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href="/www/command-line-options.html#precision">‑precision</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#preview">‑preview</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#print">‑print</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#process">‑process</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#profile">‑profile</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#quality">‑quality</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#quantize">‑quantize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#quiet">‑quiet</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#radial-blur">‑radial‑blur</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#raise">‑raise</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#random-threshold">‑random‑threshold</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#red-primary">‑red‑primary</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#regard-warnings">‑regard‑warnings</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#region">‑region</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#remap">‑remap</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#remote">‑remote</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#render">‑render</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#repage">‑repage</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#resample">‑resample</a> <span class='bull'> • </span> <a 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 class='bull'> • </span> <a href="/www/command-line-options.html#segment">‑segment</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#selective-blur">‑selective‑blur</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#separate">‑separate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sepia-tone">‑sepia‑tone</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#set">‑set</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#shade">‑shade</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#shadow">‑shadow</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#shared-memory">‑shared‑memory</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#sharpen">‑sharpen</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#shave">‑shave</a> <span class='bull'> • </span> <a 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#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#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#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#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> 161 162<p>Below is list of command-line options recognized by the ImageMagick <a 163href="/www/command-line-tools.html">command-line 164tools</a>. If you want a description of a particular option, click on the 165option name in the navigation bar above and you will go right to it. Unless 166otherwise noted, each option is recognized by the commands <a href="/www/convert.html">convert</a>, <a href="/www/mogrify.html">mogrify</a>, and .... </p> 167 168<div style="margin: auto;"> 169 <h4><a name="adaptive-blur" id="adaptive-blur"></a>-adaptive-blur <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4> 170</div> 171 172<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> 173 "direction", 174<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> 175 176<div style="margin: auto;"> 177 <h4><a name="adaptive-resize" id="adaptive-resize"></a>-adaptive-resize <em class="arg">geometry</em></h4> 178</div> 179 180<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> 181 182<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> 183 184<div style="margin: auto;"> 185 <h4><a name="adaptive-sharpen" id="adaptive-sharpen"></a>-adaptive-sharpen <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4> 186</div> 187 188<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> 189 190<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> 191 192<div style="margin: auto;"> 193 <h4><a name="adjoin" id="adjoin"></a>-adjoin</h4> 194</div> 195 196<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> 197 198<p>This option is enabled by default. An attempt is made to save all 199images of an image sequence into the given output file. 200However, some formats, such as JPEG and PNG, do not support more than one 201image per file, and in that case ImageMagick is forced to write each image as a separate file. As 202such, if more than one image needs to be written, the filename given is 203modified by adding a <a href="#scene">-scene</a> number before the 204suffix, in order to make distinct names for each image. </p> 205 206<p>Use <a href="#adjoin">+adjoin</a> to force each image to be written 207to separate files, whether or not the file format allows multiple images 208per file (for example, GIF, MIFF, and TIFF). </p> 209 210<p>Including a C-style integer format string in the output filename will automagically enable <a href="#adjoin">+adjoin</a> and are used to specify where the <a href="#scene">-scene</a> number is placed in the filenames. These strings, such as '<kbd>%d</kbd>' or '<kbd>%03d</kbd>', are familiar to those who have used the standard <kbd>printf()</kbd>' C-library function. As an example, the command</p> 211 212<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: rose: -morph 15 my%02dmorph.jpg</span></p> 213<p>will create a sequence of 17 images named my00morph.jpg, my01morph.jpg, my02morph.jpg, ..., my16morph.jpg. 214</p> 215 216<p>In summary, ImageMagick tries to write all images to one file, but will use 217multiple files if either (1) the output image's file format does not allow multi-image files, 218(2) the <a href="#adjoin">+adjoin</a> option is given, or (3) a C-style integer format string is 219present in the output filename. </p> 220 221 222<div style="margin: auto;"> 223 <h4><a name="affine" id="affine"></a>-affine <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em>,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em><br/> 224 -affine <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em></h4> 225</div> 226 227<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> 228 229<p>This option sets a transformation matrix, encoded as (<em class="arg">s<sub>x</sub></em>, <em class="arg">r<sub>x</sub></em>, <em class="arg">r<sub>y</sub></em>, <em class="arg">s<sub>y</sub></em>, <em class="arg">t<sub>x</sub></em>, <em class="arg">t<sub>y</sub></em>), for use by subsequent <a href="#draw">-draw</a> or <a href="#transform">-transform</a> options.</p> 230 231<p>The matrix entries are entered as comma-separated numeric values <i>with no spaces</i>. </p> 232 233<p>Internally, the transformation matrix has 3x3 elements, but three of them are omitted from the input because they are constant. 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 original image are calculated using the following matrix equation.</p> 234 235<div class="eqn"> 236<img alt="affine transformation" src="/images/affine.png"/> 237</div> 238 239<p> 240The size of the resulting image is that of the smallest rectangle that contains the transformed source image. The parameters <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> subsequently shift the image pixels so that those that are moved out of the image area are cut off.</p> 241 242<p>The transformation matrix complies with the left-handed pixel coordinate system: positive <em class="arg">x</em> and <em class="arg">y</em> directions are rightward and downward, resp.; positive rotation is clockwise.</p> 243 244<p> If the translation coefficients <em class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em> are omotted they default to 0,0. Therefore, four parameters suffice for rotation and scaling without translation.</p> 245 246<p>Scaling by the factors <em class="arg">s<sub>x</sub></em> and <em class="arg">s<sub>y</sub></em> in the <em>x</em> and <em>y</em> directions, respectively, is accomplished with the following.</p> 247 248<p class="crtsnip"> 249 -affine <em class="arg">s<sub>x</sub></em>,0,0,<em class="arg">s<sub>y</sub></em> 250</p> 251 252<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> 253 254<p class="crtsnip"> 255 -affine 1,0,0,1,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em> 256</p> 257 258<p>Rotate clockwise about the origin (the upper left-hand corner) by an angle <em>a</em> by letting 259<em>c</em> = cos(<em>a</em>), <em>s</em> = sin(<em>a</em>), and using the following.</p> 260 261<p class="crtsnip"> 262 -affine <em>c</em>,<em>s</em>,-<em>s</em>,<em>c</em> 263</p> 264 265<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> 266 267<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> 268 269<div style="margin: auto;"> 270 <h4><a name="alpha" id="alpha"></a>-alpha <em class="arg">type</em></h4> 271</div> 272 273<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> 274 275<p>Used to set a flag on an image indicating whether or not to use existing alpha 276channel 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> 277 278 279<table class="doc"> 280 <tbody> 281 <tr valign="top"> 282 <th align="left" style="width: 8%">type</th> 283 <th align="left">Description</th> 284 </tr> 285 286 <tr valign="top"> 287 <td valign="top"><kbd>Off</kbd> or 288 <kbd>Deactivate</kbd></td> 289 <td valign="top"> 290 Disables the image's transparency channel. Does not delete or change the 291 existing data, just turns off the use of that data. This is the same as 292 the older <a href="#matte" >+matte</a> operator. </td></tr> 293 294 <tr valign="top"> 295 <td valign="top"><kbd>On</kbd> or 296 <kbd>Activate</kbd></td> 297 <td valign="top"> 298 Enables the image's use of transparency. If transparency data does not 299 already exist, allocates the data and sets it to opaque. If the image has 300 transparency data, the channel is enabled and the transparency data is not changed or modified in any way. This is NOT 301 the same as the older <a href="#matte" >-matte</a> operator. </td></tr> 302 303 <tr valign="top"> 304 <td valign="top"><kbd>Set</kbd></td> 305 <td valign="top"> 306 Turns '<kbd>On</kbd>' the alpha/matte channel and if it was previously 307 turned off resets the channel to opaque. If the image already had the 308 alpha channel turned on, it will have no effect. This is the same as the older <a href="#matte">-matte</a> operator. </td></tr> 309 310 <tr valign="top"> 311 <td valign="top"><kbd>Opaque</kbd></td> 312 <td valign="top"> 313 Turns '<kbd>On</kbd>' the alpha/matte channel and forces it to be fully 314 opaque. </td></tr> 315 316 <tr valign="top"> 317 <td valign="top"><kbd>Transparent</kbd></td> 318 <td valign="top"> 319 Turns '<kbd>On</kbd>' the alpha/matte channel and forces it to be fully 320 transparent. This effectively creates a fully transparent image the same 321 size as the original and with all its original RGB data still intact, 322 but fully transparent. </td></tr> 323 324 <tr valign="top"> 325 <td valign="top"><kbd>Extract</kbd></td> 326 <td valign="top"> 327 Copies the alpha channel values into all the color channels and turns 328 '<kbd>Off</kbd>' the the image's transparency, so as to generate a 329 gray-scale mask of the image's shape. This is the inverse of 330 '<kbd>Copy</kbd>'. </td></tr> 331 332 <tr valign="top"> 333 <td valign="top"><kbd>Copy</kbd></td> 334 <td valign="top"> 335 Turns '<kbd>On</kbd>' the alpha/matte channel, then copies the 336 gray-scale intensity of the image, as an alpha mask, into the alpha 337 channel, converting a gray-scale mask into a transparent shaped image 338 ready to be colored appropriately. The color channels are not modified. 339 </td></tr> 340 341 <tr valign="top"> 342 <td valign="top"><kbd>Shape</kbd></td> 343 <td valign="top"> 344 As per '<kbd>Copy</kbd>' but also colors the resulting shape mask with 345 the current background color. That is the RGB color channels is 346 replaced, with appropriate alpha shape. 347 </td></tr> 348 349 <tr valign="top"> 350 <td valign="top"><kbd>Background</kbd></td> 351 <td valign="top"> 352 Set any fully-transparent pixel to the background color, while leaving 353 it fully-transparent. This can make some image file formats, such as 354 PNG, smaller as the RGB values of transparent pixels are more uniform, 355 and thus can compress better. 356 </td></tr> 357 </tbody> 358</table> 359 360<p>Note that while the <a href="#matte" >+matte</a> operation is the same as 361"<kbd><a href="#alpha" >-alpha</a> off</kbd>", the <a href="#matte" 362>-matte</a> operation is the same as "<kbd><a href="#alpha" >-alpha</a> 363set</kbd>" and not "<kbd><a href="#alpha" >-alpha</a> on</kbd>". That is, 364"<kbd><a href="#alpha" >-alpha</a> set</kbd>" will ensure that the written 365image is opaque if the original image had no transparency channel enabled, 366regardless if transparency data is already present. </p> 367 368 369<div style="margin: auto;"> 370 <h4><a name="annotate" id="annotate"></a> 371 -annotate <em class="arg">degrees</em> <em class="arg">text</em><br /> 372 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> <em class="arg">text</em><br /> 373 -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> 374</div> 375 376<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> 377 378<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> 379 380 381<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> 382 383<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> 384 385<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> 386<div class="eqn"><img alt="annotate transformation" src="/images/annotate.png"/></div> 387 388<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> 389 390<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> 391 392<div style="margin: auto;"> 393 <h4><a name="antialias" id="antialias"></a>-antialias</h4> 394</div> 395 396<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 397drawing fonts and lines.</td><td style='text-align:right;'></td></tr></table> 398 399<p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when 400drawn. Use <a href="#antialias">+antialias</a> to disable the addition of 401antialiasing edge pixels. This will then reduce the number of colors added to 402an image to just the colors being directly drawn. That is, no mixed colors 403will be added when drawing such objects. </p> 404 405<div style="margin: auto;"> 406 <h4><a name="append" id="append"></a>-append</h4> 407</div> 408 409<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> 410 411<p>This option creates a single longer image image, by joining all the current 412images in sequence top-to-bottom. Use <a href="#append">+append</a> to 413stack images left-to-right. </p> 414 415<p>If they are not of the same width, narrower images are padded with the 416current <a href="#background">-background</a> color setting, and their 417position relative to each other can be controled by the current <a 418href="#gravity">-gravity</a> setting. </p> 419 420 421<div style="margin: auto;"> 422 <h4><a name="attenuate" id="attenuate"></a>-attenuate <em class="arg">value</em></h4> 423</div> 424 425<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> 426 427 428<div style="margin: auto;"> 429 <h4><a name="authenticate" id="authenticate"></a>-authenticate <em class="arg">password</em></h4> 430</div> 431 432<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> 433 434<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> 435 436<p>For a different encryption method, see <a href="#encipher">-encipher</a> and <a href="#decipher">-decipher</a>. </p> 437 438 439 440<div style="margin: auto;"> 441 <h4><a name="auto-gamma" id="auto-gamma"></a>-auto-gamma</h4> 442</div> 443 444<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> 445 446<p>This calculates the mean values of an image, then applies a calculated <a 447href="#gamma" >-gamma</a> adjustment so that is the mean color exists in the 448image it will get a have a value of 50%. </p> 449 450<p>This means that any solid 'gray' image will become 50% gray. </p> 451 452<p>This works well for real-life images with little or no extreme dark and 453light areas, but tend to fail for images with large amounts of bright sky or 454dark shadows. It also does not work well for diagrmas or cartoon like images. 455</p> 456 457<p>It uses the <a href="#channel" >-channel</a> setting, (including the 458'<CODE>sync</CODE>' flag for channel syncronization), to determine which color 459values will be used and modified. As the default <a href="#channel" 460>-channel</a> setting is '<CODE>RGB,sync</CODE>', channels will be modified 461together by the same gamma value, preserving colors. </p> 462 463 464 465<div style="margin: auto;"> 466 <h4><a name="auto-level" id="auto-level"></a>-auto-level</h4> 467</div> 468 469<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> 470 471<p>This is a 'perfect' image normalization operator. It finds the exact 472mimimum and maximum color values in the image and then applies a <a 473href="#level" >-level</a> operator to stretch the values to the full range of 474values. </p> 475 476<p>The operator is not typically used for real-life images, image scans, or 477JPEG format images, as a single 'out-rider' pixel can set a bad min/max values 478for the <a href="#level" >-level</a> operation. On the other hand it is the 479right operator to use for color stretching gradient images being used to 480generate Color lookup tables, distortion maps, or other 'mathematically' 481defined images. </p> 482 483<p>The operator is very similar to the <a href="#normalize">-normalize</a>, <a 484href="#contrast-stretch" >-contrast-stretch</a>, and <a href="#linear-stretch" 485>-linear-stretch</a> operators, but without 'histogram binning' or 'clipping' 486problems that these operators may have. That is <a href="#auto-level" 487>-auto-level</a> is the perfect or ideal version these operators. </p> 488 489<p>It uses the <a href="#channel" >-channel</a> setting, (including the 490special '<CODE>sync</CODE>' flag for channel syncronization), to determine 491which color values will be used and modified. As the default <a 492href="#channel" >+channel</a> setting is '<CODE>RGB,sync</CODE>', the 493'<CODE>sync</CODE>' will ensure that the color channels will be modified 494together by the same gamma value, preserving colors, and ignoring 495transparency. </p> 496 497 498 499<div style="margin: auto;"> 500 <h4><a name="auto-orient" id="auto-orient"></a>-auto-orient</h4> 501</div> 502 503<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> 504 505<p>This operator reads and resets the EXIF image profile setting 'Orientation' 506and then performs the appropriate 90 degree rotation on the image to orient 507the image, for correct viewing. </p> 508 509<p>This EXIF profile setting is usually set using a gravity sensor in digital 510camara, however photos taken directly downward or upward may not have an 511appropriate value. Also images that have been orientation 'corrected' without 512reseting this setting, may be 'corrected' again resulting in a incorrect 513result. If the he EXIF profile was previously stripped, the <a 514href="#auto-orient" >-auto-orient</a> operator will do nothing. </p> 515 516 517<div style="margin: auto;"> 518 <h4><a name="average" id="average"></a>-average</h4> 519</div> 520 521<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> 522 523<p>An error results if the images are not identically sized.</p> 524 525 526<div style="margin: auto;"> 527 <h4><a name="backdrop" id="backdrop"></a>-backdrop</h4> 528</div> 529 530<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> 531 532<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> 533 534<div style="margin: auto;"> 535 <h4><a name="background" id="background"></a>-background <em class="arg">color</em></h4> 536</div> 537 538<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> 539 540<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> 541 542<div style="margin: auto;"> 543 <h4><a name="bench" id="bench"></a>-bench <em class="arg">iterations</em></h4> 544</div> 545 546<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> 547 548<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> 549 550<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> 551<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> 552 553<div style="margin: auto;"> 554 <h4><a name="bias" id="bias"></a>-bias <em class="arg">value</em>{<em class="arg">%</em>}</h4> 555</div> 556 557<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> 558 559<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> 560 561<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> 562 563<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 564negative results without clipping to the color value range 565(0..QuantumRange).</p> 566 567<p>See the discussion on HDRI implementations of ImageMagick on the page 568<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. 569</p> 570 571<div style="margin: auto;"> 572 <h4><a name="black-point-compensation" id="black-point-compensation"></a>-black-point-compensation</h4> 573</div> 574 575<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> 576 577<div style="margin: auto;"> 578 <h4><a name="black-threshold" id="black-threshold"></a>-black-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 579</div> 580 581<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> 582 583<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. 584</p> 585 586 587<div style="margin: auto;"> 588 <h4><a name="blend" id="blend"></a>-blend <em class="arg">percent</em></h4> 589</div> 590 591<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 percent.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 592 593<p>Blend will average the images together ('plus') according to the 594percentages given and each pixels transparency. If only a single percentage 595value is given it sets the weight of the composite or 'source' image, while 596the background image is weighted by the exact opposite amount. That is a 597<kbd>-blend 30</kbd> merges 30% of the 'source' image with 70% of the 598'destination' image. Thus it is equivalent to <kbd>-blend 30x70</kbd>.</p> 599 600 601<div style="margin: auto;"> 602 <h4><a name="blue-primary" id="blue-primary"></a>-blue-primary <em class="arg">x</em>,<em class="arg">y</em></h4> 603</div> 604 605<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> 606 607<div style="margin: auto;"> 608 <h4><a name="blue-shift" id="blue-shift"></a>-blue-shift <em class="arg">factor</em></h4> 609</div> 610 611<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> 612 613<div style="margin: auto;"> 614 615<div style="margin: auto;"> 616 <h4><a name="blur" id="blur"></a>-blur <em class="arg">radius</em><br />-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4> 617</div> 618 619<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> 620 621<p>Convolve the image with a Gaussian or normal distribution. The formula is:</p> 622 623<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="/images/gaussian-blur.png"/> 624</div> 625 626<p>Where <i>r</i> is the blur radius (<i>r</i><sup>2</sup> = <i>u</i><sup>2</sup> + <i>v</i><sup>2</sup>), and σ is the standard deviation of the Gaussian distribution. As a guideline, set <i>r</i> to approximately 3σ. If a radius of 0 is specified, ImageMagick selects a suitable radius for you.</p> 627 628<p>This option differs from <a href="#gaussian-blur">-gaussian-blur</a> simply by taking advantage of the separability properties of the distribution. Here we apply a single-dimensional Gaussian matrix in the horizontal direction, then repeat the process in the vertical direction.</p> 629 630<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 631pixels which are outside the image proper are blurred into the final result. 632</p> 633 634 635<div style="margin: auto;"> 636 <h4><a name="blur-composite" id="blur"></a>-blur <em class="arg">Width</em>[x<em class="arg">Height</em>[+<em class="arg">Angle</em>]]</h4> 637</div> 638 639<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> 640 641<p>Each pixel in the overlaid region is replaced with an Elliptical Weighted 642Average (EWA) of the source image, scaled according to the grayscale 643mapping. </p> 644 645<p>The ellipse is weighted with sigma set to the given <em class="arg" 646>Width</em> and <em class="arg" >Height</em>. The <em class="arg" >Height</em> 647defaults to the <em class="arg" >Width</em> for a normal circular Guassian 648weighting. The <em class="arg" >Angle</em> will rotate the ellipse from 649horizontal clock-wise. </p> 650 651<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 652pixels which are outside the image proper are blurred into the final result. 653</p> 654 655 656<div style="margin: auto;"> 657 <h4><a name="border" id="border"></a>-border <em class="arg">geometry</em></h4> 658</div> 659 660<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> 661 662<p>Set the width and height using the <em class="arg">size</em> portion of the <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 ignored. </p> 663 664<p>Set the border color by preceding with the <a href="#bordercolor">-bordercolor</a> setting.</p> 665 666<p>See also the <a href="#frame">-frame</a> option, which has more functionality.</p> 667 668<div style="margin: auto;"> 669 <h4><a name="bordercolor" id="bordercolor"></a>-bordercolor <em class="arg">color</em></h4> 670</div> 671 672<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> 673 674<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 675 676<p>The default border color is <kbd>#DFDFDF</kbd>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p> 677 678<div style="margin: auto;"> 679 <h4><a name="borderwidth" id="borderwidth"></a>-borderwidth <em class="arg">geometry</em> </h4> 680</div> 681 682<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> 683 684<div style="margin: auto;"> 685 <h4><a name="brightness-contrast" 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> 686</div> 687 688<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> 689 690<p>Brightness and Contrast values apply changes to the input image. They are not absolute settings. A brightness or contrast value of zero means no change. The range of values is -100 to +100 on each. Positive values increase the brightness or contrast and negative values decrease the brightness or contrast. To control only contrast, set the brightness=0. To control only brightness, set contrast=0 or just leave it off.</p> 691 692<p>You may also use <a href="#fill">-channel</a> to control which channels to apply the brightness and/or contrast change. The default is to apply the same transformation to all channels.</p> 693 694<p>Brightness and Contrast arguments are converted to offset and slope of a linear transform and applied using <a href="#fill">-function polynomial "slope,offset"</a>.</p> 695 696<p>The slope varies from 0 at contrast=-100 to almost vertical at contrast=+100. For brightness=0 and contrast=-100, the result will be totally midgray. For brightness=0 and contrast=+100, the result will approach but not quite reach a threshold at midgray; that is the linear transformation will be a a very steep vertical line at mid gray.</p> 697 698<p>Negative slopes, i.e. negating the image, are not possible with this function. All achievable slopes will be zero or positive.</p> 699 700<p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5 at brightness=+100. Thus, when contrast=0 and brightness=100, the result will be totally white. Similarly, when contrast=0 and brightness=-100, the result will be totally black.</p> 701 702<p>As the range of values for the arguments are -100 to +100, adding the '%' symbol will be no different than leaving it off.</p> 703 704<div style="margin: auto;"> 705 <h4><a name="cache" id="cache"></a>-cache <em class="arg">threshold</em></h4> 706</div> 707 708<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> 709 710<div style="margin: auto;"> 711 <h4><a name="caption" id="caption"></a>-caption <em class="arg">string</em></h4> 712</div> 713 714<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> 715 716<div style="margin: auto;"> 717 <h4><a name="cdl" id="cdl"></a>-cdl <em class="arg">filename</em></h4> 718</div> 719 720<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> 721 722<p>Here is an example color correction collection:</p> 723 724<pre class="text"> 725<?xml version="1.0" encoding="UTF-8"?> 726<ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"> 727 <ColorCorrection id="cc06668"> 728 <SOPNode> 729 <Slope> 0.9 1.2 0.5 </Slope> 730 <Offset> 0.4 -0.5 0.6 </Offset> 731 <Power> 1.0 0.8 1.5 </Power> 732 </SOPNode> 733 <SATNode> 734 <Saturation> 0.85 </Saturation> 735 </SATNode> 736 </ColorCorrection> 737</ColorCorrectionCollection> 738</pre> 739 740<div style="margin: auto;"> 741 <h4><a name="channel" id="channel"></a>-channel <em class="arg">type</em></h4> 742</div> 743 744<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> 745 746<p>Choose from: <kbd>Red</kbd>, <kbd>Green</kbd>, <kbd>Blue</kbd>, <kbd>Alpha</kbd>, <kbd>Cyan</kbd>, <kbd>Magenta</kbd>, <kbd>Yellow</kbd>, <kbd>Black</kbd>, <kbd>Opacity</kbd>, <kbd>Index</kbd>, <kbd>RGB</kbd>, <kbd>RGBA</kbd>, <kbd>CMYK</kbd>, or <kbd>CMYKA</kbd>.</p> 747 748<p>To print a complete list of channel types, use <a href="#list">-list channel</a>.</p> 749 750<p>The channels above can be specified as a comma-separated list or can be 751abbreviated as a concatenation of the letters '<kbd>R</kbd>', '<kbd>G</kbd>', 752'<kbd>B</kbd>', '<kbd>A</kbd>', '<kbd>O</kbd>', '<kbd>C</kbd>', 753'<kbd>M</kbd>', '<kbd>Y</kbd>', '<kbd>K</kbd>'. 754 755For example, to negate only the alpha channel of an image, use</p> 756<p class="crtsnip"> 757 -channel Alpha -negate 758</p> 759 760Some operators also allow the use of a special channel flag 761'<code>sync</code>'. If present operators that understand this flag will 762apply the exact same image modification to all the image channels in the image 763so as to ensure that colors are kept 'in-sync'. Without this flag such 764operators will apply there function to each channel separately. See <a 765href="#auto-level">-auto-level</a> and <a href="#auto-gamma">-auto-gamma</a> 766for examples of such an operator. </p> 767 768 769<p>By default, ImageMagick sets <a href="#channel">-channel</a> to the value 770'<kbd>RGB,sync</kbd>', which specifies that operators act on all channels 771except the opacity channel, and that all the color channels are to be modified 772in exactly the same way. The 'plus' form <a href="#channel" >+channel</a> 773will reset the value back to this default. </p> 774 775<p>Options that are affected by the <a href="#channel" >-channel</a> setting 776include the following. 