Gitiles
Code Review Sign In
gerrit-public.fairphone.software / platform / external / ImageMagick / 43aaada697f6f1db77428eb6b4168ef7bb4160c7 / . / www / api / enhance.html
blob: 6f5ff79d4de1532c57be68daef01b773cee3843b [file] [log] [blame]
cristyf3bb4782009-09-08 13:10:04 +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">
3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
4<head>
cristy1f9e1ed2009-11-18 04:09:38 +0000[diff] [blame]5 <meta http-equiv="Content-Type" value="application/xhtml+xml" />
cristyf3bb4782009-09-08 13:10:04 +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" />
8 <style type="text/css" media="screen,projection"><!--
9 @import url("../../www/magick.css");
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: Enhance 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:, enhance, 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"/>
cristyf3bb4782009-09-08 13:10:04 +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
45<div class="eastbar">
46
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]47<div class="menu">
48 <a href="../../index.html">About ImageMagick</a>
49</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]50<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]51<div class="menu">
52 <a href="../../www/command-line-tools.html">Command-line Tools</a>
53</div>
54<div class="sub">
55 <a href="../../www/command-line-processing.html">Processing</a>
56</div>
57<div class="sub">
58 <a href="../../www/command-line-options.html">Options</a>
59</div>
60<div class="sub">
61 <a href="http://www.imagemagick.org/Usage/">Usage</a>
62</div>
63<div class="menu">
64 <a href="../../www/api.html">Program Interfaces</a>
65</div>
66<div class="sub">
67 <a href="../../www/magick-wand.html">MagickWand</a>
68</div>
69<div class="sub">
70 <a href="../../www/magick-core.html">MagickCore</a>
71</div>
72<div class="sub">
73 <a href="../../www/perl-magick.html">PerlMagick</a>
74</div>
75<div class="sub">
76 <a href="../../Magick++/">Magick++</a>
77</div>
78<div class="menu">
79 <a href="../../www/architecture.html">Architecture</a>
80</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]81<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]82<div class="menu">
83 <a href="../../www/install-source.html">Install from Source</a>
84</div>
85<div class="sub">
86 <a href="../../www/install-source.html#unix">Unix</a>
87</div>
88<div class="sub">
89 <a href="../../www/install-source.html#windows">Windows</a>
90 </div>
91<div class="menu">
92 <a href="../../www/binary-releases.html">Binary Releases</a>
93</div>
94<div class="sub">
95 <a href="../../www/binary-releases.html#unix">Unix</a>
96</div>
97<div class="sub">
98 <a href="../../www/binary-releases.html#macosx">Mac OS X</a>
99</div>
100<div class="sub">
101 <a href="../../www/binary-releases.html#windows">Windows</a>
102</div>
103<div class="menu">
104 <a href="../../www/resources.html">Resources</a>
105</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]106<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]107<div class="menu">
108 <a href="../../www/download.html">Download</a>
109</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]110<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]111<div class="menu">
112 <a href="../http://www.imagemagick.org/script/search.php">Search</a>
113</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]114<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]115<div class="menu">
116 <a href="../../www/sitemap.html">Site Map</a>
117</div>
118<div class="sub">
119 <a href="../../www/links.html">Links</a>
120</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]121<div class="sep"></div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]122<div class="menu">
123 <a href="../../www/sponsors.html">Sponsors:</a>
124
125<div class="sponsbox">
126<div class="sponsor">
cristyd6a37032010-02-02 04:14:40 +0000[diff] [blame]127 <a href="http://www.hygi.de">Reinigungsmittel</a><!-- 201002000400+ -->
cristyb29bc032010-02-01 20:29:43 +0000[diff] [blame]128</div>
129<div class="sponsor">
cristy1f9e1ed2009-11-18 04:09:38 +0000[diff] [blame]130 <a href="http://www.tomsgutscheine.de">Tom's Gutscheine</a><!-- 201005010360 invendio.de-->
cristy5f2356f2009-11-16 00:40:46 +0000[diff] [blame]131</div>
132<div class="sponsor">
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]133 <a href="http://www.online-kredit-index.de">Kredit</a><!-- 201006010120 Buchhorn -->
