command-line-processing.html revision e1319bc80e8035ab0cb428c6e2e716466abb1a06
1<!DOCTYPE html> 2<html lang="en"> 3<head> 4 <title>ImageMagick: Command-line Processing</title> 5 <meta http-equiv="content-type" content="text/html; charset=utf-8"> 6 <meta name="application-name" content="ImageMagick"> 7 <meta name="description" content="ImageMagick® is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 200) including PNG, JPEG, JPEG-2000, GIF, WebP, Postscript, PDF, and SVG. 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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> 65 66<ul> 67 <a href="/images/label.gif"><img src="/images/label.gif" width="78" height="53" alt="label"></a> 68<img style="margin-top:16px; margin-bottom:17px;" src="/images/right.gif" width="20" height="20" alt="==>"> 69 <a href="/images/button.gif"> 70 <img src="/images/button.gif" width="78" height="53" alt="button"></a> 71</ul> 72 73<p class="warn">[ <var>A quick word about our formatting of commands:</var> 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 (<code>\</code>). The backslash is the Unix <var>line continuation</var> character. In the Windows shell, use a carat character (<code>^</code>) 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 <var>parentheses</var> that are <var>escaped</var> 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> 74 75<p>Here we show percent completion of a task as a shaded cylinder:</p> 76 77<ul> 78 <img src="/images/cylinder_shaded.png" width="320" height="200" alt="Shaded Cylinder"> 79</ul> 80 81<p>Given the complexity of the rendering, you might be surprised it is accomplished by a single command-line:</p> 82 83<pre> 84convert -size 320x90 canvas:none -stroke snow4 -size 1x90 -tile gradient:white-snow4 \ 85 -draw 'roundrectangle 16, 5, 304, 85 20,40' +tile -fill snow \ 86 -draw 'roundrectangle 264, 5, 304, 85 20,40' -tile gradient:chartreuse-green \ 87 -draw 'roundrectangle 16, 5, 180, 85 20,40' -tile gradient:chartreuse1-chartreuse3 \ 88 -draw 'roundrectangle 140, 5, 180, 85 20,40' +tile -fill none \ 89 -draw 'roundrectangle 264, 5, 304, 85 20,40' -strokewidth 2 \ 90 -draw 'roundrectangle 16, 5, 304, 85 20,40' \( +clone -background snow4 \ 91 -shadow 80x3+3+3 \) +swap -background none -layers merge \( +size -font Helvetica \ 92 -pointsize 90 -strokewidth 1 -fill red label:'50 %' -trim +repage \( +clone \ 93 -background firebrick3 -shadow 80x3+3+3 \) +swap -background none -layers merge \) \ 94 -insert 0 -gravity center -append -background white -gravity center -extent 320x200 \ 95 cylinder_shaded.png 96</pre> 97 98<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="api.html">program interfaces</a>.</p> 99 100<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> 101 102<h2 class="magick-header"><a id="anatomy"></a>The Anatomy of the Command Line</h2> 103<p>The ImageMagick command line consists of</p> 104 105<ol> 106<li>one or more required input filenames.</li> 107<li>zero, one, or more image settings.</li> 108<li>zero, one, or more image operators.</li> 109<li>zero, one, or more image sequence operators.</li> 110<li>zero, one, or more image stacks.</li> 111<li>zero or one output image filenames (required by 112<a href="convert.html">convert</a>, 113<a href="composite.html">composite</a>, 114<a href="montage.html">montage</a>, 115<a href="compare.html">compare</a>, 116<a href="import.html">import</a>, 117<a href="conjure.html">conjure</a>). 118</li> 119</ol> 120 121<p>You can find a detailed explanation of each of the constituent parts of the command line in the sections that follow.</p> 122 123<h2 class="magick-header"><a id="input"></a>Input Filename</h2> 124 125<p>ImageMagick extends the concept of an input filename to include:</p> 126<ul> 127<li>filename globbing</li> 128<li>an explicit image format</li> 129<li>using built-in images and patterns</li> 130<li>STDIN, STDOUT, and file descriptors</li> 131<li>selecting certain frames from an image</li> 132<li>selecting a region of an image</li> 133<li>forcing an inline image resize</li> 134<li>forcing an inline image crop</li> 135<li>using filename references</li> 136</ul> 137 138<p>These extensions are explained in the next few paragraphs.</p> 139 140<h3>Filename Globbing</h3> 141<p>In Unix shells, certain characters such as the asterisk (<code>*</code>) and question mark (<code>?</code>) 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 <code>1.jpg</code>, <code>2.jpg</code>, <code>3.jpg</code>, <code>4.jpg</code>, and <code>5.jpg</code> in your current directory to a GIF animation. You can conveniently refer to all of the JPEG files with this command: 142</p> 143 144<pre> 145convert *.jpg images.gif 146</pre> 147 148<h3>Explicit Image Format</h3> 149<p>Images are stored in a myriad of image formats including 150the better known JPEG, PNG, TIFF and others. ImageMagick must know the format 151of the image before it can be read and processed. Most formats have a 152signature within the image that uniquely identifies the format. Failing 153that, ImageMagick leverages the filename extension to determine the format. 