777 778<a href="#auto-gamma">-auto-gamma</a>, 779<a href="#auto-level">-auto-level</a>, 780<a href="#black-threshold">-black-threshold</a>, 781<a href="#blur">-blur</a>, 782<a href="#clamp">-clamp</a>, 783<a href="#clut">-clut</a>, 784<a href="#combine">-combine</a>, 785<a href="#contrast-stretch">-contrast-stretch</a>, 786<a href="#evaluate">-evaluate</a>, 787<a href="#function">-function</a>, 788<a href="#fx">-fx</a>, 789<a href="#gaussian-blur">-gaussian-blur</a>, 790<a href="#hald-clut">-hald-clut</a>, 791<a href="#motion-blur">-motion-blur</a>, 792<a href="#negate">-negate</a>, 793<a href="#normalize">-normalize</a>, 794<a href="#ordered-dither">-ordered-dither</a>, 795<a href="#radial-blur">-radial-blur</a>, 796<a href="#random-threshold">-random-threshold</a>, 797<a href="#separate">-separate</a>, and 798<a href="#threshold">-threshold</a>, and 799<a href="#white-threshold">-white-threshold</a>. 800</p> 801 802<p>Warning, some operators behave differentally when the <a href="#channel" 803>+channel</a> default setting is in effect, verses ANY user defined <a 804href="#channel" >-channel</a> setting (including the equivelent of the 805default). For example <a href="#threshold">-threshold</a> will by default 806gray-scale the image before thresholding, if no <a href="#channel" 807>-channel</a> setting has been defined. </p> 808 809<p>Also some operators such as <a href="#blur">-blur</a>, <a 810href="#gaussian-blur">-gaussian-blur</a>, will modify their handling of the 811color channels if the '<kbd>alpha</kbd>' channel is also enabled by <a 812href="#channel" >-channel</a>. Generally this done to ensure that 813fully-transparent colors are treated as being fully-transparent, and thus any 814underlying 'hidden' color has no effect on the final results. Typically 815resulting in 'halo' effects. </p> 816 817<p>As a alpha channel is optional within images some operators will read the 818color channels of an image as a greyscale alpha mask, when the image has no 819alpha channel present, but the <a href="#channel" >-channel</a> setting tells 820the operator to apply the alpha channel. The <a href="#clut">-clut</a> 821operator is a good example of this. </p> 822 823 824<div style="margin: auto;"> 825 <h4><a name="clamp" id="clamp"></a>-clamp</h4> 826</div> 827 828<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> 829 830<div style="margin: auto;"> 831 <h4><a name="charcoal" id="charcoal"></a>-charcoal <em class="arg">factor</em></h4> 832</div> 833 834<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> 835 836<div style="margin: auto;"> 837 <h4><a name="chop" id="chop"></a>-chop <em class="arg">geometry</em></h4> 838</div> 839 840<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> 841 842<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> and <em class="arg">height</em> given in the of the <em class="arg">size</em> portion of the <em class="arg">geometry</em> argument give the number of columns and rows to remove. The <em class="arg">offset</em> portion of the <em class="arg">geometry</em> argument is influenced by a <a href="#gravity">-gravity</a> setting, if present.</p> 843 844<p>The <a href="#chop">-chop</a> option removes entire rows and columns, and moves the remaining corner blocks leftward and upward to close the gaps.</p> 845 846<div style="margin: auto;"> 847 <h4><a name="clip" id="clip"></a>-clip</h4> 848</div> 849 850<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> 851 852<p>If a clipping path is present, it is applied to subsequent operations.</p> 853 854<p>For example, in the command</p> 855 856<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -clip -negate cockatoo.tif negated.tif</span></p> 857<p>only the pixels within the clipping path are negated.</p> 858 859<p>The <a href="#clip">-clip</a> feature requires the XML library. If the XML library is not present, the option is ignored.</p> 860 861<div style="margin: auto;"> 862 <h4><a name="clip-mask" id="clip-mask"></a>-clip-mask</h4> 863</div> 864 865<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> 866 867<div style="margin: auto;"> 868 <h4><a name="clip-path" id="clip-path"></a>-clip-path <em class="arg">id</em></h4> 869</div> 870 871<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> 872 873<div style="margin: auto;"> 874 <h4><a name="clone" id="clone"></a>-clone <em class="arg">index(s)</em></h4> 875</div> 876 877<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make a copy of an image (or images).</td><td style='text-align:right;'></td></tr></table> 878 879<p>Specify the image by its index in the sequence. The first image is index 8800. Negative indexes are relative to the end of the sequence; for example, −1 881represents the last image of the sequence. Specify a range of images with a 882dash (e.g. 0−4). Separate multiple indexes with commas but no spaces (e.g. 0,2,5). Use <a 883href="#clone">+clone</a> make a copy of the last image in the image 884sequence.</p> 885 886<div style="margin: auto;"> 887 <h4><a name="clut" id="clut"></a>-clut</h4> 888</div> 889 890<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 891corresponding channel in the second image as a <b>c</b>olor 892<b>l</b>ook<b>u</b>p <b>t</b>able.</td><td style='text-align:right;'></td></tr></table> 893 894<p>The second (LUT) image is ordinarily a gradient image containing the 895histogram mapping of how each channel should be modified. Typically it is a 896either a single row or column image of replacement color values. If larger 897than a single row or column, values are taken from a diagonal line from 898top-left to bottom-right corners.</p> 899 900<p>The lookup is further controlled by the <a 901href="#interpolate">-interpolate</a> setting, which is especially handy for an 902LUT which is not the full length needed by the ImageMagick installed Quality 903(Q) level. Good settings for this are the '<kbd>bilinear</kbd>' and 904'<kbd>bicubic</kbd>' interpolation settings, which give smooth color 905gradients, and the '<kbd>integer</kbd>' setting for a direct, unsmoothed 906lookup of color values. </p> 907 908<p>This operator is especially suited to replacing a grayscale image with a 909specific color gradient from the CLUT image. </p> 910 911<p>Only the channel values defined by the <a href="#channel">-channel</a> 912setting will have their values replaced. In particular, since the default <a 913href="#channel">-channel</a> setting is <kbd>RGB</kbd>, this means that 914transparency (alpha/matte channel) is not affected, unless the <a 915href="#channel">-channel</a> setting is modified. When the alpha channel is 916set, it is treated by the <a href="#clut" >-clut</a> operator in the same way 917as the other channels, implying that alpha/matte values are replaced using the 918alpha/matte values of the original image. </p> 919 920<p>If either the image being modified, or the lookup image, conatins no 921transparency (i.e. <a href="#alpha" >-alpha</a> is turned 'off') but the <a 922href="#channel">-channel</a> setting includes alpha replacement, then it is 923assumed that image represents a gray-scale graident which will be used for the 924replacement alpha values. That is you can use a gray-scale CLUT image to 925adjust a existing images alpha channel, or you can color a gray-scale image 926using colors form CLUT containing the desired colors, including transparency. 927</p> 928 929<p>See also <a href="#hald-clut" >-hald-clut</a> which replaces colors according 930the lookup of the full color RGB value from a 2D representation of a 3D color 931cube. </p> 932 933 934<div style="margin: auto;"> 935 <h4><a name="coalesce" id="coalesce"></a>-coalesce</h4> 936</div> 937 938<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> 939 940<p>Overlay each image in an image sequence according to its <a href="#dispose">-dispose</a> meta-data, to reproduce the look of an animation at each point in the animation sequence. All images should be the same size, and are assigned appropriate GIF disposal settings for the animation to continue working as expected as a GIF animation. Such frames are more easilly viewed and processed than the highly optimized GIF overlay images. </p> 941 942<p>The animation can be re-optimized after processing using the <a href="#layers">-layers</a> method '<kbd>optimize</kbd>', though there is no guarantee that the restored GIF animation optimization is better than the original. </p> 943 944 945<div style="margin: auto;"> 946 <h4><a name="colorize" id="colorize"></a>-colorize <em class="arg">value</em></h4> 947</div> 948 949<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> 950 951<p>Specify the amount of colorization as a percentage. Separate colorization values can be applied to the red, green, and blue channels of the image with a comma-delimited list of colorization values (e.g., <kbd>-colorize 0,0,50</kbd>).</p> 952 953<div style="margin: auto;"> 954 <h4><a name="colormap" id="colormap"></a>-colormap <em class="arg">type</em></h4> 955</div> 956 957<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> 958 959<p>The <em class="arg">type</em> can be <kbd>shared</kbd> or <kbd>private</kbd>.</p> 960 961<p>This option only applies when the default X server visual is <kbd>PseudoColor</kbd> or <kbd>GrayScale</kbd>. Refer to <a href="#visual">-visual</a> for more details. By default, a shared colormap is allocated. The image shares colors with other X clients. Some image colors could be approximated, therefore your image may look very different than intended. If <kbd>private</kbd> is chosen, the image colors appear exactly as they are defined. However, other clients may go <em>technicolor</em> when the image colormap is installed.</p> 962 963<div style="margin: auto;"> 964 <h4><a name="colors" id="colors"></a>-colors <em class="arg">value</em></h4> 965</div> 966 967<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> 968 969<p>The actual number of colors in the image may be less than your request, but never more. Note that this a color reduction option. Images with fewer unique colors than specified by <em class="arg">value</em> will have any duplicate or unused colors removed. The ordering of an existing color palette may be altered. When converting an image from color to grayscale, it is more efficient to convert the image to the gray colorspace before reducing the number of colors. Refer to the <a href="/www/quantize.html">color reduction algorithm</a> for more details.</p> 970 971<div style="margin: auto;"> 972 <h4><a name="color-matrix" id="color-matrix"></a>-color-matrix <em class="arg">matrix</em></h4> 973</div> 974 975<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> 976 977<p>This option permits saturation changes, hue rotation, luminance to alpha, and various other effects. Although variable-sized transformation matrices can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6 for CMYKA (or RGBA with offsets). The matrix is similar to those used by Adobe Flash except offsets are in column 6 rather than 5 (in support of CMYKA images) and offsets are normalized (divide Flash offset by 255).</p> 978 979<p>As an example, to add contrast to an image with offsets, try this command:</p> 980 981<pre class="text"> 982convert kittens.jpg -color-matrix \ 983 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \ 984 0.0 1.5 0.0 0.0, 0.0, -0.157 \ 985 0.0 0.0 1.5 0.0, 0.0, -0.157 \ 986 0.0 0.0 0.0 1.0, 0.0, 0.0 \ 987 0.0 0.0 0.0 0.0, 1.0, 0.0 \ 988 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png 989</pre> 990<div style="margin: auto;"> 991 <h4><a name="colorspace" id="colorspace"></a>-colorspace <em class="arg">value</em></h4> 992</div> 993 994<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> 995 996<p>Choices are:</p> 997 998<pre class="text"> 999 CMY 1000 CMYK 1001 Gray 1002 HSB 1003 HSL 1004 HWB 1005 Lab 1006 Log 1007 OHTA 1008 Rec601Luma 1009 Rec601YCbCr 1010 Rec709Luma 1011 Rec709YCbCr 1012 RGB 1013 sRGB 1014 Transparent 1015 XYZ 1016 YCbCr 1017 YCC 1018 YIQ 1019 YPbPr 1020 YUV 1021</pre> 1022 1023<p>To print a complete list of colorspaces, use <a href="#list">-list colorspace</a>.</p> 1024 1025<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> 1026 1027<table class="doc"> 1028 <caption>Conversion Of RGB To Other Color Spaces</caption> 1029 <tr><th align="left" valign="middle">CMY</th></tr> 1030 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>−R</td></tr> 1031 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>−G</td></tr> 1032 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>−B</td></tr> 1033 <tr><th align="left" valign="middle">CMYK — starts with CMY from above</th></tr> 1034 <tr><td align="left" valign="middle">K=min(C,Y,M)</td></tr> 1035 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>*(C−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1036 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>*(M−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1037 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>*(Y−K)/(<em class="QR">QuantumRange</em>−K)</td></tr> 1038 1039 <tr><th align="left" valign="middle">Gray</th></tr> 1040 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr> 1041 1042 <tr><th align="left" valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr> 1043 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr> 1044 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr> 1045 <tr><td align="left" valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <em>intensity-like</em></td></tr> 1046 1047 <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> 1048 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr> 1049 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr> 1050 <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> 1051 1052 <tr><th align="left" valign="middle">HWB — Hue, Whiteness, Blackness</th></tr> 1053 <tr><td align="left" valign="middle">Hue (complicated equation)</td></tr> 1054 <tr><td align="left" valign="middle">Whiteness (complicated equation)</td></tr> 1055 <tr><td align="left" valign="middle">Blackness (complicated equation)</td></tr> 1056 1057 <tr><th align="left" valign="middle">LAB</th></tr> 1058 <tr><td align="left" valign="middle">L (complicated equation relating X,Y,Z)</td></tr> 1059 <tr><td align="left" valign="middle">A (complicated equation relating X,Y,Z)</td></tr> 1060 <tr><td align="left" valign="middle">B (complicated equation relating X,Y,Z)</td></tr> 1061 1062 <tr><th align="left" valign="middle">LOG</th></tr> 1063 <tr><td align="left" valign="middle">I1 (complicated equation involving logarithm of R)</td></tr> 1064 <tr><td align="left" valign="middle">I2 (complicated equation involving logarithm of G)</td></tr> 1065 <tr><td align="left" valign="middle">I3 (complicated equation involving logarithm of B)</td></tr> 1066 1067 <tr><th align="left" valign="middle">OHTA — approximates principal components transformation</th></tr> 1068 <tr><td align="left" valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <em>intensity-like</em></td></tr> 1069 <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> 1070 <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> 1071 1072 <tr><th align="left" valign="middle">Rec601Luma</th></tr> 1073 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr> 1074 1075 <tr><th align="left" valign="middle">Rec601YCbCr</th></tr> 1076 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1077 <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> 1078 <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> 1079 1080 <tr><th align="left" valign="middle">Rec709Luma</th></tr> 1081 <tr><td align="left" valign="middle">Gray=0.21260*R+0.71520*G+0.07220*B</td></tr> 1082 1083 <tr><th align="left" valign="middle">Rec709YCbCr</th></tr> 1084 <tr><td align="left" valign="middle">Y=0.212600*R+0.715200*G+0.072200*B; <em>intensity-like</em></td></tr> 1085 <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> 1086 <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> 1087 1088 <tr><th align="left" valign="middle">sRGB</th></tr> 1089 <tr><td align="left" valign="middle">if Rs ≤ .03928 then Rs=R/12.92 else Rs=((R+.055)/1.055)^2.4</td></tr> 1090 <tr><td align="left" valign="middle">if Gs ≤ .03928 then Gs=B/12.92 else Gs=((G+.055)/1.055)^2.4</td></tr> 1091 <tr><td align="left" valign="middle">if Bs ≤ .03928 then Bs=B/12.92 else Bs=((B+.055)/1.055)^2.4</td></tr> 1092 1093 <tr><th align="left" valign="middle">XYZ</th></tr> 1094 <tr><td align="left" valign="middle">X=0.4124240*R+0.3575790*G+0.1804640*B</td></tr> 1095 <tr><td align="left" valign="middle">Y=0.2126560*R+0.7151580*G+0.0721856*B</td></tr> 1096 <tr><td align="left" valign="middle">Z=0.0193324*R+0.1191930*G+0.9504440*B</td></tr> 1097 1098 <tr><th align="left" valign="middle">YCC</th></tr> 1099 <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> 1100 <tr><td align="left" valign="middle">C1=(−0.29900*R−0.58700*G+0.88600*B) (with complicated scaling)</td></tr> 1101 <tr><td align="left" valign="middle">C2=(0.70100*R−0.58700*G−0.11400*B) (with complicated scaling)</td></tr> 1102 1103 <tr><th align="left" valign="middle">YCbCr</th></tr> 1104 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1105 <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> 1106 <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> 1107 1108 <tr><th align="left" valign="middle">YIQ</th></tr> 1109 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr> 1110 <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> 1111 <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> 1112 1113 <tr><th align="left" valign="middle">YPbPr</th></tr> 1114 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr> 1115 <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> 1116 <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> 1117 1118 <tr><th align="left" valign="middle">YUV</th></tr> 1119 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr> 1120 <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> 1121 <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> 1122</table> 1123 1124<div style="margin: auto;"> 1125 <h4><a name="combine" id="combine"></a>-combine</h4> 1126</div> 1127 1128<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> 1129 1130<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> 1131 1132<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. 1133</p> 1134 1135<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> 1136<div style="margin: auto;"> 1137 <h4><a name="comment" id="comment"></a>-comment <em class="arg">string</em></h4> 1138</div> 1139 1140<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> 1141 1142<p>This option places comments in a non-pixel portion of the image file. For a comment to be visibly written on the image itself, use the <a href="#annotate">-annotate</a> or <a href="#draw">-draw</a> options.</p> 1143 1144<p>Use this option to assign a specific comment to the image, when writing to an image format that supports comments. You can include the image filename, type, width, height, or other image attribute by embedding special format characters listed under the <a href="#format">-format</a> option. The comment is not drawn on the image, but is embedded in the image datastream via "Comment" tag or similar mechanism. </p> 1145 1146<p>For example,</p> 1147 1148<p class="crtsnip"> 1149 -comment "%m:%f %wx%h" 1150</p> 1151 1152<p>produces an image comment 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> 1153 1154<p>If the first character of <em class="arg">string</em> is <em class="arg">@</em>, the image comment is read from a file titled by the remaining characters in the string. Comments in a file are literal; no embedded formatting characters are recognized.</p> 1155 1156<div style="margin: auto;"> 1157 <h4><a name="compose" id="compose"></a>-compose <em class="arg">operator</em></h4> 1158</div> 1159 1160<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> 1161 1162<p>The description of composition uses abstract terminology in order to allow 1163the description to be more precise, while avoiding constant values which are 1164specific to a particular build configuration. Each image pixel is represented 1165by red, green, and blue levels (which are equal for a gray pixel). The 1166build-dependent value <em class="QR">QuantumRange</em> is the maximum integral 1167value which may be stored, per pixel, in the red, green, or blue channels of 1168the image. Each image pixel may also optionally (if the image matte channel is 1169enabled) have an associated level of opacity, ranging from <em>opaque</em> to 1170<em>transparent</em>, which may be used to determine the influence of the pixel 1171color when compositing the pixel with another image pixel. If the image matte 1172channel is disabled, then all pixels in the image are treated as opaque. The 1173color of an opaque pixel is fully visible while the color of a transparent 1174pixel color is entirely absent (pixel color is ignored).</p> 1175 1176<p>By definition, raster images have a rectangular shape. All image rows are of 1177equal length, as are all image columns. By treating the alpha channel as a 1178visual "mask" the rectangular image may be given a "shape" by treating the 1179alpha channel as a cookie-cutter for the image. This is done by setting the 1180pixels within the shape to be opaque, with pixels outside the shape set as 1181transparent. Pixels on the boundary of the shape may be between opaque and 1182transparent in order to provide antialiasing (visually smooth edges). The 1183description of the composition operators use this concept of image "shape" in 1184order to make the description of the operators easier to understand. While it 1185is convenient to describe the operators in terms of "shapes" they are by no 1186means limited to mask-style operations since they are based on continuous 1187floating-point mathematics rather than simple boolean operations.</p> 1188 1189<p>The following alpha blending (Duff-Porter) compose methods are available:</p> 1190 1191<table class="doc"> 1192 <tbody> 1193 <tr valign="top"> 1194 <th align="left" style="width: 8%">Method</th> 1195 <th align="left">Description</th> 1196 </tr> 1197 1198 <tr valign="top"> 1199 <td valign="top">clear</td> 1200 <td valign="top">Both the color and the alpha of the destination are 1201 cleared. Neither the source nor the destination are used (except for 1202 destinations size and other meta-data which is always preserved.</td> 1203 </tr> 1204 1205 <tr valign="top"> 1206 <td valign="top">src</td> 1207 <td valign="top">The source is copied to the destination. The destination 1208 is not used as input, though it is cleared.</td> 1209 </tr> 1210 1211 <tr valign="top"> 1212 <td valign="top">dst</td> 1213 <td valign="top">The destination is left untouched. The source image is 1214 completely ignored.</td> 1215 </tr> 1216 1217 <tr valign="top"> 1218 <td valign="top">src-over</td> 1219 <td valign="top">The source is composited over the destination. this is 1220 the default alpha blending compose method, when neither the compose 1221 setting is set, nor is set in the image meta-data.</td> 1222 </tr> 1223 1224 <tr valign="top"> 1225 <td valign="top">dst-over</td> 1226 <td valign="top">The destination is composited over the source and the 1227 result replaces the destination.</td> 1228 </tr> 1229 1230 <tr valign="top"> 1231 <td valign="top">src-in</td> 1232 <td valign="top">The part of the source lying inside of the destination 1233 replaces the destination.</td> 1234 </tr> 1235 1236 <tr valign="top"> 1237 <td valign="top">dst-in</td> 1238 <td valign="top">The part of the destination lying inside of the source 1239 replaces the destination. Areas not overlaid are cleared.</td> 1240 </tr> 1241 1242 <tr valign="top"> 1243 <td valign="top">src-out</td> 1244 <td valign="top">The part of the source lying outside of the destination 1245 replaces the destination.</td> 1246 </tr> 1247 1248 <tr valign="top"> 1249 <td valign="top">dst-out</td> 1250 <td valign="top">The part of the destination lying outside of the source 1251 replaces the destination.</td> 1252 </tr> 1253 1254 <tr valign="top"> 1255 <td valign="top">src-atop</td> 1256 <td valign="top">The part of the source lying inside of the destination is 1257 composited onto the destination.</td> 1258 </tr> 1259 1260 <tr valign="top"> 1261 <td valign="top">dst-atop</td> 1262 <td valign="top">The part of the destination lying inside of the source is 1263 composited over the source and replaces the destination. Areas not 1264 overlaid are cleared. </td> 1265 </tr> 1266 1267 <tr valign="top"> 1268 <td valign="top">xor</td> 1269 <td valign="top">The part of the source that lies outside of the 1270 destination is combined with the part of the destination that lies 1271 outside of the source. Source or Destination, but not both. </td> 1272 </tr> 1273 1274 </tbody> 1275</table> 1276 1277<p>Any of the 'Src-*' methods can also be specified without the 'Src-' part. 1278For example the defaul compose method can be specified as just 'Over'.</p> 1279 1280 1281<p>The following mathemathical composition methods are also available. </p> 1282 1283<p>Typically these use the default 'Over' alpha blending when transparencies 1284are also involved, except for 'Plus', 'Minus', 'Add', and 'Subtract', which 1285also composes the alpha channel using the same process as the color channels. 1286This allows them to be used for special image masking techniques. </p> 1287 1288<table class="doc"> 1289 <tbody> 1290 <tr valign="top"> 1291 <th align="left" style="width: 8%">Method</th> 1292 <th align="left">Description</th> 1293 </tr> 1294 1295 <tr valign="top"> 1296 <td valign="top">multiply</td> 1297 <td valign="top">The source is multiplied by the destination and replaces the destination. The resultant color is always at least as dark as either of the two constituent colors. Multiplying any color with black produces black. Multiplying any color with white leaves the original color unchanged.</td> 1298 </tr> 1299 1300 <tr valign="top"> 1301 <td valign="top">screen</td> 1302 <td valign="top">The source and destination are complemented and then multiplied and then replace the destination. The resultant color is always at least as light as either of the two constituent colors. Screening any color with white produces white. Screening any color with black leaves the original color unchanged.</td> 1303 </tr> 1304 1305 <tr valign="top"> 1306 <td valign="top">plus</td> 1307 <td valign="top">The source is added to the destination and replaces the 1308 destination. This operator is useful for averaging or a controled 1309 merger of two images, rather than a direct overlay.</td> 1310 </tr> 1311 1312 <tr valign="top"> 1313 <td valign="top">add</td> 1314 <td valign="top">As per 'plus' but transparency data is treated as matte 1315 values. As such any transparent areas in either image remain 1316 transparent. </td> 1317 </tr> 1318 1319 <tr valign="top"> 1320 <td valign="top">minus</td> 1321 <td valign="top">Subtract the colors in the source image from the 1322 destination image. When transparency is involved, opaque areas is 1323 subtracted from any destination opaque areas. </td> 1324 </tr> 1325 1326 <tr valign="top"> 1327 <td valign="top">subtract</td> 1328 <td valign="top">Subtract the colors in the source image from the 1329 destination image. When transparency is involved transparent areas are 1330 subtracted, so only the opaque areas in the source remain opaque in 1331 the destination image. </td> 1332 </tr> 1333 1334 <tr valign="top"> 1335 <td valign="top">difference</td> 1336 <td valign="top">Subtracts the darker of the two constituent colors from 1337 the lighter. Painting with white inverts the destination color. 1338 Painting with black produces no change.</td> 1339 </tr> 1340 1341 <tr valign="top"> 1342 <td valign="top">exclusion</td> 1343 <td valign="top">Produces an effect similar to that of 'difference', but 1344 appears as lower contrast. Painting with white inverts the 1345 destination color. Painting with black produces no change.</td> 1346 </tr> 1347 1348 <tr valign="top"> 1349 <td valign="top">darken</td> 1350 <td valign="top">Selects the darker of the destination and source colors. 1351 The destination is replaced with the source when the source is darker, 1352 otherwise it is left unchanged.</td> 1353 </tr> 1354 1355 <tr valign="top"> 1356 <td valign="top">lighten</td> 1357 <td valign="top">Selects the lighter of the destination and source colors. 1358 The destination is replaced with the source when the source is 1359 lighter, otherwise it is left unchanged. </td> 1360 </tr> 1361 1362 <tr valign="top"> 1363 <td valign="top">linear-dodge</td> 1364 <td valign="top">This is equivelent to 'Plus' in that the color channels 1365 are simply added, however it does not 'Plus' the alpha channel, but 1366 uses the normal 'Over' alpha blending, which transparencies are 1367 involved. Produces a sort of additive multiply-like result. Added 1368 ImageMagick version 6.5.4-3. </td> 1369 </tr> 1370 1371 <tr valign="top"> 1372 <td valign="top">linear-burn</td> 1373 <td valign="top">As 'Linear-Dodge', but also subtract one from the result. 1374 Sort of a additive 'Screen' of the images. Added ImageMagick version 1375 6.5.4-3. </td> 1376 </tr> 1377 1378 <tr valign="top"> 1379 <td valign="top">color-dodge</td> 1380 <td valign="top">Brightens the destination color to reflect the source 1381 color. Painting with black produces no change.</td> 1382 </tr> 1383 1384 <tr valign="top"> 1385 <td valign="top">color-burn</td> 1386 <td valign="top">Darkens the destination color to reflect the source 1387 color. Painting with white produces no change. Fixed in ImageMagick 1388 version 6.5.4-3. </td> 1389 </tr> 1390 1391 <tr valign="top"> 1392 <td valign="top">overlay</td> 1393 <td valign="top">Multiplies or screens the colors, dependent on the 1394 destination color. Source colors overlay the destination whilst 1395 preserving its highlights and shadows. The destination color is not 1396 replaced, but is mixed with the source color to reflect the lightness 1397 or darkness of the destination.</td> 1398 </tr> 1399 1400 <tr valign="top"> 1401 <td valign="top">hard-light</td> 1402 <td valign="top">Multiplies or screens the colors, dependent on the source 1403 color value. If the source color is lighter than 0.5, the destination 1404 is lightened as if it were screened. If the source color is darker 1405 than 0.5, the destination is darkened, as if it were multiplied. The 1406 degree of lightening or darkening is proportional to the difference 1407 between the source color and 0.5. If it is equal to 0.5 the 1408 destination is unchanged. Painting with pure black or white produces 1409 black or white.</td> 1410 </tr> 1411 1412 1413 <tr valign="top"> 1414 <td valign="top">linear-light</td> 1415 <td valign="top">Like 'Hard-Light' but using linear-dodge and linear-burn 1416 instead. Increases contrast slightly with an impact on the 1417 foreground's tonal values.