cristyb4c03bb2009-09-27 13:55:46 +0000[diff] [blame]134</div>
135<div class="sponsor">
cristy0f61e612009-11-10 20:03:57 +0000[diff] [blame]136 <a href="http://www.blumenversender.com">Blumenversand</a><!-- 201005010120 -->
cristy916e1922009-10-01 12:52:47 +0000[diff] [blame]137</div>
138<div class="sponsor">
cristyb4c03bb2009-09-27 13:55:46 +0000[diff] [blame]139 <a href="http://www.print24.de/">Druckerei</a><!-- 201009010720 -->
140</div>
141<div class="sponsor">
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]142 <a href="http://www.goyax.de">Börse</a><!-- 201004010240 Gewiese digital-finance.de -->
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]143</div>
144<div class="sponsor">
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]145 <a href="http://www.allesdruck.de">Druckerei Online</a><!-- 201012011200 allesdruck.de-->
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]146</div>
147<div class="sponsor">
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]148 <a href="http://www.who-sells-it.com/">Free Catalogs</a><!-- 201002010000 -->
149</div>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]150</div>
151</div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]152
153
154</div>
155
156<div class="main">
157
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]158<p class="navigation-index">[<a href="#AutoGammaImage">AutoGammaImage</a> &bull; <a href="#AutoLevelImage">AutoLevelImage</a> &bull; <a href="#Use BrightnessContrastImage">Use BrightnessContrastImage</a> &bull; <a href="#ColorDecisionListImage">ColorDecisionListImage</a> &bull; <a href="#ClutImage">ClutImage</a> &bull; <a href="#ContrastImage">ContrastImage</a> &bull; <a href="#The ContrastStretchImage">The ContrastStretchImage</a> &bull; <a href="#EnhanceImage">EnhanceImage</a> &bull; <a href="#EqualizeImage">EqualizeImage</a> &bull; <a href="#GammaImage">GammaImage</a> &bull; <a href="#HaldClutImage">HaldClutImage</a> &bull; <a href="#LevelImage">LevelImage</a> &bull; <a href="#LevelizeImage">LevelizeImage</a> &bull; <a href="#LevelizeImageChannel">LevelizeImageChannel</a> &bull; <a href="#LevelImageColor">LevelImageColor</a> &bull; <a href="#The LinearStretchImage">The LinearStretchImage</a> &bull; <a href="#ModulateImage">ModulateImage</a> &bull; <a href="#NegateImage">NegateImage</a> &bull; <a href="#The NormalizeImage">The NormalizeImage</a> &bull; <a href="#SigmoidalContrastImage">SigmoidalContrastImage</a>]</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]159
160<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
161_8c.html" target="source" name="AutoGammaImage">AutoGammaImage</a></h2>
162<div class="doc-section">
163
164<p>AutoGammaImage() extract the 'mean' from the image and adjust the image to try make set its gamma appropriatally.</p></ol>
165
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]166<p>The format of the AutoGammaImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]167
168<pre class="code">
169 MagickBooleanType AutoGammaImage(Image *image)
170 MagickBooleanType AutoGammaImageChannel(Image *image,
171 const ChannelType channel)
172</pre>
173
174<p>A description of each parameter follows:</p></ol>
175
176<h5>image</h5>
177<ol><p>The image to auto-level</p></ol>
178
179<h5>channel</h5>
180<ol><p>The channels to auto-level. If the special 'SyncChannels' flag is set all given channels is adjusted in the same way using the mean average of those channels.</p></ol>
181
182 </div>
183<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
184_8c.html" target="source" name="AutoLevelImage">AutoLevelImage</a></h2>
185<div class="doc-section">
186
187<p>AutoLevelImage() adjusts the levels of a particular image channel by scaling the minimum and maximum values to the full quantum range.</p></ol>
188
189<p>The format of the LevelImage method is:</p>
190
191<pre class="code">
192 MagickBooleanType AutoLevelImage(Image *image)
193 MagickBooleanType AutoLevelImageChannel(Image *image,
194 const ChannelType channel)
195</pre>
196
197<p>A description of each parameter follows:</p></ol>
198
199<h5>image</h5>
200<ol><p>The image to auto-level</p></ol>
201
202<h5>channel</h5>
203<ol><p>The channels to auto-level. If the special 'SyncChannels' flag is set the min/max/mean value of all given channels is used for all given channels, to all channels in the same way.</p></ol>
204
205 </div>