154For example, <code>image.jpg</code> or <code>image.JPG</code> tells ImageMagick 155it is reading an image in the JPEG format. </p> 156 157 <p>In some cases the image may not contain a signature 158and/or the filename does not identify the image format. In these cases an 159explicit image format must be specified. For example, suppose our image 160is named <code>image</code> and contains raw red, green, and blue intensity 161values. ImageMagick has no way to automagically determine the image format 162so we explicitly set one: 163</p> 164 165<pre> 166convert -size 640x480 -depth 8 rgb:image image.png 167</pre> 168 169<h3>Built-in Images and Patterns</h3> 170 171<p>ImageMagick has a number of built-in <a href="formats.html#builtin-images">images</a> and <a href="formats.html#builtin-patterns">patterns</a>. To utilize the checkerboard pattern, for example, use: 172</p> 173 174<pre> 175convert -size 640x480 pattern:checkerboard checkerboard.png 176</pre> 177 178<h3>STDIN, STDOUT, and file descriptors</h3> 179<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 (<var>standard in</var>) and STDOUT (<var>standard out</var>), respectively, using a pseudo-filename of <code>-</code>. In this example we pipe the output of 180 <a href="convert.html">convert</a> to the <a href="display.html">display</a> program: 181</p> 182 183<pre> 184convert logo: gif:- | display gif:- 185</pre> 186 187<p>The second explicit format "<code>gif:</code>" is optional in the preceding example. The GIF image format has a unique signature within the image so ImageMagick's <a href="display.html">display</a> command can readily recognize the format as GIF. The <a href="convert.html">convert</a> program also accepts STDIN as input in this way: 188</p> 189 190<pre> 191convert rose: gif:- | convert - -resize "200%" bigrose.jpg' 192</pre> 193 194<p>Other pipes can be accessed via their <var>file descriptors</var> (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 <var>N</var>>2 can be accessed using the pseudonym <code>fd:</code><var>N</var>. (The pseudonyms <code>fd:0</code> and <code>fd:1</code> 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. 195</p> 196 197<pre> 198convert fd:3 fd:4 -append fd:5 199</pre> 200 201<p>When needed, explicit image formats can be given as mentioned earlier, as in the following. 202</p> 203 204<pre> 205convert gif:fd:3 jpg:fd:4 -append tif:fd:5 206</pre> 207 208<h3>Selecting Frames</h3> 209<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: 210</p> 211 212<pre> 213convert 'images.gif[0]' image.png 214</pre> 215 216<p class="warn">[Unix shells generally interpret brackets so we enclosed the filename in quotes above. 217In 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.] 218</p> 219 220<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: 221</p> 222 223<pre> 224convert 'images.gif[0-3]' images.mng 225</pre> 226 227<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: 228</p> 229 230<pre> 231convert 'images.gif[3,2,4]' images.mng 232</pre> 233 234<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="command-line-processing.html#output">Output Filename</a>. 235</p> 236 237<h3>Selecting an Image Region</h3> 238<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: 239</p> 240 241<pre> 242convert -size 6000x4000 -depth 8 \ 243 'rgb:image[600x400+1900+2900]' image.jpg 244</pre> 245 246<p> 247 You can get the same results with the <a href="command-line-options.html#extract">‑extract</a> option: 248</p> 249 250<pre> 251convert -size 6000x4000 -depth 8 \ 252 -extract 600x400+1900+2900 rgb:image image.jpg 253</pre> 254 255<h3>Inline Image Resize</h3> 256<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: 257</p> 258 259<pre> 260convert '*.jpg' -resize 120x120 thumbnail%03d.png 261</pre> 262 263<p>Here <var>all</var> the images are read and subsequently 264resized. It is faster and less resource intensive to resize each image it 265is read: 266</p> 267 268<pre> 269convert '*.jpg[120x120]' thumbnail%03d.png 270</pre> 271 272<h3>Inline Image Crop</h3> 273<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: 274</p> 275 276<pre> 277convert '*.jpg' -crop 120x120+10+5 thumbnail%03d.png 278</pre> 279 280<p>Here <var>all</var> the images are read and subsequently cropped. It is faster and less resource-intensive to crop each image as it is read: 281</p> 282 283<pre> 284convert '*.jpg[120x120+10+5]' thumbnail%03d.png 285</pre> 286 287 288<h3>Filename References</h3> 289 290<p>There are two methods to use a filename to reference other image filenames. 