</td> 1418 </tr> 1419 1420 <tr valign="top"> 1421 <td valign="top">soft-light</td> 1422 <td valign="top">Darkens or lightens the colors, dependent on the source 1423 color value. If the source color is lighter than 0.5, the destination 1424 is lightened. If the source color is darker than 0.5, the destination 1425 is darkened, as if it were burned in. The degree of darkening or 1426 lightening is proportional to the difference between the source color 1427 and 0.5. If it is equal to 0.5, the destination is unchanged. Painting 1428 with pure black or white produces a distinctly darker or lighter area, 1429 but does not result in pure black or white. Fixed in ImageMagick 1430 version 6.5.4-3. </td> 1431 </tr> 1432 1433 <tr valign="top"> 1434 <td valign="top">pegtop-light</td> 1435 <td valign="top">Almost equivelent to 'Soft-Light', but using a 1436 continuious mathematical formula rather than two conditionally 1437 selected formulae. Added ImageMagick version 6.5.4-3. </td> 1438 </tr> 1439 1440 <tr valign="top"> 1441 <td valign="top">vivid-light</td> 1442 <td valign="top">A modified 'Linear-Light' designed to preserve very stong 1443 primary and secondary colors in the image. Added ImageMagick version 1444 6.5.4-3. </td> 1445 </tr> 1446 1447 <tr valign="top"> 1448 <td valign="top">pin-light</td> 1449 <td valign="top">Similar to 'Hard-Light', but using sharp linear shadings, 1450 to similate the effects of a strong 'pinhole' light source. Added 1451 ImageMagick version 6.5.4-3. </td> 1452 </tr> 1453 1454 </tbody> 1455</table> 1456 1457 1458<p>Also included are these special purpose compose methods:</p> 1459 1460<table class="doc"> 1461 <tbody> 1462 <tr valign="top"> 1463 <th align="left" style="width: 8%">Method</th> 1464 <th align="left">Description</th> 1465 </tr> 1466 1467 <tr valign="top"> 1468 <td valign="top">copy-*</td> 1469 <td valign="top">Copy the specified channel (Red, Green, Blue, Cyan, 1470 Magenta, Yellow, Black, or Opacity) in the source image to the 1471 same channel in the destination image. If the channel specified 1472 does not exist in the source image, (which can only happen for methods, 1473 '<kbd>copy-opacity</kbd>' or '<kbd>copy-black</kbd>') then it is 1474 assumed that the source image is a special grayscale channel image 1475 of the values to be copied. </td> 1476 </tr> 1477 1478 <tr valign="top"> 1479 <td valign="top">change-mask</td> 1480 <td valign="top">Replace any destination pixel that is the similar to the source images pixel (as defined by the current <a href="#fuzz">-fuzz</a> factor), with transparency. </td> 1481 </tr> 1482 </tbody> 1483</table> 1484 1485<p>On top of these composed methods are a few special ones that not only require 1486the two images that are being merged or overlaid, but have some extra numerical 1487arguments, which are tabled below. </p> 1488 1489<p>In the "<code>composite</code>" command these composition methods are 1490selected using special options with the arguments needed. They are usually, 1491but not always, the same name as the composte 'method' they use, and replaces 1492the normal use of the <a href="#compose" >-compose</a> setting in the 1493"<code>composite</code>" command. For example... </p> 1494 1495<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>composite ... -blend 50x50 ...</span></p> 1496<p>As of IM v6.5.3-4 the "<code>convert</code>" command can now also supply 1497these extra arguments to its <a href="#composite" >-composite</a> operator, 1498using the special <a href="#set">-set</a> attribute of '<kbd class="arg">option:compose:args</kbd>'. This means you can now make use of 1499these special argumented <a href="#compose" >-compose</a> methods, those the 1500argument and the method both need to be set separatally. For example... </p> 1501 1502<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert ... -compose blend -set option:compose:args 50x50 -composite ...</span></p> 1503<p>The following is a table of these special 'argumented' compose methods, 1504with a brief summary of what they do. For more details see the equivalent 1505"composite" command option name. </p> 1506 1507<table class="doc"> 1508 <tbody> 1509 <tr valign="top"> 1510 <th align="left" style="width: 8%">Method</th> 1511 <th align="left">Description</th> 1512 </tr> 1513 1514 <tr valign="top"> 1515 <td valign="top">dissolve</td> 1516 <td valign="top">Arguments: 1517 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>] 1518 <br>Equivalent to "<code>composite</code>" <a href="#dissolve">-dissolve</a> 1519 <br>Dissolve the 'source' image by the percentage given before overlaying 1520 'over' the 'destination' image. If <em class="arg">src_percent</em> is 1521 greater than 100, it starts dissolving the main image so it will 1522 become transparent at a value of '<kbd class="arg">200</kbd>'. If 1523 both percentages are given, each image are dissolved to the 1524 percentages given. 1525 </td> 1526 </tr> 1527 1528 <tr valign="top"> 1529 <td valign="top">blend</td> 1530 <td valign="top">Arguments: 1531 <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>] 1532 <br>Equivalent to "<code>composite</code>" <a href="#blend">-blend</a> 1533 <br>Average the images together ('plus') according to the percentages 1534 given and each pixels transparency. If only a single percentage value 1535 is given it sets the weight of the composite or 'source' image, while 1536 the background image is weighted by the exact opposite amount. That is 1537 a <kbd>-blend 30</kbd> merges 30% of the 'source' image with 70% of 1538 the 'destination' image. Thus it is equivalent to <kbd>-blend 1539 30x70</kbd>. 1540 </td> 1541 </tr> 1542 1543 <tr valign="top"> 1544 <td valign="top">mathematics</td> 1545 <td valign="top">Arguments: <em class="arg">A, B, C, D</em> 1546 <br>Not available in "<code>composite</code>" at this time. 1547 <br>Merge the source and destination images according to the formula 1548 <br> <code>A*Sc*Dc + B*Sc + C*Dc + D</code> 1549 <br>Can be used to generate a custom composition method that would 1550 otherwise need to be implemented using the slow <a href="#fx">-fx</a> 1551 DIY image operator. Added to ImageMagick version 6.5.4-3. 1552 </td> 1553 </tr> 1554 1555 <tr valign="top"> 1556 <td valign="top">modulate</td> 1557 <td valign="top">Arguments: 1558 <em class="arg">brightness</em>[x<em class="arg">saturation</em>] 1559 <br>Equivalent to "<code>composite</code>" <a href="#watermark">-watermark</a> 1560 <br>Take a grayscale image (with alpha mask) and modify the destination 1561 image's brightness according to watermark image's grayscale value and 1562 the <em class="arg">brightness</em> percentage. The destinations 1563 color saturation attribute is just direct modified by the <em 1564 class="arg">saturation</em> percentage, which defaults to 100 percent 1565 (no color change). 1566 1567 </td> 1568 </tr> 1569 1570 <tr valign="top"> 1571 <td valign="top">displace</td> 1572 <td valign="top">Arguments: 1573 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em>][!][%] 1574 <br>Equivalent to "<code>composite</code>" <a href="#displace">-displace</a> 1575 <br>With this option, the 'overlay' image, and optionally the 'mask' 1576 image, is used as a relative displacement map, which is used to 1577 displace the lookup of what part of the destination image is seen at 1578 each point of the overlaid area. Much like the displacement map is a 1579 'lens' that distorts the original 'background' image behind it. 1580 <br><br> 1581 The X-scale is modilated by the 'red' channel of the overlay image 1582 while the Y-scale is modulated by the green channel, (the mask image 1583 if given is rolled into green channel of the overlay image. This 1584 separation allows you to modulate the X and Y lookup displacement 1585 separatally allowing you to di 2 dimentional displacements, rather 1586 than 1 dimentional verctored displacements (using grayscale image). 1587 <br><br> 1588 If the overlay image contains transparency this is used as a mask 1589 of the resulting image to remove 'invalid' pixels. 1590 <br><br> 1591 The '%' flag makes the displacement scale relative to the size of the 1592 overlay image (100% = half width/height of image). Using '!' switches 1593 percentage arguments to refer to the destination image size instead. 1594 <br><br> 1595 Special flags were added Added to ImageMagick version 6.5.3-5. 1596 </td> 1597 </tr> 1598 1599 <tr valign="top"> 1600 <td valign="top">distort</td> 1601 <td valign="top">Arguments: 1602 <em class="arg">X-scale</em>[x<em class="arg">Y-scale</em 1603 >[+<em class="arg">X-center</em>+<em class="arg">Y-center</em>]][!][%] 1604 <br>Not available in "<code>composite</code>" at this time. 1605 <br>Exactly as per 'Displace' (above), but using absolute coordinates, 1606 relative to the center of the overlay (or that given). Basically 1607 allows you to generate absolute distortion maps where 'black' will 1608 look up the left/top edge, and 'white' looks up the bottom/right 1609 edge of the destination image, according to the scale given. 1610 <br><br> 1611 The '!' flag not only switches percentage scaling, to use the 1612 destination image, but also the image the center offset of the lookup. 1613 This means the overlay can lookup a completely different region of the 1614 destination image. 1615 <br><br> 1616 Added to ImageMagick version 6.5.3-5. 1617 </td> 1618 </tr> 1619 1620 <tr valign="top"> 1621 <td valign="top">blur</td> 1622 <td valign="top">Arguments: 1623 <em class="arg">Width</em>[x<em class="arg">Height</em 1624 >[+<em class="arg">Angle</em>]] 1625 <br>Equivalent to "<code>composite</code>" 1626 <a href="#blur-composite">-blur</a> 1627 <br>A Variable Blur Mapping Composition method, where each pixel in the 1628 overlaid region is replaced with an Elliptical Weighted Average (EWA), 1629 with an ellipse (typically a circle) of the given sigma size, scaled 1630 according to overlay (source image) grayscale mapping. 1631 <br><br> 1632 As per 'Displace' and 'Distort', the red channel will modulate the 1633 width of the ellipse, while the green channel will modulate the height 1634 of the ellipse. However at this time the ellipse angle is not 1635 modulated though this may be a future posibility (perhaps with a 1636 special flag to enable use of blur channel for this purpose). 1637 <br><br> 1638 Added to ImageMagick version 6.5.4-0. 1639 </td> 1640 </tr> 1641 1642 </tbody> 1643</table> 1644 1645<p>To print a complete list of all the available compose operators, use <a href="#list">-list compose</a>.</p> 1646 1647 1648<div style="margin: auto;"> 1649 <h4><a name="composite" id="composite"></a>-composite</h4> 1650</div> 1651 1652<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Perform alpha composition on the current image sequence.</td><td style='text-align:right;'></td></tr></table> 1653 1654<p>Take the first image 'destination' and overlay the second 'source' image 1655according to the current <a href="#compose">-compose</a> setting. The location 1656of the 'source' or 'overlay' image is controlled according to <a 1657href="#geometry" >-geometry</a>, and <a href="#geometry" >-geometry</a> 1658settings. </p> 1659 1660<p>If a third image is given this is treated as a gray-scale 'mask' image 1661relative to the first 'destination' image. This mask will limit what parts of 1662the destination can be modified by the image composition. However for the 1663'<kbd>displace</kbd>' compose method, the mask is used to provide a separate 1664Y-displacement image instead. </p> 1665 1666<p>If a <a href="#compose">-compose</a> method requires extra numerical 1667arguments or flags these can be provided by setting the <a 1668href="#set">-set</a> '<kbd class="arg">option:compose:args</kbd>' 1669appropriatally for the compose method. </p> 1670 1671<p>Some <a href="#compose">-compose</a> methods can modify the 'destination' 1672image outside the overlay area. You can disable this by setting the special <a 1673href="#set">-set</a> '<kbd class="arg">option:compose:outside-overlay</kbd>' 1674to '<kbd>false</kbd>'. </p> 1675 1676 1677<div style="margin: auto;"> 1678 <h4><a name="compress" id="compress"></a>-compress <em class="arg">type</em></h4> 1679</div> 1680 1681<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> 1682 1683<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> 1684 1685<p>To print a complete list of compression types, use <a href="#list">-list compress</a>.</p> 1686 1687<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> 1688 1689<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> 1690 1691<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> 1692 1693<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> 1694 1695<div style="margin: auto;"> 1696 <h4><a name="contrast" id="contrast"></a>-contrast</h4> 1697</div> 1698 1699<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> 1700 1701<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> 1702 1703<p>For a more pronounced effect you can repeat the option:</p> 1704 1705<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -contrast -contrast rose_c2.png</span></p> 1706<div style="margin: auto;"> 1707 <h4><a name="contrast-stretch" 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> 1708</div> 1709 1710<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> 1711 1712<p>While performing the stretch, black-out at most <em 1713class="arg" >black-point</em> pixels and white-out at most <em 1714class="arg" >white-point</em> pixels. Or, if percent is used, black-out at most 1715<em class="arg" >black-point %</em> pixels and white-out at most <em 1716class="arg" >white-point %</em> pixels.</p> 1717 1718<p>Prior to ImageMagick 6.4.7-0, <a href="#contrast-stretch" 1719>-contrast-stretch</a> will black-out at most <em class="arg" 1720>black-point</em> pixels and white-out at most <em class="arg" >total pixels 1721minus white-point</em> pixels. Or, if percent is used, black-out at most <em 1722class="arg">black-point %</em> pixels and white-out at most <em class="arg" 1723>100% minus white-point %</em> pixels.</p> 1724 1725<p>Note that <kbd>-contrast-stretch 0</kbd> will modify the image such that 1726the image's min and max values are stretched to 0 and <em class="QR" 1727>QuantumRange</em>, respectively, without any loss of data due to burn-out or 1728clipping at either end. This is not the same as <a href="#normalize" 1729>-normalize</a>, which is equivalent to <kbd>-contrast-stretch 2%x1%</kbd> (or 1730prior to ImageMagick 6.4.7-0, <kbd>-contrast-stretch 2%x99%</kbd>).</p> 1731 1732<p>Internally operator works by creating a histogram bin, and then uses that 1733bin to modify the image. As such some colors may be merged together when they 1734originally fell into the same 'bin'. </p> 1735 1736<p>All the channels are normalized in concert by the came amount so as to 1737preserve color integrity, when the default <a href="#channel" >+channel</a> 1738setting is in use. Specifing any other <a href="#channel" >-channel</a> 1739setting will normalize the RGB channels independently.</p> 1740 1741<p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect' 1742normalization of mathematical images. </p> 1743 1744<p>This operator is under review for re-development. </p> 1745 1746 1747<div style="margin: auto;"> 1748 <h4><a name="convolve" id="convolve"></a>-convolve <em class="arg">kernel</em></h4> 1749</div> 1750 1751<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> 1752 1753<p>The <em class="arg">kernel</em> is a matrix specified as 1754a comma-separated list of integers (with no spaces), ordered left-to right, 1755starting with the top row. Presently, only odd-dimensioned kernels are 1756supported, and therefore the number of entries in the specified <em 1757class="arg">kernel</em> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25, 17587<sup>2</sup>=49, etc. </p> 1759 1760<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 1761positive and negative results are relative to a user-specified bias value. 1762This is important for non-HDRI compilations of ImageMagick when dealing with 1763convolutions that contain negative as well as positive values. This is 1764especially the case with convolutions involving high pass filters or edge 1765detection. Without an output bias, the negative values is clipped at zero. 1766</p> 1767 1768<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 1769negative results without clipping to the color value range (0..QuantumRange). 1770See the discussion on HDRI implementations of ImageMagick on the page <a 1771href="/www/high-dynamic-range.html">High 1772Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a 1773href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this 1774<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a> 1775entry. </p> 1776 1777 1778<div style="margin: auto;"> 1779 <h4><a name="crop" id="crop"></a>-crop <em class="arg">geometry</em></h4> 1780</div> 1781 1782<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> 1783 1784<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> 1785 1786<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> 1787 1788<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> 1789 1790<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> 1791 1792<p>By adding a exclamation character flag to the geometry argument, the 1793cropped images virtual canvas page size and offset is set as if the 1794geometry argument was a viewport or window. This means the canvas page size 1795is set to exactly the same size you specified, the image offset set 1796relative top left corner of the region cropped. </p> 1797 1798<p>If the cropped image 'missed' the actual image on its virtual canvas, a 1799special single pixel transparent 'missed' image is returned, and a 'crop 1800missed' warning given. </p> 1801 1802<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> 1803 1804<div style="margin: auto;"> 1805 <h4><a name="cycle" id="cycle"></a>-cycle <em class="arg">amount</em></h4> 1806</div> 1807 1808<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> 1809 1810<p><em class="arg">Amount</em> defines the number of positions each 1811colormap entry is shifted.</p> 1812 1813 1814<div style="margin: auto;"> 1815 <h4><a name="debug" id="debug"></a>-debug <em class="arg">events</em></h4> 1816</div> 1817 1818<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> 1819 1820<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> 1821 1822 1823<p>For example, to log cache and blob events, use.</p> 1824 1825<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -debug "Cache,Blob" rose: rose.png</span></p> 1826<p>The <kbd>User</kbd> domain is normally empty, but developers can log user events in their private copy of ImageMagick.</p> 1827 1828<p>To print the complete list of debug methods, use <a href="#list">-list debug</a>.</p> 1829 1830<p>Use the <a href="#log">-log</a> option to specify the format for debugging output.</p> 1831 1832<p>Use <a href="#debug">+debug</a> to turn off all logging.</p> 1833 1834<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> 1835 1836 1837<div style="margin: auto;"> 1838 <h4><a name="decipher" id="decipher"></a>-decipher <em class="arg">filename</em></h4> 1839</div> 1840 1841<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> 1842 1843<p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p> 1844 1845<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p> 1846 1847 1848<div style="margin: auto;"> 1849 <h4><a name="deconstruct" id="deconstruct"></a>-deconstruct</h4> 1850</div> 1851 1852<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> 1853 1854<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> 1855 1856<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> 1857 1858<p>This option is actually equivalent to the <a href="#layers">-layers</a> method '<kbd>compare-any</kbd>'. </p> 1859 1860 1861<div style="margin: auto;"> 1862 <h4><a name="define" id="define"></a>-define <em class="arg">key</em>{<em class="arg">=value</em>}<em class="arg">...</em></h4> 1863</div> 1864 1865<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add coder/decoder specific options.</td><td style='text-align:right;'></td></tr></table> 1866 1867<p>This option creates one or more definitions for coders and decoders to use while reading and writing image data. Definitions may be passed to coders and decoders to control options that are specific to certain image formats. If <em class="arg">value</em> is missing for a definition, an empty-valued definition of a flag is created with that name. This used to control on/off options. Use <a href="#define">+define key</a> to remove definitions previously created. Use <a href="#define">+define "*"</a> to remove all existing definitions.</p> 1868 1869<p>The following definitions may be created:</p> 1870 1871<ul> 1872<dt>dcm:display-range=reset</dt> 1873 <dd>Set the display range to the minimum and maximum pixel values for the DCM image format.</dd><br /> 1874<dt>dot:layout-engine=<em class="arg">value</em></dt> 1875 <dd>Set the specify the layout engine for the DOT image format (e.g. <kbd>neato</kbd>).</dd><br /> 1876<dt>jpeg:extent=<em class="arg">value</em></dt> 1877 <dd>Restrict the maximum JPEG file size, for example <kbd>-define jpeg:extent=400kb</kbd>.</dd><br /> 1878<dt>jpeg:size=<em class="arg">geometry</em></dt> 1879 <dd>Set the size hint of a JPEG image, for example, -define jpeg:size=128x128. It is most useful for increasing performance and reducing the memory requirements when reducing the size of a large JPEG image.</dd><br /> 1880<dt>jp2:rate=<em class="arg">value</em></dt> 1881 <dd>Specify the compression factor to use while writing JPEG-2000 files. The compression factor is the reciprocal of the compression ratio. The valid range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined, this value overrides the -quality setting. A quality setting of 75 results in a rate value of 0.06641.</dd><br /> 1882<dt>mng:need-cacheoff</dt> 1883 <dd>turn playback caching off for streaming MNG.</dd><br /> 1884<dt>png:bit-depth=<em class="arg">value</em></dt> 1885<dt>png:color-type=<em class="arg">value</em></dt> 1886 <dd>desired bit-depth and color-type for PNG output. You can force the PNG encoder to use a different bit-depth and color-type than it would have normally selected, but only if this does not cause any loss of image quality. Any attempt to reduce image quality is treated as an error and no PNG file is written. E.g., if you have a 1-bit black-and-white image, you can use these "defines" to cause it to be written as an 8-bit grayscale, indexed, or even a 64-bit RGBA. But if you have a 16-million color image, you cannot force it to be written as a grayscale or indexed PNG. If you wish to do this, you must use the appropriate <a href="#depth">-depth</a>, <a href="#colors">-colors</a>, or <a href="#type">-type</a> directives to reduce the image quality prior to using the PNG encoder. Note that in indexed PNG files, "bit-depth" refers to the number of bits per index, which can range from 1 to 8. In such files, the color samples always have 8-bit depth.</dd><br /> 1887<dt>ps:imagemask</dt> 1888 <dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create Postscript files that render bilevel images with the Postscript imagemask operator instead of the image operator.</dd><br /> 1889<dt>quantum:format=<em class="arg">type</em></dt> 1890 <dd>Set the type to <kbd>floating-point</kbd> to specify a single precision floating-point format for raw files (e.g. GRAY:).</dd> 1891</ul> 1892 1893<p>For example, to create a postscript file that will render only the black pixels of a bilevel image, use:</p> 1894 1895<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bilevel.tif -define ps:imagemask eps3:stencil.ps</span></p> 1896<p>Set attributes of the image registry by prefixing the value with <kbd>registry:</kbd>. For example, to set a temporary path to put work files, use:</p> 1897 1898<p class="crtsnip"> 1899-define registry:temporary-path=/data/tmp 1900</p> 1901 1902<div style="margin: auto;"> 1903 <h4><a name="delay" 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> 1904</div> 1905 1906<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> 1907 1908<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> 1909 1910<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> 1911 1912 1913<div style="margin: auto;"> 1914 <h4><a name="delete" id="delete"></a>-delete <em class="arg">index</em></h4> 1915</div> 1916 1917<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> 1918 1919<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> 1920 1921 1922<div style="margin: auto;"> 1923 <h4><a name="density" id="density"></a>-density <em class="arg">width</em><br />-density <em class="arg">width</em>x<em class="arg">height</em></h4> 1924</div> 1925 1926<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> 1927 1928<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> 1929 1930<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> 1931 1932<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> 1933 1934<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> 1935 1936<div style="margin: auto;"> 1937 <h4><a name="depth" id="depth"></a>-depth <em class="arg">value</em></h4> 1938</div> 1939 1940<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> 1941 1942<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> 1943 1944<div style="margin: auto;"> 1945 <h4><a name="descend" id="descend"></a>-descend</h4> 1946</div> 1947 1948<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> 1949 1950<div style="margin: auto;"> 1951 <h4><a name="deskew" id="deskew"></a>-deskew <em class="arg">threshold</em></h4> 1952</div> 1953 1954<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> 1955 1956<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> 1957 1958<div style="margin: auto;"> 1959 <h4><a name="despeckle" id="despeckle"></a>-despeckle</h4> 1960</div> 1961 1962<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> 1963 1964<div style="margin: auto;"> 1965 <h4><a name="direction" id="direction"></a>-direction <em class="arg">type</em></h4> 1966</div> 1967 1968<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> 1969 1970<div style="margin: auto;"> 1971 <h4><a name="displace" 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> 1972</div> 1973 1974<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> 1975 1976<p>With this option, the 'overlay' image, and optionally the 'mask' image, 1977will be used as a displacement map, which is used to displace the lookup of 1978what part of the 'background' image is seen at each point of the overlaid 1979area. Much like the displacement map is a 'lens' that redirects light shining 1980through it so as to present a distorted view the original 'background' image 1981behind it. </p> 1982 1983<p>Any perfect grey areas of the displacement map produce a zero 1984displacement of the image. Black areas produce the given maximum negative 1985displacement of the lookup point, while white produce a maximum positive 1986displacement of the lookup. </p> 1987 1988<p>Note that it is the lookup of the 'background' that is displaced, not a 1989displacement of the image itself. As such an area of the displacement map 1990containing 'white' will have the lookup point 'shifted' by a positive amount, 1991and thus generating a copy of the destination image to the right/downward from 1992the correct position. That is the image will look like it may have been 1993'shifted' in a negative left/upward direction. Understanding this is a very 1994important in understanding how displacement maps work. </p> 1995 1996<p>The given arguments define the maximum amount of displacement in pixels 1997that a particular map can produce. If the displacement scale is large enough 1998it is also posible to lookup parts of the 'background' image that lie well 1999outside the bounds of the displacement map itself. That is you could very 2000easilly copy a section of the original image from outside the overlay area 2001into the overlay area. </p> 2002 2003<p>The '%' flag makes the displacement scale relative to the size of the 2004overlay image (100% = half width/height of image). Using '!' switches 2005percentage arguments to refer to the destination image size instead. 2006these flags were added as of IM v6.5.3-5.</p> 2007 2008<p>Normally a single grayscale displacement map is provided, which with the 2009given scaling values will determine a single direction (vector) in which 2010displacements can occur (positivally or negativally). However, if you also 2011specify a third image which is normally used as a <em class="arg">mask</em>, 2012then the <em class="arg">composite image</em> will be used for horizontal X 2013displacement, while the <em class="arg">mask image</em> is used for vertical Y 2014displacement. This allows you to define completely different displacement 2015values for the X and Y directions, and allowing you to lookup any point within 2016the <em class="arg">scale</em> bounds. In other words each pixel can lookup 2017any other nearby pixel, producing complex 2 dimentional displacements, rather 2018than a simple 1 dimentional vector displacements. </p> 2019 2020<p>Alternativally rather than suppling two separate images, as of IM v6.4.4-0, 2021you can use the 'red' channel of the overlay image to specify the horizontal 2022or X displacement, and the 'green' channel for the vertical or Y displacement. 2023</p> 2024 2025<p>As of IM v6.5.3-5 any alpha channel in the overlay image will be used as a 2026mask the transparency of the destination image. However areas outside the 2027overlaid areas will not be effected. </p> 2028 2029 2030<div style="margin: auto;"> 2031 <h4><a name="display" id="display"></a>-display <em class="arg">host:display[.screen]</em></h4> 2032</div> 2033 2034<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> 2035 2036<p>This option is used with convert for obtaining image or font from this X server. See <em class="arg">X(1)</em>.</p> 2037 2038<div style="margin: auto;"> 2039 <h4><a name="dispose" id="dispose"></a>-dispose <em class="arg">method</em></h4> 2040</div> 2041 2042<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> 2043 2044<p>The layer disposal method defines the way each the displayed image is to be 2045modified after the current 'frame' of an animation has finished being 2046displayed (after its 'delay' period), but before the next frame on an 2047animation is to be overlaid onto the display. </p> 2048 2049<p>Here are the valid methods:</p> 2050 2051<pre class="text"> 2052Undefined 0 No disposal specified (equivalent to '<kbd>none</kbd>'). 2053None 1 Do not dispose, just overlay next frame image. 2054Background 2 Clear the frame area with the background color. 2055Previous 3 Clear to the image prior to this frames overlay. 2056</pre> 2057 2058<p>You can also use the numbers given above, which is what the GIF format 2059uses internally to represent the above settings. </p> 2060 2061<p>To print a complete list of dispose methods, use <a href="#list">-list dipose</a>.