Gitiles
Code Review Sign In
gerrit-public.fairphone.software / platform / external / ImageMagick / 851dbceb0a51cbcd3ed512f074e9f2d797b7cbc1 / . / www / api / quantize.html
blob: c3eca08d6a1d1be1b7cb852aa51067e4f1e81d02 [file] [log] [blame]
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
cristy2c839602010-04-03 02:32:08 +0000[diff] [blame]3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" dir="ltr">
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]4<head>
cristy3de29cc2010-04-15 02:34:44 +0000[diff] [blame]5 <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]6 <meta name="verify-v1" content="g222frIIxcQTrvDR3NBRUSKP3AnMNoqxOkIniCEkV7U=" />
7 <link rel="meta" type="application/rdf+xml" title="ICI" href="http://imagemagick.org/ici.rdf" />
cristy3de29cc2010-04-15 02:34:44 +0000[diff] [blame]8 <style type="text/css" media="all">
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]9 @import url("../../www/magick.css");
cristy3de29cc2010-04-15 02:34:44 +0000[diff] [blame]10 </style>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]11 <link rel="shortcut icon" href="../../images/wand.ico" type="images/vnd.microsoft.icon"/>
12 <title>ImageMagick: MagickCore, C API for ImageMagick: Reduce the Number of Unique Colors in an Image</title>
13 <meta http-equiv="Content-Language" content="en-US"/>
14 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
15 <meta http-equiv="Reply-to" content="magick-users@imagemagick.org"/>
16 <meta name="Generator" content="PHP"/>
17 <meta name="Keywords" content="magickcore, c, api, for, imagemagick:, reduce, the, number, of, unique, colors, in, an, image, ImageMagick, ImageMagic, MagickCore, MagickWand, PerlMagick, Magick++, RMagick, PythonMagick, JMagick, TclMagick, Image, Magick, Magic, Wand, ImageMagickObject, Swiss, Army, Knife, Image, Processing"/>
18 <meta name="Description" content="ImageMagick® is a software suite to create, edit, and compose bitmap images. It can read, convert and write images in a variety of formats (about 100) including GIF, JPEG, JPEG-2000, PNG, PDF, PhotoCD, TIFF, and DPX. Use ImageMagick to translate, flip, mirror, rotate, scale, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves. ImageMagick is free software delivered as a ready-to-run binary distribution or as source code that you can freely use, copy, modify, and distribute. Its license is compatible with the GPL. It runs on all major operating systems. The functionality of ImageMagick is typically utilized from the command line or you can use the features from programs written in your favorite programming language. Choose from these interfaces: MagickCore (C), MagickWand (C), ChMagick (Ch), Magick++ (C++), JMagick (Java), L-Magick (Lisp), PascalMagick (Pascal), PerlMagick (Perl), MagickWand for PHP (PHP), PythonMagick (Python), RMagick (Ruby), or TclMagick (Tcl/TK). With a language interface, use ImageMagick to modify or create images automagically and dynamically."/>
19 <meta name="Rating" content="GENERAL"/>
20 <meta name="Robots" content="INDEX, FOLLOW"/>
21 <meta name="Generator" content="ImageMagick Studio LLC"/>
22 <meta name="Author" content="ImageMagick Studio LLC"/>
23 <meta name="Revisit-after" content="2 DAYS"/>
24 <meta name="Resource-type" content="document"/>
cristy16af1cb2009-12-11 21:38:29 +0000[diff] [blame]25 <meta name="Copyright" content="Copyright (c) 1999-2010 ImageMagick Studio LLC"/>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]26 <meta name="Distribution" content="Global"/>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]27</head>
28
29<body id="www-imagemagick-org">
30<div class="titlebar">
31<a href="../../index.html">
32 <img src="../../images/script.png" alt="[ImageMagick]"
33 style="width: 350px; height: 60px; margin: 28px auto; float: left;" /></a>
34<a href="http://www.networkredux.com">
35 <img src="../../images/networkredux.png" alt="[sponsor]"
36 style="margin: 45px auto; border: 0px; float: left;" /></a>
37<a href="http://www.imagemagick.org/discourse-server/">
38 <img src="../../images/logo.jpg" alt=""
39 style="width: 114px; height: 118px; border: 0px; float: right;" /></a>
40<a href="../../index.html">
41 <img src="../../images/sprite.jpg" alt=""
42 style="width: 114px; height: 118px; border: 0px; float: right;" /></a>
43</div>
44
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]45<div class="westbar">
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]46
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]47<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]48 <a title="About ImageMagick" href="../../index.html">About ImageMagick</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]49</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]50<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]51<div class="menu">
