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177 google_ad_slot = "0574824969"; 178 google_ad_width = 160; 179 google_ad_height = 600; 180 //--> 181 </script> 182 <script type="text/javascript" 183 src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> 184 </script> 185</div> 186 187<div class="main"> 188 189 190 191 192<h1>ImageMagick Command-line Processing</h1> 193<p class="navigation-index">[<a href="#anatomy">The Anatomy of the Command Line</a> • <a href="#input">Input Filename</a> • <a href="#setting">Image Setting</a> • <a href="#operator">Image Operator</a> • <a href="#sequence">Image Sequence Operator</a> • <a href="#geometry">Image Geometry</a> • <a href="#stack">Image Stack</a> • <a href="#output">Output Filename</a>]</p> 194 195<div class="doc-section"> 196 197<p>The ImageMagick command line can be as simple as this.</p> 198 199<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.jpg image.png</span></p> 200<p>Or it can be very complex, as in the following.</p> 201 202<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert label.gif +matte \ <br/> 203 \( +clone -shade 110x90 -normalize -negate +clone -compose Plus -composite \) \<br/> 204 \( -clone 0 -shade 110x50 -normalize -channel BG -fx 0 +channel -matte \) \<br/> 205 -delete 0 +swap -compose Multiply -composite button.gif</span></p> 206<p>Without knowing much about the ImageMagick command line, you can probably figure out that the first command above converts an image in the JPEG format to one in the PNG format. However, very few may realize the second, more complex command, gives a flat two-dimensional label a three-dimensional look with rich textures and simulated depth:</p> 207 208<div class="image"> 209 <a href="/images/label.gif"><img src="/images/label.gif" width="78" height="53" alt="label" /></a> 210<img style="margin-top:16px; margin-bottom:17px;" src="/images/right.gif" width="20" height="20" alt="==>" /> 211 <a href="/images/button.gif"> 212 <img src="/images/button.gif" width="78" height="53" alt="button" /></a> 213</div> 214 215<p class="warn">[ <em>A quick word about our formatting of commands:</em> The second example above is long enough that the command must be written across several lines, so we formatted it for clarity by inserting backslashes (<kbd>\</kbd>). The backslash is the Unix <em>line continuation</em> character. In the Windows shell, use a carat character (<kbd>^</kbd>) for line continuation. We use the Unix style on these web pages, as above. Sometimes, however, the lines are wrapped by your browser if the browser window is small enough, but the command lines, shown in white, are still intended to be typed as one line. Line continuation characters need not be entered. The <em>parentheses</em> that are <em>escaped</em> above using the backslash are not escaped in Windows. There are some other differences between Windows and Unix (involving quotation marks, for instance), but we'll discuss some of those issues later, as they arise. ]</p> 216 217<p>Here we show percent completion of a task as a shaded cylinder:</p> 218 219<div class="image"> 220 <img src="/images/cylinder_shaded.png" width="320" height="200" alt="Shaded Cylinder" /> 221</div> 222 223<p>Given the complexity of the rendering, you might be surprised it is accomplished by a single command-line:</p> 224 225<pre class="text"> 226convert -size 320x90 xc:none -stroke snow4 -size 1x90 -tile gradient:white-snow4 \ 227 -draw 'roundrectangle 16, 5, 304, 85 20,40' +tile -fill snow \ 228 -draw 'roundrectangle 264, 5, 304, 85 20,40' -tile gradient:chartreuse-green \ 229 -draw 'roundrectangle 16, 5, 180, 85 20,40' -tile gradient:chartreuse1-chartreuse3 \ 230 -draw 'roundrectangle 140, 5, 180, 85 20,40' +tile -fill none \ 231 -draw 'roundrectangle 264, 5, 304, 85 20,40' -strokewidth 2 \ 232 -draw 'roundrectangle 16, 5, 304, 85 20,40' \( +clone -background snow4 \ 233 -shadow 80x3+3+3 \) +swap -background none -layers merge \( +size -font Helvetica \ 234 -pointsize 90 -strokewidth 1 -fill red label:'50 %' -trim +repage \( +clone \ 235 -background firebrick3 -shadow 80x3+3+3 \) +swap -background none -layers merge \) \ 236 -insert 0 -gravity center -append -background white -gravity center -extent 320x200 \ 237 cylinder_shaded.png 238</pre> 239 240<p>In the next sections we dissect the anatomy of the ImageMagick command line. Hopefully, after carefully reading and better understanding how the command line works, you should be able to accomplish complex image-processing tasks without resorting to the sometimes daunting <a href="/www/api.html">program interfaces</a>.</p> 241 242<p>See <a href="http://www.imagemagick.org/Usage/">Examples of ImageMagick Usage</a> for additional help when using ImageMagick from the command-line.</p> 243</div> 244 245<h2><a id="anatomy"></a>The Anatomy of the Command Line</h2> 246<div class="doc-section"> 247<p>The ImageMagick command line consists of</p> 248 249<ol> 250<li>one or more required input filenames.</li> 251<li>zero, one, or more image settings.</li> 252<li>zero, one, or more image operators.</li> 253<li>zero, one, or more image sequence operators.</li> 254<li>zero, one, or more image stacks.</li> 255<li>zero or one output image filenames (required by 256<a href="/www/convert.html">convert</a>, 257<a href="/www/composite.html">composite</a>, 258<a href="/www/montage.html.html">montage.html</a>, 259<a href="/www/compare.html">compare</a>, 260<a href="/www/import.html">import</a>, 261<a href="/www/conjure.html">conjure</a>). 262</li> 263</ol> 264 265<p>You can find a detailed explanation of each of the constituent parts of the command line in the sections that follow.</p> 266</div> 267 268<h2><a id="input"></a>Input Filename</h2> 269<div class="doc-section"> 270 271<p>ImageMagick extends the concept of an input filename to include:</p> 272<ul> 273<li>filename globbing</li> 274<li>an explicit image format</li> 275<li>using built-in images and patterns</li> 276<li>STDIN, STDOUT, and file descriptors</li> 277<li>selecting certain frames from an image</li> 278<li>selecting a region of an image</li> 279<li>forcing an inline image resize</li> 280<li>forcing an inline image crop</li> 281<li>using filename references</li> 282</ul> 283 284<p>These extensions are explained in the next few paragraphs.