</p> 2062 2063<p>Use <a href="#dispose" >+dispose</a>, turn off the setting and prevent 2064resetting the layer disposal methods of images being read in. </p> 2065 2066<p>Use <a href="#set">-set</a> '<kbd>dispose</kbd>' method to set the image 2067disposal method for images already in memory.</p> 2068 2069<div style="margin: auto;"> 2070 <h4><a name="dissimilarity-threshold" id="dissimilarity-threshold"></a>-dissimilarity-threshold <em class="arg">value</em></h4> 2071</div> 2072 2073<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> 2074 2075 2076<div style="margin: auto;"> 2077 <h4><a name="dissolve" id="dissolve"></a>-dissolve <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]</h4> 2078</div> 2079 2080<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> 2081 2082<p>The opacity of the composite image is multiplied by the given percent, then 2083it is composited 'over' the main image. If <em class="arg">src_percent</em> 2084is greater than 100, start dissolving the main image so it will become 2085transparent at a value of '<kbd class="arg">200</kbd>'. If both percentages 2086are given, each image are dissolved to the percentages given. </p> 2087 2088<p>Note that dissolve percentages do not add, two opaque images dissolved 2089'50,50', produce a 75% transparency. For a 50% + 50% blending of the two 2090images, you would need to use dissolve values of '50,100'. </p> 2091 2092<div style="margin: auto;"> 2093 <h4><a name="distort" id="distort"></a>-distort <em class="arg">method arguments</em></h4> 2094</div> 2095 2096<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> 2097 2098<p>The <em class="arg">arguments</em> is a single string containing a list 2099of floating point numbers separated by commas or spaces. The number of 2100and meaning of the floating point values depends on the distortion <em 2101class="arg">method</em> being used. </p> 2102 2103<p>Choose from these distortion types:</p> 2104 2105<table class="doc"> 2106 <tr valign="top"> 2107 <th align="left" style="width: 8%">Method</th> 2108 <th align="left">Description</th> 2109 </tr> 2110 2111 <tr valign="top"> 2112 <td valign="top"><kbd>ScaleRotateTranslate</kbd> 2113 <br/>or <kbd>SRT</kbd></td> 2114 <td valign="top"> 2115 Distort image by first scaling and rotating about a given 'center', 2116 before translating that 'center' to the new location, in that order. It 2117 is an alternative method of specifying a '<kbd>Affine</kbd>' type of 2118 distortion, but without shearing effects. It also provides a good way 2119 of rotating and displacing a smaller image for tiling onto a larger 2120 background (IE 2-dimensional animations). <br/> 2121 2122 The number of arguments determine the specific meaning of each 2123 argument for the scales, rotation, and translation operations. <br/> 2124 2125 <table style="margin-left:auto; margin-right:auto;"> 2126 <tr><td># </td><td>arguments meaning</td></tr> 2127 <tr><td>1:</td><td><em>Angle_of_Rotation</em></td></tr> 2128 <tr><td>2:</td><td><em>Scale Angle</em></td></tr> 2129 <tr><td>3:</td><td><em>ScaleX,ScaleY Angle</em></td></tr> 2130 <tr><td>4:</td><td><em>X,Y Scale Angle</em></td></tr> 2131 <tr><td>5:</td> 2132 <td><em>X,Y ScaleX,ScaleY Angle</em></td></tr> 2133 <tr><td>6:</td> 2134 <td><em>X,Y Scale Angle NewX,NewY</em></td></tr> 2135 <tr><td>7:</td> 2136 <td><em>X,Y ScaleX,ScaleY Angle 2137 NewX,NewY</em></td></tr> 2138 </table> 2139 2140 This is actually an alternative way of specifing a 2 dimensional linear 2141 '<kbd>Affine</kbd>' or '<kbd>AffineProjection</kbd>' distortion. </td> </tr> 2142 2143 <tr valign="top"> 2144 <td valign="top"><kbd>Affine</kbd></td> 2145 <td valign="top"> 2146 Distort the image linearly by moving a list of at least 3 or more sets 2147 of control points (as defined below). Idealy 3 sets or 12 floating 2148 point values are given allowing the image to be linearly scaled, 2149 rotated, sheared, and translated, according to those three points. See 2150 also the related '<kbd>AffineProjection</kbd>' and '<kbd>SRT</kbd>' 2151 distortions. <br/> 2152 2153 More than 3 sets given control point pairs (12 numbers) is least 2154 squares fitted to best match a lineary affine distortion. If only 2 2155 control point pairs (8 numbers) are given a two point image translation 2156 rotation and scaling is performed, without any posible shearing, 2157 flipping or changes in aspect ratio to the resulting image. If only one 2158 control point pair is provides the image is only translated, (which may 2159 be a floating point non-integer translation). <br/> 2160 2161 This distortion does not include any form of perspective distortion. 2162 </td> 2163 2164 </tr> 2165 2166 <tr valign="top"> 2167 <td valign="top"><kbd>AffineProjection</kbd></td> 2168 <td valign="top"> 2169 Linearly distort an image using the given Affine Matrix of 6 2170 pre-calculated coefficients forming a set of Affine Equations to map 2171 the source image to the destination image. 2172 2173 <div style="text-align: center"><em> 2174 s<sub>x</sub>, r<sub>x</sub>, 2175 r<sub>y</sub>, s<sub>y</sub>, 2176 t<sub>x</sub>, t<sub>y</sub> 2177 </em></div> 2178 2179 See <a href="#affine" >-affine</a> setting for more detail, and 2180 meanings of these coefficients. <br/> 2181 2182 The distortions '<kbd>Affine</kbd>' and '<kbd>SRT</kbd>' provide 2183 alternative methods of defining this distortion, with ImageMagick doing the 2184 calculations needed to generate the required coefficients. You can see 2185 the internally generated coefficients, by using a <a href="#verbose" 2186 >-verbose</a> setting. </td> 2187 2188 </tr> 2189 2190<!-- still under development, do not display - Anthony 2191 <tr valign="top"> 2192 <td valign="top"><kbd>Bilinear</kbd></td> 2193 <td valign="top"> 2194 Bilinear (reversed) Distortion, given a minimum of 4 sets of 2195 coordinate pairs, or 16 values (see below). Not that lines may not 2196 appear straight after distortion, though the distance between 2197 coordinates will remain consistant. </td> 2198 </tr> 2199--> 2200 2201 <tr valign="top"> 2202 <td valign="top"><kbd>Perspective</kbd></td> 2203 <td valign="top"> 2204 Perspective distort the images, using a list of 4 or more sets of 2205 control points (as defined below). More that 4 sets (16 numbers) of 2206 control points provide least squares fitting for more accurate 2207 distortions (for the purposes of image registration and panarama 2208 effects). Less than 4 sets will fall back to a '<kbd>Affine</kbd>' 2209 linear distortion. <br/> 2210 2211 Perspective Distorted images ensures that straight lines remain 2212 straight, but the scale of the distorted image will vary. The horizon 2213 is anti-aliased, and the 'sky' color may be set using the 2214 <a href="#mattecolor" >-mattecolor</a> setting. </td> 2215 </tr> 2216 2217 <tr valign="top"> 2218 <td valign="top"><kbd>PerspectiveProjection</kbd> </td> 2219 <td valign="top"> 2220 Do a '<kbd>Perspective</kbd>' distortion basied on a set of 8 2221 pre-calculated coefficients. You can get these coefficients by looking 2222 at the <a href="#verbose" >-verbose</a> output of a 2223 '<kbd>Prespective</kbd>' distortion, or by calculating them yourself. 2224 If the last two perspective scaling coefficients are zero, the 2225 remaining 6 represents a transposed 'Affine Matrix'. </td> 2226 2227 </tr> 2228 2229 <tr valign="top"> 2230 <td valign="top"><kbd>Arc</kbd></td> 2231 <td valign="top"> 2232 Arc the image (variation of polar mapping) over the angle given around 2233 a circle. <br/> 2234 <table width="90%" style = "margin-left: auto; margin-right: auto;"> 2235 <tr valign="top"><td>Argument</td> 2236 <td>Meaning</td></tr> 2237 <tr valign="top"><td><em>arc_angle</em></td> 2238 <td>The angle over which to arc the image side-to-side</td></tr> 2239 <tr valign="top"><td><em>rotate_angle</em></td> 2240 <td>Angle to rotate resulting image from vertical center</td></tr> 2241 <tr valign="top"><td><em>top_radius</em></td> 2242 <td>Set top edge of source image at this radius</td></tr> 2243 <tr valign="top"><td><em>bottom_radius</em> </td> 2244 <td>Set bottom edge to this radius (radial scaling)</td></tr> 2245 </table> 2246 2247 The resulting image is always resized to best fit the resulting image, 2248 (as if using <a href="#distort" >+distort</a>) while attempting to 2249 preserve scale and aspect ratio of the original image as much as 2250 possible with the arguments given by the user. All four arguments will 2251 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/> 2252 2253 This a variation of a polar distortion designed to try to preserve the 2254 aspect ratio of the image rather than direct Cartesian to Polar 2255 conversion. </td> 2256 </tr> 2257 2258 <tr valign="top"> 2259 <td valign="top"><kbd>Polar</kbd></td> 2260 <td valign="top"> 2261 Like '<kbd>Arc</kbd>' but do a complete Cartesian to Polar mapping of 2262 the image. that is the height of the input image is mapped to the 2263 radius limits, while the width is wrapped around between the 2264 angle limits. <br/> 2265 2266 Arguments: <em>Rmax,Rmin CenterX,CenterY, start,end_angle</em> <br/> 2267 2268 All arguments are optional. With <em>Rmin</em> defaulting to zero, the 2269 center to the center of the image, and the angles going from -180 (top) 2270 to +180 (top). If <em>Rmax</em> is given the special value of 2271 '<code>0</code>', the the distance from the center to the nearest edge 2272 is used for the radius of the output image, which will ensure the whole 2273 image is visible (though scaled smaller). However a special value of 2274 '<code>-1</code>' will use the distance from the center to the furthest 2275 corner, This may 'clip' the corners from the input rectangular image, 2276 but will generate the exact reverse of a '<kbd>DePolar</kbd>' with 2277 the same arguments. <br/> 2278 2279 If the plus form of distort (<a href="#distort" >+distort</a>) is used 2280 output image center will default to <code>0,0</code> of the virtual 2281 canvas, and the image size adjusted to ensure the whole input image is 2282 made visible in the output image on the virtual canvas. </td> 2283 2284 </tr> 2285 2286 <tr valign="top"> 2287 <td valign="top"><kbd>DePolar</kbd></td> 2288 <td valign="top"> 2289 Uses the same arguments and meanings as a '<kbd>Polar</kbd>' distortion 2290 but generates the reverse Polar to Cartesian distortion. <br/> 2291 2292 The special <em>Rmax</em> setting of '<code>0</code>' may however clip 2293 the corners of the input image. However using the special 2294 <em>Rmax</em> setting of '<code>-1</code>' (maximum center to corner 2295 distance) will ensure the whole distorted image is preserved in the 2296 generated result, so that the same argument to '<kbd>Polar</kbd>' will 2297 reverse the distortion re-producing the original. 2298 2299 Note that as this distortion requires the area resampling of a circular 2300 arc, which can not be handled by the builtin EWA resampling function. 2301 As such the normal EWA filters are turned off. It is recomended some 2302 form of 'super-sampling' image processing technique be used to produce 2303 a high quality result. </td> 2304 2305 </tr> 2306 2307 <tr valign="top"> 2308 <td valign="top"><kbd>Barrel</kbd></td> 2309 <td valign="top"> 2310 Given the four coefficients (A,B,C,D) as defined by <a 2311 href="http://www.all-in-one.ee/~dersch/barrel/barrel.html" >Helmut 2312 Dersch</a>, perform a barrell or pincussion distortion appropriate to 2313 correct radial lens distortions. That is in photographs, make straight 2314 lines straight again. <br/> 2315 2316 Arguments: <em>A B C</em> [ <em>D</em> [ 2317 <em>X</em> , <em>Y</em> ] ] <br/> 2318 or <em>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub> 2319 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></em> 2320 [ <em>X</em> , <em>Y</em> ] <br/> 2321 So that it forms the function <br/> 2322 Rsrc = r * ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> + 2323 <em>C</em>*r + <em>D</em> )<br/> 2324 2325 Where <em>X</em>,<em>Y</em> is the optional center of the distortion 2326 (defaulting to the center of the image). <br/> 2327 The second form is typically used to distort images, rather than 2328 correct lens distortions. <br/> 2329 </td> 2330 2331 </tr> 2332 2333 <tr valign="top"> 2334 <td valign="top"><kbd>BarrelInverse</kbd></td> 2335 <td valign="top"> 2336 This is very simular to '<kbd>Barrel</kbd>' with the same set of 2337 arguments, and argument handling. However it uses the inverse 2338 of the radial polynomial, 2339 so that it forms the function <br/> 2340 Rsrc = r / ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> + 2341 <em>C</em>*r + <em>D</em> ) 2342 </td> 2343 </tr> 2344 2345 <tr valign="top"> 2346 <td valign="top"><kbd>Shepards</kbd></td> 2347 <td valign="top"> 2348 Distort the given list control points (any number) using an Inverse 2349 Squared Distance Interpolation Method (<a 2350 href="http://www.ems-i.com/smshelp/Data_Module/Interpolation/Inverse_Distance_Weighted.htm" 2351 >Shepards Method</a>). The control points in effect do 'localized' 2352 distortions of the image around the given control point. For best 2353 results extra control points should be added to 'lock' the positions of 2354 the corners and other unchanging parts of the image. <br/> 2355 2356 The distortion has been likened to 'taffy pulling' using nails, pins or 2357 sticks. It basically uses the <a href="#sparse-color" 2358 >-sparse-color</a> method of the same name to generate separate X and Y 2359 displacement maps (see <a href="#displace" >-displace</a>) for source 2360 image color look-up. </td> 2361 2362 </tr> 2363 2364</table> 2365 2366<p>To print a complete list of distortion methods, use <a href="#list">-list distort</a>.</p> 2367 2368<p>Many of the above distortion methods such as '<kbd>Affine</kbd>', 2369'<kbd>Perspective</kbd>', and '<kbd>Shepards</kbd>' use a list control points 2370defining how these points in the given image should be distorted in the 2371destination image. Each set of four floating point values represent a source 2372image coordinate, followed immediately by the destination image coordinate. 2373This produces a list of values such as...</p> 2374<div style="text-align: center"><em> 2375 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub> 2376 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub> 2377 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub> 2378 ... 2379 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub> 2380</em></div> 2381<p>where <em>U,V</em> on the source image is mapped to <em>X,Y</em> on the 2382destination image. </p> 2383 2384<p>For example, to warp an image using '<kbd>perspective</kbd>' distortion, 2385needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the 2386perspective distortion of the built-in "rose:" image. Note how spaces were 2387used to group the 4 sets of coordinate pairs, to make it easier to read and 2388understand.</p> 2389 2390<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'> 2391 convert rose: -virtual-pixel black \ <br/> 2392 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \ <br/> 2393 rose_3d_rotated.gif</span></p> 2394<p>If more that the required number of coordinate pairs are given for a 2395distortion, the distortion method is 'least squares' fitted to 2396produce the best result for all the coordinate pairs given. If less than the 2397ideal number of points are given, the distort will generally fall back to a 2398simpler form of distortion that can handles the smaller number of coordinates 2399(usally a linear '<kbd>Affine</kbd>' distortion). </p> 2400 2401<p>By using more coodinates you can make use of image registration tool to 2402find matching coordinate pairs in overlaping images, so as to improve the 'fit' 2403of the distortion. Of course a bad coordinate pair can also make the 'fit' 2404worse. Caution is always advised. </p> 2405 2406<p>Colors are acquired from the source image according to the <a 2407href="#interpolate" >-interpolate</a> color lookup setting, when the image is 2408magnified. However if the viewed image is minified (image becomes smaller), a 2409special area resampling function (added ImageMagick v6.3.5-9), is used to 2410produce a higher quality image. For example you can use a 2411'<kbd>perspective</kbd>' distortion to view a infinitely tiled 'plane' all the 2412way to the horizon. </p> 2413 2414<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \ <br/> 2415 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \ <br/> 2416 checks_tiled.jpg</span></p> 2417<p>Note that a infinitely tiled perspective images involving the horizon can 2418be very slow to generate due to the use of the high quality 'area resampling' 2419function (added ImageMagick v6.3.5-9). You can turn off 'area resampling' 2420using a <a href="#filter" >-filter</a> setting of '<kbd>point</kbd>' 2421(recommended if you plan to use super-sampling instead). </p> 2422 2423<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last 2424'<kbd>perspective</kbd>' distortion example, <a href="#distort" >-distort</a> 2425will use the current <a href="#mattecolor" >-mattecolor</a> setting for these 2426pixels. If you do not what these pixels to be visible, set the color to match 2427the rest of the ground. </p> 2428 2429<p>The output image size will by default be the same as the input image. This 2430means that if the part of the distorted image falls outside the viewed area of 2431the 'distorted space', those parts is clipped and lost. However if you 2432use the plus form of the operator (<a href="#distort" >+distort</a>) the 2433operator will attempt (if posible) to show the whole of the distorted image, 2434while retaining a correct 'virtual canvas' offset, for image layering. This 2435offset may need to be removed using <a href="#repage" >+repage</a>, to remove 2436if it is unwanted. </p> 2437 2438<p>You can alternatively specify a special "<kbd><a href="#set" >-set</a> 2439option:distort:viewport {geometry_string}</kbd>" setting which will specify 2440the size and the offset of the generated 'viewport' image of the distorted 2441image space.</p> 2442 2443<p>Adding a "<kbd><a href="#set" >-set</a> option:distort:scale 2444{scale_factor}</kbd>" will scale the output image (viewport or otherwise) by 2445that factor without changing the viewed contents of the distorted image. This 2446can be used either for 'super-sampling' the image for a higher quality result, 2447or for panning and zooming around the image (with appropriate viewport 2448changes, or post-distort cropping and resizing). </p> 2449 2450<p>Setting <a href="#verbose" >-verbose</a> setting, will cause <a 2451href="#distort" >-distort</a> to attempt to output the internal coefficients, 2452and the <a href="#fx" >-fx</a> equivalent to the distortion, for expert study, 2453and debugging purposes. This many not be available for all distorts. </p> 2454 2455<p>Affine rotations and shears (such as '<kbd>SRT</kbd>' distortion), tend to 2456produce a cleaner result that the equivalent <a href="#rotate" >-rotate</a> 2457and/or <a href="#shear" >-shear</a> operation, with more control of due to the 2458above settings. It is algorithmically slower, though in ImageMagick it may be faster. 2459</p> 2460 2461 2462<div style="margin: auto;"> 2463 <h4><a name="dither" id="dither"></a>-dither <em class="arg">method</em></h4> 2464</div> 2465 2466<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> 2467 2468<p>Dithering places two or more colors in neighbouring 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> 2469 2470<p>Dithering is turned on by default, to turn it off use the plus form of the 2471setting, <a href="#dither">+dither</a>. This will also also render PostScript 2472without text or graphic aliasing. Disabling dithering often (but not always) 2473leads to faster process, a smaller number of colors, but more cartoon like 2474image coloring. Generally resulting in 'color banding' effects in areas with 2475color gradients. </p> 2476 2477<p>The color reduction operators <a href="#colors">-colors</a>, <a 2478href="#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> 2479 2480<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> 2481 2482 2483<div style="margin: auto;"> 2484 <h4><a name="draw" id="draw"></a>-draw <em class="arg">string</em></h4> 2485</div> 2486 2487<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> 2488 2489<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> 2490 2491<p>The shape primitives:</p> 2492 2493<pre class="text"> 2494 point x,y 2495 line x0,y0 x1,y1 2496 rectangle x0,y0 x1,y1 2497 roundRectangle x0,y0 x1,y1 wc,hc 2498 arc x0,y0 x1,y1 a0,a1 2499 ellipse x0,y0 rx,ry a0,a1 2500 circle x0,y0 x1,y1 2501 polyline x0,y0 ... xn,yn 2502 polygon x0,y0 ... xn,yn 2503 bezier x0,y0 ... xn,yn 2504 path path specification 2505 image operator x0,y0 w,h filename 2506</pre> 2507 2508<p>The text primitive:</p> 2509 2510<pre class="text"> 2511 text x0,y0 string 2512</pre> 2513<p>The text gravity primitive:</p> 2514 2515<pre class="text"> 2516 gravity NorthWest, North, NorthEast, West, Center, 2517 East, SouthWest, South, or SouthEast 2518</pre> 2519 2520<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> 2521 2522<p>The transformation primitives:</p> 2523 2524<pre class="text"> 2525 rotate degrees 2526 translate dx,dy 2527 scale sx,sy 2528 skewX degrees 2529 skewY degrees 2530</pre> 2531 2532<p>The pixel operation primitives:</p> 2533 2534<pre class="text"> 2535 color x0,y0 method 2536 matte x0,y0 method 2537</pre> 2538 2539<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> 2540 2541<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> 2542 2543<p>A <kbd>line</kbd> primitive requires a start point and end point.</p> 2544 2545<p>A <kbd>rectangle</kbd> primitive is specified by the pair of points at the upper left and lower right corners.</p> 2546 2547<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> 2548 2549<p>The <kbd>circle</kbd> primitive makes a disk (filled) or circle (unfilled). Give the center and any point on the perimeter (boundary).</p> 2550 2551<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> 2552 2553<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> 2554 2555<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>. 2556</p> 2557 2558<p>A <em>coordinate</em> is a pair of integers separated by a space or optional comma. </p> 2559 2560<p>As an example, to define a circle centered at 100,100 that extends to 150,150 use:</p> 2561 2562<p class="crtsnip"> 2563 -draw 'circle 100,100 150,150' 2564</p> 2565 2566<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 2567draw 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> 2568 2569<p class="crtsnip"> 2570 -draw 'bezier 20,50 45,100 45,0 70,50' 2571</p> 2572<p class="crtsnip"> 2573 -draw 'bezier 70,50 95,100 95,0 120,50' 2574</p> 2575 2576 2577<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> 2578 2579<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> 2580 2581<p class="crtsnip"> 2582 -draw 'image SrcOver 100,100 225,225 image.jpg' 2583</p> 2584 2585<p>You can use 0,0 for the image size, which means to use the actual dimensions found in the image header. Otherwise, it is scaled to the given dimensions. See <a href="#compose">-compose</a> for a description of the composite operators.</p> 2586 2587<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> 2588 2589<p>For example, the following annotates the image with <kbd>Works like magick!</kbd> for an image titled <kbd>bird.miff</kbd>. </p> 2590 2591<p class="crtsnip"> 2592 -draw 'text 100,100 "Works like magick!"' 2593</p> 2594 2595<p>See the <a href="#annotate">-annotate</a> option for another convenient way to annotate an image with text.</p> 2596 2597<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> 2598 2599<p>The <kbd>translate</kbd> primitive translates subsequent shape and text primitives.</p> 2600 2601<p>The <kbd>scale</kbd> primitive scales them.</p> 2602 2603<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> 2604 2605<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 2606matrix.</p> 2607 2608<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> 2609 2610<pre class="text"> 2611 point 2612 replace 2613 floodfill 2614 filltoborder 2615 reset 2616</pre> 2617 2618<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> 2619 2620<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> 2621 2622<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> 2623 2624<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather than 1.png).</p> 2625 2626<p>Drawing primitives conform to the <a href="/www/magick-vector-graphics.html">Magick Vector Graphics</a> format.</p> 2627 2628 2629<div style="margin: auto;"> 2630 <h4><a name="edge" id="edge"></a>-edge <em class="arg">radius</em></h4> 2631</div> 2632 2633<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> 2634 2635<div style="margin: auto;"> 2636 <h4><a name="emboss" id="emboss"></a>-emboss <em class="arg">radius</em></h4> 2637</div> 2638 2639<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> 2640 2641<div style="margin: auto;"> 2642 <h4><a name="encipher" id="encipher"></a>-encipher <em class="arg">filename</em></h4> 2643</div> 2644 2645<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> 2646 2647<p>Get the passphrase from the file specified by <em class="arg">filename</em>.</p> 2648 2649<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or Decipher an Image</a>.</p> 2650 2651<div style="margin: auto;"> 2652 <h4><a name="encoding" id="encoding"></a>-encoding <em class="arg">type</em></h4> 2653</div> 2654 2655<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> 2656 2657<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> 2658 2659<div style="margin: auto;"> 2660 <h4><a name="endian" id="endian"></a>-endian <em class="arg">type</em></h4> 2661</div> 2662 2663<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> 2664 2665<p>To print a complete list of endian types, use the <a href="#list">-list endian</a> option.</p> 2666 2667<p>Use <a href="#endian">+endian</a> to revert to unspecified endianness.</p> 2668 2669 2670<div style="margin: auto;"> 2671 <h4><a name="enhance" id="enhance"></a>-enhance</h4> 2672</div> 2673 2674<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> 2675 2676 2677<div style="margin: auto;"> 2678 <h4><a name="equalize" id="equalize"></a>-equalize</h4> 2679</div> 2680 2681<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> 2682 2683<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> 2684 2685<p>For example using HSL, we have: ... <kbd>-colorspace HSL -channel lightness -equalize -colorspace RGB</kbd> ...</p> 2686 2687<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> 2688 2689<div style="margin: auto;"> 2690 <h4><a name="evaluate" id="evaluate"></a>-evaluate <em class="arg">operator value</em></h4> 2691</div> 2692 2693<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> 2694 2695<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> 2696 2697<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> 2698 2699<table class="doc"> 2700 <col width="25%" /> 2701 <col width="75%" /> 2702 <thead> 2703 <tr> 2704 <th><em class="arg">operator</em></th> 2705 <th>Summary (see further below for details)</th> 2706 </tr> 2707 </thead> 2708 <tbody> 2709 2710 <tr><td>Add </td> <td>Add <em class="arg">value</em> to pixels. </td></tr> 2711 <tr><td>AddModulus </td> <td>Add <em class="arg">value</em> to pixels modulo <em class="QR">QuantumRange</em>.</td></tr> 2712 <tr><td>And </td> <td>Binary AND of pixels with <em class="arg">value</em>.</td></tr> 2713 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr> 2714 <tr><td>Divide </td> <td>Divide pixels by <em class="arg">value</em>.</td></tr> 2715 <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> 2716 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr> 2717 <tr><td>Max </td> <td>Clip pixels at lower bound <em class="arg">value</em>.</td></tr> 2718 <tr><td>Mean </td> <td>Add the <em class="arg">value</em> and divide by 2.</td></tr> 2719 <tr><td>Min </td> <td>Clip pixels at upper bound <em class="arg">value</em>.</td></tr> 2720 <tr><td>Multiply </td> <td>Multiply pixels by <em class="arg">value</em>.</td></tr> 2721 <tr><td>Or </td> <td>Binary OR of pixels with <em class="arg">value</em>.</td></tr> 2722 <tr><td>Pow </td> <td>Raise normalized pixels to the power <em class="arg">value</em>.</td></tr> 2723 <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> 2724 <tr><td>Set </td> <td>Set pixel equal to <em class="arg">value</em>.</td></tr> 2725 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr> 2726 <tr><td>Subtract </td> <td>Subtract <em class="arg">value</em> from pixels.</td></tr> 2727 <tr><td>Xor </td> <td>Binary XOR of pixels with <em class="arg">value.</em></td></tr> 2728 2729 <tr><td> </td></tr> 2730 2731 <tr><td>Gaussian-noise</td></tr> 2732 <tr><td>Impulse-noise</td></tr> 2733 <tr><td>Laplacian-noise</td></tr> 2734 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="#noise" >-noise</a> operators.)</td></tr> 2735 <tr><td>PoissonNoise</td></tr> 2736 <tr><td>Uniform-noise</td></tr> 2737 2738 <tr><td> </td></tr> 2739 2740 <tr><td>Threshold </td> <td>Threshold pixels larger than <em class="arg">value</em>.</td></tr> 2741 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <em class="arg">value</em>.</td></tr> 2742 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <em class="arg">value</em>. </td></tr> 2743 </tbody> 2744 </table> 2745 2746<p>The specified functions are applied only to each previously set <a 2747href="#channel" >-channel</a> in the image. If necessary, the results of the 2748calculations are truncated (clipped) to fit in the interval [0, <em 2749class="QR">QuantumRange</em>]. The transparency channel of the image is 2750represented as a 'alpha' values (0 = fully transparent), so, for example, a 2751<kbd>Divide</kbd> by 2 of the alpha channel will make the image 2752semi-transparent. Append the percent symbol '<kbd>%</kbd>' to specify a value 2753as a percentage of the <em class="QR">QuantumRange</em>.</p> 2754 2755<p>To print a complete list of <a href="#evaluate">-evaluate</a> operators, use 2756<a href="#list">-list evaluate</a>.</p> 2757 2758<p>The results of the <kbd>Add</kbd>, <kbd>Subtract</kbd> and 2759<kbd>Multiply</kbd> methods can also be achieved using either the <a 2760href="#level" >-level</a> or the <a href="#level" >+level</a> operator, with 2761appropriate argument, to linearly modify the overall range of color values. 2762Please note, however, that <a href="#level" >-level</a> treats transparency as 2763'matte' values (0 = opaque), while <a href="#level" >-evaluate</a> works with 2764'alpha' values.