206<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]207_8c.html" target="source" name="Use BrightnessContrastImage">Use BrightnessContrastImage</a></h2>
208<div class="doc-section">
209
210<p>Use BrightnessContrastImage() to change the brightness and/or contrast of an image. It converts the brightness and contrast parameters into slope and intercept and calls a polynomical function to apply to the image.</p></ol>
211
212<p>The format of the BrightnessContrastImage method is:</p>
213
214<pre class="code">
215 MagickBooleanType BrightnessContrastImage(Image *image,
216 const double brightness,const double contrast)
217 MagickBooleanType BrightnessContrastImageChannel(Image *image,
218 const ChannelType channel,const double brightness,
219 const double contrast)
220</pre>
221
222<p>A description of each parameter follows:</p></ol>
223
224<h5>image</h5>
225<ol><p>the image.</p></ol>
226
227<h5>channel</h5>
228<ol><p>the channel.</p></ol>
229
230<h5>brightness</h5>
231<ol><p>the brightness percent (-100 .. 100).</p></ol>
232
233<h5>contrast</h5>
234<ol><p>the contrast percent (-100 .. 100).</p></ol>
235
236 </div>
237<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]238_8c.html" target="source" name="ColorDecisionListImage">ColorDecisionListImage</a></h2>
239<div class="doc-section">
240
241<p>ColorDecisionListImage() accepts a lightweight Color Correction Collection (CCC) file which solely contains one or more color corrections and applies the correction to the image. Here is a sample CCC file:</p>
242
243<pre class="text">
244 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
245 <ColorCorrection id="cc03345">
246 <SOPNode>
247 <Slope> 0.9 1.2 0.5 </Slope>
248 <Offset> 0.4 -0.5 0.6 </Offset>
249 <Power> 1.0 0.8 1.5 </Power>
250 </SOPNode>
251 <SATNode>
252 <Saturation> 0.85 </Saturation>
253 </SATNode>
254 </ColorCorrection>
255 </ColorCorrectionCollection>
256</pre>
257
258<p>which includes the slop, offset, and power for each of the RGB channels as well as the saturation.</p></ol>
259
260<p>The format of the ColorDecisionListImage method is:</p>
261
262<pre class="code">
263 MagickBooleanType ColorDecisionListImage(Image *image,
264 const char *color_correction_collection)
265</pre>
266
267<p>A description of each parameter follows:</p></ol>
268
269<h5>image</h5>
270<ol><p>the image.</p></ol>
271
272<h5>color_correction_collection</h5>
273<ol><p>the color correction collection in XML.</p></ol>
274
275 </div>
276<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
277_8c.html" target="source" name="ClutImage">ClutImage</a></h2>
278<div class="doc-section">
279
280<p>ClutImage() replaces each color value in the given image, by using it as an index to lookup a replacement color value in a Color Look UP Table in the form of an image. The values are extracted along a diagonal of the CLUT image so either a horizontal or vertial gradient image can be used.</p></ol>
281
282<p>Typically this is used to either re-color a gray-scale image according to a color gradient in the CLUT image, or to perform a freeform histogram (level) adjustment according to the (typically gray-scale) gradient in the CLUT image.</p></ol>
283
284<p>When the 'channel' mask includes the matte/alpha transparency channel but one image has no such channel it is assumed that that image is a simple gray-scale image that will effect the alpha channel values, either for gray-scale coloring (with transparent or semi-transparent colors), or a histogram adjustment of existing alpha channel values. If both images have matte channels, direct and normal indexing is applied, which is rarely used.</p></ol>
285
286<p>The format of the ClutImage method is:</p>
287
288<pre class="code">
289 MagickBooleanType ClutImage(Image *image,Image *clut_image)
290 MagickBooleanType ClutImageChannel(Image *image,
291 const ChannelType channel,Image *clut_image)
292</pre>
293
294<p>A description of each parameter follows:</p></ol>
295
296<h5>image</h5>
297<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
298
299<h5>clut_image</h5>
300<ol><p>the color lookup table image for replacement color values.</p></ol>
301
302<h5>channel</h5>
303<ol><p>the channel.</p></ol>
304
305 </div>
306<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
307_8c.html" target="source" name="ContrastImage">ContrastImage</a></h2>
308<div class="doc-section">
309
310<p>ContrastImage() enhances the intensity differences between the lighter and darker elements of the image. Set sharpen to a MagickTrue to increase the image contrast otherwise the contrast is reduced.</p></ol>
