1 2 3 4 5 <!DOCTYPE html> 6 <html lang="en"> 7 <head> 8 <title>ImageMagick: MagickCore, C API for ImageMagick: Image Histograms</title> 9 <meta charset="utf-8" /> 10 <meta http-equiv="X-UA-Compatible" content="IE=edge" /> 11 <meta name="viewport" content="width=device-width, initial-scale=1" /> 12 <meta http-equiv="content-type" content="text/html; charset=utf-8"/> 13 <meta name="application-name" content="ImageMagick"/> 14 <meta name="description" content="ImageMagick is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 200) including PNG, JPEG, JPEG-2000, GIF, WebP, Postscript, PDF, and SVG. 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44 </script> 45 <nav class="magick-nav"> 46 <a class="magick-nav-item " href="../index.html">Home</a> 47 <a class="magick-nav-item " href="../binary-releases.html">Download</a> 48 <a class="magick-nav-item " href="../command-line-tools.html">Tools</a> 49 <a class="magick-nav-item " href="../command-line-processing.html">Command-line</a> 50 <a class="magick-nav-item " href="../resources.html">Resources</a> 51 <a class="magick-nav-item " href="api.html">Develop</a> 52 <a class="magick-nav-item " href="http://www.imagemagick.org/script/search.php">Search</a> 53 <a class="magick-nav-item pull-right" href="https://www.imagemagick.org/discourse-server/">Community</a> 54 </nav> 55 </div> 56 </div> 57 <div class="container"> 58 <div class="magick-header"> 59 <p class="text-center"><a href="histogram.html#GetImageHistogram">GetImageHistogram</a> • <a href="histogram.html#IdentifyPaletteImage">IdentifyPaletteImage</a> • <a href="histogram.html#IsHistogramImage">IsHistogramImage</a> • <a href="histogram.html#IsPaletteImage">IsPaletteImage</a> • <a href="histogram.html#MinMaxStretchImage">MinMaxStretchImage</a> • <a href="histogram.html#GetNumberColors">GetNumberColors</a> • <a href="histogram.html#UniqueImageColors">UniqueImageColors</a></p> 60 61 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="GetImageHistogram">GetImageHistogram</a></h2> 62 63 <p>GetImageHistogram() returns the unique colors in an image.</p> 64 65 <p>The format of the GetImageHistogram method is:</p> 66 67 <pre class="text"> 68 size_t GetImageHistogram(const Image *image, 69 size_t *number_colors,ExceptionInfo *exception) 70 </pre> 71 72 <p>A description of each parameter follows.</p> 73 74 <dt>image</dt> 75 <p>the image.</p> 76 77 <dt>file</dt> 78 <p>Write a histogram of the color distribution to this file handle.</p> 79 80 <dt>exception</dt> 81 <p>return any errors or warnings in this structure.</p> 82 83 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="IdentifyPaletteImage">IdentifyPaletteImage</a></h2> 84 85 <p>IdentifyPaletteImage() returns MagickTrue if the image has 256 unique colors or less.</p> 86 87 <p>The format of the IdentifyPaletteImage method is:</p> 88 89 <pre class="text"> 90 MagickBooleanType IdentifyPaletteImage(const Image *image, 91 ExceptionInfo *exception) 92 </pre> 93 94 <p>A description of each parameter follows.</p> 95 96 <dt>image</dt> 97 <p>the image.</p> 98 99 <dt>exception</dt> 100 <p>return any errors or warnings in this structure.</p> 101 102 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="IsHistogramImage">IsHistogramImage</a></h2> 103 104 <p>IsHistogramImage() returns MagickTrue if the image has 1024 unique colors or less.</p> 105 106 <p>The format of the IsHistogramImage method is:</p> 107 108 <pre class="text"> 109 MagickBooleanType IsHistogramImage(const Image *image, 110 ExceptionInfo *exception) 111 </pre> 112 113 <p>A description of each parameter follows.</p> 114 115 <dt>image</dt> 116 <p>the image.</p> 117 118 <dt>exception</dt> 119 <p>return any errors or warnings in this structure.