</p> 2765 2766<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> 2767 2768<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> 2769 2770 <div style="text-align:center;"> 2771 log(<em class="arg">value</em> × <b><em>u</em></b> + 1) / log(<em class="arg">value</em> + 1) 2772 </div> 2773 2774<p><kbd>Pow</kbd> has been added as of ImageMagick 6.4.1-9, and works on 2775normalized pixel values. Note that <kbd>Pow</kbd> is related to the <a 2776href="#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent 2777to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used 2778with <a href="#gamma" >-gamma</a> is simply the reciprocal of the value used 2779with <kbd>Pow</kbd>.</p> 2780 2781<p><kbd>Cosine</kbd> and <kbd>Sine</kbd> was added as of IM v6.4.8-8 and 2782converts the image values into a value according to a (co)sine wave function. 2783The synonyms <kbd>Cos</kbd> and <kbd>Sin</kbd> may also be used. The output 2784is biased 50% and normalized by 50% so as to fit in the respective color value 2785range. The <em class="arg">value</em> scaling of the <em>period</em> of the 2786function (its frequency), and thus determines the number of 'waves' that will 2787be generated over the input color range. For example, if the <em 2788class="arg">value</em> is 1, the effective period is simply the <em 2789class="QR">QuantumRange</em>; but if the <em class="arg">value</em> is 2, 2790then the effective period is the <em>half</em> the <em 2791class="QR">QuantumRange</em>. 2792 2793 <div style="text-align:center;"> 2794 0.5 + 0.5 × cos(2 π <b><em>u</em></b> × <em class="arg">value</em>). 2795 </div> 2796 2797See also the <a href="#function" >-function</a> operator, which is a 2798multi-value version of evaluate. </P> 2799 2800<div style="margin: auto;"> 2801 <h4><a name="evaluate-sequence" id="evaluate-sequence"></a>-evaluate-sequence <em class="arg">operator</em></h4> 2802</div> 2803 2804<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> 2805 2806<div style="margin: auto;"> 2807 <h4><a name="extent" id="extent"></a>-extent <em class="arg">geometry</em></h4> 2808</div> 2809 2810<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> 2811 2812<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> 2813 2814<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> 2815 2816<div style="margin: auto;"> 2817 <h4><a name="extract" id="extract"></a>-extract <em class="arg">geometry</em></h4> 2818</div> 2819 2820<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> 2821 2822<p>This option is most useful for extracting a subregion of a very large raw image. Note that these two commands are equivalent:</p> 2823 2824<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> 2825 2826<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> 2827<p>then the image will be <em>resized</em> to the specified dimensions instead, 2828equivalent to:</p> 2829 2830<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png</span></p> 2831<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> 2832 2833<div style="margin: auto;"> 2834 <h4><a name="family" id="family"></a>-family <em class="arg">fontFamily</em></h4> 2835</div> 2836 2837<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> 2838 2839<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). 2840</p> 2841 2842<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>. 2843</p> 2844 2845<div style="margin: auto;"> 2846 <h4><a name="features" id="features"></a>-features <em class="arg">distance</em></h4> 2847</div> 2848 2849<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> 2850 2851<div style="margin: auto;"> 2852 <h4><a name="fft" id="fft"></a>-fft</h4> 2853</div> 2854 2855<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> 2856 2857<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" target="_blank">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT" target="_blank">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT" target="_blank">Fast Fourier Transform</a>.</p> 2858 2859<p>A single image name is provided as output for this option. However, the output result will have two components. It will be 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" target="_blank">Complex Numbers</a>.<p> 2860 2861<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> 2862 2863<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.miff</span></p> 2864<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> 2865 2866<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -fft fft_image.png</span></p> 2867<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> 2868 2869<p>The input image can be any size, but if not square and even-dimensioned, it will be 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 will be square at this size. The kind of padding relies on the <a href="#virtual-pixel">-virtual-pixel</a> setting.</p> 2870 2871<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> 2872 2873<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff[0] -contrast-stretch 0 \ <br /> 2874 -evaluate log 1000 fft_image_spectrum.png</span></p> 2875<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> 2876 2877<p>The <a href="http://www.fftw.org/" target="_blank">FFTW</a> delegate library is required to use <a href="#fft">-fft</a>. 2878 2879<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> 2880 2881<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> 2882 2883<p>The real and imaginary component images resulting from <a href="#fft">+fft</a> also will be square, even dimensioned images due to the same padding that was discussed above for the magnitude and phase component images.</a> 2884 2885<p>See the discussion on HDRI implementations of ImageMagick on the page 2886<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. 2887</p> 2888 2889 2890<div style="margin: auto;"> 2891 <h4><a name="fill" id="fill"></a>-fill <em class="arg">color</em></h4> 2892</div> 2893 2894<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> 2895 2896<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> 2897 2898<p>Enclose the color specification in quotation marks to prevent the "#" or the parentheses from being interpreted by your shell.</p> 2899 2900<p>For example,</p> 2901 2902<p class="crtsnip"> 2903 -fill blue 2904</p> 2905<p class="crtsnip"> 2906 -fill "#ddddff" 2907</p> 2908<p class="crtsnip"> 2909 -fill "rgb(255,255,255)" 2910</p> 2911 2912<p>See <a href="#draw">-draw</a> for further details.</p> 2913 2914<p>To print a complete list of color names, use the <a href="#list">-list color</a> option.</p> 2915 2916<div style="margin: auto;"> 2917 <h4><a name="filter" id="filter"></a>-filter <em class="arg">type</em></h4> 2918</div> 2919 2920<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 an image.</td><td style='text-align:right;'></td></tr></table> 2921 2922<p>Use this option to affect the resizing operation of an image (see <a 2923href="#resize">-resize</a>). For example you can use a simple resize filter 2924such as:</p> 2925 2926<pre class="text"> 2927 Point Hermite Cubic 2928 Box Gaussian Catrom 2929 Triangle Quadratic Mitchell 2930</pre> 2931 2932<p>The <kbd>Bessel</kbd> and <kbd>Sinc</kbd> filter is also provided, but are 2933by default <kbd>blackman</kbd>-windowed. However these filters define a 2934windowing filter for the Sinc or Bessel filter function, as appropriate for 2935the scaling operator used (usally Sinc for orthogonal <a href="#resize" 2936>-resize</a>). Windowed filters include: </p> 2937 2938<pre class="text"> 2939 Lanczos Hamming Parzen 2940 Blackman Kaiser Welsh 2941 Hanning Bartlett Bohman 2942</pre> 2943 2944<p>Also one special self-windowing filter is also provided 2945<kbd>Lagrange</kbd>, which will automagically re-adjust its function depending 2946on the current 'support' or 'lobes' expert settings (see below).</p> 2947 2948<p>If you do not select a filter with this option, the filter defaults to <kbd>Mitchell</kbd> for a colormapped image, a image with a matte channel, or if the image is enlarged. Otherwise the filter default to <kbd>Lanczos</kbd>.</p> 2949 2950<p>To print a complete list of resize filters, use the <a href="#list">-list filter</a> option.</p> 2951 2952<p>You can modify how the filter behaves as it scales your image through the 2953use of these expert settings:</p> 2954 2955<dl class="doc"> 2956<dt>-set filter:blur <em>factor</em></dt> 2957<dd>Scale the X axis of the filter (and its window). Use > 1.0 for 2958 blurry or < 1.0 for sharp.</dd> 2959 2960<dt>-set filter:support <em>radius</em></dt> 2961<dd>Set the filter support radius.</dd> 2962 2963<dt>-set filter:lobes <em>count</em></dt> 2964<dd>Set the number of lobes to use for the Sinc/Bessel filter. This an 2965 alternative way of specifying the 'support' range of the filter.</dd> 2966 2967<dt>-set filter:b <em>b-spline_factor</em></dt> 2968<dt>-set filter:c <em>keys_alpha_factor</em></dt> 2969<dd>Redefine the values used for cubic filters such as <kbd>Cubic</kbd>, 2970 <kbd>Catrom</kbd>, <kbd>Mitchel</kbd>, and <kbd>Hermite</kbd>, as well as 2971 the <kbd>Parzen</kbd> Sinc windowing function. If only one of the values 2972 are defined, the other is set so as to generate a 'Keys' type cubic 2973 filter. 2974 2975<dt>-set filter:filter <em>filter</em></dt> 2976<dd>Use this function directly as the scaling filter. This will allow 2977 you to directly use a 'windowing filter' such as <kbd>blackman</kbd>, 2978 rather than as its normal usage as a windowing function for 'Sinc' or 2979 'Bessel'. If defined, no windowing function is used, unless the following 2980 expert setting is also defined.</dd> 2981 2982<dt>-set filter:window <em>filter</em></dt> 2983<dd>The IIR (infinite impulse response) filters <kbd>bessel</kbd> and 2984 <kbd>sinc</kbd> are windowed (brought down to zero over the defined 2985 support range) with the given filter. This allows you to use a filter that 2986 is not normally used as a windowing function, such as <kbd>box</kbd>, 2987 (which effectivally turns off the windowing function). </dd> 2988 2989</dl> 2990 2991<p>For example, to get a 8 lobe Lanczos-Bessel filter:</p> 2992 2993<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -filter bessel \ <br/> 2994 -set filter:window=bessel -set filter:lobes=8 \ <br/> 2995 -resize 150% image.jpg</span></p> 2996<p>Or a raw un-windowed Sinc filter with 4 lobes:</p> 2997 2998<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png -set filter:filter=sinc -set filter:lobes=4 \ <br/> 2999 -resize 150% image.jpg</span></p> 3000<p>Note that the use of expert options (except for 'blur' with simple resize 3001filters), are provided for image processing experts who have studied and 3002understood how resize filters work. Without this knowledge, and an 3003understanding of the defination of the actual filters involved, using expert 3004settings are more likely to be detremental to your image resizing.</p> 3005 3006 3007<div style="margin: auto;"> 3008 <h4><a name="flatten" id="flatten"></a>-flatten</h4> 3009</div> 3010 3011<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> 3012 3013 3014<div style="margin: auto;"> 3015 <h4><a name="flip" id="flip"></a>-flip</h4> 3016</div> 3017 3018<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> 3019 3020<p>reflect the scanlines in the vertical direction.</p> 3021 3022<div style="margin: auto;"> 3023 <h4><a name="floodfill" 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> 3024</div> 3025 3026<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> 3027 3028<div style="margin: auto;"> 3029 <h4><a name="flop" id="flop"></a>-flop</h4> 3030</div> 3031 3032<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> 3033 3034<p>reflect the scanlines in the horizontal direction.</p> 3035 3036 3037<div style="margin: auto;"> 3038 <h4><a name="font" id="font"></a>-font <em class="arg">name</em></h4> 3039</div> 3040 3041<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> 3042 3043<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> 3044 3045<p>In addition to the fonts specified by the above pre-defined list, you can 3046also specify a font from a specific source. For example <kbd>Arial.ttf</kbd> 3047is a TrueType font file, <kbd>ps:helvetica</kbd> is PostScript font, and 3048<kbd>x:fixed</kbd> is X11 font.</p> 3049 3050<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> 3051 3052 3053<div style="margin: auto;"> 3054 <h4><a name="foreground" id="foreground"></a>-foreground <em class="arg">color</em></h4> 3055</div> 3056 3057<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> 3058 3059<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 3060 3061<p>The default foreground color is black.</p> 3062 3063<div style="margin: auto;"> 3064 <h4><a name="format" id="format"></a>-format <em class="arg">type</em></h4> 3065</div> 3066 3067<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> 3068 3069<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> 3070 3071<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> 3072 3073<div style="margin: auto;"> 3074 <h4><a name="format_identify_" id="format_identify_"></a>-format <em class="arg">string</em></h4> 3075</div> 3076 3077<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> 3078 3079<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> 3080 3081<div style="margin: auto;"> 3082 <h4><a name="frame" id="frame"></a>-frame <em class="arg">geometry</em></h4> 3083</div> 3084 3085<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> 3086 3087<p>The color of the border is specified with the <a href="#mattecolor">-mattecolor</a> command line option. </p> 3088 3089<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 class="arg">geometry</em> argument indicates the amount of extra width and height that is added to the dimensions of the image. If no offsets are given in the <em class="arg">geometry</em> argument, then the border added is a solid color. Offsets <em>x</em> and <em>y</em>, if present, specify that the width and height of the border is partitioned to form an outer bevel of thickness <em>x</em> pixels and an inner bevel of thickness <em>y</em> pixels. (Negative offsets make no sense here.) The <a href="#frame">-frame</a> option is not affected by the <a href="#gravity">-gravity</a> option.</p> 3090 3091 3092<div style="margin: auto;"> 3093 <h4><a name="frame_import_" id="frame_import_"></a>-frame</h4> 3094</div> 3095 3096<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> 3097 3098<div style="margin: auto;"> 3099 <h4><a name="function" id="function"></a>-function <em class="arg">function</em> <em class="arg">parameters</em></h4> 3100</div> 3101 3102<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> 3103 3104<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> 3105 3106<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> 3107 3108<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> 3109 3110<pre class="text"> 3111 Polynomial 3112 Sinusoid 3113 Arcsin 3114 Arctan 3115</pre> 3116 3117<p>To print a complete list of <a href="#function">-function</a> operators, use <a href="#list">-list function</a>. Descriptions follow.</p> 3118 3119<dl class="doc"> 3120<dt><kbd>Polynomial</kbd></dt> 3121<dd> 3122<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> 3123 3124<div style="text-align: center"> 3125 -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> 3126</div> 3127 3128<p>will invoke a polynomial function given by</p> 3129 3130<div style="text-align: center"> 3131 <em>a</em><sub><em>n</em></sub> <b><em>u</em></b><sup><em>n</em></sup> + 3132 <em>a</em><sub><em>n</em>-1</sub> <b><em>u</em></b><sup><em>n</em>-1</sup> + 3133 ··· <em>a</em><sub>1</sub> <b><em>u</em></b> + <em>a</em><sub>0</sub>, 3134</div> 3135 3136<p>where <b><em>u</em></b> is pixel's original normalized channel value.</p> 3137 3138<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> 3139 3140<table class="doc"> 3141 <col width="35%" /> 3142 <col width="35%" /> 3143 <col width="30%" /> 3144 <tr> 3145 <td>-evaluate Set <em class="arg">value</em> </td> 3146 <td>-function Polynomial <em class="arg">value</em></td> 3147 <td>(Constant functions; set <em class="arg">value</em>×100% gray when channels are RGB.)</td> 3148 </tr> 3149 <tr> 3150 <td>-evaluate Add <em class="arg">value</em> </td> 3151 <td>-function Polynomial 1,<em class="arg">value</em></td> 3152 </tr> 3153 <tr> 3154 <td>-evaluate Subtract <em class="arg">value</em> </td> 3155 <td>-function Polynomial 1,−<em class="arg">value</em></td> 3156 </tr> 3157 <tr> 3158 <td>-evaluate Multiply <em class="arg">value</em> </td> 3159 <td>-function Polynomial <em class="arg">value</em>,0</td> 3160 </tr> 3161 <tr> 3162 <td>+level black% x white%</td> 3163 <td>-function Polynomial A,B</td> 3164 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td> 3165 </tr> 3166</table> 3167 3168<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> 3169</dd> 3170 3171<dt><kbd>Sinusoid</kbd></dt> 3172<dd> 3173<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> 3174 3175<div style="text-align: center"> 3176 -function <kbd>Sinusoid</kbd> <em class="arg">freq</em>,[<em class="arg">phase</em>,[<em class="arg">amp</em>,[<em class="arg">bias</em>]]] 3177</div> 3178 3179<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> 3180 3181<div style="text-align: center"> 3182<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> 3183</div> 3184 3185<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> 3186 3187<p class="crtsnip"> 3188 -function Sinusoid 3,-90,.2,.7 3189</p> 3190 3191<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> 3192 3193<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> 3194 3195<table class="doc"> 3196 <tr> 3197 <td>-evaluate Sin <em class="arg">freq</em> </td> 3198 <td>-function Sinusoid <em class="arg">freq</em>,0 </td> 3199 </tr> 3200 <tr> 3201 <td>-evaluate Cos <em class="arg">freq</em> </td> 3202 <td>-function Sinusoid <em class="arg">freq</em>,90 </td> 3203 </tr> 3204</table> 3205</dd> 3206 3207<dt><kbd>ArcSin</kbd></dt> 3208<dd> 3209<p>The <kbd>ArcSin</kbd> function generates the inverse curve of a Sinusoid, 3210and can be used to generate cylindrical distortion and displacement maps. 3211The curve can be adjusted relative to both the input values and output range 3212of values. 3213 3214<div style="text-align: center"> 3215 -function <kbd>ArcSin</kbd> <em class="arg">width</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]] 3216</div> 3217 3218<p>with all values given in terms of noramlize color values (0.0 for black, 32191.0 for white). Defaulting to values covering the full range from 0.0 to 1.0 3220for bout input (<em class="arg">width</em>), and output (<em 3221class="arg">width</em>) values. '<code>1.0,0.5,1.0,0.5</code>' </p> 3222 3223<div style="text-align: center"> 3224<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> 3225</div> 3226 3227</dd> 3228 3229<dt><kbd>ArcTan</kbd></dt> 3230<dd> 3231<p>The <kbd>ArcTan</kbd> function generates a curve that smooth crosses from 3232limit values at infinities, though a center using the given slope value. 3233All these values can be adjusted via the arguments. 3234 3235<div style="text-align: center"> 3236 -function <kbd>ArcTan</kbd> <em class="arg">slope</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]] 3237</div> 3238 3239<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'. 3240</p> 3241 3242<div style="text-align: center"> 3243<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> 3244</div> 3245 3246</dd> 3247 3248</dl> 3249 3250 3251<div style="margin: auto;"> 3252 <h4><a name="fuzz" id="fuzz"></a>-fuzz <em class="arg">distance</em>{<em class="arg">%</em>}</h4> 3253</div> 3254 3255<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> 3256 3257<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> 3258 3259<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> 3260 3261 3262<div style="margin: auto;"> 3263 <h4><a name="fx" id="fx"></a>-fx <em class="arg">expression</em></h4> 3264</div> 3265 3266<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> 3267 3268<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> 3269 3270<p>See <a href="/www/fx.html">FX, The Special Effects Image Operator</a> for a detailed discussion of this option.</p> 3271 3272 3273<div style="margin: auto;"> 3274 <h4><a name="gamma" id="gamma"></a>-gamma <em class="arg">value</em></h4> 3275</div> 3276 3277<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> 3278 3279<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> 3280 3281<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> 3282 3283<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> 3284 3285<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> 3286 3287<p>Note that gamma adjustments are also available via the <a href="#level">-level</a> operator.</p> 3288 3289<div style="margin: auto;"> 3290 <h4><a name="gaussian-blur" 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> 3291</div> 3292 3293<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> 3294 3295<p>Convolve the image with a Gaussian or normal distribution. The formula is:</p> 3296 3297<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="/images/gaussian-blur.png"/> 3298</div> 3299 3300<p>where <i>r</i> is the blur radius (<i>r</i><sup>2</sup> = <i>u</i><sup>2</sup> + <i>v</i><sup>2</sup>), and σ is the standard deviation of the Gaussian distribution. As a guideline, set <i>r</i> to approximately 3σ. Specify a radius of 0 and ImageMagick selects a suitable radius for you.</p> 3301 3302<p>This differs from the faster <a href="#blur">-blur</a> operator in that a 3303full 2-dimentional convolution is used to generate the weighted average of the 3304neighbouring pixels. </p> 3305 3306<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 3307pixels which are outside the image proper are blurred into the final result. 3308</p> 3309 3310 3311<div style="margin: auto;"> 3312 <h4><a name="geometry" id="geometry"></a>-geometry <em class="arg">geometry</em></h4> 3313</div> 3314 3315<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> 3316 3317<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> 3318 3319<div style="margin: auto;"> 3320 <h4><a name="gravity" id="gravity"></a>-gravity <em class="arg">type</em></h4> 3321</div> 3322 3323<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> 3324 3325<p>Choices include: <kbd>NorthWest</kbd>, <kbd>North</kbd>, <kbd>NorthEast</kbd>, 3326<kbd>West</kbd>, <kbd>Center</kbd>, <kbd>East</kbd>, <kbd>SouthWest</kbd>, 3327<kbd>South</kbd>, <kbd>SouthEast</kbd>. Use <a href="#list">-list gravity</a> to get a complete 3328list of <a href="#gravity">-gravity</a> settings available in your ImageMagick 3329installation.</p> 3330 3331<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> 3332 3333<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> 3334 3335<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> 3336 3337<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> 3338<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> 3339 3340<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> 3341 3342 3343<div style="margin: auto;"> 3344 <h4><a name="green-primary" id="green-primary"></a>-green-primary <em class="arg">x,y</em></h4> 3345</div> 3346 3347<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> 3348 3349 3350<div style="margin: auto;"> 3351 <h4><a name="hald-clut" id="hald-clut"></a>-hald-clut</h4> 3352</div> 3353 3354<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> 3355 3356<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2 3357dimensions. Create it with the <kbd>HALD:</kbd> prefix (e.g. HALD:8). You 3358can apply any color transformation to the Hald image and then use this option 3359to apply the transform to the image. </p> 3360 3361<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.png hald.png -hald-clut transform.png</span></p> 3362<p>This option provides a convenient method for you to use Gimp or Photoshop 3363to make color corrections to the Hald CLUT image and subsequently apply them 3364to multiple images using an ImageMagick script. </p> 3365 3366<p>Note that the representation is only of the normal RGB color space and that 3367the whole color value triplet is used for the interpolated lookup of the 3368represented Hald color cube image. Because of this the operation is not <a 3369href="#channel" >-channel</a> setting effected, nor can it adjust or modify an 3370images transparency or alpha/matte channel.</p> 3371 3372<p>See also <a href="#clut" >-clut</a> which provides color value replacement 3373of the individual color channels, usally involving a simplier gray-scale 3374image. E.g: gray-scale to color replacement, or modification by a histogram 3375mapping. </p> 3376 3377 3378<div style="margin: auto;"> 3379 <h4><a name="help" id="help"></a>-help</h4> 3380</div> 3381 3382<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> 3383 3384<div style="margin: auto;"> 3385 <h4><a name="highlight-color" id="highlight-color"></a>-highlight-color <em class="arg">color</em></h4> 3386</div> 3387 3388<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> 3389 3390<div style="margin: auto;"> 3391 <h4><a name="iconGeometry" id="iconGeometry"></a>-iconGeometry <em class="arg">geometry</em></h4> 3392</div> 3393 3394<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> 3395 3396<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> 3397 3398<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> 3399 3400<div style="margin: auto;"> 3401 <h4><a name="iconic" id="iconic"></a>-iconic</h4> 3402</div> 3403 3404<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> 3405 3406<div style="margin: auto;"> 3407 <h4><a name="identify" id="identify"></a>-identify</h4> 3408</div> 3409 3410<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> 3411 3412<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> 3413 3414<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> 3415 3416<p>If <a href="#verbose">-verbose</a> preceds this option, copious 3417amounts of image properties are displayed including image statistics, profiles, 3418image histogram, and others.</p> 3419 3420<div style="margin: auto;"> 3421 <h4><a name="ift" id="ift"></a>-ift</h4> 3422</div> 3423 3424<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> 3425 3426<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" target="_blank">Fourier Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT" target="_blank">Discrete Fourier Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT" target="_blank">Fast Fourier Transform</a>.</p> 3427 3428<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> 3429 3430<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fft_image.miff -ift fft_image_ift.png</span></p> 3431<p>or</p> 3432 3433<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> 3434 3435<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 will be at the right and/or bottom sides of the image. 3436 3437<p>The <a href="http://www.fftw.org/" target="_blank">FFTW</a> delegate library is required to use <a href="#ift">-ift</a>. 3438 3439<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. 3440 3441<div style="margin: auto;"> 3442 <h4><a name="immutable" id="immutable"></a>-immutable</h4> 3443</div> 3444 3445<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> 3446 3447<div style="margin: auto;"> 3448 <h4><a name="implode" id="implode"></a>-implode <em class="arg">factor</em></h4> 3449</div> 3450 3451<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> 3452 3453<div style="margin: auto;"> 3454 <h4><a name="insert" id="insert"></a>-insert <em class="arg">index</em></h4> 3455</div> 3456 3457<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> 3458 3459<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> 3460 3461<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> 3462 3463<div style="margin: auto;"> 3464 <h4><a name="intent" id="intent"></a>-intent <em class="arg">type</em></h4> 3465</div> 3466 3467<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> 3468 3469<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> 3470 3471<p>The default intent is undefined.</p> 3472 3473<p>To print a complete list of rendering intents, use <a href="#list">-list intent</a>.</p> 3474 3475<div style="margin: auto;"> 3476 <h4><a name="interlace" id="interlace"></a>-interlace <em class="arg">type</em></h4> 3477</div> 3478 3479<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> 3480 3481<p>Choose from:</p> 3482 3483<pre class="text"> 3484 none 3485 line 3486 plane 3487 partition 3488 JPEG 3489 GIF 3490 PNG 3491</pre> 3492 3493<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> 3494 3495<p><kbd>None</kbd> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p> 3496 3497<p><kbd>Line</kbd> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p> 3498 3499<p><kbd>Plane</kbd> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p> 3500 3501<p><kbd>Partition</kbd> is like plane except the different planes are saved to individual files (e.g. image.R, 3502image.G, and image.B).</p> 3503 3504<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> 3505image.</p> 3506 3507<p>To print a complete list of interlacing schemes, use <a href="#list">-list interlace</a>.</p> 3508 3509<div style="margin: auto;"> 3510 <h4><a name="interpolate" id="interpolate"></a>-interpolate <em class="arg">type</em></h4> 3511</div> 3512 3513<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> 3514 3515<p>When looking up the color of a pixel using a non-interger floating point 3516value, you typically fall in between the pixel colors defined by the source 3517image. This setting determines how the color is determined from the colors of 3518the pixels surrounding that point. That is how to determine the color of a 3519point that falls between two, or even four different colored pixels. </p> 3520 3521<pre class="text"> 3522 integer: The color of the top-left pixel (floor function) 3523 nearest-neighbor: The nearest pixel to the lookup point (rounded function) 3524 average: The average color of the surrounding four pixels 3525 bilinear A double linear interpolation of pixels (the default) 3526 mesh Divide area into two flat triangular interpolations 3527 bicubic Fitted bicubic-spines of surrounding 16 pixels 3528 spline Direct spline curves (colors are blurred) 3529 filter Use resize <a href="#filter">-filter</a> settings 3530</pre> 3531 3532<p>This most important for distortion operators such as <a href="#distort" 3533>-distort</a>, <a href="#implode" >-implode</a>, <a href="#transform" 3534>-transform</a> and <a href="#fx" >-fx</a>. </p> 3535 3536<p>To print a complete list of interpolation methods, use <a href="#list">-list interpolate</a>.