along the x-axis or y-axis (i.e., horizontally or vertically, respectively),creating a parallelogram. The amount of each is controlled by the respective shear angle. For horizontal shears, <em class="arg">Xdegrees</em> is measured clockwise relative to "up" (the negative y-axis), sliding the top edge to the right when 0°<<em class="arg">Xdegrees</em><90° and to the left when 90°<<em class="arg">Xdegrees</em><180°. For vertical shears <em class="arg">Ydegrees</em> is measured clockwise relative to "right" (the positive x-axis), sliding the right edge down when 0°<<em class="arg">Ydegrees</em><90° and up when 90°<<em class="arg">Ydegrees</em><180°.</p> 5318 5319<p>Empty triangles left over from shearing the image are filled with the color defined by the <a href="#fill">-background</a> option. The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 5320 5321<p>The horizontal shear is performed before the vertical part. This is important to note, since horizontal and vertical shears do not <em>commute</em>, i.e., the order matters in a sequence of shears. For example, the following two commands are not equivalent.</p> 5322 5323<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 20x0 -shear 0x60 logo-sheared.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 0x60 -shear 20x0 logo-sheared.png</span></p> 5324<p>The first of the two commands above is equivalent to the following, except for the amount of empty space created; the command that follows generates a smaller image, and so is a better choice in terms of time and space.</p> 5325 5326<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 20x60 logo-sheared.png</span></p> 5327<div style="margin: auto;"> 5328 <h4><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <em class="arg">contrast</em>x<em class="arg">mid-point</em></h4> 5329</div> 5330 5331<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>increase the contrast without saturating highlights or shadows.</td><td style='text-align:right;'></td></tr></table> 5332 5333<p>Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. <em class="arg">Contrast</em> indicates how much to increase the contrast (0 is none; 3 is typical; 20 is a lot); <em class="arg">mid-point</em> indicates where midtones fall in the resultant image (0 is white; 50% is middle-gray; 100% is black). By default the image contrast is increased, use <em class="arg">+sigmoidal-contrast</em> to decrease the contrast.</p> 5334 5335<div style="margin: auto;"> 5336 <h4><a id="silent"></a>-silent</h4> 5337</div> 5338 5339<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>operate silently.</td><td style='text-align:right;'></td></tr></table> 5340 5341<div style="margin: auto;"> 5342 <h4><a id="size"></a>-size <em class="arg">width</em>[x<em class="arg">height</em>][<em class="arg">+offset</em>]</h4> 5343</div> 5344 5345<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the width and height of the image.</td><td style='text-align:right;'></td></tr></table> 5346 5347<p>Use this option to specify the width and height of raw images whose dimensions are unknown such as <kbd>GRAY</kbd>, <kbd>RGB</kbd>, or <kbd>CMYK</kbd>. In addition to width and height, use <a href="#size">-size</a> with an offset to skip any header information in the image or tell the number of colors in a <kbd>MAP</kbd> image file, (e.g. -size 640x512+256).</p> 5348 5349<p>For Photo CD images, choose from these sizes:</p> 5350 5351<pre class="text"> 5352 192x128 5353 384x256 5354 768x512 5355 1536x1024 5356 3072x2048 5357</pre> 5358 5359<div style="margin: auto;"> 5360 <h4><a id="sketch"></a>-sketch <em class="arg">radius</em><br />-sketch <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em></h4> 5361</div> 5362 5363<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a pencil sketch.</td><td style='text-align:right;'></td></tr></table> 5364 5365<p>Sketch with the given radius, standard deviation (sigma), and angle. The angle given is the angle toward which the image is sketched. That is the direction people would consider the object is coming from. </p> 5366 5367<div style="margin: auto;"> 5368 <h4><a id="smush"></a>-smush <em class="arg">offset</em></h4> 5369</div> 5370 5371<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>smush an image sequence together.</td><td style='text-align:right;'></td></tr></table> 5372 5373<div style="margin: auto;"> 5374 <h4><a id="snaps"></a>-snaps <em class="arg">value</em></h4> 5375</div> 5376 5377<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the number of screen snapshots.</td><td style='text-align:right;'>[<a href="/www/import.html">import</a>]</td></tr></table> 5378 5379<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p> 5380 5381<div style="margin: auto;"> 5382 <h4><a id="solarize"></a>-solarize <em class="arg">threshold</em></h4> 5383</div> 5384 5385<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>negate all pixels above the threshold level.</td><td style='text-align:right;'></td></tr></table> 5386 5387<p>Specify <em class="arg">factor</em> as the percent threshold of the intensity (0 - 99.9%).</p> 5388 5389<p>This option produces a <em class="arg">solarization</em> effect seen when exposing a photographic film to light during the development process.</p> 5390 5391<div style="margin: auto;"> 5392 <h4><a id="sparse-color"></a>-sparse-color <em 5393 class="arg">method</em> '<em class="arg">x</em>,<em class="arg">y</em> <em class="arg">color</em> ...'