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cristy350dea42011-02-15 17:31:04 +0000196<h1>Module histogram Methods</h1>
cristy6f77f692011-02-15 15:31:39 +0000197<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 +0000198
cristy350dea42011-02-15 17:31:04 +0000199<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="GetImageHistogram">GetImageHistogram</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000200<div class="doc-section">
201
202<p>GetImageHistogram() returns the unique colors in an image.</p>
203
204<p>The format of the GetImageHistogram method is:</p>
205
206<pre class="code">
207 size_t GetImageHistogram(const Image *image,
208 size_t *number_colors,ExceptionInfo *exception)
209</pre>
210
211<p>A description of each parameter follows.</p>
212
213<h5>image</h5>
214<p>the image.</p>
215
216<h5>file</h5>
217<p>Write a histogram of the color distribution to this file handle.</p>
218
219<h5>exception</h5>
220<p>return any errors or warnings in this structure.</p>
221
222 </div>
cristy350dea42011-02-15 17:31:04 +0000223<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="IsHistogramImage">IsHistogramImage</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000224<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>
cristy350dea42011-02-15 17:31:04 +0000244<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="IsPaletteImage">IsPaletteImage</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000245<div class="doc-section">
246
247<p>IsPaletteImage() returns MagickTrue if the image is PseudoClass and has 256 unique colors or less.</p>
248
249<p>The format of the IsPaletteImage method is:</p>
250
251<pre class="code">
252 MagickBooleanType IsPaletteImage(const Image *image,
253 ExceptionInfo *exception)
254</pre>
255
256<p>A description of each parameter follows.</p>
257
258<h5>image</h5>
259<p>the image.</p>
260
261<h5>exception</h5>
262<p>return any errors or warnings in this structure.</p>
263
264 </div>
cristy350dea42011-02-15 17:31:04 +0000265<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="MinMaxStretchImage">MinMaxStretchImage</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000266<div class="doc-section">
267
268<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>
269
270<p>If the adjustment values are both zero this function is equivelent to a perfect normalization (or autolevel) of the image.</p>
271
272<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>
273
274<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>
275
276<p>The 'SyncChannels' is turned on in the 'DefaultChannels' setting by default.</p>
277
278<p>The format of the MinMaxStretchImage method is:</p>
279
280<pre class="code">
281 MagickBooleanType MinMaxStretchImage(Image *image,
282 const ChannelType channel, const double black_adjust,
283 const double white_adjust)
284</pre>
285
286<p>A description of each parameter follows:</p>
287
288<h5>image</h5>
289<p>The image to auto-level</p>
290
291<h5>channel</h5>
292<p>The channels to auto-level. If the special 'SyncChannels' flag is set, all the given channels are stretched by the same amount.</p>
293
294<h5>black_adjust, white_adjust</h5>
295<p>Move the Black/White Point inward from the minimum and maximum points by this color value.</p>
296
297 </div>
cristy350dea42011-02-15 17:31:04 +0000298<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="GetNumberColors">GetNumberColors</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000299<div class="doc-section">
300
301<p>GetNumberColors() returns the number of unique colors in an image.</p>
302
303<p>The format of the GetNumberColors method is:</p>
304
305<pre class="code">
306 size_t GetNumberColors(const Image *image,FILE *file,
307 ExceptionInfo *exception)
308</pre>
309
310<p>A description of each parameter follows.</p>
311
312<h5>image</h5>
313<p>the image.</p>
314
315<h5>file</h5>
316<p>Write a histogram of the color distribution to this file handle.</p>
317
318<h5>exception</h5>
319<p>return any errors or warnings in this structure.</p>
320
321 </div>
cristy350dea42011-02-15 17:31:04 +0000322<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="UniqueImageColors">UniqueImageColors</a></h2>
cristy6f77f692011-02-15 15:31:39 +0000323<div class="doc-section">
324
325<p>UniqueImageColors() returns the unique colors of an image.</p>
326
327<p>The format of the UniqueImageColors method is:</p>
328
329<pre class="code">
330 Image *UniqueImageColors(const Image *image,ExceptionInfo *exception)
331</pre>
332
333<p>A description of each parameter follows.</p>
334
335<h5>image</h5>
336<p>the image.</p>
337
338<h5>exception</h5>
339<p>return any errors or warnings in this structure.</p>
340
341 </div>
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