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cristy6f77f692011-02-15 15:31:39 +0000193<h1>Module histogram
194 Methods</h1>
195<p class="navigation-index">[<a href="#GetImageHistogram">GetImageHistogram</a> &bull; <a href="#IsHistogramImage">IsHistogramImage</a> &bull; <a href="#IsPaletteImage">IsPaletteImage</a> &bull; <a href="#MinMaxStretchImage">MinMaxStretchImage</a> &bull; <a href="#GetNumberColors">GetNumberColors</a> &bull; <a href="#UniqueImageColors">UniqueImageColors</a>]</p>
cristy3ed852e2009-09-05 21:47:34 +0000196
cristy6f77f692011-02-15 15:31:39 +0000197<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
198_8c.html" id="GetImageHistogram">GetImageHistogram</a></h2>
199<div class="doc-section">
200
201<p>GetImageHistogram() returns the unique colors in an image.</p>
202
203<p>The format of the GetImageHistogram method is:</p>
204
205<pre class="code">
206 size_t GetImageHistogram(const Image *image,
207 size_t *number_colors,ExceptionInfo *exception)
208</pre>
209
210<p>A description of each parameter follows.</p>
211
212<h5>image</h5>
213<p>the image.</p>
214
215<h5>file</h5>
216<p>Write a histogram of the color distribution to this file handle.</p>
217
218<h5>exception</h5>
219<p>return any errors or warnings in this structure.</p>
220
221 </div>
222<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
223_8c.html" id="IsHistogramImage">IsHistogramImage</a></h2>
224<div class="doc-section">
225
226<p>IsHistogramImage() returns MagickTrue if the image has 1024 unique colors or less.</p>
227
228<p>The format of the IsHistogramImage method is:</p>
229
230<pre class="code">
231 MagickBooleanType IsHistogramImage(const Image *image,
232 ExceptionInfo *exception)
233</pre>
234
235<p>A description of each parameter follows.</p>
236
237<h5>image</h5>
238<p>the image.</p>
239
240<h5>exception</h5>
241<p>return any errors or warnings in this structure.</p>
242
243 </div>
244<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
245_8c.html" id="IsPaletteImage">IsPaletteImage</a></h2>
246<div class="doc-section">
247
248<p>IsPaletteImage() returns MagickTrue if the image is PseudoClass and has 256 unique colors or less.</p>
249
250<p>The format of the IsPaletteImage method is:</p>
251
252<pre class="code">
253 MagickBooleanType IsPaletteImage(const Image *image,
254 ExceptionInfo *exception)
255</pre>
256
257<p>A description of each parameter follows.</p>
258
259<h5>image</h5>
260<p>the image.</p>
261
262<h5>exception</h5>
263<p>return any errors or warnings in this structure.</p>
264
265 </div>
266<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
267_8c.html" id="MinMaxStretchImage">MinMaxStretchImage</a></h2>
268<div class="doc-section">
269
270<p>MinMaxStretchImage() uses the exact minimum and maximum values found in each of the channels given, as the BlackPoint and WhitePoint to linearly stretch the colors (and histogram) of the image. The stretch points are also moved further inward by the adjustment values given.</p>
271
272<p>If the adjustment values are both zero this function is equivelent to a perfect normalization (or autolevel) of the image.</p>
273
274<p>Each channel is stretched independantally of each other (producing color distortion) unless the special 'SyncChannels' flag is also provided in the channels setting. If this flag is present the minimum and maximum point will be extracted from all the given channels, and those channels will be stretched by exactly the same amount (preventing color distortion).</p>
275
276<p>In the special case that only ONE value is found in a channel of the image that value is not stretched, that value is left as is.</p>
277
278<p>The 'SyncChannels' is turned on in the 'DefaultChannels' setting by default.</p>
279
280<p>The format of the MinMaxStretchImage method is:</p>
281
282<pre class="code">
283 MagickBooleanType MinMaxStretchImage(Image *image,
284 const ChannelType channel, const double black_adjust,
285 const double white_adjust)
286</pre>
287
288<p>A description of each parameter follows:</p>
289
290<h5>image</h5>
291<p>The image to auto-level</p>
292
293<h5>channel</h5>
294<p>The channels to auto-level. If the special 'SyncChannels' flag is set, all the given channels are stretched by the same amount.</p>
295
296<h5>black_adjust, white_adjust</h5>
297<p>Move the Black/White Point inward from the minimum and maximum points by this color value.</p>
298
299 </div>
300<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
301_8c.html" id="GetNumberColors">GetNumberColors</a></h2>
302<div class="doc-section">
303
304<p>GetNumberColors() returns the number of unique colors in an image.</p>
305
306<p>The format of the GetNumberColors method is:</p>
307
308<pre class="code">
309 size_t GetNumberColors(const Image *image,FILE *file,
310 ExceptionInfo *exception)
311</pre>
312
313<p>A description of each parameter follows.</p>
314
315<h5>image</h5>
316<p>the image.</p>
317
318<h5>file</h5>
319<p>Write a histogram of the color distribution to this file handle.</p>
320
321<h5>exception</h5>
322<p>return any errors or warnings in this structure.</p>
323
324 </div>
325<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
326_8c.html" id="UniqueImageColors">UniqueImageColors</a></h2>
327<div class="doc-section">
328
329<p>UniqueImageColors() returns the unique colors of an image.</p>
330
331<p>The format of the UniqueImageColors method is:</p>
332
333<pre class="code">
334 Image *UniqueImageColors(const Image *image,ExceptionInfo *exception)
335</pre>
336
337<p>A description of each parameter follows.</p>
338
339<h5>image</h5>
340<p>the image.</p>
341
342<h5>exception</h5>
343<p>return any errors or warnings in this structure.</p>
344
345 </div>
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