</h4> 5394</div> 5395 5396<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </td><td style='text-align:right;'></td></tr></table> 5397 5398 5399<table class="doc"> 5400 <tbody> 5401 <tr valign="top"> 5402 <th align="left" style="width: 8%">Method</th> 5403 <th align="left">Description</th> 5404 </tr> 5405 5406 <tr valign="top"> 5407 <td valign="top">barycentric</td> 5408 <td valign="top">three point triangle of color given 3 points. 5409 Giving only 2 points will form a linear gradient between those points. 5410 The gradient generated extends beyond the triangle created by those 5411 3 points. </td> 5412 </tr> 5413 5414 <tr valign="top"> 5415 <td valign="top">bilinear</td> 5416 <td valign="top">Like barycentric but for 4 points. Less than 4 points 5417 fall back to barycentric. </td> 5418 </tr> 5419 <tr valign="top"> 5420 <td valign="top">voronoi</td> 5421 <td valign="top">Simply map each pixel to the to nearest color point 5422 given. The result are polygonal 'cells' of solid color. </td> 5423 </tr> 5424 5425 <tr valign="top"> 5426 <td valign="top">shepards</td> 5427 <td valign="top">Colors points biased on the ratio of inverse distance 5428 squared. Generating spots of color in a sea of the average of 5429 colors. </td> 5430 </tr> 5431 5432 <tr valign="top"> 5433 <td valign="top">inverse</td> 5434 <td valign="top">Colors points biased on the ratio of inverse distance. 5435 This generates sharper points of color rather than rounded spots of 5436 '<kbd>shepards</kbd>' Generating spots of color in a sea of the 5437 average of colors. </td> 5438 </tr> 5439 5440 </tbody> 5441</table> 5442 5443<p>The points are placed according to the images location on the virtual 5444canvas (<a href="#page" >-page</a> or <a href="#repage" >-repage</a> 5445offset), and do not actually have to exist on the given image, but may be 5446some point beyond the edge of the image. All points are floating point values. 5447</p> 5448 5449<p>Only the color channels defined by the <a href="#channel" >-channel</a> are 5450modified, which means that by default matte/alpha transparency channel is not 5451effected. Typically transparency channel is turned off either before or after 5452the operation. </P> 5453 5454Of course if some color points are transparent to generate a transparent 5455gradient, then the image also requires transparency enabled to store the 5456values. </p> 5457 5458<p>All the above methods when given a single point of color will replace all 5459the colors in the image with the color given, regardless of the point. This is 5460logical, and provides an alternative technique to recolor a image to some 5461default value. </p> 5462 5463 5464<div style="margin: auto;"> 5465 <h4><a id="splice"></a>-splice <em class="arg">geometry</em></h4> 5466</div> 5467 5468<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Splice the current background color into the image.</td><td style='text-align:right;'></td></tr></table> 5469 5470<p>This will add rows and columns of the current <a 5471href="#background">-background</a> color into the given image according to the 5472given <a href="#gravity">-gravity</a> effectd geometry setting. >See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Essentually <a href="#splice">-splice</a> will divide the 5473image into four quadrants, separating them by the inserted rows and columns. 5474</P> 5475 5476If a dimension of geometry is zero no rows or columns will be added for that 5477dimension. Similarly using a zero offset with the appropriate <a 5478href="#gravity">-gravity</a> setting will add rows and columns to the edges of 5479the image, padding the image only along that one edge. Edge padding is what <a 5480href="#splice">-splice</a> is most commonly used for. </p> 5481 5482<p>If the exact same <em class="arg">geometry</em> and <a 5483href="#gravity">-gravity</a> is later used with <a href="#chop">-chop</a> the 5484added added all splices removed. </p> 5485 5486<div style="margin: auto;"> 5487 <h4><a id="spread"></a>-spread <em class="arg">amount</em></h4> 5488</div> 5489 5490<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image pixels by a random amount.</td><td style='text-align:right;'></td></tr></table> 5491 5492<p>The argument <em class="arg">amount</em> defines the size of the neighborhood around each pixel from which to choose a candidate pixel to swap.</p> 5493 5494<div style="margin: auto;"> 5495 <h4><a id="statistic"></a>-statistic <em class="arg">type</em> <em class="arg">geometry</em></h4> 5496</div> 5497 5498<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with corresponding statistic from the neighborhood.</td><td style='text-align:right;'>[<a href="/www/convert.html">convert</a>, <a href="/www/mogrify.html">mogrify</a>]</td></tr></table> 5499 5500<p>Choose from these statistic types:</p> 5501<pre class="text"> 5502 Gradient maximum difference in area 5503 Maximum maximum value per channel in neighborhood 5504 Minimum minimum value per channel in neighborhood 5505 Mean average value per channel in neighborhood 5506 Median median value per channel in neighborhood 5507 Mode mode (most frequent) value per channel in neighborhood 5508 Nonpeak value just before or after the median value per channel in neighborhood 5509</pre> 5510 5511<div style="margin: auto;"> 5512 <h4><a id="stegano"></a>-stegano <em class="arg">offset</em></h4> 5513</div> 5514 5515<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>hide watermark within an image.</td><td style='text-align:right;'></td></tr></table> 5516 5517<p>Use an offset to start the image hiding some number of pixels from the beginning of the image. Note this offset and the image size. You will need this information to recover the steganographic image (e.g. display -size 320x256+35 stegano:image.png).