291The first is with '<code>@</code>' which reads image filenames separated by white space from the specified file. Assume the file <code>myimages.txt</code> consists of a list of filenames, like so: 292</p> 293 294<pre> 295frame001.jpg 296frame002.jpg 297frame003.jpg 298</pre> 299 300<p>We then expect this command:</p> 301 302<pre> 303convert @myimages.txt mymovie.gif 304</pre> 305 306<p>to read the images <code>frame001.jpg</code>, <code>frame002.jpg</code>, and <code>frame003.jpg</code> and convert them to a GIF image sequence. </p> 307<p>If the image path includes one or more spaces, enclose the path in quotes:</p> 308<pre> 309'my title.jpg' 310</pre> 311 312 313 <p>Some ImageMagick command-line options may exceed the capabilities of 314your command line processor. Windows, for example, limits command lines 315to 8192 characters. If, for example, you have a draw option with polygon 316points that exceed the command-line length limit, put the draw option instead 317in a file and reference the file with 318the <code>@</code> (e.g. <code>@mypoly.txt</code>).</p> 319 320<p>Another method of referring to other image files is by 321embedding a formatting character in the filename with a scene range. Consider 322the filename <code>image-%d.jpg[1-5]</code>. The command</p> 323 324<pre> 325convert image-%d.jpg[1-5] 326</pre> 327 328<p>causes ImageMagick to attempt to read images with these filenames: 329</p> 330 331<pre> 332image-1.jpg 333image-2.jpg 334image-3.jpg 335image-4.jpg 336image-5.jpg 337</pre> 338 339<h3>Stream Buffering</h3> 340<p>By default, the input stream is buffered. To ensure information on the source file or terminal is read as soon as its available, set the buffer size to 0:</p> 341 342<pre> 343convert logo: gif:- | display -define stream:buffer-size=0 gif:- 344</pre> 345 346<h2 class="magick-header"><a id="setting"></a>Image Setting</h2> 347 348<p>An image setting persists as it appears on the command line and may affect 349subsequent processing such as reading an image, an image operator, or when 350writing an image as appropriate. An image setting stays in effect until it 351is reset or the command line terminates. The image settings include:</p> 352 353<p class="options"> 354<a href="command-line-options.html#adjoin">‑adjoin</a> • <a href="command-line-options.html#affine">‑affine</a> • <a href="command-line-options.html#alpha">‑alpha</a> • <a href="command-line-options.html#antialias">‑antialias</a> • <a href="command-line-options.html#authenticate">‑authenticate</a> • <a href="command-line-options.html#background">‑background</a> • <a href="command-line-options.html#bias">‑bias</a> • <a href="command-line-options.html#black-point-compensation">‑black‑point‑compensation</a> • <a href="command-line-options.html#blue-primary">‑blue‑primary</a> • <a href="command-line-options.html#bordercolor">‑bordercolor</a> • <a href="command-line-options.html#caption">‑caption</a> • <a href="command-line-options.html#channel">‑channel</a> • <a href="command-line-options.html#comment">‑comment</a> • <a href="command-line-options.html#compress">‑compress</a> • <a href="command-line-options.html#debug">‑debug</a> • <a href="command-line-options.html#define">‑define</a> • <a href="command-line-options.html#delay">‑delay</a> • <a href="command-line-options.html#density">‑density</a> • <a href="command-line-options.html#depth">‑depth</a> • <a href="command-line-options.html#direction">‑direction</a> • <a href="command-line-options.html#display">‑display</a> • <a href="command-line-options.html#dispose">‑dispose</a> • <a href="command-line-options.html#dither">‑dither</a> • <a href="command-line-options.html#encoding">‑encoding</a> • <a href="command-line-options.html#endian">‑endian</a> • <a href="command-line-options.html#extract">‑extract</a> • <a href="command-line-options.html#family">‑family</a> • <a href="command-line-options.html#fill">‑fill</a> • <a href="command-line-options.html#filter">‑filter</a> • <a href="command-line-options.html#font">‑font</a> • <a href="command-line-options.html#format">‑format</a> • <a href="command-line-options.html#fuzz">‑fuzz</a> • <a href="command-line-options.html#geometry">‑geometry</a> • <a href="command-line-options.html#gravity">‑gravity</a> • <a href="command-line-options.html#green-primary">‑green‑primary</a> • <a href="command-line-options.html#interlace">‑interlace</a> • <a href="command-line-options.html#intent">‑intent</a> • <a href="command-line-options.html#interpolate">‑interpolate</a> • <a href="command-line-options.html#label">‑label</a> • <a href="command-line-options.html#limit">‑limit</a> • <a href="command-line-options.html#linewidth">‑linewidth</a> • <a href="command-line-options.html#log">‑log</a> • <a href="command-line-options.html#loop">‑loop</a> • <a href="command-line-options.html#mask">‑mask</a> • <a href="command-line-options.html#mattecolor">‑mattecolor</a> • <a href="command-line-options.html#monitor">‑monitor</a> • <a href="command-line-options.html#orient">‑orient</a> • <a href="command-line-options.html#page">‑page</a> • <a href="command-line-options.html#pointsize">‑pointsize</a> • <a href="command-line-options.html#preview">‑preview</a> • <a href="command-line-options.html#quality">‑quality</a> • <a href="command-line-options.html#quiet">‑quiet</a> • <a