cristybb503372010-05-27 20:51:26 +0000[diff] [blame]52 <a title="Binary Releases" href="../../www/binary-releases.html">Binary Releases</a>
53</div>
54<div class="sub">
55 <a title="Binary Release: Unix" href="../../www/binary-releases.html#unix">Unix</a>
56</div>
57<div class="sub">
58 <a title="Binary Release: MacOS X" href="../../www/binary-releases.html#macosx">Mac OS X</a>
59</div>
60<div class="sub">
61 <a title="Binary Release: Windows" href="../../www/binary-releases.html#windows">Windows</a>
62</div>
63<div class="sep"></div>
64<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]65 <a title="Command-line Tools" href="../../www/command-line-tools.html">Command-line Tools</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]66</div>
67<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]68 <a title="Command-line Tools: Processing" href="../../www/command-line-processing.html">Processing</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]69</div>
70<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]71 <a title="Command-line Tools: Options" href="../../www/command-line-options.html">Options</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]72</div>
73<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]74 <a title="Command-line Tools: Usage" href="http://www.imagemagick.org/Usage/">Usage</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]75</div>
76<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]77 <a title="Program Interfaces" href="../../www/api.html">Program Interfaces</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]78</div>
79<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]80 <a title="Program Interface: MagickWand" href="../../www/magick-wand.html">MagickWand</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]81</div>
82<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]83 <a title="Program Interface: MagickCore" href="../../www/magick-core.html">MagickCore</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]84</div>
85<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]86 <a title="Program Interface: PerlMagick" href="../../www/perl-magick.html">PerlMagick</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]87</div>
88<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]89 <a title="Program Interface: Magick++" href="../../Magick++/">Magick++</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]90</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]91<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]92<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]93 <a title="Install from Source" href="../../www/install-source.html">Install from Source</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]94</div>
95<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]96 <a title="Install from Source: Unix" href="../../www/install-source.html#unix">Unix</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]97</div>
98<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]99 <a title="Install from Source: Windows" href="../../www/install-source.html#windows">Windows</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]100 </div>
101<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]102 <a title="Resources" href="../../www/resources.html">Resources</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]103</div>
cristybb503372010-05-27 20:51:26 +0000[diff] [blame]104<div class="menu">
105 <a title="Architecture" href="../../www/architecture.html">Architecture</a>
106</div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]107<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]108 <a title="Download" href="../../www/download.html">Download</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]109</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]110<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]111<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]112 <a title="Search" href="../http://www.imagemagick.org/script/search.php">Search</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]113</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]114<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]115<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]116 <a title="Site Map"href="../../www/sitemap.html">Site Map</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]117</div>
118<div class="sub">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]119 <a title="Site Map: Links"href="../../www/links.html">Links</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]120</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]121<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]122<div class="menu">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]123 <a title="Sponsors" href="../../www/sponsors.html">Sponsors:</a>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]124