</p> 5518 5519<div style="margin: auto;"> 5520 <h4><a id="stereo"></a>-stereo <em class="arg">+x</em>{<em class="arg">+y</em>}</h4> 5521</div> 5522 5523<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>composite two images to create a stereo anaglyph.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 5524 5525<p>The left side of the stereo pair is saved as the red channel of the output image. The right side is saved as the green channel. Red-green stereo glasses are required to properly view the stereo image.</p> 5526 5527<div style="margin: auto;"> 5528 <h4><a id="storage-type"></a>-storage-type <em class="arg">type</em></h4> 5529</div> 5530 5531<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel storage type. Here are the valid types:</td><td style='text-align:right;'></td></tr></table> 5532 5533<pre class="text"> 5534 char unsigned characters 5535 double doubles 5536 float floats 5537 integer integers 5538 long longs 5539 quantum pixels in the native depth of your ImageMagick distribution 5540 short unsigned shorts 5541</pre> 5542 5543<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels 5544values range from 0 to the maximum value the storage type can support.</p> 5545 5546<div style="margin: auto;"> 5547 <h4><a id="stretch"></a>-stretch <em class="arg">fontStretch</em></h4> 5548</div> 5549 5550<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a type of stretch style for fonts.</td><td style='text-align:right;'></td></tr></table> 5551 5552<p>This setting suggests a type of stretch that ImageMagick should try to apply to the currently selected font family. Select <em class="arg">fontStretch</em> from the following.</p> 5553 5554<pre class="text"> 5555 Any 5556 Condensed 5557 Expanded 5558 ExtraCondensed 5559 ExtraExpanded 5560 Normal 5561 SemiCondensed 5562 SemiExpanded 5563 UltraCondensed 5564 UltraExpanded 5565</pre> 5566 5567<p>To print a complete list of stretch types, use <a href="#list">-list stretch</a>.</p> 5568 5569<p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#style">-style</a>, and <a href="#weight">-weight</a>. </p> 5570 5571<div style="margin: auto;"> 5572 <h4><a id="strip"></a>-strip</h4> 5573</div> 5574 5575<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>strip the image of any profiles or comments.</td><td style='text-align:right;'></td></tr></table> 5576 5577<div style="margin: auto;"> 5578 <h4><a id="stroke"></a>-stroke <em class="arg">color</em></h4> 5579</div> 5580 5581<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when stroking a graphic primitive.</td><td style='text-align:right;'></td></tr></table> 5582 5583<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 5584 5585<p>See <a href="#draw">-draw</a> for further details.</p> 5586 5587<div style="margin: auto;"> 5588 <h4><a id="strokewidth"></a>-strokewidth <em class="arg">value</em></h4> 5589</div> 5590 5591<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the stroke width.</td><td style='text-align:right;'></td></tr></table> 5592 5593<p>See <a href="#draw">-draw</a> for further details.</p> 5594 5595<div style="margin: auto;"> 5596 <h4><a id="style"></a>-style <em class="arg">fontStyle</em></h4> 5597</div> 5598 5599<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font style for text.</td><td style='text-align:right;'></td></tr></table> 5600 5601<p>This setting suggests a font style that ImageMagick should try to apply to 5602the currently selected font family. Select <em class="arg">fontStyle</em> from 5603the following.</p> 5604 5605<pre class="text"> 5606 Any 5607 Italic 5608 Normal 5609 Oblique 5610</pre> 5611 5612<p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, and <a href="#weight">-weight</a>. </p> 5613 5614<div style="margin: auto;"> 5615 <h4><a id="subimage-search"></a>-subimage-search</h4> 5616</div> 5617 5618<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>search for subimage.</td><td style='text-align:right;'>[<a href="/www/compare.html">compare</a>]</td></tr></table> 5619 5620<p>This option is required to have compare search for the best match location 5621of a small image within a larger image. This search will produce two images 5622(or two frames). The first is the "difference" image and the second will 5623be the "match score" image.</p> 5624 5625<p>The "match-score" image is smaller containing a pixel for ever possible 5626position of the top-left corner of the given sub-image. that is its size will 5627be the size of the larger_image - sub_image + 1. The brightest location in 5628this image is the location s the locate on the best match that is also 5629reported. Note that this may or may nor be a perfect match, and the actual 5630brightness will reflect this. Other bright 'peaks' can be used to locate other 5631possible matching loctions. </p> 5632 5633<p>Note that the search will try to compare teh sub-image at every possible 5634location in the larger image, as such it can be very slow. The smaller the 5635sub-image the faster this search is. </p> 5636 5637 5638<div style="margin: auto;"> 5639 <h4><a id="swap"></a>-swap <em class="arg">index,index</em></h4> 5640</div> 5641 5642<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Swap the positions of two images in the image sequence.</td><td style='text-align:right;'></td></tr></table> 5643 5644<p>For example, <a href="#swap">-swap 0,2</a> swaps the first and the third 5645images in the current image sequence. Use <a href="#swap">+swap</a> to switch 5646the last two images in the sequence.</p> 5647 5648<div style="margin: auto;"> 5649 <h4><a id="swirl"></a>-swirl <em class="arg">degrees</em></h4> 5650</div> 5651 5652<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>swirl image pixels about the center.