311
312<p>The format of the ContrastImage method is:</p>
313
314<pre class="code">
315 MagickBooleanType ContrastImage(Image *image,
316 const MagickBooleanType sharpen)
317</pre>
318
319<p>A description of each parameter follows:</p></ol>
320
321<h5>image</h5>
322<ol><p>the image.</p></ol>
323
324<h5>sharpen</h5>
325<ol><p>Increase or decrease image contrast.</p></ol>
326
327 </div>
328<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
329_8c.html" target="source" name="The ContrastStretchImage">The ContrastStretchImage</a></h2>
330<div class="doc-section">
331
332<p>The ContrastStretchImage() is a simple image enhancement technique that attempts to improve the contrast in an image by `stretching' the range of intensity values it contains to span a desired range of values. It differs from the more sophisticated histogram equalization in that it can only apply a linear scaling function to the image pixel values. As a result the `enhancement' is less harsh.</p></ol>
333
334<p>The format of the ContrastStretchImage method is:</p>
335
336<pre class="code">
337 MagickBooleanType ContrastStretchImage(Image *image,
338 const char *levels)
339 MagickBooleanType ContrastStretchImageChannel(Image *image,
340 const unsigned long channel,const double black_point,
341 const double white_point)
342</pre>
343
344<p>A description of each parameter follows:</p></ol>
345
346<h5>image</h5>
347<ol><p>the image.</p></ol>
348
349<h5>channel</h5>
350<ol><p>the channel.</p></ol>
351
352<h5>black_point</h5>
353<ol><p>the black point.</p></ol>
354
355<h5>white_point</h5>
356<ol><p>the white point.</p></ol>
357
358<h5>levels</h5>
359<ol><p>Specify the levels where the black and white points have the range of 0 to number-of-pixels (e.g. 1, 10x90, etc.).</p></ol>
360
361 </div>
362<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
363_8c.html" target="source" name="EnhanceImage">EnhanceImage</a></h2>
364<div class="doc-section">
365
366<p>EnhanceImage() applies a digital filter that improves the quality of a noisy image.</p></ol>
367
368<p>The format of the EnhanceImage method is:</p>
369
370<pre class="code">
371 Image *EnhanceImage(const Image *image,ExceptionInfo *exception)
372</pre>
373
374<p>A description of each parameter follows:</p></ol>
375
376<h5>image</h5>
377<ol><p>the image.</p></ol>
378
379<h5>exception</h5>
380<ol><p>return any errors or warnings in this structure.</p></ol>
381
382 </div>
383<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
384_8c.html" target="source" name="EqualizeImage">EqualizeImage</a></h2>
385<div class="doc-section">
386
387<p>EqualizeImage() applies a histogram equalization to the image.</p></ol>
388
389<p>The format of the EqualizeImage method is:</p>
390
391<pre class="code">
392 MagickBooleanType EqualizeImage(Image *image)
393 MagickBooleanType EqualizeImageChannel(Image *image,
394 const ChannelType channel)
395</pre>
396
397<p>A description of each parameter follows:</p></ol>
398
399<h5>image</h5>
400<ol><p>the image.</p></ol>
401
402<h5>channel</h5>
403<ol><p>the channel.</p></ol>
404
405 </div>
406<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
407_8c.html" target="source" name="GammaImage">GammaImage</a></h2>
408<div class="doc-section">
409
410<p>GammaImage() gamma-corrects a particular image channel. The same image viewed on different devices will have perceptual differences in the way the image's intensities are represented on the screen. Specify individual gamma levels for the red, green, and blue channels, or adjust all three with the gamma parameter. Values typically range from 0.8 to 2.3.</p></ol>
411
412<p>You can also reduce the influence of a particular channel with a gamma value of 0.</p></ol>
413
414<p>The format of the GammaImage method is:</p>
415
416<pre class="code">
417 MagickBooleanType GammaImage(Image *image,const double gamma)
418 MagickBooleanType GammaImageChannel(Image *image,
419 const ChannelType channel,const double gamma)
420</pre>
421
422<p>A description of each parameter follows:</p></ol>
423
424<h5>image</h5>
425<ol><p>the image.</p></ol>
426
427<h5>channel</h5>
428<ol><p>the channel.</p></ol>
429
430<h5>gamma</h5>
431<ol><p>the image gamma.</p></ol>
432
433 </div>
434<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
435_8c.html" target="source" name="HaldClutImage">HaldClutImage</a></h2>
436<div class="doc-section">
437