</p> 285 286<h3>Filename Globbing</h3> 287<div class="doc-section"> 288<p>In Unix shells, certain characters such as the asterisk (<kbd>*</kbd>) and question mark (<kbd>?</kbd>) automagically cause lists of filenames to be generated based on pattern matches. This feature is known as globbing. ImageMagick supports filename globbing for systems, such as Windows, that does not natively support it. For example, suppose you want to convert <kbd>1.jpg</kbd>, <kbd>2.jpg</kbd>, <kbd>3.jpg</kbd>, <kbd>4.jpg</kbd>, and <kbd>5.jpg</kbd> in your current directory to a GIF animation. You can conveniently refer to all of the JPEG files with this command: 289</p> 290 291<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert *.jpg images.gif</span></p> 292</div> 293 294<h3>Explicit Image Format</h3> 295<div class="doc-section"> 296<p>Images are stored in a myriad of image formats including 297the better known JPEG, PNG, TIFF and others. ImageMagick must know the format 298of the image before it can be read and processed. Most formats have a 299signature within the image that uniquely identifies the format. Failing 300that, ImageMagick leverages the filename extension to determine the format. 301For example, <kbd>image.jpg</kbd> or <kbd>image.JPG</kbd> tells ImageMagick 302it is reading an image in the JPEG format. </p> 303 304 <p>In some cases the image may not contain a signature 305and/or the filename does not identify the image format. In these cases an 306explicit image format must be specified. For example, suppose our image 307is named <kbd>image</kbd> and contains raw red, green, and blue intensity 308values. ImageMagick has no way to automagically determine the image format 309so we explicitly set one: 310</p> 311 312<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 640x480 -depth 8 rgb:image image.png</span></p> 313 </div> 314 315<h3>Built-in Images and Patterns</h3> 316<div class="doc-section"> 317<p>ImageMagick has a number of built-in <a href="/www/formats.html#builtin-images">images</a> and <a href="/www/formats.html#builtin-patterns">patterns</a>. To utilize the checkerboard pattern, for example, use: 318</p> 319 320<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 640x480 pattern:checkerboard checkerboard.png</span></p> 321</div> 322 323<h3>STDIN, STDOUT, and file descriptors</h3> 324<div class="doc-section"> 325<p>Unix and Windows permit the output of one command to be piped to the input of another. ImageMagick permits image data to be read and written from the <a href="http://en.wikipedia.org/wiki/Standard_streams">standard streams</a> STDIN (<em>standard in</em>) and STDOUT (<em>standard out</em>), respectively, using a pseudo-filename of <kbd>-</kbd>. In this example we pipe the output of 326 <a href="/www/convert.html">convert</a> to the <a href="/www/display.html">display</a> program: 327</p> 328 329<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: gif:- | display gif:-</span></p> 330<p>The second explicit format "<kbd>gif:</kbd>" is optional in the preceding example. The GIF image format has a unique signature within the image so ImageMagick's <a href="/www/display.html">display</a> command can readily recognize the format as GIF. The <a href="/www/convert.html">convert</a> program also accepts STDIN as input in this way: 331</p> 332 333<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: gif:- | convert - -resize "200%" bigrose.jpg</span></p> 334<p>Other pipes can be accessed via their <em>file descriptors</em> (as of version 6.4.9-3). The file descriptors 0, 1, and 2 are reserved for the standard streams STDIN, STDOUT, and STDERR, respectively, but a pipe associated with a file descriptor number <em>N</em>>2 can be accessed using the pseudonym <kbd>fd:</kbd><em>N</em>. (The pseudonyms <kbd>fd:0</kbd> and <kbd>fd:1</kbd> can be used for STDIN and STDOUT.) The next example shows how to append image data piped from files with descriptors 3 and 4 and direct the result to the file with descriptor number 5. 335</p> 336 337<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert fd:3 fd:4 -append fd:5</span></p> 338<p>When needed, explicit image formats can be given as mentioned earlier, as in the following. 339</p> 340 341<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert gif:fd:3 jpg:fd:4 -append tif:fd:5</span></p> 342</div> 343 344<h3>Selecting Frames</h3> 345<div class="doc-section"> 346<p>Some images formats contain more than one image frame. Perhaps you only want the first image, or the last, or some number of images in-between. You can specify which image frames to read by appending the image filename with the frame range enclosed in brackets. Here our image (an animated GIF) contains more than one frame but we only want the first: 347</p> 348 349<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert 'images.gif[0]' image.png</span></p> 350<p class="warn">[Unix shells generally interpret brackets so we enclosed the filename in quotes above. 351In a Windows command shell the brackets are not interpreted but using quotes doesn't hurt. However, in most cases the roles of single-quotes and double-quotes are reversed with respect to Unix and Windows, so Windows users should usually try double-quotes where we display single-quotes, and vice versa.] 352</p> 353 354<p>You can read more than one image from a sequence with a frame range. For example, you can extract the first four frames of an image sequence: 355</p> 356 357<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert 'images.gif[0-3]' images.mng</span></p> 358<p>Finally, you can read more than one image from a sequence, out-of-order. The next command gets the third image in the sequence, followed by the second, and then the fourth: 359</p> 360 361<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert 'images.gif[3,2,4]' images.mng</span></p> 362<p>Notice that in the last two commands, a single image is written. The output in this case, where the image type is MNG, is a multi-frame file because the MNG format supports multiple frames. Had the output format been JPG, which only supports single frames, the output would have consisted of separate frames. More about that below, in the section about the <a href="#output">Output Filename</a>. 