</p> 3537 3538<p>See also <a href="#virtual-pixel" >-virtual-pixel</a>, for control of the 3539lookup for positions outside the boundaries of the image. </p> 3540 3541 3542<div style="margin: auto;"> 3543 <h4><a name="interline-spacing" id="interline-spacing"></a>-interline-spacing <em class="arg">value</em></h4> 3544</div> 3545 3546<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> 3547 3548<div style="margin: auto;"> 3549 <h4><a name="interword-spacing" id="interword-spacing"></a>-interword-spacing <em class="arg">value</em></h4> 3550</div> 3551 3552<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> 3553 3554<div style="margin: auto;"> 3555 <h4><a name="kerning" id="kerning"></a>-kerning <em class="arg">value</em></h4> 3556</div> 3557 3558<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> 3559 3560<div style="margin: auto;"> 3561 <h4><a name="label" id="label"></a>-label <em class="arg">name</em></h4> 3562</div> 3563 3564<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> 3565 3566<p>Use this option to assign a specific label to the image, as it is read in or created. You can use the <a href="#set" >-set</a> operation to re-assign a the labels of images already read in. Image formats such as TIFF, PNG, MIFF, supports saving the label information with the image.</p> 3567 3568<p>When saving an image to a <em class="arg">PostScript</em> file, any label assigned to an image is used as a header string to print above the postscript image. </p> 3569 3570<p>You can include the image filename, type, width, height, or other image attribute by embedding special format character. See <a href="#format">-format</a> for details of the percent escape codes.</p> 3571 3572<p>For example,</p> 3573 3574<p class="crtsnip"> 3575 -label "%m:%f %wx%h" bird.miff 3576</p> 3577 3578<p>assigns an image label of <kbd>MIFF:bird.miff 512x480</kbd> to the "<kbd>bird.miff</kbd>" image and whose width is 512 and height is 480, as it is read in. If a <a href="#label">+label</a> option was used instead, any existing label present in the image would be used. You can remove all labels from an image by assigning the empty string. </p> 3579 3580<p>A label is not drawn on the image, but is embedded in the image datastream via <em>Label</em> tag or similar mechanism. If you want the label to be visible on the image itself, use the <a href="#draw">-draw</a> option, or during the final processing in the creation of a image montage.</p> 3581 3582<p>The label font can be specified with <a href="#font">-font</a>, and the 3583other font attribute settings.</p> 3584 3585<p>If the first character of <em class="arg">string</em> is <em class="arg">@</em>, the image label is read from a file titled by the remaining characters in the string. Labels in a file are literal, no embedded formatting characters are recognized.</p> 3586 3587 3588<div style="margin: auto;"> 3589 <h4><a name="lat" 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> 3590</div> 3591 3592<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> 3593 3594<p>Adaptively threshold each pixel based on the value of pixels in a 3595surrounding window. If the current pixel is lighter than this average plus 3596the optional <kbd>offset</kbd>, then it is made white, otherwise it is made 3597black. Small variations in pixel values such as found in scanned documents 3598can be ignored if offset is positive. A negative offset will make it more 3599sensitive to those small variations. </p> 3600 3601<p>This is commonly used to threshold images with an uneven background. It is 3602based on the assumption that average color of the small window is the 3603the local background color, from which to separate the forground color. </p> 3604 3605 3606<div style="margin: auto;"> 3607 <h4><a name="layers" id="layers"></a>-layers <em class="arg">method</em></h4> 3608</div> 3609 3610<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> 3611 3612<p>Perform various image operation methods to a ordered sequence of images 3613which may represent either a set of overlaid 'image layers', a GIF disposal 3614animation, or a fully-'coalesced' animation sequence. </p> 3615 3616<table class="doc"> 3617 <tbody> 3618 <tr valign="top"> 3619 <th align="left" style="width: 8%">Method</th> 3620 <th align="left">Description</th> 3621 </tr> 3622 3623 <tr valign="top"> 3624 <td valign="top">compare-any</td> 3625 <td valign="top">Crop the second and later frames to the smallest rectangle 3626 that contains all the differences between the two images. No GIF <a 3627 href="#dispose" >-dispose</a> methods are taken into account. </td> 3628 </tr> 3629 3630 <tr><td></td><td>This exactly the same as the <a href="#deconstruct" 3631 >-deconstruct</a> operator, and does not preserve animations normal 3632 working, especially when animation used layer disposal methods such as 3633 '<kbd>Previous</kbd>' or '<kbd>Background</kbd>'. </td> 3634 </tr> 3635 3636 <tr valign="top"> 3637 <td valign="top">compare-clear</td> 3638 <td valign="top">As '<kbd>compare-any</kbd>' but crop to the bounds of any 3639 opaque pixels which become transparent in the second frame. That is the 3640 smallest image needed to mask or erase pixels for the next frame. </td> 3641 </tr> 3642 3643 <tr valign="top"> 3644 <td valign="top">compare-overlay</td> 3645 <td valign="top">As '<kbd>compare-any</kbd>' but crop to pixels that add 3646 extra color to the next image, as a result of overlaying color pixels. 3647 That is the smallest single overlaid image to add or change colors. </td> 3648 </tr> 3649 3650 <tr><td></td><td>This can be used with the <a href="#compose" >-compose</a> alpha 3651 composition method '<kbd>change-mask</kbd>', to reduce the image to 3652 just the pixels that need to be overlaid. </td> 3653 </tr> 3654 3655 <tr valign="top"> 3656 <td valign="top">coalesce</td> 3657 <td valign="top">Equivalent to a call to the <a href="#coalesce" 3658 >-coalesce</a> operator. Apply the layer disposal methods set in the 3659 current image sequence to form a fully defined animation sequence, as 3660 it should be displayed. Effectively converting a GIF animation into a 3661 'film strip'-like animation. </td> 3662 </tr> 3663 3664 <tr valign="top"> 3665 <td valign="top">composite</td> 3666 <td valign="top">Alpha Composition of two image lists, separated by a 3667 "<kbd>null:</kbd>" image, with the destination image list first, and 3668 the source images last. An image from each list are composited 3669 together until one list is finished. The separator image and source 3670 image lists are removed. </td> 3671 </tr> 3672 3673 3674 <tr><td></td><td>The <a href="#geometry" >-geometry</a> offset is adjusted according to 3675 <a href="#gravity" >-gravity</a> in accordance of the virtual canvas 3676 size of the first image in each list. Unlike a normal <a 3677 href="#composite" >-composite</a> operation, the canvas offset is also 3678 added to the final composite positioning of each image. </td> 3679 </tr> 3680 3681 <tr><td></td><td>If one of the image lists only contains one image, that image is 3682 applied to all the images in the other image list, regardless of which 3683 list it is. In this case it is the image meta-data of the list which 3684 preserved. </td> 3685 </tr> 3686 3687 3688 <tr valign="top"> 3689 <td valign="top">dispose</td> 3690 <td valign="top">This like '<kbd>coalesce</kbd>' but shows the look of 3691 the animation after the layer disposal method has been applied, before 3692 the next sub-frame image is overlaid. That is the 'dispose' image that 3693 results from the application of the GIF <a href="#dispose" 3694 >-dispose</a> method. This allows you to check what 3695 is going wrong with a particular animation you may be developing. 3696 </td> 3697 </tr> 3698 3699 <tr valign="top"> 3700 <td valign="top">flatten</td> 3701 <td valign="top">Create a canvas the size of the first images virtual 3702 canvas using the current <a href="#background" >-background</a> color, 3703 and <a href="#compose" >-compose</a> each image in turn onto that 3704 canvas. Images falling outside that canvas is clipped. Final 3705 image will have a zero virtual canvas offset. </td> 3706 </tr> 3707 3708 <tr><td></td><td>This usally used as one of the final 'image layering' operations 3709 overlaying all the prepared image layers into a final image. </td> 3710 </tr> 3711 3712 <tr><td></td><td>For a single image this method can also be used to fillout a virtual 3713 canvas with real pixels, or to underlay a opaque color to remove 3714 transparency from an image.</td> 3715 </tr> 3716 3717 3718 <tr valign="top"> 3719 <td valign="top">merge</td> 3720 <td valign="top">As 'flatten' method but merging all the given image 3721 layers into a new layer image just large enough to hold all the image 3722 without clipping or extra space. The new images virtual offset will 3723 prevere the position of the new layer, even if this offset is 3724 negative. the virtual canvas size of the first image is preserved. 3725 </td> 3726 </tr> 3727 3728 <tr><td></td><td>Caution is advised when handling image layers with negative offsets 3729 as few image file formats handle them correctly. </td> 3730 </tr> 3731 3732 <tr valign="top"> 3733 <td valign="top">mosaic</td> 3734 <td valign="top">As 'flatten' method but expanding the initial canvas size 3735 of the first image so as to hold all the image layers. However as a 3736 virtual canvas is 'locked' to the origin, by defination, image layers 3737 with a negative offsets will still be clipped by the top and left 3738 edges.</td> 3739 </tr> 3740 3741 <tr><td></td><td>This method is commonly used to layout individual image using various 3742 offset but without knowning the final canvas size. The resulting image 3743 will, like 'flatten' not have any virtual offset, so can be saved to 3744 any image file format. </td> 3745 </tr> 3746 3747 3748 <tr valign="top"> 3749 <td valign="top">optimize</td> 3750 <td valign="top">Optimize a coalesced animation, into GIF animation using 3751 a number of general techniques. This currently a short cut to 3752 apply both the '<kbd>optimize-frame</kbd>', and 3753 '<kbd>optimize-transparency</kbd>' methods but may be expanded to 3754 include other optimization methods as they are developed. </td> 3755 </tr> 3756 3757 <tr valign="top"> 3758 <td valign="top">optimize-frame</td> 3759 <td valign="top">Optimize a coalesced animation, into GIF animation by 3760 reducing the number of pixels per frame as much as possible by 3761 attempting to pick the best layer disposal method to use, while ensuring 3762 the result will continue to animate properly. </td> 3763 </tr> 3764 3765 <tr><td></td><td> There is no guarantee that the best optimization is found. But 3766 then no reasonably fast GIF optimization algorithm can do this. 3767 However this does seem to do better than most other GIF frame 3768 optimizers seen. </td> 3769 </tr> 3770 3771 <tr valign="top"> 3772 <td valign="top">optimize-plus</td> 3773 <td valign="top">As '<kbd>optimize-frame</kbd>' but attempt to improve the 3774 overall optimization by adding extra frames to the animation, without 3775 changing the final look or timing of the animation. The frames are 3776 added to attempt to separate the clearing of pixels from the 3777 overlaying of new additional pixels from one animation frame to the 3778 next. If this does not improve the optimization (for the next frame 3779 only), it will fall back to the results of the previous normal 3780 '<kbd>optimize-frame</kbd>' technique. </td> 3781 </tr> 3782 3783 <tr><td></td><td>There is the possibility that the change in the disposal style will 3784 result in a worsening in the optimization of later frames, though this 3785 is unlikely. In other words there no guarantee that it is better than 3786 the normal '<kbd>optimize-frame</kbd>' technique. For some animations 3787 however you can get a vast improvment in the final animation size. </td> 3788 </tr> 3789 3790 <tr valign="top"> 3791 <td valign="top">optimize-transparency</td> 3792 <td valign="top">Given a GIF animation, replace any pixel in the sub-frame 3793 overlay images with transparency, if it does not change the resulting 3794 animation by more than the current <a href="#fuzz" >-fuzz</a> factor. 3795 </td> 3796 </tr> 3797 3798 <tr><td></td><td>This should allow a existing frame optimized GIF animation to compress 3799 into a smaller file size due to larger areas of one (transparent) 3800 color rather than a pattern of multiple colors repeating the current 3801 disposed image of the last frame. </td> 3802 </tr> 3803 3804 <tr valign="top"> 3805 <td valign="top">remove-dups</td> 3806 <td valign="top">Remove (and merge time delays) of duplicate consecutive 3807 images, so as to simplify layer overlays of coalesced animations. 3808 </td> 3809 </tr> 3810 3811 <tr><td></td><td>Usually this a result of using a constant time delay across the 3812 whole animation, or after a larger animation was split into smaller 3813 sub-animations. The duplicate frames could also have been used as 3814 part of some frame optimization methods. </td> 3815 </tr> 3816 3817 <tr valign="top"> 3818 <td valign="top">remove-zero</td> 3819 <td valign="top">Remove any image with a zero time delay, unless ALL the 3820 images have a zero time delay (and is not a proper timed animation, a 3821 warning is then issued). </td> 3822 </tr> 3823 3824 <tr><td></td><td>In a GIF animation, such images are usually frames which provide 3825 partial intermediary updates between the frames that are actually 3826 displayed to users. These frames are usally added for improved frame 3827 optimization in GIF animations. </td> 3828 </tr> 3829 3830 <tr valign="top"> 3831 <td valign="top">trim-bounds</td> 3832 <td valign="top">Find the bounds of all the images in the current 3833 image sequence, then adjust the offsets so all images are contained on 3834 a minimal positive canvas. None of the image data is modified, only 3835 there virtual canvas size and offset. The all the image is given 3836 the same canvas size, and and will have a positive offset, but will 3837 remain in the same position relative to each other. As a result of the 3838 minimal canvas size at least one image will touch every edge of that 3839 canvas. The image data however may be transparent. 3840 </td> 3841 </tr> 3842 3843 </tbody> 3844</table> 3845 3846<p>To print a complete list of layer types, use <a href="#list">-list layers</a>.</p> 3847 3848<p>The operators <a href="#coalesce" >-coalesce</a>, <a href="#deconstruct" 3849>-deconstruct</a>, <a href="#flatten" >-flatten</a>, and <a href="#mosaic" 3850>-mosaic</a> are only aliases for the above methods. Also see <a 3851href="#page" >-page</a>, <a href="#repage" >-repage</a> operators, the <a 3852href="#compose" >-compose</a> setting, and the GIF <a href="#dispose" 3853>-dispose</a> and <a href="#delay" >-delay</a> settings. </p> 3854 3855 3856<div style="margin: auto;"> 3857 <h4><a name="level" 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> 3858</div> 3859 3860<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> 3861 3862<p>Given one, two or three values delimited with commas: black-point, 3863white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and 3864white points range from 0 to <em class="QR">QuantumRange</em>, or from 0 to 100%; if the white 3865point is omitted it is set to (<em class="QR">QuantumRange</em> - black_point), so as to center 3866contrast changes. If a <kbd>%</kbd> sign is present anywhere in the string, 3867both black and white points are percentages of the full color range. Gamma 3868will do a <a href="#gamma">-gamma</a> adjustment of the values. If it is 3869omitted, the default of 1.0 (no gamma correction) is assumed.</p> 3870 3871<p>In normal usage (<kbd>-level</kbd>) the image values are stretched so that 3872the given '<kbd>black_point</kbd>' value in the original image is set to 3873zero (or black), while the given '<kbd>white_point</kbd>' value is set to 3874<em class="QR">QuantumRange</em> (or white). This provides you with direct contrast adjustments 3875to the image. The '<kbd>gamma</kbd>' of the resulting image will then be 3876adjusted. </p> 3877 3878<p>From ImageMagick v6.4.1-9 using the plus form of the operator (<kbd>+level</kbd>) or 3879adding the special '!' flag anywhere in the argument list, will cause the 3880operator to do the reverse of the level adjustment. That is a zero, or 3881<em class="QR">QuantumRange</em> value (black, and white, resp.) in the original image, is 3882adjusted to the given level values, allowing you to de-contrast, or compress 3883the channel values within the image. The '<kbd>gamma</kbd>' is adjusted before the level adjustment to de-contrast the image is made. </p> 3884 3885<p>Only the channels defined by the current <a href="#channel">-channel</a> 3886setting are adjusted (defaults to RGB color channels only), allowing you to 3887limit the effect of this operator. </p> 3888 3889<p>Please note that the transparency channel is treated as 'matte' 3890values (0 is opaque) and not as 'alpha' values (0 is transparent).</p> 3891 3892 3893<div style="margin: auto;"> 3894 <h4><a name="level-colors" id="level-colors"></a>-level-colors {<em 3895 class="arg">black_color</em>}{,}{<em class="arg">white_color</em>}</h4> 3896</div> 3897 3898<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 seperated colors.</td><td style='text-align:right;'></td></tr></table> 3899 3900<p>This function is exactly like <a href="#level">-level</a>, except that the 3901value value for each color channel is determined by the 3902'<kbd>black_color</kbd>' and '<kbd>white_color</kbd>' colors given (as 3903described under the <a href="#fill">-fill</a> option). </p> 3904 3905<p>This effectivally means the colors provided to <kbd>-level-colors</kbd> 3906is mapped to become 'black' and 'white' respectivally, with all the other 3907colors linearly adjusted (or clipped) to match that change. Each channel is 3908adjusted separatally using the channel values of the colors specified. </p> 3909 3910<p>On the other hand the plus form of the operator (<kbd>+level-colors</kbd>) 3911will map the image color 'black' and 'white' to the given colors 3912respectivally, resulting in a gradient (de-contrasting) tint of the image to 3913those colors. This can also be used to convert a plain gray-scale image into a 3914one using the gradient of colors specified. </p> 3915 3916<p>By supplying a single color with a comma separator either before or after 3917that color, will just replace the respective 'black' or 'white' point 3918respectivally. But if no comma separator is provided, the given color is 3919used for both the black and white color points, making the operator either 3920threshold the images around that color (- form) or set all colors to that 3921color (+ form). </p> 3922 3923 3924<div style="margin: auto;"> 3925 <h4><a name="limit" id="limit"></a>-limit <em class="arg">type value</em></h4> 3926</div> 3927 3928<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> 3929 3930<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> 3931 3932<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> 3933 3934<p class="crtsnip"> 3935 -limit memory 32MiB -limit map 64MiB 3936</p> 3937 3938<p>Use <a href="#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p> 3939 3940<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list resource</span><span class='crtout'><pre>File Area Memory Map Disk Thread Time 3941------------------------------------------------------------------------------ 3942 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited</pre> 3943</span></p> 3944<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> 3945 3946<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> 3947 3948<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> 3949 3950<p class="crtsnip"> 3951-limit area 10mb 3952</p> 3953 3954<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 inadvertedly upload a huge image to process, you should set a disk limit as well:</p> 3955 3956<p class="crtsnip"> 3957-limit area 10mb -limit disk 500mb 3958</p> 3959 3960<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p> 3961 3962<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> 3963 3964<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. 3965</p> 3966 3967<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. 3968</p> 3969 3970<div style="margin: auto;"> 3971 <h4><a name="linear-stretch" 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> 3972</div> 3973 3974<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> 3975 3976<p>This is very similar to <a href="#contrast-stretch" >-contrast-stretch</a>, 3977and uses a 'histogram bin' to determine the range of color values that needs to 3978be stretched. However it then stretchs those colors using the <a 3979href="#level" >-level</a> operator.</p> 3980 3981<p>As such while the initial determination may have 'binning' round off 3982effects, the image colors are stretched mathematically, rather than using the 3983histogram bins. This makes the operator more accurate. </p> 3984 3985<p>note however that a <a href="#linear-stretch" >-linear-stretch</a> of 3986'<kbd>0</kbd>' does nothing, while a value of '<kbd>1</kbd>' does a near 3987perfect stretch of the color range. </p> 3988 3989<p>See also <a href="#auto-level" >-auto-level</a> for a 'perfect' 3990normalization of mathematical images. </p> 3991 3992<p>This operator is under review for re-development. </p> 3993 3994 3995<div style="margin: auto;"> 3996 <h4><a name="linewidth" id="linewidth"></a>-linewidth</h4> 3997</div> 3998 3999<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> 4000 4001<div style="margin: auto;"> 4002 <h4><a name="liquid-rescale" id="liquid-rescale"></a>-liquid-rescale <em class="arg">geometry</em></h4> 4003</div> 4004 4005<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> 4006 4007<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> 4008 4009<div style="margin: auto;"> 4010 <h4><a name="list" id="list"></a>-list <em class="arg">type</em></h4> 4011</div> 4012 4013<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> 4014 4015<pre class="text"> 4016 Layers 4017 LineCap 4018 LineJoin 4019 List 4020 Locale 4021 LogEvent 4022 Log 4023 Magic 4024 Method 4025 Metric 4026 Mime 4027 Mode 4028 Morphology 4029 Module 4030 Noise 4031 Orientation 4032 Policy 4033 PolicyDomain 4034 PolicyRights 4035 Preview 4036 Primitive 4037 QuantumFormat 4038 Resource 4039 SparseColor 4040 Storage 4041 Stretch 4042 Style 4043 Threshold 4044 Type 4045 Units 4046 Validate 4047 VirtualPixel 4048</pre> 4049 4050<p>These lists vary depending on your version of ImageMagick. Use "<kbd>-list list</kbd>" to get a complete listing of all the "<kbd>-list</kbd>" arguments available:</p> 4051 4052<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>identify -list list</span></p> 4053<div style="margin: auto;"> 4054 <h4><a name="log" id="log"></a>-log <em class="arg">string</em></h4> 4055</div> 4056 4057<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> 4058 4059<p>This option specifies the format for the log printed when the <a href="#debug">-debug</a> option is active.</p> 4060 4061<p>You can display the following components by embedding special format characters:</p> 4062 4063<pre class="text"> 4064 %d domain 4065 %e event 4066 %f function 4067 %l line 4068 %m module 4069 %p process ID 4070 %r real CPU time 4071 %t wall clock time 4072 %u user CPU time 4073 %% percent sign 4074 \n newline 4075 \r carriage return 4076</pre> 4077 4078<p>For example:</p> 4079 4080<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> 4081<p>The default behavior is to print all of the components.</p> 4082 4083<div style="margin: auto;"> 4084 <h4><a name="loop" id="loop"></a>-loop <em class="arg">iterations</em></h4> 4085</div> 4086 4087<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> 4088 4089<p>Set iterations to zero to repeat the animation an infinite number of times, otherwise the animation repeats itself up to <em class="arg">iterations</em> times.</p> 4090 4091<div style="margin: auto;"> 4092 <h4><a name="lowlight-color" id="lowlight-color"></a>-lowlight-color <em class="arg">color</em></h4> 4093</div> 4094 4095<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> 4096 4097<div style="margin: auto;"> 4098 <h4><a name="magnify" id="magnify"></a>-magnify <em class="arg">factor</em></h4> 4099</div> 4100 4101<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> 4102 4103 4104<div style="margin: auto;"> 4105 <h4><a name="map" id="map"></a>-map <em class="arg">type</em></h4> 4106</div> 4107 4108<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> 4109 4110<p>Choose from these <em class="arg">Standard Colormap</em> types:</p> 4111 4112<pre class="text"> 4113 best 4114 default 4115 gray 4116 red 4117 green 4118 blue 4119</pre> 4120 4121<p>The <em class="arg">X server</em> must support the <em class="arg">Standard Colormap</em> you choose, otherwise an error occurs. Use <kbd>list</kbd> as the type and <kbd>display</kbd> searches the list of colormap types in <kbd>top-to-bottom</kbd> order until one is located. See <em class="arg">xstdcmap(1)</em> for one way of creating Standard Colormaps.</p> 4122 4123 4124<div style="margin: auto;"> 4125 <h4><a name="map_stream_" id="map_stream_"></a>-map <em class="arg">components</em></h4> 4126</div> 4127 4128<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> 4129 4130<p>Here are the valid components of a map:</p> 4131 4132<pre class="text"> 4133 r red pixel component 4134 g green pixel component 4135 b blue pixel component 4136 a alpha pixel component (0 is transparent) 4137 o opacity pixel component (0 is opaque) 4138 i grayscale intensity pixel component 4139 c cyan pixel component 4140 m magenta pixel component 4141 y yellow pixel component 4142 k black pixel component 4143 p pad component (always 0) 4144</pre> 4145 4146<p>You can specify as many of these components as needed in any order (e.g. bgr). The components can repeat as well (e.g. rgbr).</p> 4147 4148<div style="margin: auto;"> 4149 <h4><a name="mask" id="mask"></a>-mask 4150<em class="arg">filename</em></h4> 4151</div> 4152 4153<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Composite the image pixels as defined by the mask.</td><td style='text-align:right;'></td></tr></table> 4154 4155<p>Use <a href="#mask">+mask</a> to remove the image mask.</p> 4156 4157<div style="margin: auto;"> 4158 <h4><a name="mattecolor" id="mattecolor"></a>-mattecolor <em class="arg">color</em></h4> 4159</div> 4160 4161<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> 4162 4163<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 4164 4165<p>The default matte color is <kbd>#BDBDBD</kbd>, <span style="background-color: #bdbdbd;">this shade of gray</span>.</p> 4166 4167<div style="margin: auto;"> 4168 <h4><a name="maximum" id="maximum"></a>-maximum</h4> 4169</div> 4170 4171<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> 4172 4173<div style="margin: auto;"> 4174 <h4><a name="median" id="median"></a>-median <em class="arg">radius</em></h4> 4175</div> 4176 4177<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> 4178 4179<div style="margin: auto;"> 4180 <h4><a name="metric" id="metric"></a>-metric <em class="arg">type</em></h4> 4181</div> 4182 4183<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> 4184 4185<p>Choose from:</p> 4186 4187<pre class="text"> 4188 AE absolute number of different pixels 4189 MAE mean absolute error (normalized), average channel error distance 4190 MEPP mean error per pixel (normalized mean error, normalized peak error) 4191 MSE mean error squared, average of the channel error squared 4192 PAE peak absolute (normalize peak absolute) 4193 PSNR peak signal to noise ratio 4194 RMSE root mean squared (normalized root mean squared) 4195</pre> 4196 4197<p>The '<kbd>AE</kbd>' or absolute count of pixels that are different, can be 4198controled using a <a href="#fuzz" >-fuzz</a> factor to ignore pixels which 4199only changed by a small amount. The '<kbd>PAE</kbd>' can be used to find the 4200size of the <a href="#fuzz" >-fuzz</a> factor needed to make all pixels 4201'similar'. </p> 4202 4203<p>The '<kbd>MEPP</kbd>' metric returns three different metrics 4204('<kbd>MAE</kbd>', '<kbd>MAE</kbd>' normalized, and '<kbd>PAE</kbd>' 4205normalized) from the single comparision run. </p> 4206 4207<p>To print a complete list of metrics, use the <a href="#list">-list metrics</a> option.</p> 4208 4209<div style="margin: auto;"> 4210 <h4><a name="minimum" id="minimum"></a>-minimum</h4> 4211</div> 4212 4213<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> 4214 4215 4216<div style="margin: auto;"> 4217 <h4><a name="mode" id="mode"></a>-mode <em class="arg">value</em></h4> 4218</div> 4219 4220<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> 4221 4222<p>Choose the <em class="arg">value</em> from these styles: <kbd>Frame, Unframe, or Concatenate</kbd></p> 4223 4224<p>Use the <a href="#list" >-list</a> option with a '<kbd>Mode</kbd>' 4225argument for a list of <a href="#mode" >-mode</a> arguments available 4226in your ImageMagick installation.</p> 4227 4228 4229<div style="margin: auto;"> 4230 <h4><a name="modulate" id="modulate"></a>-modulate <em class="arg">brightness</em>[,<em class="arg">saturation</em>,<em class="arg">hue</em>]</h4> 4231</div> 4232 4233<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 class="arg">saturation</em>, and <em class="arg">hue</em> of an image.</td><td style='text-align:right;'></td></tr></table> 4234 4235<p>The arguments are given as a percentages of variation. A value of 100 means 4236no change, and any missing values are taken to mean 100.</p> 4237 4238<p>The <em class="arg">brightness</em> is a multiplier of the overall 4239brightness of the image, so 0 means pure black, 50 is half as bright, 200 is 4240twice as bright. To invert its meaning <a href="#negate">-negate</a> the image 4241before and after. </p> 4242 4243<p>The <em class="arg">saturation</em> controls the amount of color in an 4244image. For example, 0 produce a grayscale image, while a large value such as 4245200 produce a very colorful, 'cartoonish' color.</p> 4246 4247<p>The <em class="arg">hue</em> argument causes a "rotation" of the colors 4248within the image by the amount specified. For example, 50 results in 4249a counter-clockwise rotation of 90, mapping red shades to purple, and so on. 4250A value of either 0 or 200 results in a complete 180 degree rotation of the 4251image. Using a value of 300 is a 360 degree rotation resulting in no change to 4252the original image. </p> 4253 4254<p>For example, to increase the color brightness by 20% and decrease the color 4255saturation by 10% and leave the hue unchanged, use <a 4256href="#modulate">-modulate 120,90</a>.