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cristy4e638cd2015-05-07 16:47:40 +0000[diff] [blame]74<div class="magick-header">
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]75<p class="text-center"><a href="compare.html#usage">Example Usage</a> • <a href="compare.html#options">Option Summary</a></p>
cristy06f63f22012-10-31 00:50:07 +0000[diff] [blame]76
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]77<p class="lead magick-description">Use the <code>compare</code> program to mathematically and visually annotate the difference between an image and its reconstruction. See <a href="../command-line-processing.html">Command Line Processing</a> for advice on how to structure your <code>compare</code> command or see below for example usages of the command.</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]78
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]79<h2 class="magick-post-title"><a id="usage"></a>Example Usage</h2>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]80
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]81<p>We list a few examples of the <code>compare</code> command here to illustrate its usefulness and ease of use. To get started, lets compare an image to one thats been sharpened:</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]82
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]83<pre class="highlight"><code>magick convert rose.jpg -sharpen 0x1 reconstruct.jpg
84magick compare rose.jpg reconstruct.jpg difference.png
85magick compare -compose src rose.jpg reconstruct.jpg difference.png
86</code></pre>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]87
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]88<ul>
89 <a href="../../images/rose.jpg"><img src="../../images/rose.jpg" width="70" height="46" alt="rose" /></a>
90 <a href="../../images/reconstruct.jpg"><img src="../../images/reconstruct.jpg" width="70" height="46" alt="rose" /></a>
91 <img style="margin:13px 0;" src="../../images/right.gif" width="20" height="20" alt="==>" />
92 <a href="../../images/difference.png"><img src="../../images/difference.png" width="70" height="46" alt="rose" /></a>
93</ul>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]94
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]95<p>The red areas of the difference image emphasizes (highlight) pixels that are affected by the image sharpening, whereas white de-emphasizes (lowlight) pixels that are untouched by the sharpening process.</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]96
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]97<p>In addition to the visual interpretation of the difference in an image and its reconstruction, we report a mathematical measure of the difference:</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]98
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]99<pre class="highlight"><code>-> magick compare -verbose -metric mae rose.jpg reconstruct.jpg difference.png
100Image: rose.jpg
101 Channel distortion: MAE
102 red: 2282.91 (0.034835)
103 green: 1853.99 (0.0282901)
104 blue: 2008.67 (0.0306503)
105 all: 1536.39 (0.0234439)
106</code></pre>
107<p>Or, if you just want the red channel distortion, use this command:</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]108
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]109<pre class="highlight"><code>-> magick compare -channel red -metric PSNR rose.jpg reconstruct.jpg difference.png
11019.63
111</code></pre>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]112
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]113<p>Or, if you just want the overall image distortion, use this command:</p>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]114
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]115<pre class="highlight"><code>-> magick compare -metric PSNR rose.jpg reconstruct.jpg difference.png
11628.31
117</code></pre>
cristycecc9492015-06-09 16:53:50 +0000[diff] [blame]118
Cristy72727872017-12-08 15:08:14 -0500[diff] [blame^]119<p>If the reconstructed image is a subimage of the image, the compare program returns the best match offset. In addition, it returns a similarity image such that an exact match location is completely white and if none of the pixels match, black, otherwise some gray level in-between:</p>
120
121<pre class="highlight"><code>-> magick compare -metric RMSE -subimage-search logo.png wizard.jpg similarity.gif
12285.05 (0.00129778) @ 353,157
123</code></pre>
124
125<p>You can find additional examples of using <code>compare</code> in <a href="http://www.ibm.com/developerworks/library/l-graf/?ca=dnt-428">Graphics from the Command Line</a>. Further discussion is available in <a href="http://www.ibm.com/developerworks/library/l-graf2/?ca=dgr-lnxw15GraphicsLine">More Graphics from the Command Line</a> and <a href="https://www.imagemagick.org/Usage/">Examples of ImageMagick Usage</a>.</p>