363</p> 364</div> 365 366<h3>Selecting an Image Region</h3> 367<div class="doc-section"> 368<p>Raw images are a sequence of color intensities without additional meta information such as width, height, or image signature. With raw image formats, you must specify the image width and height but you can also specify a region of the image to read. In our example, the image is in the raw 8-bit RGB format and is 6000 pixels wide and 4000 pixels high. However, we only want a region of 600 by 400 near the center of the image: 369</p> 370 371<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 6000x4000 -depth 8 \ <br/> 'rgb:image[600x400+1900+2900]' image.jpg</span></p> 372<p> 373 You can get the same results with the <a href="/www/command-line-options.html#extract">‑extract</a> option: 374</p> 375 376<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -size 6000x4000 -depth 8 \ <br/> -extract 600x400+1900+2900 rgb:image image.jpg</span></p> 377</div> 378 379<h3>Inline Image Resize</h3> 380<div class="doc-section"> 381<p>It is sometimes convenient to resize an image as they are read. Suppose you have hundreds of large JPEG images you want to convert to a sequence of PNG thumbails: 382</p> 383 384<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert '*.jpg' -resize 120x120 thumbnail%03d.png</span></p> 385<p>Here <em>all</em> the images are read and subsequently 386resized. It is faster and less resource intensive to resize each image it 387is read: 388</p> 389 390<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert '*.jpg[120x120]' thumbnail%03d.png</span></p> 391</div> 392 393<h3>Inline Image Crop</h3> 394<div class="doc-section"> 395<p>It is sometimes convenient to crop an image as they are read. Suppose you have hundreds of large JPEG images you want to convert to a sequence of PNG thumbails: 396</p> 397 398<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert '*.jpg' -crop 120x120+10+5 thumbnail%03d.png</span></p> 399<p>Here <em>all</em> the images are read and subsequently cropped. It is faster and less resource-intensive to crop each image as it is read: 400</p> 401 402<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert '*.jpg[120x120+10+5]' thumbnail%03d.png</span></p> 403</div> 404 405<h3>Filename References</h3> 406<div class="doc-section"> 407<p>There are two methods to use a filename to reference other image filenames. 408The first is with '<kbd>@</kbd>' which reads image filenames separated by white space from the specified file. Assume the file <kbd>myimages.txt</kbd> consists of a list of filenames, like so: 409</p> 410 411<pre class="text"> 412 frame001.jpg 413 frame002.jpg 414 frame003.jpg 415</pre> 416 417<p>We then expect this command:</p> 418<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert @myimages.txt mymovie.gif</span></p><p>to read the images <kbd>frame001.jpg</kbd>, <kbd>frame002.jpg</kbd>, and <kbd>frame003.jpg</kbd> and convert them to a GIF image sequence. </p> 419<p>If the image path includes one or more spaces, enclose the path in quotes:</p> 420<pre class="text"> 421 'my title.jpg' 422</pre> 423 424 425 <p>Some ImageMagick command-line options may exceed the capabilities of 426your command line processor. Windows, for example, limits command lines 427to 8192 characters. If, for example, you have a draw option with polygon 428points that exceed the command-line length limit, put the draw option instead 429in a file and reference the file with 430the <kbd>@</kbd> (e.g. <kbd>@mypoly.txt</kbd>).</p> 431 432<p>Another method of referring to other image files is by 433embedding a formatting character in the filename with a scene range. Consider 434the filename <kbd>image-%d.jpg[1-5]</kbd>. The command</p> 435 436<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image-%d.jpg[1-5]</span></p> 437<p>causes ImageMagick to attempt to read images with these filenames: 438</p> 439 440<pre class="text"> 441 image-1.jpg 442 image-2.jpg 443 image-3.jpg 444 image-4.jpg 445 image-5.jpg 446</pre> 447 448</div> 449</div> 450 451 452<h2><a id="setting"></a>Image Setting</h2> 453<div class="doc-section"> 454 455<p>An image setting persists as it appears on the command line and may affect 456subsequent processing such as reading an image, an image operator, or when 457writing an image as appropriate. An image setting stays in effect until it 458is reset or the command line terminates. The image settings include:</p> 459 460<p class="options"> 461<a href="/www/command-line-options.html#adjoin">‑adjoin</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#affine">‑affine</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#alpha">‑alpha</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#antialias">‑antialias</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#authenticate">‑authenticate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#background">‑background</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#bias">‑bias</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#black-point-compensation">‑black‑point‑compensation</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#blue-primary">‑blue‑primary</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#bordercolor">‑bordercolor</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#caption">‑caption</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#channel">‑channel</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#comment">‑comment</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#compress">‑compress</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#debug">‑debug</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#define">‑define</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#delay">‑delay</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#density">‑density</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#depth">‑depth</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#direction">‑direction</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#display">‑display</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#dispose">‑dispose</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#dither">‑dither</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#encoding">‑encoding</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#endian">‑endian</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#extract">‑extract</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#family">‑family</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#fill">‑fill</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