438<p>HaldClutImage() applies a Hald color lookup table to the image. A Hald color lookup table is a 3-dimensional color cube mapped to 2 dimensions. Create it with the HALD coder. You can apply any color transformation to the Hald image and then use this method to apply the transform to the image.</p></ol>
439
440<p>The format of the HaldClutImage method is:</p>
441
442<pre class="code">
443 MagickBooleanType HaldClutImage(Image *image,Image *hald_image)
444 MagickBooleanType HaldClutImageChannel(Image *image,
445 const ChannelType channel,Image *hald_image)
446</pre>
447
448<p>A description of each parameter follows:</p></ol>
449
450<h5>image</h5>
451<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
452
453<h5>hald_image</h5>
454<ol><p>the color lookup table image for replacement color values.</p></ol>
455
456<h5>channel</h5>
457<ol><p>the channel.</p></ol>
458
459 </div>
460<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
461_8c.html" target="source" name="LevelImage">LevelImage</a></h2>
462<div class="doc-section">
463
464<p>LevelImage() adjusts the levels of a particular image channel by scaling the colors falling between specified white and black points to the full available quantum range.</p></ol>
465
466<p>The parameters provided represent the black, and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value.</p></ol>
467
468<p>If a '!' flag is given, map black and white colors to the given levels rather than mapping those levels to black and white. See LevelizeImageChannel() and LevelizeImageChannel(), below.</p></ol>
469
470<p>Gamma specifies a gamma correction to apply to the image.</p></ol>
471
472<p>The format of the LevelImage method is:</p>
473
474<pre class="code">
475 MagickBooleanType LevelImage(Image *image,const char *levels)
476</pre>
477
478<p>A description of each parameter follows:</p></ol>
479
480<h5>image</h5>
481<ol><p>the image.</p></ol>
482
483<h5>levels</h5>
484<ol><p>Specify the levels where the black and white points have the range of 0-QuantumRange, and gamma has the range 0-10 (e.g. 10x90+2). A '!' flag inverts the re-mapping.</p></ol>
485
486 </div>
487<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]488_8c.html" target="source" name="LevelizeImage">LevelizeImage</a></h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]489<div class="doc-section">
490
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]491<p>LevelizeImage() applies the normal level operation to the image, spreading out the values between the black and white points over the entire range of values. Gamma correction is also applied after the values has been mapped.</p></ol>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]492
493<p>It is typically used to improve image contrast, or to provide a controlled linear threshold for the image. If the black and white points are set to the minimum and maximum values found in the image, the image can be normalized. or by swapping black and white values, negate the image.</p></ol>
494
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]495<p>The format of the LevelizeImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]496
497<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]498 MagickBooleanType LevelizeImage(Image *image,const double black_point,
499 const double white_point,const double gamma)
500 MagickBooleanType LevelizeImageChannel(Image *image,
501 const ChannelType channel,const double black_point,
502 const double white_point,const double gamma)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]503</pre>
504
505<p>A description of each parameter follows:</p></ol>
506
507<h5>image</h5>
508<ol><p>the image.</p></ol>
509
510<h5>channel</h5>
511<ol><p>the channel.</p></ol>
512
513<h5>black_point</h5>
514<ol><p>The level which is to be mapped to zero (black)</p></ol>
515
516<h5>white_point</h5>
517<ol><p>The level which is to be mapped to QuantiumRange (white)</p></ol>
518
519<h5>gamma</h5>
520<ol><p>adjust gamma by this factor before mapping values. use 1.0 for purely linear stretching of image color values</p></ol>
521
522 </div>
523<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
524_8c.html" target="source" name="LevelizeImageChannel">LevelizeImageChannel</a></h2>
525<div class="doc-section">
526
527<p>LevelizeImageChannel() applies the reversed LevelImage() operation to just the specific channels specified. It compresses the full range of color values, so that they lie between the given black and white points. Gamma is applied before the values are mapped.</p></ol>