</td><td style='text-align:right;'></td></tr></table> 5653 5654<p><em class="arg">Degrees</em> defines the tightness of the swirl.</p> 5655 5656<div style="margin: auto;"> 5657 <h4><a id="synchronize"></a>-synchronize</h4> 5658</div> 5659 5660<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>synchronize image to storage device.</td><td style='text-align:right;'></td></tr></table> 5661 5662<div style="margin: auto;"> 5663 <h4><a id="taint"></a>-taint</h4> 5664</div> 5665 5666<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mark the image as modified.</td><td style='text-align:right;'></td></tr></table> 5667 5668<div style="margin: auto;"> 5669 <h4><a id="text-font"></a>-text-font <em class="arg">name</em></h4> 5670</div> 5671 5672<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>font for writing fixed-width text.</td><td style='text-align:right;'></td></tr></table> 5673 5674<p>Specifies the name of the preferred font to use in fixed (typewriter style) formatted text. The default is 14 point <em class="arg">Courier</em>.</p> 5675 5676<p>You can tag a font to specify whether it is a PostScript, TrueType, or OPTION1 font. For example, <kbd>Courier.ttf</kbd> is a TrueType font and <kbd>x:fixed</kbd> is OPTION1.</p> 5677 5678<div style="margin: auto;"> 5679 <h4><a id="texture"></a>-texture <em class="arg">filename</em></h4> 5680</div> 5681 5682<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name of texture to tile onto the image background.</td><td style='text-align:right;'></td></tr></table> 5683 5684<div style="margin: auto;"> 5685 <h4><a id="threshold"></a>-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 5686</div> 5687 5688<!-- {<em class="arg">green,blue,opacity</em>} 5689<p>If the green or blue value is omitted, these channels use the same value as the first one provided. If all three color values are the same, the result is a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used and any partially transparent pixel becomes fully transparent.</p> 5690--> 5691 5692<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply simultaneous black/white threshold to the image.</td><td style='text-align:right;'></td></tr></table> 5693 5694<p>Any pixel values (more specifically, those channels set using <a href="/www/command-line-options.html#channel">‑channel</a>) that exceed the specified threshold are reassigned the maximum channel value, while all other values are assigned the minimum.</p> 5695 5696<p> The threshold value can be given as a percentage or as an absolute integer value corresponding to the desired channel value. When given as an integer, the minimum attainable value is 0 (corresponding to black when all channels are affected), but the maximum value (corresponding to white) is that of the <kbd>quantum depth</kbd> of the particular build of ImageMagick, and is therefore dependent on the installation. For that reason, a reasonable recommendation for most applications is to specify the threshold values as a percentage. 5697</p> 5698 5699<p> The following would force pixels with red values above 50% to have 100% red values, while those at or below 50% red would be set to 0 in the red channel. The green, blue, and alpha channels (if present) would be unchanged. </p> 5700 5701<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -channel red -threshold 50% out.png</span></p> 5702<p>As (possibly) impractical but instructive examples, the following would generate an all-black and an all-white image with the same dimensions as the input image.</p> 5703 5704 5705<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -threshold 100% black.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -threshold -1 white.png</span></p> 5706<p>Note that the values of the transparency channel is treated as 'matte' 5707values (0 is opaque) and not as 'alpha' values (0 is transparent).</p> 5708 5709<p> See also <a href="/www/command-line-options.html#black-threshold">‑black‑threshold</a> and <a href="/www/command-line-options.html#white-threshold">‑white‑threshold</a>. 5710</p> 5711 5712<div style="margin: auto;"> 5713 <h4><a id="thumbnail"></a>-thumbnail <em class="arg">geometry</em></h4> 5714</div> 5715 5716<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Create a thumbnail of the image.</td><td style='text-align:right;'></td></tr></table> 5717 5718<p>This is similar to <a href="#resize">-resize</a>, except it is optimized for speed and any image profile, other than a color profile, is removed to reduce the thumbnail size. To strip the color profiles as well, add <a href="#strip">-strip</a> just before of after this option.</p> 5719 5720<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 5721 5722<div style="margin: auto;"> 5723 <h4><a id="tile"></a>-tile <em class="arg">filename</em></h4> 5724</div> 5725 5726<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the tile image used for filling a subsequent graphic primitive.</td><td style='text-align:right;'></td></tr></table> 5727 5728<div style="margin: auto;"> 5729 <h4>-tile <em class="arg">geometry</em></h4> 5730</div> 5731 5732<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the layout of images .</td><td style='text-align:right;'>[<a href="/www/montage.html">montage</a>]</td></tr></table> 5733 5734<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p> 5735 5736<div style="margin: auto;"> 5737 <h4>-tile</h4> 5738</div> 5739 5740<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies that a subsequent composite operation is repeated across and down image.