#filter">‑filter</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#font">‑font</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#format">‑format</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#fuzz">‑fuzz</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#geometry">‑geometry</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#gravity">‑gravity</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#green-primary">‑green‑primary</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#interlace">‑interlace</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#intent">‑intent</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#interpolate">‑interpolate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#label">‑label</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#limit">‑limit</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#linewidth">‑linewidth</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#log">‑log</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#loop">‑loop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#mask">‑mask</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#mattecolor">‑mattecolor</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#monitor">‑monitor</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#orient">‑orient</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#page">‑page</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#pointsize">‑pointsize</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#quality">‑quality</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#red-primary">‑red‑primary</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#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#sampling-factor">‑sampling‑factor</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#seed">‑seed</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#stretch">‑stretch</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#texture">‑texture</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#transparent-color">‑transparent‑color</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#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#units">‑units</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#virtual-pixel">‑virtual‑pixel</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#weight">‑weight</a> </p> 462 463<p>In this example, <em class="arg">-channel</em> applies to each of the images, since, as we mentioned, settings persist: 464</p> 465 466<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert -channel RGB wand.png wizard.png images.png</span></p> 467</div> 468 469<h2><a id="operator"></a>Image Operator</h2> 470<div class="doc-section"> 471 472<p>An image operator differs from a setting in that it affects the image 473immediately as it appears on the command line. An operator is 474any <a href="/script../www/command-line-options.html">command line option</a> 475not listed as a <a href="#setting">image setting</a> 476or <a href="#sequence">image sequence operator</a>. Unlike an 477image setting, which persists until the command line terminates, 478an operator is applied to an image and forgotten. The image operators 479include:</p> 480 481<p class="options"> 482<a href="/www/command-line-options.html#annotate">‑annotate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#black-threshold">‑black‑threshold</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#blur">‑blur</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#border">‑border</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#charcoal">‑charcoal</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#chop">‑chop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#clip">‑clip</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#clip-path">‑clip‑path</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#clip-mask">‑clip‑mask</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#colors">‑colors</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#colorize">‑colorize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#colorspace">‑colorspace</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#compose">‑compose</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#contrast">‑contrast</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#convolve">‑convolve</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#crop">‑crop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#cycle">‑cycle</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#despeckle">‑despeckle</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#draw">‑draw</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#edge">‑edge</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#emboss">‑emboss</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#enhance">‑enhance</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#equalize">‑equalize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#evaluate">‑evaluate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#extent">‑extent</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#flip">‑flip</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#flop">‑flop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#floodfill">‑floodfill</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#frame">‑frame</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#gamma">‑gamma</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#gaussian-blur">‑gaussian‑blur</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#implode">‑implode</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#lat">‑lat</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#level">‑level</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#map">‑map</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#median">‑median</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#modulate">‑modulate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#monochrome">‑monochrome</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#negate">‑negate</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#noise">‑noise</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#normalize">‑normalize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#opaque">‑opaque</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#ordered-dither">‑ordered‑dither</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