528
529<p>LevelizeImageChannel() can be called with by using a +level command line API option, or using a '!' on a -level or LevelImage() geometry string.</p></ol>
530
531<p>It can be used for example de-contrast a greyscale image to the exact levels specified. Or by using specific levels for each channel of an image you can convert a gray-scale image to any linear color gradient, according to those levels.</p></ol>
532
533<p>The format of the LevelizeImageChannel method is:</p>
534
535<pre class="code">
536 MagickBooleanType LevelizeImageChannel(Image *image,
537 const ChannelType channel,const char *levels)
538</pre>
539
540<p>A description of each parameter follows:</p></ol>
541
542<h5>image</h5>
543<ol><p>the image.</p></ol>
544
545<h5>channel</h5>
546<ol><p>the channel.</p></ol>
547
548<h5>black_point</h5>
549<ol><p>The level to map zero (black) to.</p></ol>
550
551<h5>white_point</h5>
552<ol><p>The level to map QuantiumRange (white) to.</p></ol>
553
554<h5>gamma</h5>
555<ol><p>adjust gamma by this factor before mapping values.</p></ol>
556
557 </div>
558<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
559_8c.html" target="source" name="LevelImageColor">LevelImageColor</a></h2>
560<div class="doc-section">
561
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]562<p>LevelImageColor() maps the given color to "black" and "white" values, linearly spreading out the colors, and level values on a channel by channel bases, as per LevelImage(). The given colors allows you to specify different level ranges for each of the color channels seperatally.</p></ol>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]563
564<p>If the boolean 'invert' is set true the image values will modifyed in the reverse direction. That is any existing "black" and "white" colors in the image will become the color values given, with all other values compressed appropriatally. This effectivally maps a greyscale gradient into the given color gradient.</p></ol>
565
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]566<p>The format of the LevelColorsImageChannel method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]567
568<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]569 MagickBooleanType LevelColorsImage(Image *image,
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]570 const MagickPixelPacket *black_color,
571 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]572 MagickBooleanType LevelColorsImageChannel(Image *image,
573 const ChannelType channel,const MagickPixelPacket *black_color,
574 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]575</pre>
576
577<p>A description of each parameter follows:</p></ol>
578
579<h5>image</h5>
580<ol><p>the image.</p></ol>
581
582<h5>channel</h5>
583<ol><p>the channel.</p></ol>
584
585<h5>black_color</h5>
586<ol><p>The color to map black to/from</p></ol>
587
588<h5>white_point</h5>
589<ol><p>The color to map white to/from</p></ol>
590
591<h5>invert</h5>
592<ol><p>if true map the colors (levelize), rather than from (level)</p></ol>
593
594 </div>
595<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
596_8c.html" target="source" name="The LinearStretchImage">The LinearStretchImage</a></h2>
597<div class="doc-section">
598
599<p>The LinearStretchImage() discards any pixels below the black point and above the white point and levels the remaining pixels.</p></ol>
600
601<p>The format of the LinearStretchImage method is:</p>
602
603<pre class="code">
604 MagickBooleanType LinearStretchImage(Image *image,
605 const double black_point,const double white_point)
606</pre>
607
608<p>A description of each parameter follows:</p></ol>
609
610<h5>image</h5>
611<ol><p>the image.</p></ol>
612
613<h5>black_point</h5>
614<ol><p>the black point.</p></ol>
615
616<h5>white_point</h5>
617<ol><p>the white point.</p></ol>
618
619 </div>
620<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
621_8c.html" target="source" name="ModulateImage">ModulateImage</a></h2>
622<div class="doc-section">
623
624<p>ModulateImage() lets you control the brightness, saturation, and hue of an image. Modulate represents the brightness, saturation, and hue as one parameter (e.g. 90,150,100). If the image colorspace is HSL, the modulation is lightness, saturation, and hue. And if the colorspace is HWB, use blackness, whiteness, and hue.</p></ol>
625