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 5741 5742<div style="margin: auto;"> 5743 <h4><a id="tile-offset"></a>-tile-offset {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4> 5744</div> 5745 5746<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the offset for tile images, relative to the background image it is tiled on.</td><td style='text-align:right;'></td></tr></table> 5747 5748<p>This should be set before the tiling image is set by <a href="#tile" >-tile</a> or <a href="#texture" >-texture</a>, or directly applied for creating a tiled canvas using <kbd>TILE:</kbd> or <kbd>PATTERN:</kbd> input formats. </p> 5749 5750<p>Internally ImageMagick does a <a href="#roll" >-roll</a> of the tile image by the arguments given when the tile image is set. </p> 5751 5752<div style="margin: auto;"> 5753 <h4><a id="tint"></a>-tint <em class="arg">value</em></h4> 5754</div> 5755 5756<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Tint the image with the fill color.</td><td style='text-align:right;'></td></tr></table> 5757 5758<p>Tint the image with the fill color.</p> 5759 5760<p>Specify the amount of tinting as a percentage. Pure colors like black, white red, yellow, will not be affected by -tint. Only mid-range colors such as the various shades of grey.</p> 5761 5762<div style="margin: auto;"> 5763 <h4><a id="title"></a>-title <em class="arg">string</em></h4> 5764</div> 5765 5766<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a title to displayed image.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>, <a href="/www/montage.html">montage</a>]</td></tr></table> 5767 5768<p>Use this option to assign a specific title to the image. This assigned to the image window and is typically displayed in the window title bar. Optionally you can include the image filename, type, width, height, Exif data, or other image attribute by embedding special format characters described under the <a href="#format">-format</a> option.</p> 5769 5770<p>For example,</p> 5771 5772<p class="crtsnip"> 5773 -title "%m:%f %wx%h" 5774</p> 5775 5776<p>produces an image title of <kbd>MIFF:bird.miff 512x480</kbd> for an image titled <kbd>bird.miff</kbd> and whose width is 512 and height is 480.</p> 5777 5778 5779<div style="margin: auto;"> 5780 <h4><a id="transform"></a>-transform</h4> 5781</div> 5782 5783<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image.</td><td style='text-align:right;'></td></tr></table> 5784 5785<p>This option applies the transformation matrix from a previous <a href="#affine">-affine</a> option.</p> 5786 5787<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg</span></p> 5788 5789<p>This operator has been now been superseded by the <a 5790href="#distort">-distort</a> '<kbd>AffineProjection</kbd>' method. </p> 5791 5792 5793<div style="margin: auto;"> 5794 <h4><a id="transparent"></a>-transparent <em class="arg">color</em></h4> 5795</div> 5796 5797<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make this color transparent within the image.</td><td style='text-align:right;'></td></tr></table> 5798 5799<p>The <em class="arg">color</em> argument is defined using the format 5800described under the <a href="#fill">-fill</a> option. The <a href="#fuzz" 5801>-fuzz</a> setting can be used to match and replace colors similar to the one 5802given. </p> 5803 5804<p>Use <a href="#transparent" >+transparent</a> to invert the pixels matched. 5805that is make all non-matching colors transparent. </p> 5806 5807<p>The <a href="#opaque">-opaque</a> operator is exactly the same as <a 5808href="#transparent" >-transparent</a> but replaces the matching color with the 5809current <a href="#fill">-fill</a> color setting, rather than transparent. 5810However the <a href="#transparent" >-transparent</a> operator also ensures 5811that the image has an alpha channel enabled, as per "<kbd><a href="#alpha" 5812>-alpha</a> set</kbd>", and does not require you to modify the <a 5813href="#channel">-channel</a> to enable alpha channel handling. </p> 5814 5815<p>Note that this does not define the color as being the 'transparency color' 5816used for color-mapped image formats, such as GIF. For that use <a 5817href="#transparent-color" >-transparent-color</a> </p> 5818 5819 5820<div style="margin: auto;"> 5821 <h4><a id="transparent-color"></a>-transparent-color <em class="arg">color</em></h4> 5822</div> 5823 5824<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the transparent color.</td><td style='text-align:right;'></td></tr></table> 5825 5826<p>Sometimes this is used for saving to image formats such as 5827GIF and PNG8 which uses this color to represent boolean transparency. This 5828does not make a color transparent, it only defines what color the transparent 5829color is in the color palette of the saved image. Use <a 5830href="#transparent">-transparent</a> to make an opaque color transparent.</p> 5831 5832<p>This option allows you to have both an opaque visible color, as well as a 5833transparent color of the same color value without conflict. That is, you can 5834use the same color for both the transparent and opaque color areas within an 5835image. This, in turn, frees to you to select a transparent color that is 5836appropriate when an image is displayed by an application that does not handle a 5837transparent color index, while allowing ImageMagick to correctly handle images of this 5838type. </p> 5839 5840<p>The default transparent color is <kbd>#00000000</kbd>, which is fully transparent black.</p> 5841 5842<div style="margin: auto;"> 5843 <h4><a id="transpose"></a>-transpose</h4> 5844</div> 5845 5846<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the top-left to bottom-right diagonal.