#paint">‑paint</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#posterize">‑posterize</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#profile">‑profile</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#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#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#scale">‑scale</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#segment">‑segment</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#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#solarize">‑solarize</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#strip">‑strip</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#threshold">‑threshold</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#thumbnail">‑thumbnail</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#transform">‑transform</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#unsharp">‑unsharp</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#wave">‑wave</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> </p> 483 484<p>In this example, <em class="arg">-negate</em> negates the wand image but not the wizard:</p> 485 486<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert wand.png -negate wizard.png images.png</span></p></div> 487 488<h2><a id="sequence"></a>Image Sequence Operator</h2> 489<div class="doc-section"> 490 491<p>An image sequence operator differs from a setting in that it affects an 492image sequence immediately as it appears on the command line. Choose from 493these image sequence operators:</p> 494 495<p class="options"> 496<a href="/www/command-line-options.html#append">‑append</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#affinity">‑affinity</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#average">‑average</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#clut">‑clut</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#coalesce">‑coalesce</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#combine">‑combine</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#composite">‑composite</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#crop">‑crop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#debug">‑debug</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#deconstruct">‑deconstruct</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#delete">‑delete</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#evaluate-seqence">‑evaluate‑seqence</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#fft">‑fft</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#flatten">‑flatten</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#fx">‑fx</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#hald-clut">‑hald‑clut</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#ift">‑ift</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#identify">‑identify</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#insert">‑insert</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#layers">‑layers</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#limit">‑limit</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#map">‑map</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#maximum">‑maximum</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#minimum">‑minimum</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#morph">‑morph</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#mosaic">‑mosaic</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#optimize">‑optimize</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#quiet">‑quiet</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#swap">‑swap</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#write">‑write</a> </p> 497</div> 498 499<h2><a id="geometry"></a>Image Geometry</h2> 500<div class="doc-section"> 501 502<p>Many command-line options take a <em class="arg">geometry</em> argument 503to specify such things as the desired width and height of an image and other 504dimensional quantities. Because users want so many variations on the resulting 505dimensions, sizes, and positions of images (and because ImageMagick wants to 506provide them), the <em class="arg">geometry</em> argument can take many 507forms. We describe many of these in this section. </p> 508 509<p>The image options and settings that take some form of 510a <em class="arg">geometry</em> argument include the following. 511Keep in mind that some of these parse their arguments in slightly 512different ways. See the documentation for the individual option or 513setting for more specifics.</p> 514 515<p class="options" style="text-align:justify"> 516<a href="/www/command-line-options.html#adaptive-resize">‑adaptive‑resize</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#border">‑border</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#borderwidth">‑borderwidth</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#chop">‑chop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#crop">‑crop</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#density">‑density</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#extent">‑extent</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#extract">‑extract</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#frame">‑frame</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#geometry">‑geometry</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#iconGeometry">‑iconGeometry</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#liquid-rescale">‑liquid‑rescale</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#page">‑page</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#repage">‑repage</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#sample">‑sample</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#shave">‑shave</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#thumbnail">‑thumbnail</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#window">‑window</a> </p> 517 518<p>The <em class="arg">geometry</em> argument might take any of the forms listed in the table below. These will described in more detail in the subsections following the table. The usual form is <em class="arg">size</em>[<em class="arg">offset</em>], meaning <em class="arg">size</em> is required and <em class="arg">offset</em> is optional. Occasionally, [<em class="arg">size</em>]<em class="arg">offset</em> is possible. In no cases are spaces permitted within the <em class="arg">geometry</em> argument.