href="command-line-options.html#red-primary">‑red‑primary</a> • <a href="command-line-options.html#region">‑region</a> • <a href="command-line-options.html#render">‑render</a> • <a href="command-line-options.html#repage">‑repage</a> • <a href="command-line-options.html#sampling-factor">‑sampling‑factor</a> • <a href="command-line-options.html#scene">‑scene</a> • <a href="command-line-options.html#seed">‑seed</a> • <a href="command-line-options.html#size">‑size</a> • <a href="command-line-options.html#stretch">‑stretch</a> • <a href="command-line-options.html#stroke">‑stroke</a> • <a href="command-line-options.html#strokewidth">‑strokewidth</a> • <a href="command-line-options.html#style">‑style</a> • <a href="command-line-options.html#texture">‑texture</a> • <a href="command-line-options.html#tile">‑tile</a> • <a href="command-line-options.html#transparent-color">‑transparent‑color</a> • <a href="command-line-options.html#treedepth">‑treedepth</a> • <a href="command-line-options.html#type">‑type</a> • <a href="command-line-options.html#undercolor">‑undercolor</a> • <a href="command-line-options.html#units">‑units</a> • <a href="command-line-options.html#verbose">‑verbose</a> • <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> • <a href="command-line-options.html#weight">‑weight</a> </p> 355 356<p>In this example, <var>-channel</var> applies to each of the images, since, as we mentioned, settings persist: 357</p> 358 359<pre> 360convert -channel RGB wand.png wizard.png images.png 361</pre> 362 363<h2 class="magick-header"><a id="operator"></a>Image Operator</h2> 364 365<p>An image operator differs from a setting in that it affects the image 366immediately as it appears on the command line. An operator is 367any <a href="command-line-options.html">command line option</a> 368not listed as a <a href="command-line-processing.html#setting">image setting</a> 369or <a href="command-line-processing.html#sequence">image sequence operator</a>. Unlike an 370image setting, which persists until the command line terminates, 371an operator is applied to an image and forgotten. The image operators 372include:</p> 373 374<p class="options"> 375<a href="command-line-options.html#annotate">‑annotate</a> • <a href="command-line-options.html#black-threshold">‑black‑threshold</a> • <a href="command-line-options.html#blur">‑blur</a> • <a href="command-line-options.html#border">‑border</a> • <a href="command-line-options.html#charcoal">‑charcoal</a> • <a href="command-line-options.html#chop">‑chop</a> • <a href="command-line-options.html#clip">‑clip</a> • <a href="command-line-options.html#clip-path">‑clip‑path</a> • <a href="command-line-options.html#clip-mask">‑clip‑mask</a> • <a href="command-line-options.html#colors">‑colors</a> • <a href="command-line-options.html#colorize">‑colorize</a> • <a href="command-line-options.html#colorspace">‑colorspace</a> • <a href="command-line-options.html#compose">‑compose</a> • <a href="command-line-options.html#contrast">‑contrast</a> • <a href="command-line-options.html#convolve">‑convolve</a> • <a href="command-line-options.html#crop">‑crop</a> • <a href="command-line-options.html#cycle">‑cycle</a> • <a href="command-line-options.html#despeckle">‑despeckle</a> • <a href="command-line-options.html#draw">‑draw</a> • <a href="command-line-options.html#edge">‑edge</a> • <a href="command-line-options.html#emboss">‑emboss</a> • <a href="command-line-options.html#enhance">‑enhance</a> • <a href="command-line-options.html#equalize">‑equalize</a> • <a href="command-line-options.html#evaluate">‑evaluate</a> • <a href="command-line-options.html#extent">‑extent</a> • <a href="command-line-options.html#flip">‑flip</a> • <a href="command-line-options.html#flop">‑flop</a> • <a href="command-line-options.html#floodfill">‑floodfill</a> • <a href="command-line-options.html#frame">‑frame</a> • <a href="command-line-options.html#gamma">‑gamma</a> • <a href="command-line-options.html#gaussian-blur">‑gaussian‑blur</a> • <a href="command-line-options.html#implode">‑implode</a> • <a href="command-line-options.html#lat">‑lat</a> • <a href="command-line-options.html#level">‑level</a> • <a href="command-line-options.html#map">‑map</a> • <a href="command-line-options.html#median">‑median</a> • <a href="command-line-options.html#modulate">‑modulate</a> • <a href="command-line-options.html#monochrome">‑monochrome</a> • <a href="command-line-options.html#negate">‑negate</a> • <a href="command-line-options.html#noise">‑noise</a> • <a href="command-line-options.html#normalize">‑normalize</a> • <a href="command-line-options.html#opaque">‑opaque</a> • <a href="command-line-options.html#ordered-dither">‑ordered‑dither</a> • <a href="command-line-options.html#paint">‑paint</a> • <a href="command-line-options.html#posterize">‑posterize</a> • <a href="command-line-options.html#raise">‑raise</a> • <a href="command-line-options.html#profile">‑profile</a> • <a href="command-line-options.html#radial-blur">‑radial‑blur</a> • <a