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12 <title>ImageMagick: MagickCore, C API for ImageMagick: Image Histograms</title>
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150
151</div>
152
153<div class="main">
154
cristy83543962009-10-16 19:04:28 +0000[diff] [blame]155<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 +0000[diff] [blame]156
157<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
cristy83543962009-10-16 19:04:28 +0000[diff] [blame]158_8c.html" target="source" name="GetImageHistogram">GetImageHistogram</a></h2>
159<div class="doc-section">
160
161<p>GetImageHistogram() returns the unique colors in an image.</p></ol>
162
163<p>The format of the GetImageHistogram method is:</p>
164
165<pre class="code">
166 unsigned long GetImageHistogram(const Image *image,
167 unsigned long *number_colors,ExceptionInfo *exception)
168</pre>
169
170<p>A description of each parameter follows.</p></ol>
171
172<h5>image</h5>
173<ol><p>the image.</p></ol>
174
175<h5>file</h5>
176<ol><p>Write a histogram of the color distribution to this file handle.</p></ol>
177
178<h5>exception</h5>
179<ol><p>return any errors or warnings in this structure.</p></ol>
180
181 </div>
182<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
183_8c.html" target="source" name="IsHistogramImage">IsHistogramImage</a></h2>
184<div class="doc-section">
185
186<p>IsHistogramImage() returns MagickTrue if the image has 1024 unique colors or less.</p></ol>
187
188<p>The format of the IsHistogramImage method is:</p>
189
190<pre class="code">
191 MagickBooleanType IsHistogramImage(const Image *image,
192 ExceptionInfo *exception)
193</pre>
194
195<p>A description of each parameter follows.</p></ol>
196
197<h5>image</h5>
198<ol><p>the image.</p></ol>
199
200<h5>exception</h5>
201<ol><p>return any errors or warnings in this structure.</p></ol>
202
203 </div>
204<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
205_8c.html" target="source" name="IsPaletteImage">IsPaletteImage</a></h2>
206<div class="doc-section">
207
208<p>IsPaletteImage() returns MagickTrue if the image is PseudoClass and has 256 unique colors or less.</p></ol>
209
210<p>The format of the IsPaletteImage method is:</p>
211
212<pre class="code">
213 MagickBooleanType IsPaletteImage(const Image *image,
214 ExceptionInfo *exception)
215</pre>
216
217<p>A description of each parameter follows.</p></ol>
218
219<h5>image</h5>
220<ol><p>the image.</p></ol>
221
222<h5>exception</h5>
223<ol><p>return any errors or warnings in this structure.</p></ol>
224
225 </div>
226<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]227_8c.html" target="source" name="MinMaxStretchImage">MinMaxStretchImage</a></h2>
228<div class="doc-section">
229
230<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></ol>
231
232<p>If the adjustment values are both zero this function is equivelent to a perfect normalization (or autolevel) of the image.</p></ol>
233
234<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></ol>
235
236<p>The 'SyncChannels' is turned on in the 'DefaultChannels' setting by default.</p></ol>
237
238<p>The format of the MinMaxStretchImage method is:</p>
239
240<pre class="code">
241 MagickBooleanType MinMaxStretchImage(Image *image,
242 const ChannelType channel, const double black_adjust,
243 const double white_adjust)
244</pre>
245
246<p>A description of each parameter follows:</p></ol>
247
248<h5>image</h5>
249<ol><p>The image to auto-level</p></ol>
250
251<h5>channel</h5>
252<ol><p>The channels to auto-level. If the special 'SyncChannels' flag is set, all the given channels are stretched by the same amount.</p></ol>
253
254<h5>black_adjust, white_adjust</h5>
255<ol><p>Move the Black/White Point inward from the minimum and maximum points by this color value.</p></ol>
256
257 </div>
cristy83543962009-10-16 19:04:28 +0000[diff] [blame]258<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
259_8c.html" target="source" name="GetNumberColors">GetNumberColors</a></h2>
260<div class="doc-section">
261
262<p>GetNumberColors() returns the number of unique colors in an image.</p></ol>
263
264<p>The format of the GetNumberColors method is:</p>
265
266<pre class="code">
267 unsigned long GetNumberColors(const Image *image,FILE *file,
268 ExceptionInfo *exception)
269</pre>
270
271<p>A description of each parameter follows.</p></ol>
272
273<h5>image</h5>
274<ol><p>the image.</p></ol>
275
276<h5>file</h5>
277<ol><p>Write a histogram of the color distribution to this file handle.</p></ol>
278
279<h5>exception</h5>
280<ol><p>return any errors or warnings in this structure.</p></ol>
281
282 </div>
283<h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
284_8c.html" target="source" name="UniqueImageColors">UniqueImageColors</a></h2>
285<div class="doc-section">
286
287<p>UniqueImageColors() returns the unique colors of an image.</p></ol>
288
289<p>The format of the UniqueImageColors method is:</p>
290
291<pre class="code">
292 Image *UniqueImageColors(const Image *image,ExceptionInfo *exception)
293</pre>
294
295<p>A description of each parameter follows.</p></ol>
296
297<h5>image</h5>
298<ol><p>the image.</p></ol>
299
300<h5>exception</h5>
301<ol><p>return any errors or warnings in this structure.</p></ol>
302
303 </div>
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