</td><td style='text-align:right;'></td></tr></table> 5847 5848<p> This option mathematically transposes the pixel array. It is equivalent to the sequence <kbd>-flip -rotate 90</kbd>. 5849</p> 5850 5851<div style="margin: auto;"> 5852 <h4><a id="transverse"></a>-transverse</h4> 5853</div> 5854 5855<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations <kbd>-flop -rotate 90</kbd>.</td><td style='text-align:right;'></td></tr></table> 5856 5857 5858<div style="margin: auto;"> 5859 <h4><a id="treedepth"></a>-treedepth <em class="arg">value</em></h4> 5860</div> 5861 5862<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>tree depth for the color reduction algorithm.</td><td style='text-align:right;'></td></tr></table> 5863 5864<p>Normally, this integer value is zero or one. A value of zero or one causes the use of an optimal tree depth for the color reduction algorithm.</p> 5865 5866<p>An optimal depth generally allows the best representation of the source image with the fastest computational speed and the least amount of memory. However, the default depth is inappropriate for some images. To assure the best representation, try values between 2 and 8 for this parameter. Refer to the <a href="/www/quantize.html">color reduction algorithm</a> for more details.</p> 5867 5868<p>The <a href="#colors">-colors</a> or <a href="#monochrome">-monochrome</a> option, or writing to an image format which requires color reduction, is required for this option to take effect.</p> 5869 5870<div style="margin: auto;"> 5871 <h4><a id="trim"></a>-trim</h4> 5872</div> 5873 5874<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>trim an image.</td><td style='text-align:right;'></td></tr></table> 5875 5876<p>This option removes any edges that are exactly the same color as the corner pixels. Use <a href="#fuzz">-fuzz</a> to make <a href="#trim">-trim</a> remove edges that are nearly the same color as the corner pixels.</p> 5877 5878<p>The page or virtual canvas information of the image is preserved allowing 5879you to extract the result of the <a href="#trim">-trim</a> operation from the 5880image. Use a <a href="#repage">+repage</a> to remove the virtual canvas page 5881information if it is unwanted.</p> 5882 5883<p>If the trimmed image 'disappears' an warning is produced, and a special 5884single pixel transparent 'missed' image is returned, in the same way as when a 5885<a href="#crop">-crop</a> operation 'misses' the image proper. </p> 5886 5887 5888<div style="margin: auto;"> 5889 <h4><a id="type"></a>-type <em class="arg">type</em></h4> 5890</div> 5891 5892<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image type.</td><td style='text-align:right;'></td></tr></table> 5893 <p>Choose from: <kbd>Bilevel</kbd>, <kbd>Grayscale</kbd>, <kbd>GrayscaleMatte</kbd>, <kbd>Palette</kbd>, <kbd>PaletteMatte</kbd>, <kbd>TrueColor</kbd>, <kbd>TrueColorMatte</kbd>, <kbd>ColorSeparation</kbd>, or <kbd>ColorSeparationMatte</kbd>.</p> 5894 5895<p>Normally, when a format supports different subformats such as grayscale and truecolor, the encoder will try to choose an efficient subformat. The <a href="#type">-type</a> option can be used to overrride this behavior. For example, to prevent a JPEG from being written in grayscale format even though only gray pixels are present, use.</p> 5896 5897<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bird.png -type TrueColor bird.jpg</span></p> 5898<p>Similarly, use <a href="#type">-type TrueColorMatte</a> to force the encoder to write an alpha channel even though the image is opaque, if the output format supports transparency.</p> 5899 5900<p>Use <a href="#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p> 5901 5902<div style="margin: auto;"> 5903 <h4><a id="undercolor"></a>-undercolor <em class="arg">color</em></h4> 5904</div> 5905 5906<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the color of the annotation bounding box.</td><td style='text-align:right;'></td></tr></table> 5907 5908<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 5909 5910<p>See <a href="#draw">-draw</a> for further details.</p> 5911 5912 5913<div style="margin: auto;"> 5914 <h4><a id="update"></a>-update <em class="arg">seconds</em></h4> 5915</div> 5916 5917<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect when image file is modified and redisplay.</td><td style='text-align:right;'></td></tr></table> 5918 5919<p>Suppose that while you are displaying an image the file that is currently displayed is over-written. <kbd>display</kbd> will automagically detect that the input file has been changed and update the displayed image accordingly.</p> 5920 5921 5922<div style="margin: auto;"> 5923 <h4><a id="unique-colors"></a>-unique-colors</h4> 5924</div> 5925 5926<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>discard all but one of any pixel color.</td><td style='text-align:right;'></td></tr></table> 5927 5928 5929<div style="margin: auto;"> 5930 <h4><a id="units"></a>-units <em class="arg">type</em></h4> 5931</div> 5932 5933<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the units of image resolution.</td><td style='text-align:right;'></td></tr></table> 5934 5935<p>Choose from: <kbd>Undefined</kbd>, <kbd>PixelsPerInch</kbd>, or <kbd>PixelsPerCentimeter</kbd>. This option is normally used in conjunction with the <a href="#density">-density</a> option.</p> 5936 5937 5938<div style="margin: auto;"> 5939 <h4><a id="unsharp"></a>-unsharp <em class="arg">radius</em><br />-unsharp <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+amount</em>}{<em class="arg">+threshold</em>}</h4> 5940</div> 5941 5942<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image with an unsharp mask operator.