125<div class="sponsbox">
126<div class="sponsor">
cristy851dbce2010-08-06 21:40:00 +0000[diff] [blame^]127 <a title="Sponsor: Flyer drucken" href="http://www.online-druck.biz">Flyer drucken</a><!-- 201109010900 Floeter-->
128</div>
129<div class="sponsor">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]130 <a title="Sponsor: Webdesign Agentur" href="http://www.ventzke-partner.de">Webdesign Agentur</a><!-- 201101010480 invendio.de-->
cristy9b5852d2010-03-08 18:18:01 +0000[diff] [blame]131</div>
132<div class="sponsor">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]133 <a title="Sponsor: LVM Versicherung" href="http://www.neu-reich.de">LVM Versicherung</a><!-- 201101010480 -->
cristy8f900122010-03-05 15:26:31 +0000[diff] [blame]134</div>
135<div class="sponsor">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]136 <a title="Sponsor: Deko.net" href="http://www.deko.net">Deko.net</a><!-- 201101010600 Peterssen-->
cristy1f9e1ed2009-11-18 04:09:38 +0000[diff] [blame]137</div>
138<div class="sponsor">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]139 <a title="Sponsor: Druckerei" href="http://www.print24.de/">Druckerei</a><!-- 201009010720 -->
cristyb4c03bb2009-09-27 13:55:46 +0000[diff] [blame]140</div>
141<div class="sponsor">
cristy83a272e2010-05-07 20:40:35 +0000[diff] [blame]142 <a title="Sponsor: Druckerei Online" href="http://www.allesdruck.de">Druckerei Online</a><!-- 201012011200 allesdruck.de-->
cristyb4c03bb2009-09-27 13:55:46 +0000[diff] [blame]143</div>
cristyfbb4a972010-06-30 17:42:22 +0000[diff] [blame]144<div class="sponsor">
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]145 <a title="Sponsor: Webdesign" href="http://www.renehornig.com/">Webdesign</a><!-- 20111001000240 -->
cristyfbb4a972010-06-30 17:42:22 +0000[diff] [blame]146</div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]147</div>
148</div>
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]149</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]150
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]151<div class="eastbar">
152 <script type="text/javascript">
153 <!--
154 google_ad_client = "pub-3129977114552745";
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]155 google_ad_slot = "0574824969";
156 google_ad_width = 160;
157 google_ad_height = 600;
158 //-->
159 </script>
160 <script type="text/javascript"
161 src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
162 </script>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]163</div>
164
165<div class="main">
166
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]167<p class="navigation-index">[<a href="#QuantizeImage">QuantizeImage</a> &bull; <a href="#AcquireQuantizeInfo">AcquireQuantizeInfo</a> &bull; <a href="#CloneQuantizeInfo">CloneQuantizeInfo</a> &bull; <a href="#CompressImageColormap">CompressImageColormap</a> &bull; <a href="#DestroyQuantizeInfo">DestroyQuantizeInfo</a> &bull; <a href="#GetImageQuantizeError">GetImageQuantizeError</a> &bull; <a href="#GetQuantizeInfo">GetQuantizeInfo</a> &bull; <a href="#PosterizeImage">PosterizeImage</a> &bull; <a href="#QuantizeImage">QuantizeImage</a> &bull; <a href="#QuantizeImages">QuantizeImages</a> &bull; <a href="#RemapImage">RemapImage</a> &bull; <a href="#RemapImages">RemapImages</a> &bull; <a href="#SetGrayscaleImage">SetGrayscaleImage</a>]</p>
168
169<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
170_8c.html" target="source" name="QuantizeImage">QuantizeImage</a></h2>
171<div class="doc-section">
172
173<p>QuantizeImage() takes a standard RGB or monochrome images and quantizes them down to some fixed number of colors.</p></ol>
174
175<p>For purposes of color allocation, an image is a set of n pixels, where each pixel is a point in RGB space. RGB space is a 3-dimensional vector space, and each pixel, Pi, is defined by an ordered triple of red, green, and blue coordinates, (Ri, Gi, Bi).</p></ol>
176
177<p>Each primary color component (red, green, or blue) represents an intensity which varies linearly from 0 to a maximum value, Cmax, which corresponds to full saturation of that color. Color allocation is defined over a domain consisting of the cube in RGB space with opposite vertices at (0,0,0) and (Cmax, Cmax, Cmax). QUANTIZE requires Cmax = 255.</p></ol>
178
179<p>The algorithm maps this domain onto a tree in which each node represents a cube within that domain. In the following discussion these cubes are defined by the coordinate of two opposite vertices:</p>
180
181<pre class="text">
182 the origin.