</p> 120 121 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="IsPaletteImage">IsPaletteImage</a></h2> 122 123 <p>IsPaletteImage() returns MagickTrue if the image is PseudoClass and has 256 unique colors or less.</p> 124 125 <p>The format of the IsPaletteImage method is:</p> 126 127 <pre class="text"> 128 MagickBooleanType IsPaletteImage(const Image *image) 129 </pre> 130 131 <p>A description of each parameter follows.</p> 132 133 <dt>image</dt> 134 <p>the image.</p> 135 136 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="MinMaxStretchImage">MinMaxStretchImage</a></h2> 137 138 <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> 139 140 <p>If the adjustment values are both zero this function is equivalent to a perfect normalization (or autolevel) of the image.</p> 141 142 <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> 143 144 <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> 145 146 <p>The 'SyncChannels' is turned on in the 'DefaultChannels' setting by default.</p> 147 148 <p>The format of the MinMaxStretchImage method is:</p> 149 150 <pre class="text"> 151 MagickBooleanType MinMaxStretchImage(Image *image,const double black, 152 const double white,const double gamma,ExceptionInfo *exception) 153 </pre> 154 155 <p>A description of each parameter follows:</p> 156 157 <dd> 158 </dd> 159 160 <dd> </dd> 161 <dl class="dl-horizontal"> 162 <dt>image</dt> 163 <dd>The image to auto-level </dd> 164 165 <dd> </dd> 166 <dt>black, white</dt> 167 <dd> move the black / white point inward from the minimum and maximum points by this color value. </dd> 168 169 <dd> </dd> 170 <dt>gamma</dt> 171 <dd>the gamma. </dd> 172 173 <dd> </dd> 174 <dt>exception</dt> 175 <dd>return any errors or warnings in this structure. </dd> 176 177 <dd> </dd> 178 </dl> 179 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="GetNumberColors">GetNumberColors</a></h2> 180 181 <p>GetNumberColors() returns the number of unique colors in an image.</p> 182 183 <p>The format of the GetNumberColors method is:</p> 184 185 <pre class="text"> 186 size_t GetNumberColors(const Image *image,FILE *file, 187 ExceptionInfo *exception) 188 </pre> 189 190 <p>A description of each parameter follows.</p> 191 192 <dt>image</dt> 193 <p>the image.</p> 194 195 <dt>file</dt> 196 <p>Write a histogram of the color distribution to this file handle.</p> 197 198 <dt>exception</dt> 199 <p>return any errors or warnings in this structure.</p> 200 201 <h2><a href="http://www.imagemagick.org/api/MagickCore/histogram_8c.html" id="UniqueImageColors">UniqueImageColors</a></h2> 202 203 <p>UniqueImageColors() returns the unique colors of an image.</p> 204 205 <p>The format of the UniqueImageColors method is:</p> 206 207 <pre class="text"> 208 Image *UniqueImageColors(const Image *image,ExceptionInfo *exception) 209 </pre> 210 211 <p>A description of each parameter follows.</p> 212 213 <dt>image</dt> 214 <p>the image.</p> 215 216 <dt>exception</dt> 217 <p>return any errors or warnings in this structure.</p> 218 219 </div> 220 <footer class="magick-footer"> 221 <p><a href="../support.html">Donate</a> 222 <a href="../sitemap.html">Sitemap</a> 223 <a href="../links.html">Related</a> 224 <a href="../architecture.html">Architecture</a> 225 </p> 226 <p><a href="histogram.html#">Back to top</a> 227 <a href="http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x89AB63D48277377A">Public Key</a> 228 <a href="http://www.imagemagick.org/script/contact.php">Contact Us</a></p> 229 <p><small> 1999-2016 ImageMagick Studio LLC</small></p> 230 </footer> 231 </div><!-- /.container --> 232 233 <script src="https://localhost/ajax/libs/jquery/1.11.3/jquery.min.js"></script> 234 <script src="../js/magick.html"></script> 235 </div> 236 </body> 237 </html> 238