126
127<p>The compare program returns 2 on error otherwise 0 if the images are similar or 1 if they are dissimilar.</p>
128
129<h2 class="magick-post-title"><a id="options"></a>Option Summary</h2>
130
131<p>The <code>compare</code> command recognizes these options. Click on an option to get more details about how that option works.</p>
132
133<table class="table table-sm table-striped">
134 <tbody>
135 <tr>
136 <th align="left">Option</th>
137 <th align="left">Description</th>
138 </tr>
139
140 <tr>
141 <td><a href="../command-line-options.html#alpha">-alpha</a></td>
142 <td>on, activate, off, deactivate, set, opaque, copy",
143transparent, extract, background, or shape the alpha channel</td>
144 </tr>
145
146 <tr>
147 <td><a href="../command-line-options.html#authenticate">-authenticate <var>value</var></a></td>
148 <td>decrypt image with this password</td>
149 </tr>
150
151 <tr>
152 <td><a href="../command-line-options.html#background">-background <var>color</var></a></td>
153 <td>background color</td>
154 </tr>
155
156 <tr>
157 <td><a href="../command-line-options.html#brightness-contrast">-brightness-contrast <var>geometry</var></a></td>
158 <td>improve brightness / contrast of the image</td>
159 </tr>
160
161 <tr>
162 <td><a href="../command-line-options.html#channel">-channel <var>type</var></a></td>
163 <td>apply option to select image channels</td>
164 </tr>
165
166 <tr>
167 <td><a href="../command-line-options.html#colorspace">-colorspace <var>type</var></a></td>
168 <td>set image colorspace</td>
169 </tr>
170
171 <tr>
172 <td><a href="../command-line-options.html#compose">-compose <var>operator</var></a></td>
173 <td>set image composite operator</td>
174 </tr>
175
176 <tr>
177 <td><a href="../command-line-options.html#crop">-crop <var>geometry</var></a></td>
178 <td>crop the image</td>
179 </tr>
180
181 <tr>
182 <td><a href="../command-line-options.html#decipher">-decipher <var>filename</var></a></td>
183 <td>convert cipher pixels to plain</td>
184 </tr>
185
186 <tr>
187 <td><a href="../command-line-options.html#debug">-debug <var>events</var></a></td>
188 <td>display copious debugging information</td>
189 </tr>
190
191 <tr>
192 <td><a href="../command-line-options.html#define">-define <var>format:option</var></a></td>
193 <td>define one or more image format options</td>
194 </tr>
195
196 <tr>
197 <td><a href="../command-line-options.html#density">-density <var>geometry</var></a></td>
198 <td>horizontal and vertical density of the image</td>
199 </tr>
200
201 <tr>
202 <td><a href="../command-line-options.html#depth">-depth <var>value</var></a></td>
203 <td>image depth</td>
204 </tr>
205
206 <tr>
207 <td><a href="../command-line-options.html#dissimilarity-threshold">-dissimilarity-threshold <var>value</var></a></td>
208 <td>maximum distortion for (sub)image match (default 0.2)</td>
209 </tr>
210
211 <tr>
212 <td><a href="../command-line-options.html#distort">-distort <var>type coefficients</var></a></td>
213 <td>distort image</td>
214 </tr>
215
216 <tr>
217 <td><a href="../command-line-options.html#encipher">-encipher <var>filename</var></a></td>
218 <td>convert plain pixels to cipher pixels</td>
219 </tr>
220
221 <tr>
222 <td><a href="../command-line-options.html#extract">-extract <var>geometry</var></a></td>
223 <td>extract area from image</td>
224 </tr>
225
226 <tr>
227 <td><a href="../command-line-options.html#fuzz">-fuzz <var>distance</var></a></td>
228 <td>colors within this distance are considered equal</td>
229 </tr>
230
231 <tr>
232 <td><a href="../command-line-options.html#gravity">-gravity <var>type</var></a></td>
233 <td>horizontal and vertical text placement</td>
234 </tr>
235
236 <tr>
237 <td><a href="../command-line-options.html#help">-help</a></td>
238 <td>print program options</td>
239 </tr>
240
241 <tr>
242 <td><a href="../command-line-options.html#highlight-color">-highlight-color <var>color</var></a></td>
243 <td>emphasize pixel differences with this color</td>
244 </tr>
245
246 <tr>
247 <td><a href="../command-line-options.html#identify">-identify</a></td>
248 <td>identify the format and characteristics of the image</td>
249 </tr>
250
251 <tr>
252 <td><a href="../command-line-options.html#interlace">-interlace <var>type</var></a></td>
253 <td>type of image interlacing scheme</td>
254 </tr>
255
256 <tr>
257 <td><a href="../command-line-options.html#level">-level <var>value</var></a></td>
258 <td>adjust the level of image contrast</td>
259 </tr>
260
261 <tr>
262 <td><a href="../command-line-options.html#limit">-limit <var>type value</var></a></td>
263 <td>pixel cache resource limit</td>
264 </tr>
265
266 <tr>
267 <td><a href="../command-line-options.html#log">-log <var>format</var></a></td>
268 <td>format of debugging information</td>