</td><td style='text-align:right;'></td></tr></table> 5943 5944<p>The <a href="#unsharp">-unsharp</a> option sharpens an image. The image is convolved with a Gaussian operator of the given radius and standard deviation (sigma). For reasonable results, radius should be larger than sigma. Use a radius of 0 to have the method select a suitable radius.</p> 5945 5946<p>The parameters are:</p> 5947 5948<pre class="text"> 5949 radius The radius of the Gaussian, in pixels, not counting the center 5950 pixel (default 0). 5951 sigma The standard deviation of the Gaussian, in pixels (default 1.0). 5952 amount The fraction of the difference between the original and the blur 5953 image that is added back into the original (default 1.0). 5954 threshold The threshold, as a fraction of <em class="QR">QuantumRange</em>, needed to apply the 5955 difference amount (default 0.05). 5956</pre> 5957 5958 5959<div style="margin: auto;"> 5960 <h4><a id="verbose"></a>-verbose</h4> 5961</div> 5962 5963<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print detailed information about the image when this option precedes the <a href="#identify">-identify</a> option or <kbd>info:</kbd>.</td><td style='text-align:right;'></td></tr></table> 5964 5965 5966<div style="margin: auto;"> 5967 <h4><a id="version"></a>-version</h4> 5968</div> 5969 5970<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print ImageMagick version string and exit.</td><td style='text-align:right;'></td></tr></table> 5971 5972 5973<div style="margin: auto;"> 5974 <h4><a id="view"></a>-view <em class="arg">string</em></h4> 5975</div> 5976 5977<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>FlashPix viewing parameters.</td><td style='text-align:right;'></td></tr></table> 5978 5979 5980<div style="margin: auto;"> 5981 <h4><a id="vignette"></a>-vignette <em class="arg">radius</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4> 5982</div> 5983 5984<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>soften the edges of the image in vignette style.</td><td style='text-align:right;'></td></tr></table> 5985 5986 5987<div style="margin: auto;"> 5988 <h4><a id="virtual-pixel"></a>-virtual-pixel <em class="arg">method</em></h4> 5989</div> 5990 5991<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify contents of <em>virtual pixels</em>.</td><td style='text-align:right;'></td></tr></table> 5992 5993<p>This option defines what color source should be used if and when a color 5994lookup completely 'misses' the source image. The color(s) that appear to 5995surround the source image. Generally this color is derived from the source 5996image, but could also be set to a specify background color. </p> 5997 5998<p>Choose from these methods:</p> 5999 6000<pre class="text"> 6001 background the area surrounding the image is the background color 6002 black the area surrounding the image is black 6003 checker-tile alternate squares with image and background color 6004 dither non-random 32x32 dithered pattern 6005 edge extend the edge pixel toward infinity 6006 gray the area surrounding the image is gray 6007 horizontal-tile horizontally tile the image, background color above/below 6008 horizontal-tile-edge horizontally tile the image and replicate the side edge pixels 6009 mirror mirror tile the image 6010 random choose a random pixel from the image 6011 tile tile the image (default) 6012 transparent the area surrounding the image is transparent blackness 6013 vertical-tile vertically tile the image, sides are background color 6014 vertical-tile-edge vertically tile the image and replicate the side edge pixels 6015 white the area surrounding the image is white 6016</pre> 6017 6018<p>The default value is "edge".</p> 6019 6020<p>This most important for distortion operators such as <a href="#distort" 6021>-distort</a>, <a href="#implode" >-implode</a>, and <a href="#fx" >-fx</a>. 6022However it also effects operations that may access pixels just outside the 6023image proper, such as <a href="#convolve">-convolve</a>, <a 6024href="#blur">-blur</a>, and <a href="#sharpen">-sharpen</a>. </p> 6025 6026<p>To print a complete list of virtual pixel types, use the <a href="#list">-list virtual-pixel</a> option.</p> 6027 6028 6029<div style="margin: auto;"> 6030 <h4><a id="visual"></a>-visual <em class="arg">type</em></h4> 6031</div> 6032 6033<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Animate images using this X visual type.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 6034 6035<p>Choose from these visual classes:</p> 6036 6037<pre class="text"> 6038 StaticGray 6039 GrayScale 6040 StaticColor 6041 PseudoColor 6042 TrueColor 6043 DirectColor 6044 default 6045 visual id 6046</pre> 6047 6048<p>The X server must support the visual you choose, otherwise an error occurs. If a visual is not specified, the visual class that can display the most simultaneous colors on the default screen is chosen.</p> 6049 6050 6051<div style="margin: auto;"> 6052 <h4><a id="watermark"></a>-watermark <em 6053 class="arg">brightness</em>x<em class="arg">saturation</em></h4> 6054</div> 6055 6056<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Watermark an image using the given percentages of brightness and 6057saturation.