href="command-line-options.html#raise">‑raise</a> • <a href="command-line-options.html#random-threshold">‑random‑threshold</a> • <a href="command-line-options.html#resample">‑resample</a> • <a href="command-line-options.html#resize">‑resize</a> • <a href="command-line-options.html#roll">‑roll</a> • <a href="command-line-options.html#rotate">‑rotate</a> • <a href="command-line-options.html#sample">‑sample</a> • <a href="command-line-options.html#scale">‑scale</a> • <a href="command-line-options.html#sepia-tone">‑sepia‑tone</a> • <a href="command-line-options.html#segment">‑segment</a> • <a href="command-line-options.html#shade">‑shade</a> • <a href="command-line-options.html#shadow">‑shadow</a> • <a href="command-line-options.html#sharpen">‑sharpen</a> • <a href="command-line-options.html#shave">‑shave</a> • <a href="command-line-options.html#shear">‑shear</a> • <a href="command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> • <a href="command-line-options.html#solarize">‑solarize</a> • <a href="command-line-options.html#splice">‑splice</a> • <a href="command-line-options.html#spread">‑spread</a> • <a href="command-line-options.html#strip">‑strip</a> • <a href="command-line-options.html#swirl">‑swirl</a> • <a href="command-line-options.html#threshold">‑threshold</a> • <a href="command-line-options.html#transparent">‑transparent</a> • <a href="command-line-options.html#thumbnail">‑thumbnail</a> • <a href="command-line-options.html#tint">‑tint</a> • <a href="command-line-options.html#transform">‑transform</a> • <a href="command-line-options.html#trim">‑trim</a> • <a href="command-line-options.html#unsharp">‑unsharp</a> • <a href="command-line-options.html#version">‑version</a> • <a href="command-line-options.html#wave">‑wave</a> • <a href="command-line-options.html#white-point">‑white‑point</a> • <a href="command-line-options.html#white-threshold">‑white‑threshold</a> </p> 376 377<p>In this example, <var>-negate</var> negates the wand image but not the wizard:</p> 378 379<pre> 380convert wand.png -negate wizard.png images.png 381</pre> 382 383<h2 class="magick-header"><a id="sequence"></a>Image Sequence Operator</h2> 384 385<p>An image sequence operator differs from a setting in that it affects an 386image sequence immediately as it appears on the command line. Choose from 387these image sequence operators:</p> 388 389<p class="options"> 390<a href="command-line-options.html#append">‑append</a> • <a href="command-line-options.html#affinity">‑affinity</a> • <a href="command-line-options.html#average">‑average</a> • <a href="command-line-options.html#clut">‑clut</a> • <a href="command-line-options.html#coalesce">‑coalesce</a> • <a href="command-line-options.html#combine">‑combine</a> • <a href="command-line-options.html#compare">‑compare</a> • <a href="command-line-options.html#complex">‑complex</a> • <a href="command-line-options.html#composite">‑composite</a> • <a href="command-line-options.html#copy">‑copy</a> • <a href="command-line-options.html#crop">‑crop</a> • <a href="command-line-options.html#debug">‑debug</a> • <a href="command-line-options.html#deconstruct">‑deconstruct</a> • <a href="command-line-options.html#delete">‑delete</a> • <a href="command-line-options.html#evaluate-sequence">‑evaluate‑sequence</a> • <a href="command-line-options.html#fft">‑fft</a> • <a href="command-line-options.html#flatten">‑flatten</a> • <a href="command-line-options.html#fx">‑fx</a> • <a href="command-line-options.html#hald-clut">‑hald‑clut</a> • <a href="command-line-options.html#ift">‑ift</a> • <a href="command-line-options.html#identify">‑identify</a> • <a href="command-line-options.html#insert">‑insert</a> • <a href="command-line-options.html#layers">‑layers</a> • <a href="command-line-options.html#limit">‑limit</a> • <a href="command-line-options.html#map">‑map</a> • <a href="command-line-options.html#maximum">‑maximum</a> • <a href="command-line-options.html#minimum">‑minimum</a> • <a href="command-line-options.html#morph">‑morph</a> • <a href="command-line-options.html#mosaic">‑mosaic</a> • <a href="command-line-options.html#optimize">‑optimize</a> • <a href="command-line-options.html#print">‑print</a> • <a href="command-line-options.html#process">‑process</a> • <a href="command-line-options.html#quiet">‑quiet</a> • <a href="command-line-options.html#separate">‑separate</a> • <a href="command-line-options.html#swap">‑swap</a> • <a href="command-line-options.html#write">‑write</a> </p> 391 392<h2 class="magick-header"><a id="geometry"></a>Image Geometry</h2> 393 394<p>Many command-line options take a <var>geometry</var> argument 395to specify such things as the desired width and height of an image and other 396dimensional quantities. Because users want so many variations on the resulting 397dimensions, sizes, and positions of images (and because ImageMagick wants to 398provide them), the <var>geometry</var> argument can take many 399forms. We describe many of these in this section. </p> 400 401<p>The image options and settings that take some form of 402a <var>geometry</var> argument include the following. 