183</pre>
184
185<p>The tree's root node represents the entire domain, (0,0,0) through (Cmax,Cmax,Cmax). Each lower level in the tree is generated by subdividing one node's cube into eight smaller cubes of equal size. This corresponds to bisecting the parent cube with planes passing through the midpoints of each edge.</p></ol>
186
187<p>The basic algorithm operates in three phases: Classification, Reduction, and Assignment. Classification builds a color description tree for the image. Reduction collapses the tree until the number it represents, at most, the number of colors desired in the output image. Assignment defines the output image's color map and sets each pixel's color by restorage_class in the reduced tree. Our goal is to minimize the numerical discrepancies between the original colors and quantized colors (quantization error).</p></ol>
188
189<p>Classification begins by initializing a color description tree of sufficient depth to represent each possible input color in a leaf. However, it is impractical to generate a fully-formed color description tree in the storage_class phase for realistic values of Cmax. If colors components in the input image are quantized to k-bit precision, so that Cmax= 2k-1, the tree would need k levels below the root node to allow representing each possible input color in a leaf. This becomes prohibitive because the tree's total number of nodes is 1 + sum(i=1, k, 8k).</p></ol>
190
191<p>A complete tree would require 19,173,961 nodes for k = 8, Cmax = 255.</p>
192<h5>avoid building a fully populated tree, QUANTIZE</h5>
193<ol><p>(1) Initializes data structures for nodes only as they are needed; (2) Chooses a maximum depth for the tree as a function of the desired number of colors in the output image (currently log2(colormap size)).</p></ol>
194
195<p>For each pixel in the input image, storage_class scans downward from the root of the color description tree. At each level of the tree it identifies the single node which represents a cube in RGB space containing the pixel's color. It updates the following data for each such node:</p>
196
197<pre class="text">
198 n1: Number of pixels whose color is contained in the RGB cube which
199 this node represents;
200</pre>
201
202<p>n2: Number of pixels whose color is not represented in a node at lower depth in the tree; initially, n2 = 0 for all nodes except leaves of the tree.</p></ol>
203
204<p>Sr, Sg, Sb: Sums of the red, green, and blue component values for all pixels not classified at a lower depth. The combination of these sums and n2 will ultimately characterize the mean color of a set of pixels represented by this node.</p></ol>
205
206<p>E: the distance squared in RGB space between each pixel contained within a node and the nodes' center. This represents the quantization error for a node.</p></ol>
207
208<p>Reduction repeatedly prunes the tree until the number of nodes with n2 > 0 is less than or equal to the maximum number of colors allowed in the output image. On any given iteration over the tree, it selects those nodes whose E count is minimal for pruning and merges their color statistics upward. It uses a pruning threshold, Ep, to govern node selection as follows:</p></ol>
209
210<p>Ep = 0 while number of nodes with (n2 > 0) > required maximum number of colors prune all nodes such that E <= Ep Set Ep to minimum E in remaining nodes</p></ol>
211
212<p>This has the effect of minimizing any quantization error when merging two nodes together.</p></ol>
213
214<p>When a node to be pruned has offspring, the pruning procedure invokes itself recursively in order to prune the tree from the leaves upward. n2, Sr, Sg, and Sb in a node being pruned are always added to the corresponding data in that node's parent. This retains the pruned node's color characteristics for later averaging.</p></ol>
215
216<p>For each node, n2 pixels exist for which that node represents the smallest volume in RGB space containing those pixel's colors. When n2 > 0 the node will uniquely define a color in the output image. At the beginning of reduction, n2 = 0 for all nodes except a the leaves of the tree which represent colors present in the input image.</p></ol>
217