</p> 4257 4258<p>Use <a href="#set">-set</a> attribute of '<kbd 4259class="arg">option:modulate:colorspace</kbd>' to specify which colorspace to 4260modulate. Choose from <kbd>HSB</kbd>, <kbd>HSL</kbd> (the default), or 4261<kbd>HWB</kbd>. For example,</p> 4262 4263<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> 4264 4265<div style="margin: auto;"> 4266 <h4><a name="monitor" id="monitor"></a>-monitor</h4> 4267</div> 4268 4269<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> 4270 4271 4272<div style="margin: auto;"> 4273 <h4><a name="monochrome" id="monochrome"></a>-monochrome</h4> 4274</div> 4275 4276<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> 4277 4278 4279<div style="margin: auto;"> 4280 <h4><a name="morph" id="morph"></a>-morph <em class="arg">frames</em></h4> 4281</div> 4282 4283<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> 4284 4285<p>Both the image pixels and size are linearly interpolated to give the 4286appearance of a meta-morphosis from one image to the next, over all the images 4287in the current image list. The added images are the equivalent of a <a 4288href="#blend">-blend</a> composition. The <em class="arg">frames</em> 4289argument determine how many images to interpolate between each image. </p> 4290 4291 4292<div style="margin: auto;"> 4293 <h4><a name="morphology" id="morphology"></a>-morphology</h4> 4294 <h4><a name="morphology" id="morphology"></a>-morphology <em class="arg">method</em> <em class="arg">kernel</em></h4> 4295</div> 4296 4297<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> 4298 4299<div style="margin: auto;"> 4300 <h4><a name="mosaic" id="mosaic"></a>-mosaic</h4> 4301</div> 4302 4303<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> 4304 4305 4306<div style="margin: auto;"> 4307 <h4><a name="motion-blur" 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> 4308</div> 4309 4310<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> 4311 4312<p>Blur with the given radius, standard deviation (sigma), and angle. The 4313angle given is the angle toward which the image is blurred. That is the 4314direction people would consider the object is coming from. </p> 4315 4316<p>Note that the blur is not uniform distribution, giving the motion a 4317definate sense of direction of movement. </p> 4318 4319<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 4320pixels which are outside the image proper are blurred into the final result. 4321</p> 4322 4323<div style="margin: auto;"> 4324 <h4><a name="name" id="name"></a>-name</h4> 4325</div> 4326 4327<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> 4328<div style="margin: auto;"> 4329 <h4><a name="negate" id="negate"></a>-negate</h4> 4330</div> 4331 4332<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> 4333 4334<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> 4335 4336<div style="margin: auto;"> 4337 <h4><a name="noise" id="noise"></a>-noise <em class="arg">radius</em><br/> 4338 +noise <em class="arg">type</em></h4> 4339</div> 4340 4341<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> 4342 4343<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> 4344 4345<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> 4346 4347<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> 4348 4349<pre class="text"> 4350Gaussian 4351Impulse 4352Laplacian 4353Multiplicative 4354Poisson 4355Random 4356Uniform 4357</pre> 4358 4359<p>To print a complete list of noises, use the <a href="#list">-list noise</a> option.</p> 4360 4361<p>Also see the <a href="#evaluate">-evaluate</a> noise functions that allos 4362the use of a controlling value to specify teh amount of noise that should be 4363added to an image. </p> 4364 4365 4366<div style="margin: auto;"> 4367 <h4><a name="normalize" id="normalize"></a>-normalize</h4> 4368</div> 4369 4370<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> 4371 4372<p>The intensity values are stretched to cover the entire range of possible 4373values. While doing so, black-out at most <em>2%</em> of the pixels and 4374white-out at most <em>1%</em> of the pixels.</p> 4375 4376<p>Note that as of ImageMagick 6.4.7-0, <a href="#normalize" >-normalize</a> 4377is equivalent to <a href="#contrast-stretch" >-contrast-stretch 2%x1%</a>. 4378(Before this version, it was equivalent to <a href="#contrast-stretch" 4379>-contrast-stretch 2%x99%</a>).</p> 4380 4381<p>All the channels are normalized in concert by the came amount so as to 4382preserve color integrity, when the default <a href="#channel" >+channel</a> 4383setting is in use. Specifing any other <a href="#channel" >-channel</a> 4384setting will normalize the RGB channels independently.</p> 4385 4386<p>See <a href="#contrast-stretch" >-contrast-stretch</A> for more details. 4387Also see <a href="#auto-level" >-auto-level</a> for a 'perfect' normalization 4388that is better suited to mathematically generated images. </p> 4389 4390<p>This operator is under review for re-development. </p> 4391 4392 4393<div style="margin: auto;"> 4394 <h4><a name="ordered-dither" id="ordered-dither"></a>-ordered-dither <em class="arg">threshold_map</em>{,<em class="arg">level</em>...}</h4> 4395</div> 4396 4397<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 4398class="arg">threshold map</em> specified, and a uniform color map with the 4399given number of <em class="arg">levels</em> per color channel . </td><td style='text-align:right;'></td></tr></table> 4400 4401<p>You can choose from these standard threshold maps:</p> 4402 4403<pre class="text"> 4404 threshold 4405 checks 4406 o2x2 4407 o3x3 4408 o4x4 4409 o8x8 4410 h4x4a 4411 h6x6a 4412 h8x8a 4413 h4x4o 4414 h6x6o 4415 h8x8o 4416 h16x16o 4417</pre> 4418 4419<p>The '<kbd>o</kbd>' maps are ordered diffused pixel threshold maps, while the 4420'<kbd>h</kbd>' maps are halftone threshold maps which are either 'a' angled, or 4421'o' orthogonal. The '<kbd>checks</kbd>' produce a 3 level checkerbord dither 4422pattern. Or you can define your own <em class="arg" >threshold map</em> in a 4423personal or system "<kbd>thresholds.xml</kbd>" XML file. </p> 4424 4425<p>To print a complete list of threshold, use the <a href="#list" >-list 4426threshold</a> option.</p> 4427 4428<p>It is recommended that the <a href="#map" >+map</a> operator be used after 4429applying <a href="#ordered-dither" >-ordered-dither</a> to reduce the number of 4430colors an animated image sequence, to less that 256 colors. This ensures that 4431a common or global color table is used when saving the result to a color 4432limited file format such as GIF. </p> 4433 4434<p>Note that at this time the exact same threshold dithering map is used for 4435all color channels, no attempt is made to offset or rotate the map for 4436different channels is made, to create an offset printing effect. (possible 4437future expansion) </p> 4438 4439 4440<div style="margin: auto;"> 4441 <h4><a name="opaque" id="opaque"></a>-opaque <em class="arg">color</em></h4> 4442</div> 4443 4444<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> 4445 4446<p>The <em class="arg">color</em> argument is defined using the format 4447described under the <a href="#fill" >-fill</a> option. The <a href="#fuzz" 4448>-fuzz</a> setting can be used to match and replace colors similar to the one 4449given.</p> 4450 4451<p>Use <a href="#opaque">+opaque</a> to paint any pixel that does not match 4452the target color. </p> 4453 4454<p>The <a href="#transparent">-transparent</a> operator is exactly the same 4455as <a href="#opaque" >-opaque</a> but replaces the matching color with 4456transparency rather than the current <a href="#fill">-fill</a> color setting. 4457To ensure that it can do this it also ensures that the image has an alpha 4458channel enabled, as per "<kbd><a href="#alpha" >-alpha</a> set</kbd>", for 4459the new transparent colors, and does not require you to modify the <a 4460href="#channel">-channel</a> to enable alpha channel handling. </p> 4461 4462 4463<div style="margin: auto;"> 4464 <h4><a name="orient" id="orient"></a>-orient <em class="arg">image orientation</em></h4> 4465</div> 4466 4467<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> 4468 4469<p>Choose from these orientations:</p> 4470 4471<pre class="text"> 4472 bottom-left 4473 bottom-right 4474 left-bottom 4475 left-top 4476 right-bottom 4477 right-top 4478 top-left 4479 top-right 4480 undefined 4481</pre> 4482 4483<p>To print a complete list of orientations, use the <a href="#list" >-list 4484orientation</a> option.</p> 4485 4486 4487<div style="margin: auto;"> 4488 <h4><a name="page" id="page"></a>-page <em class="arg">geometry</em><br/> 4489 -page <em class="arg">media</em>[<em class="arg">offset</em>][{<em class="arg">^!<></em>}]<br/> 4490 +page 4491 </h4> 4492</div> 4493 4494<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> 4495 4496<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> 4497 4498<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> 4499 4500<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> 4501<table id="geometryTable" cellpadding="2" cellspacing="0" border="1" width="50%" style="margin-left: auto; margin-right: auto;"> 4502<thead> 4503 <tr valign="top"> 4504 <th align="center"><em class="arg">media</em></th> 4505 <th align="center"><em class="arg">width</em></th> 4506 <th align="center"><em class="arg">height</em></th> 4507 </tr> 4508</thead> 4509<tbody> 4510<tr><td align="left"> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr> 4511<tr><td align="left"> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr> 4512<tr><td align="left"> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr> 4513<tr><td align="left"> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr> 4514<tr><td align="left"> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr> 4515<tr><td align="left"> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr> 4516<tr><td align="left"> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr> 4517<tr><td align="left"> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr> 4518<tr><td align="left"> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr> 4519<tr><td align="left"> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr> 4520<tr><td align="left"> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr> 4521<tr><td align="left"> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr> 4522<tr><td align="left"> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr> 4523<tr><td align="left"> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr> 4524<tr><td align="left"> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr> 4525<tr><td align="left"> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr> 4526<tr><td align="left"> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr> 4527<tr><td align="left"> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr> 4528<tr><td align="left"> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr> 4529<tr><td align="left"> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr> 4530<tr><td align="left"> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr> 4531<tr><td align="left"> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr> 4532<tr><td align="left"> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr> 4533<tr><td align="left"> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr> 4534<tr><td align="left"> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr> 4535<tr><td align="left"> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr> 4536<tr><td align="left"> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr> 4537<tr><td align="left"> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr> 4538<tr><td align="left"> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr> 4539<tr><td align="left"> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr> 4540<tr><td align="left"> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr> 4541<tr><td align="left"> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr> 4542<tr><td align="left"> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr> 4543<tr><td align="left"> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr> 4544<tr><td align="left"> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr> 4545<tr><td align="left"> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr> 4546<tr><td align="left"> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr> 4547<tr><td align="left"> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr> 4548</tbody> 4549</table> 4550 4551 4552 4553 4554<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> 4555 4556<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> 4557 4558<p>The default page dimensions for a TEXT image is 612x792.</p> 4559 4560<p>This option is used in concert with <a href="#density">-density</a>.</p> 4561 4562<p>Use <a href="#page">+page</a> to remove the page settings for an image.</p> 4563 4564<div style="margin: auto;"> 4565 <h4><a name="paint" id="paint"></a>-paint <em class="arg">radius</em></h4> 4566</div> 4567 4568<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> 4569 4570<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> 4571 4572<div style="margin: auto;"> 4573 <h4><a name="path" id="path"></a>-path <em class="arg">path</em></h4></div> 4574 4575<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> 4576 4577<div style="margin: auto;"> 4578 <h4><a name="pause_animate_" id="pause_animate_"></a>-pause <em class="arg">seconds</em></h4> 4579</div> 4580 4581<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> 4582 4583<p>Pause for the specified number of seconds before repeating the animation.</p> 4584 4585<div style="margin: auto;"> 4586 <h4><a name="pause_import_" id="pause_import_"></a>-pause <em class="arg">seconds</em></h4> 4587</div> 4588 4589<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> 4590 4591<p>Pause for the specified number of seconds before taking the next snapshot.</p> 4592 4593<div style="margin: auto;"> 4594 <h4><a name="ping" id="ping"></a>-ping</h4> 4595</div> 4596 4597<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> 4598 4599<div style="margin: auto;"> 4600 <h4><a name="pointsize" id="pointsize"></a>-pointsize <em class="arg">value</em></h4> 4601</div> 4602 4603<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> 4604 4605<div style="margin: auto;"> 4606 <h4><a name="polaroid" id="polaroid"></a>-polaroid <em class="arg">angle</em></h4> 4607</div> 4608 4609<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> 4610 4611<p>Use <kbd>+polaroid</kbd> to rotate the image at a random angle between -15 and +15 degrees.</p> 4612 4613<div style="margin: auto;"> 4614 <h4><a name="posterize" id="posterize"></a>-posterize <em class="arg">levels</em></h4> 4615</div> 4616 4617<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> 4618 4619<div style="margin: auto;"> 4620 <h4><a name="precision" id="precision"></a>-precision <em class="arg">value</em></h4> 4621</div> 4622 4623<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> 4624 4625<div style="margin: auto;"> 4626 <h4><a name="preview" id="preview"></a>-preview <em class="arg">type</em></h4> 4627</div> 4628 4629<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> 4630 4631<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> 4632 4633<pre class="text"> 4634 Rotate 4635 Shear 4636 Roll 4637 Hue 4638 Saturation 4639 Brightness 4640 Gamma 4641 Spiff 4642 Dull 4643 Grayscale 4644 Quantize 4645 Despeckle 4646 ReduceNoise 4647 Add Noise 4648 Sharpen 4649 Blur 4650 Threshold 4651 EdgeDetect 4652 Spread 4653 Shade 4654 Raise 4655 Segment 4656 Solarize 4657 Swirl 4658 Implode 4659 Wave 4660 OilPaint 4661 CharcoalDrawing 4662 JPEG 4663</pre> 4664 4665<p>To print a complete list of previews, use the <a href="#list">-list preview</a> option.</p> 4666 4667<p>The default preview is <kbd>JPEG</kbd>.</p> 4668 4669<div style="margin: auto;"> 4670 <h4><a name="print" id="print"></a>-print <em class="arg">string</em></h4> 4671</div> 4672 4673<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> 4674 4675<div style="margin: auto;"> 4676 <h4><a name="process" id="process"></a>-process <em class="arg">command</em></h4> 4677</div> 4678 4679<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> 4680 4681<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> 4682 4683<div style="margin: auto;"> 4684 <h4><a name="profile" id="profile"></a>-profile <em class="arg">filename</em><br/> 4685 +profile <em class="arg">profile_name</em></h4> 4686</div> 4687 4688<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> 4689 4690<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> 4691 4692<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> 4693 4694<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> 4695 4696<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> 4697 4698<p>For example, to extract the Exif data (which is stored in JPEG files in the <em class="arg">APP1</em> profile), use.</p> 4699 4700<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert cockatoo.jpg profile.exif</span></p> 4701<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> 4702 4703<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff</span></p> 4704<p>Furthermore, since ICC profiles are not necessarily symmetric, extra conversion steps can yield unwanted results. 4705CMYK profiles are often very asymmetric since they involve 3−>4 and 4−>3 channel mapping. 4706</p> 4707 4708<div style="margin: auto;"> 4709 <h4><a name="quality" id="quality"></a>-quality <em class="arg">value</em></h4> 4710</div> 4711 4712<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> 4713 4714<p>For the JPEG and MPEG image formats, quality is 0 (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 85. Use the <a href="#sampling-factor">-sampling-factor</a> option to specify the factors for chroma downsampling.</p> 4715 4716<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> 4717 4718<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 85 results in a request for 16:1 compression. The quality value 100 results in a request for non-lossy compression.</p> 4719 4720<p>For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). Compression levels range from 0 (fastest compression) to 100 (best but slowest). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression.</p> 4721 4722<p>If filter-type is 4 or less, the specified filter-type is used for all scanlines:</p> 4723 4724<pre class="text"> 4725 0: none 4726 1: sub 4727 2: up 4728 3: average 4729 4: Paeth 4730</pre> 4731 4732<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> 4733 4734<p>If filter-type is 6, adaptive filtering with <em class="arg">minimum-sum-of-absolute-values</em> is used.</p> 4735 4736<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> 4737 4738<p>The default is quality is 85, which means nearly the best compression with adaptive filtering. The quality setting has no effect on the appearance of PNG and MNG images, since the compression is always lossless.</p> 4739 4740<p>For further information, see the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p> 4741 4742<p>When writing a JNG image with transparency, two quality values are required, one for the main image and one for the grayscale image that conveys the alpha channel. These are written as a single integer equal to the main image quality plus 1000 times the opacity quality. For example, if you want to use quality 85 for the main image and quality 90 to compress the opacity data, use <a href="#quality">-quality 90085</a>.</p> 4743 4744<div style="margin: auto;"> 4745 <h4><a name="quantize" id="quantize"></a>-quantize <em class="arg">colorspace</em></h4> 4746</div> 4747 4748<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce colors in this colorspace.</td><td style='text-align:right;'></td></tr></table> 4749 4750<p>To print a complete list of colorspaces, use the <a href="#list">-list colorspace</a> option.</p> 4751 4752 4753<div style="margin: auto;"> 4754 <h4><a name="quiet" id="quiet"></a>-quiet</h4> 4755</div> 4756 4757<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> 4758 4759<div style="margin: auto;"> 4760 <h4><a name="radial-blur" id="radial-blur"></a>-radial-blur <em class="arg">angle</em></h4> 4761</div> 4762 4763<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> 4764 4765<p>Note that this is actually a rotational blur rather than a radial and as 4766such actually mis-named. </p> 4767 4768<p>The <a href="#virtual-pixel">-virtual-pixel</a> setting will determine how 4769pixels which are outside the image proper are blurred into the final result. 4770</p> 4771 4772 4773<div style="margin: auto;"> 4774 <h4><a name="raise" id="raise"></a>-raise <em class="arg">thickness</em></h4> 4775</div> 4776 4777<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> 4778 4779<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>. 4780</p> 4781 4782<p>Unlike the similar <a href="#frame">-frame</a> option, <a href="#raise">-raise</a> does not alter the dimensions of the image.</p> 4783 4784<div style="margin: auto;"> 4785 <h4><a name="random-threshold" id="random-threshold"></a>-random-threshold <em class="arg">low</em>x<em class="arg">high</em></h4> 4786</div> 4787 4788<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> 4789 4790<div style="margin: auto;"> 4791 <h4><a name="red-primary" id="red-primary"></a>-red-primary <em class="arg">x,y</em></h4> 4792</div> 4793 4794<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> 4795 4796<div style="margin: auto;"> 4797 <h4><a name="regard-warnings" id="regard-warnings"></a>-regard-warnings</h4> 4798</div> 4799 4800<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> 4801 4802<div style="margin: auto;"> 4803 <h4><a name="remap" id="remap"></a>-remap <em class="arg">filename</em></h4> 4804</div> 4805 4806<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> 4807 4808<p>If the <a href="#dither">-dither</a> setting is enabled (the default) then 4809the given colors are dithered over the image as necessary, otherwise the closest 4810color (in RGB colorspace) is selected to replace that pixel in the image. </p> 4811 4812<p>As a side effect of applying a <a href="#remap">-remap</a> of colors across all 4813images in the current image sequence, all the images will have the same color 4814table. That means that when saved to a file format such as GIF, it will use 4815that color table as a single common or global color table, for all the images, 4816without requiring extra local color tables. </p> 4817 4818<p>Use <a href="#remap">+remap</a> to reduce all images in the current image 4819sequence to use a common color map over all the images. This equivalent to 4820appending all the images together (without extra background colors) and color 4821reducing those images using <a href="#colors">-colors</a> with a 256 color 4822limit, then <a href="#remap">-remap</a> those colors over the original list of 4823images. This ensures all the images follow a single color map. </p> 4824 4825<p>If the number of colors over all the images is less than 256, then <a 4826href="#remap">+remap</a> should not perform any color reduction or dithering, as 4827no color changes are needed. In that case, its only effect is to force the use 4828of a global color table. This recommended after using either <a 4829href="#colors">-colors</a> or <a href="#ordered-dither">-ordered-dither</a> to 4830reduce the number of colors in an animated image sequence. </p> 4831 4832<div style="margin: auto;"> 4833 <h4><a name="region" id="region"></a>-region <em class="arg">geometry</em></h4> 4834</div> 4835 4836<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> 4837 4838<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> 4839 4840<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> 4841 4842<div style="margin: auto;"> 4843 <h4><a name="remote" id="remote"></a>-remote</h4> 4844</div> 4845 4846<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> 4847 4848<p>The only command recognized is the name of an image file to load.</p> 4849 4850<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> 4851 4852<div style="margin: auto;"> 4853 <h4><a name="render" id="render"></a>-render</h4> 4854</div> 4855 4856<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> 4857 4858<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> 4859 4860<div style="margin: auto;"> 4861<h4><a name="repage" id="repage"></a>-repage <em class="arg">geometry</em></h4> 4862</div> 4863 4864<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> 4865 4866<p>This option is like <a href="#page">-page</a> but acts as an image operator 4867rather than a setting. You can separately set the canvas size or the offset 4868of the image on that canvas by only providing those components. </p> 4869 4870<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> 4871 4872<p>If a <kbd>!</kbd> flag is given the offset given is added to the existing 4873offset to move the image relative to its previous position. This useful for 4874animation sequences. </p> 4875 4876<p>A given a canvas size of zero such as '<kbd>0x0</kbd>' forces it to 4877recalculate the canvas size so the image (at its current offset) will appear 4878completely on that canvas (unless it has a negative offset).</p> 4879 4880<p>Use <a href="#repage">+repage</a> to completely remove/reset the virtual 4881canvas meta-data from the images. </p> 4882 4883<p>The <a href="#set">-set</a> '<kbd>page</kbd>' option can be used to 4884directly assign virtual canvas meta-data. </p> 4885 4886 4887<div style="margin: auto;"> 4888 <h4><a name="resample" id="resample"></a>-resample <em class="arg">horizontal</em>x<em class="arg">vertical</em></h4> 4889</div> 4890 4891<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> 4892 4893<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> 4894 4895<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> 4896 4897<div style="margin: auto;"> 4898 <h4><a name="resize" id="resize"></a>-resize <em class="arg">geometry</em></h4> 4899</div> 4900 4901<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> 4902 4903<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> 4904 4905<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> 4906 4907<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> 4908 4909<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> 4910<div style="margin: auto;"> 4911 <h4><a name="respect-parentheses" id="respect-parentheses"></a>-respect-parentheses</h4> 4912</div> 4913 4914<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> 4915 4916<div style="margin: auto;"> 4917 <h4><a name="reverse" id="reverse"></a>-reverse</h4> 4918</div> 4919 4920<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> 4921 4922 4923<div style="margin: auto;"> 4924 <h4><a name="roll" id="roll"></a>-roll {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4> 4925</div> 4926 4927<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> 4928 4929<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> 4930 4931 4932<div style="margin: auto;"> 4933 <h4><a name="rotate" id="rotate"></a>-rotate <em class="arg">degrees</em>{<em class="arg"><</em>}{<em class="arg">></em>}</h4> 4934</div> 4935 4936<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> 4937 4938<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> 4939 4940<p>Empty triangles in the corners, left over from rotating the image, are 4941filled with the <kbd>background</kbd> color. </p> 4942 4943<p>See also the <a href="#distort">-distort</a> operator and specifically the 4944'<kbd>ScaleRotateTranslate</kbd>' distort method. </p> 4945 4946 4947<div style="margin: auto;"> 4948 <h4><a name="sample" id="sample"></a>-sample <em class="arg">geometry</em></h4> 4949</div> 4950 4951<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>scale image using pixel sampling.</td><td style='text-align:right;'></td></tr></table> 4952 4953<p><a href="#sample">-sample</a> ignores the current <a href="#resize">-resize</a> <a href="#filter">-filter</a> setting. The results are equivalent to using <a href="#resize">-resize</a> with a <a href="#filter">-filter</a> setting of <kbd>point</kbd>, though <a href="#sample">-sample</a> is a lot faster. </p> 4954 4955<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> 4956 4957 4958<div style="margin: auto;"> 4959 <h4><a name="sampling-factor" id="sampling-factor"></a>-sampling-factor <em class="arg">horizontal-factor</em>x<em class="arg">vertical-factor</em></h4> 4960</div> 4961 4962<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> 4963 4964<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> 4965 4966<div style="margin: auto;"> 4967 <h4><a name="scale" id="scale"></a>-scale <em class="arg">geometry</em></h4> 4968</div> 4969 4970<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>scale the image.</td><td style='text-align:right;'></td></tr></table> 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. The <a href="#scale">-scale</a> option uses a simpler, faster algorithm than <a href="#resize">-resize</a>, and it ignores the <a href="#filter">-filter</a> setting if one is present. Offsets, if present in the <em class="arg">geometry</em> string, are ignored, and the <a href="#gravity">-gravity</a> option has no effect.</p> 4973 4974<div style="margin: auto;"> 4975 <h4><a name="scene" id="scene"></a>-scene <em class="arg">value</em></h4> 4976</div> 4977 4978<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> 4979 4980<p>This option sets the scene number of an image or the first image in an image sequence.</p> 4981 4982<div style="margin: auto;"> 4983 <h4><a name="screen" id="screen"></a>-screen</h4> 4984</div> 4985 4986<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> 4987 4988<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> 4989 4990<div style="margin: auto;"> 4991 <h4><a name="seed" id="seed"></a>-seed</h4> 4992</div> 4993 4994<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> 4995 4996<div style="margin: auto;"> 4997 <h4><a name="segment" id="segment"></a>-segment <em class="arg">cluster-threshold</em>x<em class="arg">smoothing-threshold</em></h4> 4998</div> 4999 5000<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> 5001 5002<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> 5003 5004<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> 5005 5006<p>If the <a href="#verbose">-verbose</a> setting is defined, a detailed report 5007of the color clusters is returned.</p> 5008 5009 5010<div style="margin: auto;"> 5011 <h4><a name="selective-blur" id="selective-blur"></a>-selective-blur <em class="arg">geometry</em></h4> 5012</div> 5013 5014<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> 5015 5016<div style="margin: auto;"> 5017 <h4><a name="separate" id="separate"></a>-separate</h4> 5018</div> 5019 5020<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> 5021 5022<div style="margin: auto;"> 5023 <h4><a name="sepia-tone" id="sepia-tone"></a>-sepia-tone <em class="arg">threshold</em></h4> 5024</div> 5025 5026<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> 5027 5028<p>Specify <em class="arg">threshold</em> as the percent threshold of the intensity (0 - 99.9%).