403Keep in mind that some of these parse their arguments in slightly 404different ways. See the documentation for the individual option or 405setting for more specifics.</p> 406 407<p class="options" style="text-align:justify"> 408<a href="command-line-options.html#adaptive-resize">‑adaptive‑resize</a> • <a href="command-line-options.html#border">‑border</a> • <a href="command-line-options.html#borderwidth">‑borderwidth</a> • <a href="command-line-options.html#chop">‑chop</a> • <a href="command-line-options.html#crop">‑crop</a> • <a href="command-line-options.html#density">‑density</a> • <a href="command-line-options.html#extent">‑extent</a> • <a href="command-line-options.html#extract">‑extract</a> • <a href="command-line-options.html#frame">‑frame</a> • <a href="command-line-options.html#geometry">‑geometry</a> • <a href="command-line-options.html#iconGeometry">‑iconGeometry</a> • <a href="command-line-options.html#liquid-rescale">‑liquid‑rescale</a> • <a href="command-line-options.html#page">‑page</a> • <a href="command-line-options.html#region">‑region</a> • <a href="command-line-options.html#repage">‑repage</a> • <a href="command-line-options.html#resize">‑resize</a> • <a href="command-line-options.html#sample">‑sample</a> • <a href="command-line-options.html#scale">‑scale</a> • <a href="command-line-options.html#shave">‑shave</a> • <a href="command-line-options.html#splice">‑splice</a> • <a href="command-line-options.html#thumbnail">‑thumbnail</a> • <a href="command-line-options.html#window">‑window</a> </p> 409 410<p>The <var>geometry</var> 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 <var>size</var>[<var>offset</var>], meaning <var>size</var> is required and <var>offset</var> is optional. Occasionally, [<var>size</var>]<var>offset</var> is possible. In no cases are spaces permitted within the <var>geometry</var> argument.</p> 411 412 413<div class="table-responsive"> 414<table class="table table-condensed table-striped"> 415 <col width="20%"> <col width="80%"> 416 <thead> 417 <tr> 418 <th style="text-align:center"><var>size</var></th> 419 <th>General description (actual behavior can vary for different options and settings)</th> 420 </tr> 421 </thead> 422 <tbody> 423 <tr> 424 <td><var>scale</var>%</td> 425 <td>Height and width both scaled by specified percentage.</td> 426 </tr> 427 <tr> 428 <td><var>scale-x</var>%x<var>scale-y</var>%</td> 429 <td>Height and width individually scaled by specified percentages. (Only one % symbol needed.)</td> 430 </tr> 431 <tr> 432 <td><var>width</var></td> 433 <td>Width given, height automagically selected to preserve aspect ratio.</td> 434 </tr> 435 <tr> 436 <td>x<var>height</var></td> 437 <td>Height given, width automagically selected to preserve aspect ratio.</td> 438 </tr> 439 <tr> 440 <td><var>width</var>x<var>height</var></td> 441 <td>Maximum values of height and width given, aspect ratio preserved.</td> 442 </tr> 443 <tr> 444 <td><var>width</var>x<var>height</var>^</td> 445 <td>Minimum values of width and height given, aspect ratio preserved.</td> 446 </tr> 447 <tr> 448 <td><var>width</var>x<var>height</var>!</td> 449 <td>Width and height emphatically given, original aspect ratio ignored.</td> 450 </tr> 451 <tr> 452 <td><var>width</var>x<var>height</var>></td> 453 <td>Shrinks an image with dimension(s) <b>larger</b> than the corresponding <var>width</var> and/or <var>height</var> argument(s).</td> 454 </tr> 455 <tr> 456 <td><var>width</var>x<var>height</var><</td> 457 <td>Enlarges an image with dimension(s) <b>smaller</b> than the corresponding <var>width</var> and/or <var>height</var> argument(s).</td> 458 </tr> 459 <tr> 460 <td><var>area</var>@</td> 461 <td>Resize image to have specified area in pixels. Aspect ratio is preserved.</td> 462 </tr> 463 <tr> 464 <td>{<var>size</var>}{<var>offset</var>}</td> 465 <td>Specifying the <var>offset</var> (default is <code>+0+0</code>). Below, {<var>size</var>} refers to any of the forms above.</td> 466 </tr> 467 <tr> 468 <td>{<var>size</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></td> 469 <td>Horizontal and vertical offsets <var>x</var> and <var>y</var>, specified in pixels. Signs are required for both. Offsets are affected by <a href="command-line-options.html#gravity">‑gravity</a> setting. Offsets are not affected by <code>%</code> or other <var>size</var> operators.</td> 470 </tr> 471 </tbody> 472</table></div> 473 474 475<h3>Basic adjustments to width and height; the operators <code>%</code>, <code>^</code>, and <code>!</code> </h3> 476<p>Here, just below, are a few simple examples of <var>geometry</var>, showing how it might be used as an argument to the <a href="command-line-options.html#resize">‑resize</a> option. We'll use the internal image <code>logo:</code> for our input image. 