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158 <p class="navigation-index">[<a href="#GetImageHistogram">GetImageHistogram</a> • <a href="#IsHistogramImage">IsHistogramImage</a> • <a href="#IsPaletteImage">IsPaletteImage</a> • <a href="#MinMaxStretchImage">MinMaxStretchImage</a> • <a href="#GetNumberColors">GetNumberColors</a> • <a href="#UniqueImageColors">UniqueImageColors</a>]</p>
160 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
161 _8c.html" target="source" name="GetImageHistogram">GetImageHistogram</a></h2>
162 <div class="doc-section">
164 <p>GetImageHistogram() returns the unique colors in an image.</p></ol>
166 <p>The format of the GetImageHistogram method is:</p>
169 unsigned long GetImageHistogram(const Image *image,
170 unsigned long *number_colors,ExceptionInfo *exception)
173 <p>A description of each parameter follows.</p></ol>
176 <ol><p>the image.</p></ol>
179 <ol><p>Write a histogram of the color distribution to this file handle.</p></ol>
182 <ol><p>return any errors or warnings in this structure.</p></ol>
185 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
186 _8c.html" target="source" name="IsHistogramImage">IsHistogramImage</a></h2>
187 <div class="doc-section">
189 <p>IsHistogramImage() returns MagickTrue if the image has 1024 unique colors or less.</p></ol>
191 <p>The format of the IsHistogramImage method is:</p>
194 MagickBooleanType IsHistogramImage(const Image *image,
195 ExceptionInfo *exception)
198 <p>A description of each parameter follows.</p></ol>
201 <ol><p>the image.</p></ol>
204 <ol><p>return any errors or warnings in this structure.</p></ol>
207 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
208 _8c.html" target="source" name="IsPaletteImage">IsPaletteImage</a></h2>
209 <div class="doc-section">
211 <p>IsPaletteImage() returns MagickTrue if the image is PseudoClass and has 256 unique colors or less.</p></ol>
213 <p>The format of the IsPaletteImage method is:</p>
216 MagickBooleanType IsPaletteImage(const Image *image,
217 ExceptionInfo *exception)
220 <p>A description of each parameter follows.</p></ol>
223 <ol><p>the image.</p></ol>
226 <ol><p>return any errors or warnings in this structure.</p></ol>
229 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
230 _8c.html" target="source" name="MinMaxStretchImage">MinMaxStretchImage</a></h2>
231 <div class="doc-section">
233 <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>
235 <p>If the adjustment values are both zero this function is equivelent to a perfect normalization (or autolevel) of the image.</p></ol>
237 <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>
239 <p>The 'SyncChannels' is turned on in the 'DefaultChannels' setting by default.</p></ol>
241 <p>The format of the MinMaxStretchImage method is:</p>
244 MagickBooleanType MinMaxStretchImage(Image *image,
245 const ChannelType channel, const double black_adjust,
246 const double white_adjust)
249 <p>A description of each parameter follows:</p></ol>
252 <ol><p>The image to auto-level</p></ol>
255 <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>
257 <h5>black_adjust, white_adjust</h5>
258 <ol><p>Move the Black/White Point inward from the minimum and maximum points by this color value.</p></ol>
261 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
262 _8c.html" target="source" name="GetNumberColors">GetNumberColors</a></h2>
263 <div class="doc-section">
265 <p>GetNumberColors() returns the number of unique colors in an image.</p></ol>
267 <p>The format of the GetNumberColors method is:</p>
270 unsigned long GetNumberColors(const Image *image,FILE *file,
271 ExceptionInfo *exception)
274 <p>A description of each parameter follows.</p></ol>
277 <ol><p>the image.</p></ol>
280 <ol><p>Write a histogram of the color distribution to this file handle.</p></ol>
283 <ol><p>return any errors or warnings in this structure.</p></ol>
286 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram
287 _8c.html" target="source" name="UniqueImageColors">UniqueImageColors</a></h2>
288 <div class="doc-section">
290 <p>UniqueImageColors() returns the unique colors of an image.</p></ol>
292 <p>The format of the UniqueImageColors method is:</p>
295 Image *UniqueImageColors(const Image *image,ExceptionInfo *exception)
298 <p>A description of each parameter follows.</p></ol>
301 <ol><p>the image.</p></ol>
304 <ol><p>return any errors or warnings in this structure.</p></ol>
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