</p> 519 520 521<table id="geometryTable" class="doc"> 522 <col width="20%"/> <col width="80%"/> 523 <thead> 524 <tr valign="top"> 525 <th style="text-align:center"><em class="arg">size</em></th> 526 <th>General description (actual behavior can vary for different options and settings)</th> 527 </tr> 528 </thead> 529 <tbody> 530 <tr valign="top"> 531 <td><em class="arg">scale</em>%</td> 532 <td>Height and width both scaled by specified percentage.</td> 533 </tr> 534 <tr valign="top"> 535 <td><em class="arg">scale-x</em>%x<em class="arg">scale-y</em>%</td> 536 <td>Height and width individually scaled by specified percentages. (Only one % symbol needed.)</td> 537 </tr> 538 <tr valign="top"> 539 <td><em class="arg">width</em></td> 540 <td>Width given, height automagically selected to preserve aspect ratio.</td> 541 </tr> 542 <tr valign="top"> 543 <td>x<em class="arg">height</em></td> 544 <td>Height given, width automagically selected to preserve aspect ratio.</td> 545 </tr> 546 <tr valign="top"> 547 <td><em class="arg">width</em>x<em class="arg">height</em></td> 548 <td>Maximum values of height and width given, aspect ratio preserved.</td> 549 </tr> 550 <tr valign="top"> 551 <td><em class="arg">width</em>x<em class="arg">height</em>^</td> 552 <td>Minimum values of width and height given, aspect ratio preserved.</td> 553 </tr> 554 <tr valign="top"> 555 <td><em class="arg">width</em>x<em class="arg">height</em>!</td> 556 <td>Width and height emphatically given, original aspect ratio ignored.</td> 557 </tr> 558 <tr valign="top"> 559 <td><em class="arg">width</em>x<em class="arg">height</em>></td> 560 <td>Change as per <em class="arg">width</em>x<em class="arg">height</em> but only if an image dimension exceeds a specified dimension.</td> 561 </tr> 562 <tr valign="top"> 563 <td><em class="arg">width</em>x<em class="arg">height</em><</td> 564 <td>Change dimensions only if both image dimensions exceed specified dimensions.</td> 565 </tr> 566 <tr valign="top"> 567 <td><em class="arg">area</em>@</td> 568 <td>Resize image to have specified area in pixels. Aspect ratio is preserved.</td> 569 </tr> 570 </tbody> 571 </table> 572 <table class="doc"> 573 <col width="20%"/> <col width="80%"/> 574 <thead> 575 <tr valign="top"> 576 <th style="text-align:center">{<em class="arg">size</em>}{<em class="arg">offset</em>}</th> 577 <th>Specifying the <em class="arg">offset</em> (default is <kbd>+0+0</kbd>). Below, {<em class="arg">size</em>} refers to any of the forms above.</th> 578 </tr> 579 </thead> 580 581 <tbody> 582 <tr valign="top"> 583 <td>{<em class="arg">size</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></td> 584 <td>Horizontal and vertical offsets <em class="arg">x</em> and <em class="arg">y</em>, specified in pixels. Signs are required for both. Offsets are affected by <a href="/www/command-line-options.html#gravity">‑gravity</a> setting. Offsets are not affected by <kbd>%</kbd> or other <em class="arg">size</em> operators.</td> 585 </tr> 586 </tbody> 587</table> 588 589 590<h3>Basic adjustments to width and height; the operators <kbd>%</kbd>, <kbd>^</kbd>, and <kbd>!</kbd> </h3> 591<div class="doc-section"> 592<p>Here, just below, are a few simple examples of <em class="arg">geometry</em>, showing how it might be used as an argument to the <a href="/www/command-line-options.html#resize">‑resize</a> option. We'll use the internal image <kbd>logo:</kbd> for our input image. 593<a href="/images/logo-fullsize.png"> 594This fine image</a> is 640 pixels wide and 480 pixels high. We say its <em>dimensions</em> are 640x480. When we give dimensions of an image, the width (the horizontal dimension) always precedes the height (the vertical dimension). This will be true when we speak of coordinates or <em>offsets</em> into an image, which will always be <em>x</em>–value followed by <em>y</em>. Just think of your high school algebra classes and the <em>xy</em>–plane. (Well, almost: our <em>y</em>–axis will always go downward!) 595</p> 596 597<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '200%' bigWiz.png</span></p> 598<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '200x50%' longShortWiz.png</span></p> 599<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100x200' notThinWiz.png</span></p> 600<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100x200^' biggerNotThinWiz.png</span></p> 601<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100x200!' dochThinWiz.png</span></p> 602 603<p>The first of the four commands is simple—it stretches both the width and height of the input image by <kbd>200%</kbd> in each direction; it magnifies the whole thing by a factor of two. The second command specifies different percentages for each direction, stretching the width to <kbd>200</kbd>% and squashing the height to <kbd>50%</kbd>. The resulting image (in this example) has dimensions 1280x240. Notice that the percent symbol needn't be repeated; the following are equivalent: <kbd>200x50%</kbd>, <kbd>200%x50</kbd>, <kbd>200%x50%</kbd>. 604</p> 605 606<p>By default, the width and height given in a <em class="arg">geometry</em> argument are <em>maximum</em> values unless a percentage is specified. That is, the image is expanded or contracted to fit the specified width and height value while maintaining the <em>aspect ratio</em> (the ratio of its height to its width) of the image. For instance, the third command above "tries" to set the dimensions to <kbd>100x200</kbd>. Imagine gradually shrinking the original image (which is 640x480), keeping is aspect ratio constant, until it just fits into a 100x200 rectangle. Since the image is longer than it is tall, it will fit when its width shrinks to 100 pixels. To preserve the aspect ratio, the height will therefore have to be (480/640)×100 pixels=75 pixels, so the final dimensions will be 100x75.