477<a href="/images/logo.png"> 478This fine image</a> is 640 pixels wide and 480 pixels high. We say its <var>dimensions</var> 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 <var>offsets</var> into an image, which will always be <var>x</var>–value followed by <var>y</var>. Just think of your high school algebra classes and the <var>xy</var>–plane. (Well, almost: our <var>y</var>–axis will always go downward!) 479</p> 480 481<pre> 482convert logo: -resize '200%' bigWiz.png 483convert logo: -resize '200x50%' longShortWiz.png 484convert logo: -resize '100x200' notThinWiz.png 485convert logo: -resize '100x200^' biggerNotThinWiz.png 486convert logo: -resize '100x200!' dochThinWiz.png 487</pre> 488 489<p>The first of the four commands is simple—it stretches both the width and height of the input image by <code>200%</code> 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 <code>200</code>% and squashing the height to <code>50%</code>. The resulting image (in this example) has dimensions 1280x240. Notice that the percent symbol needn't be repeated; the following are equivalent: <code>200x50%</code>, <code>200%x50</code>, <code>200%x50%</code>. 490</p> 491 492<p>By default, the width and height given in a <var>geometry</var> argument are <var>maximum</var> 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 <var>aspect ratio</var> (the ratio of its height to its width) of the image. For instance, the third command above "tries" to set the dimensions to <code>100x200</code>. 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> 493 494<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 <code>^</code> operator, as in the fourth example above. In that case, when <code>100x200^</code> 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 <var>geometry</var> argument gives <var>minimum</var> 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 <code>^</code> 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 <code>^</code> feature is new as of IM 6.3.8-2.)</p> 495 496<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 <code>100x200</code>, 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 <code>100x200!</code> the dimensions will become exactly 100x200 (giving a small, vertically elongated wizard).</p> 497 498<h3>Bounding the width, height, and area; the operators <code>></code>, <code><</code>, and <code>@</code> </h3> 499<p> 500Here are a few more examples: 501</p> 502 503<pre> 504convert logo: -resize '100' wiz1.png 505convert logo: -resize 'x200' wiz2.png 506convert logo: -resize '100x200>' wiz3.png 507convert logo: -resize '100x200<' wiz4.png 508</pre> 509 510<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> 511 512 513<p>Use <code>></code> to shrink an image <var>only</var> if its dimension(s) are <b>larger</b> than the corresponding <var>width</var> and/or <var>height</var> arguments. Use <code><</code> to enlarge an image <var>only</var> if its dimension(s) are <b>smaller</b> than the corresponding <var>width</var> and/or <var>height</var> arguments. In either case, if a change is made, the result is as if the <code>></code> or <code><</code> operator was not present. So, in the third example above, we specified <code>100x200></code> and the original image size is 640x480, so the image size is reduced as if we had specified <code>100x200</code>. However, in the fourth example above, there will be no change to its size.</p> 514 515<p>Finally, use <code>@</code> 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> 516 517<pre> 518convert logo: -resize '@10000' wiz10000.png 519</pre> 520 521<p class="warn">Another word about the quotation marks: In all the examples above and below, we have enclosed the <var>geometry</var> arguments within quotation marks. Doing so is optional in many cases, but not always. We <var>must</var> enclose the geometry specifications in quotation marks when using <code><</code> or <code>></code> to prevent these characters from being interpreted by the shell as <var>file redirection</var>. On Windows systems, the carat <code>^</code> needs to be within quotes, else it is ignored. To be safe, one should probably maintain a habit of enclosing all <var>geometry</var> arguments in quotes, as we have here. 522</p> 523 524<h3>Offsets in geometry</h3> 525<p> 526Here are some examples to illustrate the use of <var>offsets</var> in <var>geometry</var> arguments. One typical use of offsets is in conjunction with the 527<a href="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 <var>offset</var> 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 <code>100x200</code> to be located at the <var>xy</var>–coordinates <var>x</var>=10, <var>y</var>=20. Let's use the usual algebraic notation (<var>x</var>,<var>y</var>)=(10,20), for convenience. 528</p> 529 530<pre> 531convert logo: -region '100x200+10+20' -negate wizNeg1.png 532convert logo: -region '100x200-10+20' -negate wizNeg2.png 533convert logo: -gravity center -region '100x200-10+20' \ 534 -negate wizNeg3.png 535</pre> 536 537<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 <var>current location</var>. 