218<p>The other pixel count, n1, indicates the total number of colors within the cubic volume which the node represents. This includes n1 - n2 pixels whose colors should be defined by nodes at a lower level in the tree.</p></ol>
219
220<p>Assignment generates the output image from the pruned tree. The output</p>
221<h5>parts</h5>
222<ol><p>(1) A color map, which is an array of color descriptions (RGB triples) for each color present in the output image; (2) A pixel array, which represents each pixel as an index into the color map array.</p></ol>
223
224<p>First, the assignment phase makes one pass over the pruned color description tree to establish the image's color map. For each node with n2 > 0, it divides Sr, Sg, and Sb by n2 . This produces the mean color of all pixels that classify no lower than this node. Each of these colors becomes an entry in the color map.</p></ol>
225
226<p>Finally, the assignment phase reclassifies each pixel in the pruned tree to identify the deepest node containing the pixel's color. The pixel's value in the pixel array becomes the index of this node's mean color in the color map.</p></ol>
227
228<p>This method is based on a similar algorithm written by Paul Raveling.</p></ol>
229
230 </div>
231<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
232_8c.html" target="source" name="AcquireQuantizeInfo">AcquireQuantizeInfo</a></h2>
233<div class="doc-section">
234
235<p>AcquireQuantizeInfo() allocates the QuantizeInfo structure.</p></ol>
236
237<p>The format of the AcquireQuantizeInfo method is:</p>
238
239<pre class="code">
240 QuantizeInfo *AcquireQuantizeInfo(const ImageInfo *image_info)
241</pre>
242
243<p>A description of each parameter follows:</p></ol>
244
245<h5>image_info</h5>
246<ol><p>the image info.</p></ol>
247
248 </div>
249<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
250_8c.html" target="source" name="CloneQuantizeInfo">CloneQuantizeInfo</a></h2>
251<div class="doc-section">
252
253<p>CloneQuantizeInfo() makes a duplicate of the given quantize info structure, or if quantize info is NULL, a new one.</p></ol>
254
255<p>The format of the CloneQuantizeInfo method is:</p>
256
257<pre class="code">
258 QuantizeInfo *CloneQuantizeInfo(const QuantizeInfo *quantize_info)
259</pre>
260
261<p>A description of each parameter follows:</p></ol>
262
263<h5>clone_info</h5>
264<ol><p>Method CloneQuantizeInfo returns a duplicate of the given quantize info, or if image info is NULL a new one.</p></ol>
265
266<h5>quantize_info</h5>
267<ol><p>a structure of type info.</p></ol>
268
269 </div>
270<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
271_8c.html" target="source" name="CompressImageColormap">CompressImageColormap</a></h2>
272<div class="doc-section">
273
274<p>CompressImageColormap() compresses an image colormap by removing any duplicate or unused color entries.</p></ol>
275
276<p>The format of the CompressImageColormap method is:</p>
277
278<pre class="code">
279 MagickBooleanType CompressImageColormap(Image *image)
280</pre>
281
282<p>A description of each parameter follows:</p></ol>
283
284<h5>image</h5>
285<ol><p>the image.</p></ol>
286
287 </div>
288<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
289_8c.html" target="source" name="DestroyQuantizeInfo">DestroyQuantizeInfo</a></h2>
290<div class="doc-section">
291
292<p>DestroyQuantizeInfo() deallocates memory associated with an QuantizeInfo structure.</p></ol>
293
294<p>The format of the DestroyQuantizeInfo method is:</p>
295
296<pre class="code">
297 QuantizeInfo *DestroyQuantizeInfo(QuantizeInfo *quantize_info)
298</pre>
299
300<p>A description of each parameter follows:</p></ol>
301
302<h5>quantize_info</h5>
303<ol><p>Specifies a pointer to an QuantizeInfo structure.</p></ol>
304
305 </div>
306<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
307_8c.html" target="source" name="GetImageQuantizeError">GetImageQuantizeError</a></h2>
308<div class="doc-section">
309
310<p>GetImageQuantizeError() measures the difference between the original and quantized images. This difference is the total quantization error. The error is computed by summing over all pixels in an image the distance squared in RGB space between each reference pixel value and its quantized value. These values are computed:</p>
311
312<pre class="text">
313 o mean_error_per_pixel: This value is the mean error for any single
314 pixel in the image.