</p> 607 608<p> Notice that in the previous example, at least one of the specified dimensions will be attained (in this case, the width, 100 pixels). The resulting image fits snugly within the original. One can do just the opposite of this by invoking the <kbd>^</kbd> operator, as in the fourth example above. In that case, when <kbd>100x200^</kbd> is given as the argument, again at least one of the dimensions will be attained, but in this case the resulting image can snugly contain the original. Here the <em class="arg">geometry</em> argument gives <em>minimum</em> values. In our example, the height will become 200 and the width will be scaled to preserve the aspect ratio, becoming (640/480)×200 pixels=267 pixels. With the <kbd>^</kbd> operator, one of those dimensions will match the requested size, but the image will likely overflow the dimensions requested to preserve its aspect ratio. (The <kbd>^</kbd> feature is new as of IM 6.3.8-2.)</p> 609 610<p>We see that ImageMagick is very good about preserving aspect ratios of images, to prevent distortion of your favorite photos and images. But you might really want the dimensions to be <kbd>100x200</kbd>, thereby stretching the image. In this case just tell ImageMagick you really mean it (!) by appending an exclamation operator to the geometry. This will force the image size to exactly what you specify. So, for example, if you specify <kbd>100x200!</kbd> the dimensions will become exactly 100x200 (giving a small, vertically elongated wizard).</p> 611</div> 612 613<h3>Bounding the width, height, and area; the operators <kbd>></kbd>, <kbd><</kbd>, and <kbd>@</kbd> </h3> 614<div class="doc-section"> 615<p> 616Here are a few more examples: 617</p> 618 619<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100' wiz1.png</span></p> 620<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize 'x200' wiz2.png</span></p> 621<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100x200>' wiz3.png</span></p> 622<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '100x200<' wiz4.png</span></p> 623<p>If only one dimension is given it is taken to be the width. When only the width is specified, as in the first example above, the width is accepted as given and the height is chosen to maintain the aspect ratio of the input image. Similarly, if only the height is specified, as in the second example above, the height is accepted and the width is chosen to maintain the aspect ratio.</p> 624 625 626<p>Use <kbd>></kbd> to change the dimensions of the image <em>only</em> if the original width or height is exeeded by one of the <em class="arg">geometry</em> specifications. Use <kbd><</kbd> to resize the image <em>only</em> if the original dimensions are more than the <em class="arg">geometry</em> specifications. In either case, if a change is made, the result is as if the <kbd>></kbd> or <kbd>></kbd> operator was not present. So, in the third example above, we specified <kbd>100x200></kbd> and the original image size is 640x480, so the image size is reduced as if we had specified <kbd>100x200</kbd>. However, in the fourth example above, there will be no change to its size.</p> 627 628<p>Finally, use <kbd>@</kbd> to specify the maximum area in pixels of an image, again while attempting to preserve aspect ratio. (Pixels take only integer values, so some approximation is always at work.) In the following example, an area of 10000 pixels is requested. The resulting file has dimensions 115x86, which has 9890 pixels. </p> 629 630<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -resize '@10000' wiz10000.png</span></p> 631<p class="warn">Another word about the quotation marks: In all the examples above and below, we have enclosed the <em class="arg">geometry</em> arguments within quotation marks. Doing so is optional in many cases, but not always. We <em>must</em> enclose the geometry specifications in quotation marks when using <kbd><</kbd> or <kbd>></kbd> to prevent these characters from being interpreted by the shell as <em>file redirection</em>. On Windows systems, the carat <kbd>^</kbd> needs to be within quotes, else it is ignored. To be safe, one should probably maintain a habit of enclosing all <em class="arg">geometry</em> arguments in quotes, as we have here. 632</p> 633</div> 634 635<h3>Offsets in geometry</h3> 636<div class="doc-section"> 637<p> 638Here are some examples to illustrate the use of <em>offsets</em> in <em class="arg">geometry</em> arguments. One typical use of offsets is in conjunction with the 639<a href="/www/command-line-options.html#region">‑region</a> option. This option allows many other options to modify the pixels within a specified rectangular subregion of an image. As such, it needs to be given the width and height of that region, and also an <em>offset</em> into the image, which is a pair of coordinates that indicate the location of the region within the larger image. Below, in the first example, we specify a region of size <kbd>100x200</kbd> to be located at the <em>xy</em>–coordinates <em>x</em>=10, <em>y</em>=20. Let's use the usual algebraic notation (<em>x</em>,<em>y</em>)=(10,20), for convenience. 640</p> 641 642<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -region '100x200+10+20' -negate wizNeg1.png</span></p> 643<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -region '100x200-10+20' -negate wizNeg2.png</span></p> 644<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: -gravity center -region '100x200-10+20' \ <br/> -negate wizNeg3.png</span></p> 645 646<p>Note that offsets always require +/− signs. The offset is not actually a true location within the image; its coordinates must be added to some other location. Let's refer to that as the <em>current location</em>. In the first two examples above, though, that location is the upper-left hand corner of the image, which has coordinates (0,0). (That is the default situation when there are no other directives given to change it.) The first example above puts the <kbd>100x200</kbd> rectangle's own upper-left corner at (10,20). </p> 647 648<p>A negative offset can make sense in many cases. In the second example above, the offset is (-10,20), specified by <kbd>-10+20</kbd>. In that case, only the portion of the (virtual) rectangle obtained that lies within the image can be negated; here it is equivalent to specifying the geometry as <kbd>90x200+0+20</kbd>.