</p> 5029 5030<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> 5031 5032<div style="margin: auto;"> 5033 <h4><a name="set" id="set"></a>-set <em class="arg">attribute value</em></h4> 5034</div> 5035 5036<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set an image attribute for all images in the current image sequence, after they have been created or read in. </td><td style='text-align:right;'></td></tr></table> 5037 5038<p>Attributes of interest include <a href="#comment">-comment</a>, <a href="#delay">-delay</a>, <a href="#dispose">-dispose</a>, and <a href="#page">-page</a>. For example:</p> 5039 5040<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' \ <br/> rose.png</span><span class='crtout'></span><span class="crtprompt"> $magick> </span><span class='crtin'>identify -format %c rose.png</span><span class='crtout'>Rose is a rose is a rose is a rose</span></p> 5041<p>The <a href="#repage">-repage</a> operator will also set the 5042'<kbd>page</kbd>' attribute of images already in memory, but allows you to 5043separately set the virtual canvas's size and offset components, and also allows 5044relative offset changes, and automatic canvas size re-calculating. The above 5045<a href="#set">-set</a> option is purely a direct, unmodified assignment of the 5046virtual canvas (page) meta-data. </p> 5047 5048<p>Use this option to associate a colorspace or profile with your image. For example,</p> 5049<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> 5050<p>Set image options by prefixing the value with <kbd>option:</kbd>. Set attributes of the image registry by prefixing the value with <kbd>registry:</kbd>.</p> 5051 5052<div style="margin: auto;"> 5053 <h4><a name="shade" id="shade"></a>-shade <em class="arg">azimuth</em>x<em class="arg">elevation</em></h4> 5054</div> 5055 5056<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> 5057 5058<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> 5059 5060<div style="margin: auto;"> 5061 <h4><a name="shadow" 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> 5062</div> 5063 5064<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> 5065 5066<div style="margin: auto;"> 5067 <h4><a name="shared-memory" 5068id="shared-memory"></a>-shared-memory</h4> 5069</div> 5070 5071<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> 5072 5073<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> 5074 5075<div style="margin: auto;"> 5076 <h4><a name="sharpen" id="sharpen"></a>-sharpen <em class="arg">radius</em>{x<em class="arg">sigma</em>}</h4> 5077</div> 5078 5079<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> 5080 5081<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p> 5082 5083<div style="margin: auto;"> 5084 <h4><a name="shave" id="shave"></a>-shave <em class="arg">geometry</em></h4> 5085</div> 5086 5087<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> 5088 5089<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> 5090 5091<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> 5092 5093<div style="margin: auto;"> 5094 <h4><a name="shear" id="shear"></a>-shear <em class="arg">Xdegrees</em>[x<em class="arg">Ydegrees</em>]</h4> 5095</div> 5096 5097<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> 5098 5099<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> 5100 5101<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> 5102 5103<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> 5104 5105<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> 5106 5107<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> 5108<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> 5109 5110<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -shear 20x60 logo-sheared.png</span></p> 5111<div style="margin: auto;"> 5112 <h4><a name="sigmoidal" id="sigmoidal-contrast"></a>-sigmoidal-contrast <em class="arg">contrast</em>x<em class="arg">mid-point</em></h4> 5113</div> 5114 5115<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> 5116 5117<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> 5118 5119<div style="margin: auto;"> 5120 <h4><a name="silent" id="silent"></a>-silent</h4> 5121</div> 5122 5123<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> 5124 5125<div style="margin: auto;"> 5126 <h4><a name="size" id="size"></a>-size <em class="arg">width</em>[x<em class="arg">height</em>][<em class="arg">+offset</em>]</h4> 5127</div> 5128 5129<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> 5130 5131<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> 5132 5133<p>For Photo CD images, choose from these sizes:</p> 5134 5135<pre class="text"> 5136 192x128 5137 384x256 5138 768x512 5139 1536x1024 5140 3072x2048 5141</pre> 5142 5143<div style="margin: auto;"> 5144 <h4><a name="sketch" 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> 5145</div> 5146 5147<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> 5148 5149<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> 5150 5151<div style="margin: auto;"> 5152 <h4><a name="snaps" id="snaps"></a>-snaps <em class="arg">value</em></h4> 5153</div> 5154 5155<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> 5156 5157<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p> 5158 5159<div style="margin: auto;"> 5160 <h4><a name="solarize" id="solarize"></a>-solarize <em class="arg">threshold</em></h4> 5161</div> 5162 5163<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> 5164 5165<p>Specify <em class="arg">factor</em> as the percent threshold of the intensity (0 - 99.9%).</p> 5166 5167<p>This option produces a <em class="arg">solarization</em> effect seen when exposing a photographic film to light during the development process.</p> 5168 5169<div style="margin: auto;"> 5170 <h4><a name="sparse-color" id="sparse-color"></a>-sparse-color <em 5171 class="arg">method</em> '<em class="arg">x</em>,<em class="arg">y</em> <em class="arg">color</em> ...'</h4> 5172</div> 5173 5174<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> 5175 5176 5177<table class="doc"> 5178 <tbody> 5179 <tr valign="top"> 5180 <th align="left" style="width: 8%">Method</th> 5181 <th align="left">Description</th> 5182 </tr> 5183 5184 <tr valign="top"> 5185 <td valign="top">voronoi</td> 5186 <td valign="top">Simply map each pixel to the to nearest color point 5187 given. The result are polygonal 'cells' of solid color. </td> 5188 </tr> 5189 5190 <tr valign="top"> 5191 <td valign="top">shepards</td> 5192 <td valign="top">Colors points basied on the ratio of inverse distance 5193 squared. Generating spots of color in a sea of the average of 5194 colors. </td> 5195 </tr> 5196 5197 <tr valign="top"> 5198 <td valign="top">barycentric</td> 5199 <td valign="top">three point triangle of color given 3 points. 5200 Giving only 2 points will form a linear gradient between those points. 5201 Gradient is however not restricted to just the triangle or line. </td> 5202 </tr> 5203 5204 <tr valign="top"> 5205 <td valign="top">bilinear</td> 5206 <td valign="top">Like barycentric but for 4 points. Less than 4 points 5207 fall back to barycentric. </td> 5208 </tr> 5209 5210 </tbody> 5211</table> 5212 5213<p>The points are placed according to the images location on the virtual 5214canvas (<a href="#page" >-page</a> or <a href="#repage" >-repage</a> 5215offset), and do not actually have to exist on the given image, but may be 5216some point beyond the edge of the image. All points are floating point values. 5217</p> 5218 5219<p>Only the color channels defined by the <a href="#channel" >-channel</a> are 5220modified, whcih means the matte/alpha transparency channel is not effected by 5221default. If enabled, the image also needs a the matte/alpha channel to be 5222enabled for this operator to effect an images transparency. This is typical 5223transparency handling for images. </p> 5224 5225<p>All the above methods when given a single point of color will replace all 5226the colors in the image with the color given, regardless of the point. This is 5227logical, and provides an alternative technique to recolor a image to some 5228default value. </p> 5229 5230 5231<div style="margin: auto;"> 5232 <h4><a name="splice" id="splice"></a>-splice <em class="arg">geometry</em></h4> 5233</div> 5234 5235<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> 5236 5237<p>See <a href="/www/command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. See <a href="#background">-background</a> to reset the background color.</p> 5238 5239<div style="margin: auto;"> 5240 <h4><a name="spread" id="spread"></a>-spread <em class="arg">amount</em></h4> 5241</div> 5242 5243<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> 5244 5245<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> 5246 5247<div style="margin: auto;"> 5248 <h4><a name="stegano" id="stegano"></a>-stegano <em class="arg">offset</em></h4> 5249</div> 5250 5251<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> 5252 5253<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> 5254 5255<div style="margin: auto;"> 5256 <h4><a name="stereo" id="stereo"></a>-stereo <em class="arg">+x</em>{<em class="arg">+y</em>}</h4> 5257</div> 5258 5259<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> 5260 5261<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> 5262 5263<div style="margin: auto;"> 5264 <h4><a name="storage-type" id="storage-type"></a>-storage-type <em class="arg">type</em></h4> 5265</div> 5266 5267<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> 5268 5269<pre class="text"> 5270 char store pixels as unsigned characters 5271 double store pixels as doubles 5272 float store pixels as floats 5273 integer store pixels as integers 5274 long store pixels as longs 5275 quantum store pixels in the native depth of your ImageMagick distribution 5276 short store pixels as unsigned shorts 5277</pre> 5278 5279<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels 5280values range from 0 to the maximum value the storage type can support.</p> 5281 5282<div style="margin: auto;"> 5283 <h4><a name="stretch" id="stretch"></a>-stretch <em class="arg">fontStretch</em></h4> 5284</div> 5285 5286<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> 5287 5288<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> 5289 5290<pre class="text"> 5291 Any 5292 Condensed 5293 Expanded 5294 ExtraCondensed 5295 ExtraExpanded 5296 Normal 5297 SemiCondensed 5298 SemiExpanded 5299 UltraCondensed 5300 UltraExpanded 5301</pre> 5302 5303<p>To print a complete list of stretch types, use <a href="#list">-list stretch</a>.</p> 5304 5305<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> 5306 5307<div style="margin: auto;"> 5308 <h4><a name="strip" id="strip"></a>-strip</h4> 5309</div> 5310 5311<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> 5312 5313<div style="margin: auto;"> 5314 <h4><a name="stroke" id="stroke"></a>-stroke <em class="arg">color</em></h4> 5315</div> 5316 5317<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> 5318 5319<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 5320 5321<p>See <a href="#draw">-draw</a> for further details.</p> 5322 5323<div style="margin: auto;"> 5324 <h4><a name="strokewidth" id="strokewidth"></a>-strokewidth <em class="arg">value</em></h4> 5325</div> 5326 5327<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> 5328 5329<p>See <a href="#draw">-draw</a> for further details.</p> 5330 5331<div style="margin: auto;"> 5332 <h4><a name="style" id="style"></a>-style <em class="arg">fontStyle</em></h4> 5333</div> 5334 5335<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> 5336 5337<p>This setting suggests a font style that ImageMagick should try to apply to the currently selected font family. Select <em class="arg">fontStyle</em> from the following.</p> 5338 5339<pre class="text"> 5340 Any 5341 Italic 5342 Normal 5343 Oblique 5344</pre> 5345 5346<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> 5347 5348<div style="margin: auto;"> 5349 <h4><a name="swap" id="swap"></a>-swap <em class="arg">index,index</em></h4> 5350</div> 5351 5352<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> 5353 5354<p>For example, <a href="#swap">-swap 0,2</a> swaps the first and the third images in the current image sequence. Use <a href="#swap">+swap</a> to switch the last two images in the sequence.</p> 5355 5356<div style="margin: auto;"> 5357 <h4><a name="swirl" id="swirl"></a>-swirl <em class="arg">degrees</em></h4> 5358</div> 5359 5360<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> 5361 5362<p><em class="arg">Degrees</em> defines the tightness of the swirl.</p> 5363 5364<div style="margin: auto;"> 5365 <h4><a name="taint" id="taint"></a>-taint</h4> 5366</div> 5367 5368<table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mark the image as modified even if it isn't.</td><td style='text-align:right;'></td></tr></table> 5369 5370<div style="margin: auto;"> 5371 <h4><a name="text-font" id="text-font"></a>-text-font <em class="arg">name</em></h4> 5372</div> 5373 5374<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> 5375 5376<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> 5377 5378<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> 5379 5380<div style="margin: auto;"> 5381 <h4><a name="texture" id="texture"></a>-texture <em class="arg">filename</em></h4> 5382</div> 5383 5384<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> 5385 5386<div style="margin: auto;"> 5387 <h4><a name="threshold" id="threshold"></a>-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 5388</div> 5389 5390<!-- {<em class="arg">green,blue,opacity</em>} 5391<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> 5392--> 5393 5394<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> 5395 5396<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> 5397 5398<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. 5399</p> 5400 5401<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> 5402 5403<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert in.png -channel red -threshold 50% out.png</span></p> 5404<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> 5405 5406 5407<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> 5408<p>Note that the values of the transparency channel is treated as 'matte' 5409values (0 is opaque) and not as 'alpha' values (0 is transparent).</p> 5410 5411<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>. 5412</p> 5413 5414<div style="margin: auto;"> 5415 <h4><a name="thumbnail" id="thumbnail"></a>-thumbnail <em class="arg">geometry</em></h4> 5416</div> 5417 5418<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> 5419 5420<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> 5421 5422<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> 5423 5424<div style="margin: auto;"> 5425 <h4><a name="tile" id="tile"></a>-tile <em class="arg">filename</em></h4> 5426</div> 5427 5428<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> 5429 5430<div style="margin: auto;"> 5431 <h4>-tile <em class="arg">geometry</em></h4> 5432</div> 5433 5434<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> 5435 5436<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> 5437 5438<div style="margin: auto;"> 5439 <h4>-tile</h4> 5440</div> 5441 5442<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> 5443 5444<div style="margin: auto;"> 5445 <h4><a name="tile-offset" 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> 5446</div> 5447 5448<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> 5449 5450<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> 5451 5452<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> 5453 5454<div style="margin: auto;"> 5455 <h4><a name="tint" id="tint"></a>-tint <em class="arg">value</em></h4> 5456</div> 5457 5458<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> 5459 5460<p>Tint the image with the fill color.</p> 5461 5462<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> 5463 5464<div style="margin: auto;"> 5465 <h4><a name="title" id="title"></a>-title <em class="arg">string</em></h4> 5466</div> 5467 5468<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> 5469 5470<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> 5471 5472<p>For example,</p> 5473 5474<p class="crtsnip"> 5475 -title "%m:%f %wx%h" 5476</p> 5477 5478<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> 5479 5480 5481<div style="margin: auto;"> 5482 <h4><a name="transform" id="transform"></a>-transform</h4> 5483</div> 5484 5485<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> 5486 5487<p>This option applies the transformation matrix from a previous <a href="#affine">-affine</a> option.</p> 5488 5489<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> 5490<div style="margin: auto;"> 5491 <h4><a name="transparent" id="transparent"></a>-transparent <em class="arg">color</em></h4> 5492</div> 5493 5494<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> 5495 5496<p>The <em class="arg">color</em> argument is defined using the format 5497described under the <a href="#fill">-fill</a> option. The <a href="#fuzz" 5498>-fuzz</a> setting can be used to match and replace colors similar to the one 5499given. </p> 5500 5501<p>Use <a href="#transparent" >+transparent</a> to invert the pixels matched. 5502that is make all non-matching colors transparent. </p> 5503 5504<p>The <a href="#opaque">-opaque</a> operator is exactly the same as <a 5505href="#transparent" >-transparent</a> but replaces the matching color with the 5506current <a href="#fill">-fill</a> color setting, rather than transparent. 5507However the <a href="#transparent" >-transparent</a> operator also ensures 5508that the image has an alpha channel enabled, as per "<kbd><a href="#alpha" 5509>-alpha</a> set</kbd>", and does not require you to modify the <a 5510href="#channel">-channel</a> to enable alpha channel handling. </p> 5511 5512<p>Note that this does not define the color as being the 'transparency color' 5513used for color-mapped image formats, such as GIF. For that use <a 5514href="#transparent-color" >-transparent-color</a> </p> 5515 5516 5517<div style="margin: auto;"> 5518 <h4><a name="transparent-color" id="transparent-color"></a>-transparent-color <em class="arg">color</em></h4> 5519</div> 5520 5521<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> 5522 5523<p>Sometimes this is used for saving to image formats such as 5524GIF and PNG8 which uses this color to represent boolean transparency. This 5525does not make a color transparent, it only defines what color the transparent 5526color is in the color palette of the saved image. Use <a 5527href="#transparent">-transparent</a> to make an opaque color transparent.</p> 5528 5529<p>This option allows you to have both an opaque visible color, as well as a 5530transparent color of the same color value without conflict. That is, you can 5531use the same color for both the transparent and opaque color areas within an 5532image. This, in turn, frees to you to select a transparent color that is 5533appropriate when an image is displayed by an application that does not handle a 5534transparent color index, while allowing ImageMagick to correctly handle images of this 5535type. </p> 5536 5537<p>The default transparent color is <kbd>#00000000</kbd>, which is fully transparent black.</p> 5538 5539<div style="margin: auto;"> 5540 <h4><a name="transpose" id="transpose"></a>-transpose</h4> 5541</div> 5542 5543<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> 5544 5545<p> This option mathematically transposes the pixel array. It is equivalent to the sequence <kbd>-flip -rotate 90</kbd>. 5546</p> 5547 5548<div style="margin: auto;"> 5549 <h4><a name="transverse" id="transverse"></a>-transverse</h4> 5550</div> 5551 5552<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> 5553 5554 5555<div style="margin: auto;"> 5556 <h4><a name="treedepth" id="treedepth"></a>-treedepth <em class="arg">value</em></h4> 5557</div> 5558 5559<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> 5560 5561<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> 5562 5563<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> 5564 5565<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> 5566 5567<div style="margin: auto;"> 5568 <h4><a name="trim" id="trim"></a>-trim</h4> 5569</div> 5570 5571<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> 5572 5573<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> 5574 5575<p>The page or virtual canvas information of the image is preserved allowing 5576you to extract the result of the <a href="#trim">-trim</a> operation from the 5577image. Use a <a href="#repage">+repage</a> to remove the virtual canvas page 5578information if it is unwanted.</p> 5579 5580<p>If the trimmed image 'disappears' an warning is produced, and a special 5581single pixel transparent 'missed' image is returned, in the same way as when a 5582<a href="#crop">-crop</a> operation 'misses' the image proper. </p> 5583 5584 5585<div style="margin: auto;"> 5586 <h4><a name="type" id="type"></a>-type <em class="arg">type</em></h4> 5587</div> 5588 5589<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> 5590 <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>, <kbd>ColorSeparationMatte</kbd>, or <kbd>Optimize</kbd>.</p> 5591 5592<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> 5593 5594<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert bird.png -type TrueColor bird.jpg</span></p> 5595<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> 5596 5597<p>Use <a href="#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p> 5598 5599<div style="margin: auto;"> 5600 <h4><a name="undercolor" id="undercolor"></a>-undercolor <em class="arg">color</em></h4> 5601</div> 5602 5603<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> 5604 5605<p>The color is specified using the format described under the <a href="#fill">-fill</a> option.</p> 5606 5607<p>See <a href="#draw">-draw</a> for further details.</p> 5608 5609 5610<div style="margin: auto;"> 5611 <h4><a name="update" id="update"></a>-update <em class="arg">seconds</em></h4> 5612</div> 5613 5614<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> 5615 5616<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> 5617 5618 5619<div style="margin: auto;"> 5620 <h4><a name="unique-colors" id="unique-colors"></a>-unique-colors</h4> 5621</div> 5622 5623<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> 5624 5625 5626<div style="margin: auto;"> 5627 <h4><a name="units" id="units"></a>-units <em class="arg">type</em></h4> 5628</div> 5629 5630<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> 5631 5632<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> 5633 5634 5635<div style="margin: auto;"> 5636 <h4><a name="unsharp" 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> 5637</div> 5638 5639<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> 5640 5641<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> 5642 5643<p>The parameters are:</p> 5644 5645<pre class="text"> 5646 radius: The radius of the Gaussian, in pixels, not counting the center 5647 pixel (default 0). 5648 sigma: The standard deviation of the Gaussian, in pixels (default 1.0). 5649 amount: The fraction of the difference between the original and the blur 5650 image that is added back into the original (default 1.0). 5651 threshold: The threshold, as a fraction of <em class="QR">QuantumRange</em>, needed to apply the 5652 difference amount (default 0.05). 5653</pre> 5654 5655 5656<div style="margin: auto;"> 5657 <h4><a name="verbose" id="verbose"></a>-verbose</h4> 5658</div> 5659 5660<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 preceds the <a href="#identify">-identify</a> option or <kbd>info:</kbd>.</td><td style='text-align:right;'></td></tr></table> 5661 5662 5663<div style="margin: auto;"> 5664 <h4><a name="version" id="version"></a>-version</h4> 5665</div> 5666 5667<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> 5668 5669 5670<div style="margin: auto;"> 5671 <h4><a name="view" id="view"></a>-view <em class="arg">string</em></h4> 5672</div> 5673 5674<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> 5675 5676 5677<div style="margin: auto;"> 5678 <h4><a name="vignette" 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> 5679</div> 5680 5681<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> 5682 5683 5684<div style="margin: auto;"> 5685 <h4><a name="virtual-pixel" id="virtual-pixel"></a>-virtual-pixel <em class="arg">method</em></h4> 5686</div> 5687 5688<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> 5689 5690<p>This option defines what color source should be used if and when a color 5691lookup completely 'misses' the source image. The color(s) that appear to 5692surround the source image. Generally this color is derived from the source 5693image, but could also be set to a specify background color. </p> 5694 5695<p>Choose from these methods:</p> 5696 5697<pre class="text"> 5698 background: the area surrounding the image is the background color 5699 black: the area surrounding the image is black 5700 checker-tile: alternate squares with image and background color 5701 dither: non-random 32x32 dithered pattern 5702 edge: extend the edge pixel toward infinity 5703 gray: the area surrounding the image is gray 5704 horizontal-tile: horizontally tile the image, background color above/below 5705 horizontal-tile-edge: horizontally tile the image and replicate the side edge pixels 5706 mirror: mirror tile the image 5707 random: choose a random pixel from the image 5708 tile: tile the image (default) 5709 transparent: the area surrounding the image is transparent blackness 5710 vertical-tile: vertically tile the image, sides are background color 5711 vertical-tile-edge: vertically tile the image and replicate the side edge pixels 5712 white: the area surrounding the image is white 5713</pre> 5714 5715<p>The default value is "edge".</p> 5716 5717<p>This most important for distortion operators such as <a href="#distort" 5718>-distort</a>, <a href="#implode" >-implode</a>, and <a href="#fx" >-fx</a>. 5719However it also effects operations that may access pixels just outside the 5720image proper, such as <a href="#convolve">-convolve</a>, <a 5721href="#blur">-blur</a>, and <a href="#sharpen">-sharpen</a>. </p> 5722 5723<p>To print a complete list of virtual pixel types, use the <a href="#list">-list virtual-pixel</a> option.</p> 5724 5725 5726<div style="margin: auto;"> 5727 <h4><a name="visual" id="visual"></a>-visual <em class="arg">type</em></h4> 5728</div> 5729 5730<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> 5731 5732<p>Choose from these visual classes:</p> 5733 5734<pre class="text"> 5735 StaticGray 5736 GrayScale 5737 StaticColor 5738 PseudoColor 5739 TrueColor 5740 DirectColor 5741 default 5742 visual id 5743</pre> 5744 5745<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> 5746 5747 5748<div style="margin: auto;"> 5749 <h4><a name="watermark" id="watermark"></a>-watermark <em 5750 class="arg">brightness</em>x<em class="arg">saturation</em></h4> 5751</div> 5752 5753<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 5754saturation.</td><td style='text-align:right;'>[<a href="/www/composite.html">composite</a>]</td></tr></table> 5755 5756<p>Take a grayscale image (with alpha mask) and modify the destination image's 5757brightness according to watermark image's grayscale value and the <em 5758class="arg">brightness</em> percentage. The destinations color saturation 5759attribute is just direct modified by the <em class="arg">saturation</em> 5760percentage, which defaults to 100 percent (no color change). </p> 5761 5762 5763<div style="margin: auto;"> 5764 <h4><a name="wave" id="wave"></a>-wave <em class="arg">amplitude</em><br />-wave <em class="arg">amplitude</em>x<em class="arg">wavelength</em></h4> 5765</div> 5766 5767<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> 5768 5769<p>Specify <em class="arg">amplitude</em> and <em class="arg">wavelength</em> of the wave.</p> 5770 5771<div style="margin: auto;"> 5772 <h4><a name="weight" id="weight"></a>-weight <em class="arg">fontWeight</em></h4> 5773</div> 5774 5775<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> 5776 5777<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> 5778 5779<table class="doc"> 5780 <col width="25%" /> 5781 <col width="75%" /> 5782 <thead> 5783 <tr> 5784 <th><em class="arg">fontWeight</em></th> 5785 <th>Description</th> 5786 </tr> 5787 </thead> 5788 <tbody> 5789 <tr><td>All </td> <td>No effect. </td></tr> 5790 <tr><td>Bold </td> <td>Same as <em class="arg">fontWeight</em> = 700.</td></tr> 5791 <tr><td>Bolder </td> <td>Add 100 to font weight if currently ≤ 800.</td></tr> 5792 <tr><td>Lighter </td> <td>Subtract 100 to font weight if currently ≤ 100.</td></tr> 5793 <tr><td>Normal </td> <td>Same as <em class="arg">fontWeight</em> = 400.</td></tr> 5794 </tbody> 5795 </table> 5796 5797<p>To print a complete list of weight types, use <a href="#list">-list weight</a>.</p> 5798 5799<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> 5800 5801<div style="margin: auto;"> 5802 <h4><a name="white-point" id="white-point"></a>-white-point <em class="arg">x,y</em></h4> 5803</div> 5804 5805<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> 5806 5807<div style="margin: auto;"> 5808 <h4><a name="white-threshold" id="white-threshold"></a>-white-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4> 5809</div> 5810 5811<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> 5812 5813<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. 5814</p> 5815 5816<div style="margin: auto;"> 5817 <h4><a name="window" id="window"></a>-window <em class="arg">id</em></h4> 5818</div> 5819 5820<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> 5821 5822<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> 5823 5824<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> 5825 5826<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> 5827 5828<div style="margin: auto;"> 5829 <h4><a name="window-group" id="window-group"></a>-window-group</h4> 5830</div> 5831 5832<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> 5833 5834<div style="margin: auto;"> 5835 <h4><a name="write" id="write"></a>-write <em class="arg">filename</em></h4> 5836</div> 5837 5838<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> 5839 <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> 5840 5841<p>Use <a href="#compress">-compress</a> to specify the type of image compression.</p> 5842 5843 5844</div> 5845 5846<div id="linkbar"> 5847 <!-- <span id="linkbar-west"> </span> --> 5848 <span id="linkbar-center"> 5849 <a href="http://www.imagemagick.org/discourse-server/">Discourse Server</a> • 5850 <a href="http://studio.webbyland.com/ImageMagick/MagickStudio/scripts/MagickStudio.cgi">Studio</a> 5851 </span> 5852 <span id="linkbar-east"> </span> 5853 </div> 5854 <div class="footer"> 5855 <span id="footer-west">© 1999-2010 ImageMagick Studio LLC</span> 5856 <span id="footer-east"> <a href="http://www.imagemagick.org/script/contact.php">Contact the Wizards</a></span> 5857 </div> 5858 <div style="clear: both; margin: 0; width: 100%; "></div> 5859</body> 5860</html> 5861