315</pre>
316
317<h5>normalized_mean_square_error</h5>
318<ol><p>This value is the normalized mean quantization error for any single pixel in the image. This distance measure is normalized to a range between 0 and 1. It is independent of the range of red, green, and blue values in the image.</p></ol>
319
320<h5>normalized_maximum_square_error</h5>
321<ol><p>Thsi value is the normalized maximum quantization error for any single pixel in the image. This distance measure is normalized to a range between 0 and 1. It is independent of the range of red, green, and blue values in your image.</p></ol>
322
323<p>The format of the GetImageQuantizeError method is:</p>
324
325<pre class="code">
326 MagickBooleanType GetImageQuantizeError(Image *image)
327</pre>
328
329<p>A description of each parameter follows.</p></ol>
330
331<h5>image</h5>
332<ol><p>the image.</p></ol>
333
334 </div>
335<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
336_8c.html" target="source" name="GetQuantizeInfo">GetQuantizeInfo</a></h2>
337<div class="doc-section">
338
339<p>GetQuantizeInfo() initializes the QuantizeInfo structure.</p></ol>
340
341<p>The format of the GetQuantizeInfo method is:</p>
342
343<pre class="code">
344 GetQuantizeInfo(QuantizeInfo *quantize_info)
345</pre>
346
347<p>A description of each parameter follows:</p></ol>
348
349<h5>quantize_info</h5>
350<ol><p>Specifies a pointer to a QuantizeInfo structure.</p></ol>
351
352 </div>
353<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
354_8c.html" target="source" name="PosterizeImage">PosterizeImage</a></h2>
355<div class="doc-section">
356
357<p>PosterizeImage() reduces the image to a limited number of colors for a "poster" effect.</p></ol>
358
359<p>The format of the PosterizeImage method is:</p>
360
361<pre class="code">
cristybb503372010-05-27 20:51:26 +0000[diff] [blame]362 MagickBooleanType PosterizeImage(Image *image,const size_t levels,
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]363 const MagickBooleanType dither)
364</pre>
365
366<p>A description of each parameter follows:</p></ol>
367
368<h5>image</h5>
369<ol><p>Specifies a pointer to an Image structure.</p></ol>
370
371<h5>levels</h5>
372<ol><p>Number of color levels allowed in each channel. Very low values (2, 3, or 4) have the most visible effect.</p></ol>
373
374<h5>dither</h5>
375<ol><p>Set this integer value to something other than zero to dither the mapped image.</p></ol>
376
377 </div>
378<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
379_8c.html" target="source" name="QuantizeImage">QuantizeImage</a></h2>
380<div class="doc-section">
381
382<p>QuantizeImage() analyzes the colors within a reference image and chooses a fixed number of colors to represent the image. The goal of the algorithm is to minimize the color difference between the input and output image while minimizing the processing time.</p></ol>
383
384<p>The format of the QuantizeImage method is:</p>
385
386<pre class="code">
387 MagickBooleanType QuantizeImage(const QuantizeInfo *quantize_info,
388 Image *image)
389</pre>
390
391<p>A description of each parameter follows:</p></ol>
392
393<h5>quantize_info</h5>
394<ol><p>Specifies a pointer to an QuantizeInfo structure.</p></ol>
395
396<h5>image</h5>
397<ol><p>the image.</p></ol>
398
399 </div>
400<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
401_8c.html" target="source" name="QuantizeImages">QuantizeImages</a></h2>
402<div class="doc-section">
403
404<p>QuantizeImages() analyzes the colors within a set of reference images and chooses a fixed number of colors to represent the set. The goal of the algorithm is to minimize the color difference between the input and output images while minimizing the processing time.</p></ol>
405
406<p>The format of the QuantizeImages method is:</p>
407
408<pre class="code">