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 6058 6059<p>Take a grayscale image (with alpha mask) and modify the destination image's 6060brightness according to watermark image's grayscale value and the <em 6061class="arg">brightness</em> percentage. The destinations color saturation 6062attribute is just direct modified by the <em class="arg">saturation</em> 6063percentage, which defaults to 100 percent (no color change). </p> 6064 6065 6066<div style="margin: auto;"> 6067 <h4><a id="wave"></a>-wave <em class="arg">amplitude</em><br />-wave <em class="arg">amplitude</em>x<em class="arg">wavelength</em></h4> 6068</div> 6069 6070<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the columns of an image into a sine wave.</td><td style='text-align:right;'></td></tr></table> 6071 6072<p>Specify <em class="arg">amplitude</em> and <em class="arg">wavelength</em> of the wave.</p> 6073 6074<div style="margin: auto;"> 6075 <h4><a id="weight"></a>-weight <em class="arg">fontWeight</em></h4> 6076</div> 6077 6078<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font weight for text.</td><td style='text-align:right;'></td></tr></table> 6079 6080<p>This setting suggests a font weight that ImageMagick should try to apply to the currently selected font family. Use a positive integer for <em class="arg">fontWeight</em> or select from the following.</p> 6081 6082<table class="doc"> 6083 <col width="25%" /> 6084 <col width="75%" /> 6085 <thead> 6086 <tr> 6087 <th><em class="arg">fontWeight</em></th> 6088 <th>Description</th> 6089 </tr> 6090 </thead> 6091 <tbody> 6092 <tr><td>All </td> <td>No effect. </td></tr> 6093 <tr><td>Bold </td> <td>Same as <em class="arg">fontWeight</em> = 700.</td></tr> 6094 <tr><td>Bolder </td> <td>Add 100 to font weight if currently ≤ 800.</td></tr> 6095 <tr><td>Lighter </td> <td>Subtract 100 to font weight if currently ≤ 100.</td></tr> 6096 <tr><td>Normal </td> <td>Same as <em class="arg">fontWeight</em> = 400.</td></tr> 6097 </tbody> 6098 </table> 6099 6100<p>To print a complete list of weight types, use <a href="#list">-list weight</a>.</p> 6101 6102<p>For other settings that affect fonts, see the options <a href="#font">-font</a>, <a href="#family">-family</a>, <a href="#stretch">-stretch</a>, and <a href="#style">-style</a>. </p> 6103 6104<div style="margin: auto;"> 6105 <h4><a id="white-point"></a>-white-point <em class="arg">x,y</em></h4> 6106</div> 6107 6108<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>chromaticity white point.</td><td style='text-align:right;'></td></tr></table> 6109 6110<div style="margin: auto;"> 6111 <h4><a id="white-threshold"></a>-white-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 6112</div> 6113 6114<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</td><td style='text-align:right;'></td></tr></table> 6115 6116<p> The threshold value can be given as a percentage or as an absolute integer value within [0, <em class="QR">QuantumRange</em>] corresponding to the desired <a href="/www/command-line-options.html#channel">‑channel</a> value. See <a href="/www/command-line-options.html#threshold">‑threshold</a> for more details on thresholds and resulting values. 6117</p> 6118 6119<div style="margin: auto;"> 6120 <h4><a id="window"></a>-window <em class="arg">id</em></h4> 6121</div> 6122 6123<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make the image the background of a window.</td><td style='text-align:right;'>[<a href="/www/animate.html">animate</a>, <a href="/www/display.html">display</a>]</td></tr></table> 6124 6125<p><em class="arg">id</em> can be a window id or name. Specify <kbd>root</kbd> to select X's root window as the target window.</p> 6126 6127<p>By default the image is tiled onto the background of the target window. If <kbd>backdrop</kbd> or <a href="#geometry">-resize</a> are specified, the image is surrounded by the background color. Refer to <kbd>X RESOURCES</kbd> for details.</p> 6128 6129<p>The image will not display on the root window if the image has more unique colors than the target window colormap allows. Use <a href="#colors">-colors</a> to reduce the number of colors.</p> 6130 6131<div style="margin: auto;"> 6132 <h4><a id="window-group"></a>-window-group</h4> 6133</div> 6134 6135<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the window group.</td><td style='text-align:right;'></td></tr></table> 6136 6137<div style="margin: auto;"> 6138 <h4><a id="write"></a>-write <em class="arg">filename</em></h4> 6139</div> 6140 6141<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write an image sequence.</td><td style='text-align:right;'></td></tr></table> 6142 <p>The image sequence preceding the <a href="#write">-write</a> <em class="arg">filename</em> option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the <a href="#write">+write</a> <em class="arg">filename</em> option.</p> 6143 6144<p>Use <a href="#compress">-compress</a> to specify the type of image compression.</p> 6145</div> 6146</div> 6147 6148</div> 6149 6150<div id="linkbar"> 6151 <span id="linkbar-west"> </span> 6152 <span id="linkbar-center"> 6153 <a href="http://www.imagemagick.org/discourse-server/">Discourse Server</a> • 6154 <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">Studio</a> 6155 </span> 6156 <span id="linkbar-east"> </span> 6157 </div> 6158 <div class="footer"> 6159 <span id="footer-west">© 1999-2011 ImageMagick Studio LLC</span> 6160 <span id="footer-east"> <a href="http://www.imagemagick.org/script/contact.php">Contact the Wizards</a></span> 6161 </div> 6162 <div style="clear: both; margin: 0; width: 100%; "></div> 6163 <script type="text/javascript"> 6164 var _gaq = _gaq || []; 6165 _gaq.push(['_setAccount', 'UA-17690367-1']); 6166 _gaq.push(['_trackPageview']); 6167 6168 (function() { 6169 var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; 6170 ga.src = ('https:' == document.location.protocol ? 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