269 </tr>
270
271 <tr>
272 <td><a href="../command-line-options.html#lowlight-color">-lowlight-color <var>color</var></a></td>
273 <td>de-emphasize pixel differences with this color</td>
274 </tr>
275
276 <tr>
277 <td><a href="../command-line-options.html#metric">-metric <var>type</var></a></td>
278 <td>measure differences between images with this metric</td>
279 </tr>
280
281 <tr>
282 <td><a href="../command-line-options.html#negate">-negate</a></td>
283 <td>replace each pixel with its complementary color </td>
284 </tr>
285
286 <tr>
287 <td><a href="../command-line-options.html#profile">-profile <var>filename</var></a></td>
288 <td>add, delete, or apply an image profile</td>
289 </tr>
290
291 <tr>
292 <td><a href="../command-line-options.html#quality">-quality <var>value</var></a></td>
293 <td>JPEG/MIFF/PNG compression level</td>
294 </tr>
295
296 <tr>
297 <td><a href="../command-line-options.html#quantize">-quantize <var>colorspace</var></a></td>
298 <td>reduce image colors in this colorspace</td>
299 </tr>
300
301 <tr>
302 <td><a href="../command-line-options.html#quiet">-quiet</a></td>
303 <td>suppress all warning messages</td>
304 </tr>
305
306 <tr>
307 <td><a href="../command-line-options.html#read-mask">-read-mask <var>filename</var></a></td>
308 <td>associate a read mask with the image</td>
309 </tr>
310
311 <tr>
312 <td><a href="../command-line-options.html#regard-warnings">-regard-warnings</a></td>
313 <td>pay attention to warning messages.</td>
314 </tr>
315
316 <tr>
317 <td><a href="../command-line-options.html#repage">-repage <var>geometry</var></a></td>
318 <td>size and location of an image canvas</td>
319 </tr>
320
321 <tr>
322 <td><a href="../command-line-options.html#resize">-resize <var>geometry</var></a></td>
323 <td>resize the image</td>
324 </tr>
325
326 <tr>
327 <td><a href="../command-line-options.html#respect-parentheses">-respect-parentheses</a></td>
328 <td>settings remain in effect until parenthesis boundary.</td>
329 </tr>
330
331 <tr>
332 <td><a href="../command-line-options.html#rotate">-rotate <var>degrees</var></a></td>
333 <td>apply Paeth rotation to the image</td>
334 </tr>
335
336 <tr>
337 <td><a href="../command-line-options.html#sampling-factor">-sampling-factor <var>geometry</var></a></td>
338 <td>horizontal and vertical sampling factor</td>
339 </tr>
340
341 <tr>
342 <td><a href="../command-line-options.html#seed">-seed <var>value</var></a></td>
343 <td>seed a new sequence of pseudo-random numbers</td>
344 </tr>
345
346 <tr>
347 <td><a href="../command-line-options.html#separate">-separate</a></td>
348 <td>separate an image channel into a grayscale image</td>
349 </tr>
350
351 <tr>
352 <td><a href="../command-line-options.html#set">-set <var>attribute value</var></a></td>
353 <td>set an image attribute</td>
354 </tr>
355
356 <tr>
357 <td><a href="../command-line-options.html#sigmoidal">-sigmoidal-contrast <var>geometry</var></a></td>
358 <td>increase the contrast without saturating highlights or shadows</td>
359 </tr>
360
361 <tr>
362 <td><a href="../command-line-options.html#similarity-threshold">-similarity-threshold <var>value</var></a></td>
363 <td>minimum distortion for (sub)image match (default 0.0)</td>
364 </tr>
365
366 <tr>
367 <td><a href="../command-line-options.html#size">-size <var>geometry</var></a></td>
368 <td>width and height of image</td>
369 </tr>
370
371 <tr>
372 <td><a href="../command-line-options.html#subimage-search">-subimage-search</a></td>
373 <td>search for subimage</td>
374 </tr>
375
376 <tr>
377 <td><a href="../command-line-options.html#synchronize">-synchronize</a></td>
378 <td>synchronize image to storage device</td>
379 </tr>
380
381 <tr>
382 <td><a href="../command-line-options.html#taint">-taint</a></td>
383 <td>mark the image as modified</td>
384 </tr>
385
386 <tr>
387 <td><a href="../command-line-options.html#transparent-color">-transparent-color <var>color</var></a></td>
388 <td>transparent color</td>
389 </tr>
390
391 <tr>
392 <td><a href="../command-line-options.html#trim">-trim</a></td>
393 <td>trim image edges</td>
394 </tr>
395
396 <tr>
397 <td><a href="../command-line-options.html#verbose">-verbose</a></td>
398 <td>print detailed information about the image</td>
399 </tr>
400
401 <tr>
402 <td><a href="../command-line-options.html#version">-version</a></td>
403 <td>print version information</td>
404 </tr>
405
406 <tr>
407 <td><a href="../command-line-options.html#virtual-pixel">-virtual-pixel <var>method</var></a></td>
408 <td>access method for pixels outside the boundaries of the image</td>
409 </tr>
410
411 <tr>
412 <td><a href="../command-line-options.html#write-mask">-read-mask <var>filename</var></a></td>
413 <td>associate a write mask with the image</td>
414 </tr>
415
416 </tbody>
417</table>
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