626<p>The format of the ModulateImage method is:</p>
627
628<pre class="code">
629 MagickBooleanType ModulateImage(Image *image,const char *modulate)
630</pre>
631
632<p>A description of each parameter follows:</p></ol>
633
634<h5>image</h5>
635<ol><p>the image.</p></ol>
636
637<h5>modulate</h5>
638<ol><p>Define the percent change in brightness, saturation, and hue.</p></ol>
639
640 </div>
641<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
642_8c.html" target="source" name="NegateImage">NegateImage</a></h2>
643<div class="doc-section">
644
645<p>NegateImage() negates the colors in the reference image. The grayscale option means that only grayscale values within the image are negated.</p></ol>
646
647<p>The format of the NegateImageChannel method is:</p>
648
649<pre class="code">
650 MagickBooleanType NegateImage(Image *image,
651 const MagickBooleanType grayscale)
652 MagickBooleanType NegateImageChannel(Image *image,
653 const ChannelType channel,const MagickBooleanType grayscale)
654</pre>
655
656<p>A description of each parameter follows:</p></ol>
657
658<h5>image</h5>
659<ol><p>the image.</p></ol>
660
661<h5>channel</h5>
662<ol><p>the channel.</p></ol>
663
664<h5>grayscale</h5>
665<ol><p>If MagickTrue, only negate grayscale pixels within the image.</p></ol>
666
667 </div>
668<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
669_8c.html" target="source" name="The NormalizeImage">The NormalizeImage</a></h2>
670<div class="doc-section">
671
672<p>The NormalizeImage() method enhances the contrast of a color image by mapping the darkest 2 percent of all pixel to black and the brightest 1 percent to white.</p></ol>
673
674<p>The format of the NormalizeImage method is:</p>
675
676<pre class="code">
677 MagickBooleanType NormalizeImage(Image *image)
678 MagickBooleanType NormalizeImageChannel(Image *image,
679 const ChannelType channel)
680</pre>
681
682<p>A description of each parameter follows:</p></ol>
683
684<h5>image</h5>
685<ol><p>the image.</p></ol>
686
687<h5>channel</h5>
688<ol><p>the channel.</p></ol>
689
690 </div>
691<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
692_8c.html" target="source" name="SigmoidalContrastImage">SigmoidalContrastImage</a></h2>
693<div class="doc-section">
694
695<p>SigmoidalContrastImage() adjusts the contrast of an image with a non-linear sigmoidal contrast algorithm. Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. Contrast indicates how much to increase the contrast (0 is none; 3 is typical; 20 is pushing it); mid-point indicates where midtones fall in the resultant image (0 is white; 50 is middle-gray; 100 is black). Set sharpen to MagickTrue to increase the image contrast otherwise the contrast is reduced.</p></ol>
696
697<p>The format of the SigmoidalContrastImage method is:</p>
698
699<pre class="code">
700 MagickBooleanType SigmoidalContrastImage(Image *image,
701 const MagickBooleanType sharpen,const char *levels)
702 MagickBooleanType SigmoidalContrastImageChannel(Image *image,
703 const ChannelType channel,const MagickBooleanType sharpen,
704 const double contrast,const double midpoint)
705</pre>
706
707<p>A description of each parameter follows:</p></ol>
708
709<h5>image</h5>
710<ol><p>the image.</p></ol>
711
712<h5>channel</h5>
713<ol><p>the channel.</p></ol>
714
715<h5>sharpen</h5>
716<ol><p>Increase or decrease image contrast.</p></ol>
717
718<h5>contrast</h5>
719<ol><p>control the "shoulder" of the contast curve.</p></ol>
720
721<h5>midpoint</h5>
722<ol><p>control the "toe" of the contast curve.</p></ol>
723
724 </div>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]725
726</div>
727
728<div id="linkbar">
729 <!-- <span id="linkbar-west">&nbsp;</span> -->
730 <span id="linkbar-center">
731 <a href="http://www.imagemagick.org/discourse-server/">Discourse Server</a> &bull;
cristy54de1f52010-02-05 03:00:05 +0000[diff] [blame]732 <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">Studio</a>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]733 </span>
734 <span id="linkbar-east">&nbsp;</span>
735 </div>
736 <div class="footer">
cristy16af1cb2009-12-11 21:38:29 +0000[diff] [blame]737 <span id="footer-west">&copy; 1999-2010 ImageMagick Studio LLC</span>
cristyf3bb4782009-09-08 13:10:04 +0000[diff] [blame]738 <span id="footer-east"> <a href="../http://www.imagemagick.org/script/contact.php">Contact the Wizards</a></span>
739 </div>
740 <div style="clear: both; margin: 0; width: 100%; "></div>
741</body>
742</html>