</p> 649 650<p>In the third example above, the <a href="/www/command-line-options.html#gravity">‑gravity</a> setting precedes the others and sets the current location within the image at the very center of the image. In this case that is at pixel (320,240), since the size of the image is 640x480. This means that the offsets apply to that location, which thereby gets moved, in this case, to (320-10,240+20)=(310,260). But the <kbd>100x200</kbd> region itself is affected by the <a href="/www/command-line-options.html#gravity">‑gravity</a> setting, so instead of affecting its upper-left corner, the region's own center (at (+50,+100) within it) is determined. Therefore the center of the <kbd>100x200</kbd> rectangle is moved to (310,260). The negated rectangle's upper-left corner is now at (310-50,260-100)=(260,160). 651</p> 652</div> 653</div> 654 655 656<h2><a id="stack"></a>Image Stack</h2> 657<div class="doc-section"> 658 659<p>In school, your teacher probably permitted you to work on problems on a scrap of paper and then copy the results to your test paper. An image stack is similar. It permits you to work on an image or image sequence in isolation and subsequently introduce the results back into the command line. The image stack is delineated with parenthesis. Image operators only affect images in the current stack. For example, we can limit the image rotation to just the wizard image like this:</p> 660 661<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert wand.gif \( wizard.gif -rotate 30 \) +append images.gif</span></p> 662 663<p class="warn">Notice again that the parentheses are <em>escaped</em> by preceding them with 664backslashes. This is required under Unix, where parentheses are special 665<em>shell</em> characters. The backslash tells the shell not to interpret 666these characters, but to pass them directly to the command being executed. Do 667not escape the parentheses under Windows. Each parenthesis (or escaped 668parenthesis) must have spaces on either side, as in the example shown 669above.</p> 670 671<p>In addition to the image operators already discussed, the following image operators are most useful when processing images in an image stack:</p> 672 673<p class="options"> 674<span class='bull'> • </span> 675<a href="/www/command-line-options.html#clone">‑clone</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#delete">‑delete</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#insert">‑insert</a> <span class='bull'> • </span> <a href="/www/command-line-options.html#swap">‑swap</a> <span class='bull'> • </span> 676</p> 677 678<p>The arguments to these operators are indexes into the image sequence by number, starting with zero, for the first image, and so on. However if you give a negative index, the images are indexed from the end (last image added). That is, an index of -1 is the last image in the current image sequence, -2 gives the second-to-last, and so on.</p> 679 680</div> <!-- end Image Stack section --> 681 682<h2><a id="output"></a>Output Filename</h2> 683<div class="doc-section"> 684 685<p>ImageMagick extends the concept of an output filename to include:</p> 686 687<ol> 688<li>an explicit image format</li> 689<li>write to <em>standard out</em></li> 690<li>filename references</li> 691</ol> 692 693<p>Each of these extensions are explained in the next few paragraphs.</p> 694 695<h3>Explicit Image Format</h3> 696<div class="doc-section"> 697 <p>Images can be stored in a mryiad of image formats including the better known JPEG, PNG, TIFF and others. ImageMagick must know the desired format of the image before it is written. ImageMagick leverages the filename extension to determine the format. For example, <kbd>image.jpg</kbd> tells ImageMagick to write the image in the JPEG format. In some cases the filename does not identify the image format. In these cases, the image is written in the format it was originally read unless an explicit image format is specified. For example, suppose we want to write our image to a filename of <kbd>image</kbd> in the raw red, green, and blue intensity format: 698 </p> 699 700<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert image.jpg rgb:image</span></p> 701</div> 702 703<h3>Standard Out</h3> 704<div class="doc-section"> 705 <p>Unix permits the output of one command to be piped to another. ImageMagick permits piping one command to another with a filename of <kbd>-</kbd>. In this example we pipe the output of <a href="/www/convert.html">convert</a> to the <a href="/www/display.html">display</a> program: 706 </p> 707 708<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert logo: gif:- | display gif:-</span></p> 709<p>Here the explicit format is optional. The GIF image format has a signature that uniquely identifies it so ImageMagick can readily recognize the format as GIF. 710</p> 711</div> 712 713<h3>Filename References</h3> 714<div class="doc-section"> 715<p>Optionally, use an embedded formatting character to write a sequential image list. Suppose our output filename is <kbd>image-%d.jpg</kbd> and our image list includes 3 images. You can expect these images files to be written: 716</p> 717 718<pre class="text"> 719 image-0.jpg 720 image-1.jpg 721 image-2.jpg 722</pre> 723 724<p>Or retrieve image properties to modify the image filename. For example, the command 725</p> 726 727<p class='crt'><span class="crtprompt"> $magick> </span><span class='crtin'>convert rose: -set filename:area '%wx%h' \ <br/> 'rose-%[filename:area].png'</span></p> 728<p>writes an image with this filename: 729</p> 730 731<pre class="text"> 732 rose-70x46.png 733</pre> 734 735<p>Finally to convert multiple JPEG images to individual PDF pages, use:</p> 736 737<pre class="text"> 738 convert *.jpg +adjoin page-%d.pdf 739</pre> 740 741</div> 742 743</div> <!-- end Output Filename section --> 744 745</div> 746 747<div id="linkbar"> 748 <span id="linkbar-west"> </span> 749 <span id="linkbar-center"> 750 <a href="http://www.imagemagick.org/discourse-server/">Discourse Server</a> • 751 <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">Studio</a> 752 </span> 753 <span id="linkbar-east"> </span> 754 </div> 755 <div class="footer"> 756 <span id="footer-west">© 1999-2011 ImageMagick Studio LLC</span> 757 <span id="footer-east"> <a href="http://www.imagemagick.org/script/contact.php">Contact the Wizards</a></span> 758 </div> 759 <div style="clear: both; margin: 0; width: 100%; "></div> 760 <script type="text/javascript"> 761 var _gaq = _gaq || []; 762 _gaq.push(['_setAccount', 'UA-17690367-1']); 763 _gaq.push(['_trackPageview']); 764 765 (function() { 766 var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; 767 ga.src = ('https:' == document.location.protocol ? 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