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168<div class="main">
169
cristy307ba182010-12-25 01:00:34 +0000[diff] [blame]170<h1>Module compare
171 Methods</h1>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]172<p class="navigation-index">[<a href="#CompareImageChannels">CompareImageChannels</a> &bull; <a href="#GetImageChannelDistortion">GetImageChannelDistortion</a> &bull; <a href="#GetImageChannelDistrortion">GetImageChannelDistrortion</a> &bull; <a href="#IsImagesEqual">IsImagesEqual</a> &bull; <a href="#SimilarityImage">SimilarityImage</a>]</p>
173
174<h2><a href="http://www.imagemagick.org/api/MagickCore/compare
175_8c.html" target="source" name="CompareImageChannels">CompareImageChannels</a></h2>
176<div class="doc-section">
177
178<p>CompareImageChannels() compares one or more image channels of an image to a reconstructed image and returns the difference image.</p></ol>
179
180<p>The format of the CompareImageChannels method is:</p>
181
182<pre class="code">
183 Image *CompareImageChannels(const Image *image,
184 const Image *reconstruct_image,const ChannelType channel,
185 const MetricType metric,double *distortion,ExceptionInfo *exception)
186</pre>
187
188<p>A description of each parameter follows:</p></ol>
189
190<h5>image</h5>
191<ol><p>the image.</p></ol>
192
193<h5>reconstruct_image</h5>
194<ol><p>the reconstruct image.</p></ol>
195
196<h5>channel</h5>
197<ol><p>the channel.</p></ol>
198
199<h5>metric</h5>
200<ol><p>the metric.</p></ol>
201
202<h5>distortion</h5>
203<ol><p>the computed distortion between the images.</p></ol>
204
205<h5>exception</h5>
206<ol><p>return any errors or warnings in this structure.</p></ol>
207
208 </div>
209<h2><a href="http://www.imagemagick.org/api/MagickCore/compare
210_8c.html" target="source" name="GetImageChannelDistortion">GetImageChannelDistortion</a></h2>
211<div class="doc-section">
212
213<p>GetImageChannelDistortion() compares one or more image channels of an image to a reconstructed image and returns the specified distortion metric.</p></ol>
214
215<p>The format of the CompareImageChannels method is:</p>
216
217<pre class="code">
218 MagickBooleanType GetImageChannelDistortion(const Image *image,
219 const Image *reconstruct_image,const ChannelType channel,
220 const MetricType metric,double *distortion,ExceptionInfo *exception)
221</pre>
222
223<p>A description of each parameter follows:</p></ol>
224
225<h5>image</h5>
226<ol><p>the image.</p></ol>
227
228<h5>reconstruct_image</h5>
229<ol><p>the reconstruct image.</p></ol>
230
231<h5>channel</h5>
232<ol><p>the channel.</p></ol>
233
234<h5>metric</h5>
235<ol><p>the metric.</p></ol>
236
237<h5>distortion</h5>
238<ol><p>the computed distortion between the images.</p></ol>
239
240<h5>exception</h5>
241<ol><p>return any errors or warnings in this structure.</p></ol>
242
243 </div>
244<h2><a href="http://www.imagemagick.org/api/MagickCore/compare
245_8c.html" target="source" name="GetImageChannelDistrortion">GetImageChannelDistrortion</a></h2>
246<div class="doc-section">
247
248<p>GetImageChannelDistrortion() compares the image channels of an image to a reconstructed image and returns the specified distortion metric for each channel.</p></ol>
249
250<p>The format of the CompareImageChannels method is:</p>
251
252<pre class="code">
253 double *GetImageChannelDistortions(const Image *image,
254 const Image *reconstruct_image,const MetricType metric,
255 ExceptionInfo *exception)
256</pre>
257
258<p>A description of each parameter follows:</p></ol>
259
260<h5>image</h5>
261<ol><p>the image.</p></ol>
262
263<h5>reconstruct_image</h5>
264<ol><p>the reconstruct image.</p></ol>
265
266<h5>metric</h5>
267<ol><p>the metric.</p></ol>
268
269<h5>exception</h5>
270<ol><p>return any errors or warnings in this structure.</p></ol>
271
272 </div>
273<h2><a href="http://www.imagemagick.org/api/MagickCore/compare
274_8c.html" target="source" name="IsImagesEqual">IsImagesEqual</a></h2>
275<div class="doc-section">
276
277<p>IsImagesEqual() measures the difference between colors at each pixel location of two images. A value other than 0 means the colors match exactly. Otherwise an error measure is computed by summing over all pixels in an image the distance squared in RGB space between each image pixel and its corresponding pixel in the reconstruct image. The error measure is assigned to these image members:</p>
278
279<pre class="text">
280 o mean_error_per_pixel: The mean error for any single pixel in
281 the image.
282</pre>
283
284<h5>normalized_mean_error</h5>
285<ol><p>The normalized mean quantization error for any single pixel in the image. This distance measure is normalized to a range between 0 and 1. It is independent of the range of red, green, and blue values in the image.</p></ol>
286
287<h5>normalized_maximum_error</h5>
288<ol><p>The normalized maximum quantization error for any single pixel in the image. This distance measure is normalized to a range between 0 and 1. It is independent of the range of red, green, and blue values in your image.</p></ol>
289
290<p>A small normalized mean square error, accessed as image->normalized_mean_error, suggests the images are very similar in spatial layout and color.</p></ol>
291
292<p>The format of the IsImagesEqual method is:</p>
293
294<pre class="code">
295 MagickBooleanType IsImagesEqual(Image *image,
296 const Image *reconstruct_image)
297</pre>
298
299<p>A description of each parameter follows.</p></ol>
300
301<h5>image</h5>
302<ol><p>the image.</p></ol>
303
304<h5>reconstruct_image</h5>
305<ol><p>the reconstruct image.</p></ol>
306
307 </div>
308<h2><a href="http://www.imagemagick.org/api/MagickCore/compare
309_8c.html" target="source" name="SimilarityImage">SimilarityImage</a></h2>
310<div class="doc-section">
311
312<p>SimilarityImage() compares the reference image of the image and 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></ol>
313
314<p>The format of the SimilarityImageImage method is:</p>
315
316<pre class="code">
317 Image *SimilarityImage(const Image *image,const Image *reference,
318 RectangleInfo *offset,double *similarity,ExceptionInfo *exception)
319</pre>
320
321<p>A description of each parameter follows:</p></ol>
322
323<h5>image</h5>
324<ol><p>the image.</p></ol>
325
326<h5>reference</h5>
327<ol><p>find an area of the image that closely resembles this image.</p></ol>
328
329<p>o the best match offset of the reference image within the image.</p></ol>
330
331<h5>similarity</h5>
332<ol><p>the computed similarity between the images.</p></ol>
333
334<h5>exception</h5>
335<ol><p>return any errors or warnings in this structure.</p></ol>
336
337 </div>
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