409 MagickBooleanType QuantizeImages(const QuantizeInfo *quantize_info,
410 Image *images)
411</pre>
412
413<p>A description of each parameter follows:</p></ol>
414
415<h5>quantize_info</h5>
416<ol><p>Specifies a pointer to an QuantizeInfo structure.</p></ol>
417
418<h5>images</h5>
419<ol><p>Specifies a pointer to a list of Image structures.</p></ol>
420
421 </div>
422<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
423_8c.html" target="source" name="RemapImage">RemapImage</a></h2>
424<div class="doc-section">
425
426<p>RemapImage() replaces the colors of an image with the closest color from a reference image.</p></ol>
427
428<p>The format of the RemapImage method is:</p>
429
430<pre class="code">
431 MagickBooleanType RemapImage(const QuantizeInfo *quantize_info,
432 Image *image,const Image *remap_image)
433</pre>
434
435<p>A description of each parameter follows:</p></ol>
436
437<h5>quantize_info</h5>
438<ol><p>Specifies a pointer to an QuantizeInfo structure.</p></ol>
439
440<h5>image</h5>
441<ol><p>the image.</p></ol>
442
443<h5>remap_image</h5>
444<ol><p>the reference image.</p></ol>
445
446 </div>
447<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
448_8c.html" target="source" name="RemapImages">RemapImages</a></h2>
449<div class="doc-section">
450
451<p>RemapImages() replaces the colors of a sequence of images with the closest color from a reference image.</p></ol>
452
453<p>The format of the RemapImage method is:</p>
454
455<pre class="code">
456 MagickBooleanType RemapImages(const QuantizeInfo *quantize_info,
457 Image *images,Image *remap_image)
458</pre>
459
460<p>A description of each parameter follows:</p></ol>
461
462<h5>quantize_info</h5>
463<ol><p>Specifies a pointer to an QuantizeInfo structure.</p></ol>
464
465<h5>images</h5>
466<ol><p>the image sequence.</p></ol>
467
468<h5>remap_image</h5>
469<ol><p>the reference image.</p></ol>
470
471 </div>
472<h2><a href="http://www.imagemagick.org/api/MagickCore/quantize
473_8c.html" target="source" name="SetGrayscaleImage">SetGrayscaleImage</a></h2>
474<div class="doc-section">
475
476<p>SetGrayscaleImage() converts an image to a PseudoClass grayscale image.</p></ol>
477
478<p>The format of the SetGrayscaleImage method is:</p>
479
480<pre class="code">
481 MagickBooleanType SetGrayscaleImage(Image *image)
482</pre>
483
484<p>A description of each parameter follows:</p></ol>
485
486<h5>image</h5>
487<ol><p>The image.</p></ol>
488
489 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]490
491</div>
492
493<div id="linkbar">
cristyce69bb02010-07-27 19:49:46 +0000[diff] [blame]494 <span id="linkbar-west">&nbsp;</span>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]495 <span id="linkbar-center">
496 <a href="http://www.imagemagick.org/discourse-server/">Discourse Server</a> &bull;
cristya8902942010-07-30 00:49:52 +0000[diff] [blame]497 <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">Studio</a>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]498 </span>
499 <span id="linkbar-east">&nbsp;</span>
500 </div>
501 <div class="footer">
502 <span id="footer-west">&copy; 1999-2010 ImageMagick Studio LLC</span>
503 <span id="footer-east"> <a href="../http://www.imagemagick.org/script/contact.php">Contact the Wizards</a></span>
504 </div>
505 <div style="clear: both; margin: 0; width: 100%; "></div>
cristya8902942010-07-30 00:49:52 +0000[diff] [blame]506 <script type="text/javascript">
507 var _gaq = _gaq || [];
508 _gaq.push(['_setAccount', 'UA-17690367-1']);
509 _gaq.push(['_trackPageview']);
510
511 (function() {
512 var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
513 ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
514 var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
515 })();
516 </script>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]517</body>
518</html>