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 <code>100x200</code> rectangle's own upper-left corner at (10,20). </p> 538 539<p>A negative offset can make sense in many cases. In the second example above, the offset is (-10,20), specified by <code>-10+20</code>. 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 <code>90x200+0+20</code>.</p> 540 541<p>In the third example above, the <a href="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 <code>100x200</code> region itself is affected by the <a href="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 <code>100x200</code> rectangle is moved to (310,260). The negated rectangle's upper-left corner is now at (310-50,260-100)=(260,160). 542</p> 543 544 545<h2 class="magick-header"><a id="stack"></a>Image Stack</h2> 546 547<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> 548 549<pre> 550convert wand.gif \( wizard.gif -rotate 30 \) +append images.gif 551</pre> 552 553 554<p class="warn">Notice again that the parentheses are <var>escaped</var> by preceding them with 555backslashes. This is required under Unix, where parentheses are special 556<var>shell</var> characters. The backslash tells the shell not to interpret 557these characters, but to pass them directly to the command being executed. Do 558not escape the parentheses under Windows. Each parenthesis (or escaped 559parenthesis) must have spaces on either side, as in the example shown 560above.</p> 561 562<p>In addition to the image operators already discussed, the following image operators are most useful when processing images in an image stack:</p> 563 564<p class="options"> 565<span class="bull"> • </span> 566<a href="command-line-options.html#clone">‑clone</a> • <a href="command-line-options.html#delete">‑delete</a> • <a href="command-line-options.html#insert">‑insert</a> • <a href="command-line-options.html#swap">‑swap</a> <span class="bull"> • </span> 567</p> 568 569<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> 570 571<h2 class="magick-header"><a id="output"></a>Output Filename</h2> 572 573<p>ImageMagick extends the concept of an output filename to include:</p> 574 575<ol> 576<li>an explicit image format</li> 577<li>write to <var>standard out</var></li> 578<li>filename references</li> 579</ol> 580 581<p>Each of these extensions are explained in the next few paragraphs.</p> 582 583<h3>Explicit Image Format</h3> 584 <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, <code>image.jpg</code> 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 <code>image</code> in the raw red, green, and blue intensity format: 585 </p> 586 587<pre> 588convert image.jpg rgb:image 589</pre> 590 591 592<h3>Standard Out</h3> 593 <p>Unix permits the output of one command to be piped to another. ImageMagick permits piping one command to another with a filename of <code>-</code>. In this example we pipe the output of <a href="convert.html">convert</a> to the <a href="display.html">display</a> program: 594 </p> 595 596<pre> 597convert logo: gif:- | display gif:- 598</pre> 599 600<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.</p> 601 602<h3>Filename References</h3> 603<p>Optionally, use an embedded formatting character to write a sequential image list. Suppose our output filename is <code>image-%d.jpg</code> and our image list includes 3 images. You can expect these images files to be written: 604</p> 605 606<pre> 607image-0.jpg 608image-1.jpg 609image-2.jpg 610</pre> 611 612<p>Or retrieve image properties to modify the image filename. For example, the command 613</p> 614 615<pre> 616convert rose: -set filename:area '%wx%h' \ 617 'rose-%[filename:area].png' 618</pre> 619 620<p>writes an image with this filename: 621</p> 622 623<pre> 624 rose-70x46.png 625</pre> 626 627<p>Finally to convert multiple JPEG images to individual PDF pages, use:</p> 628 629<pre> 630 convert *.jpg +adjoin page-%d.pdf 631</pre> 632 633<h3>Stream Buffering</h3> 634 635<p>By default, the output stream is buffered. To ensure information appears on the destination file or terminal as soon as written, set the buffer size to 0:</p> 636 637<pre> 638convert -define stream:buffer-size=0 logo: gif:- | display gif:- 639</pre> 640</div> 641 <footer class="magick-footer"> 642 <p><a href="support.html">Donate</a> • 643 <a href="sitemap.html">Sitemap</a> • 644 <a href="links.html">Related</a> • 645 <a href="architecture.html">Architecture</a> 646</p> 647 <p><a href="command-line-processing.html#">Back to top</a> • 648 <a href="http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x89AB63D48277377A">Public Key</a> • 649 <a href="http://nextgen.imagemagick.org/script/contact.php">Contact Us</a></p> 650 <p><small>© 1999-2015 ImageMagick Studio LLC</small></p> 651 </footer> 652</div><!-- /.container --> 653 654 <script src="https://localhost/ajax/libs/jquery/1.11.2/jquery.min.js"></script> 655 <script src="http://nextgen.imagemagick.org/js/magick.html"></script> 656</div> 657</body> 658</html> 659
