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12 <title>ImageMagick: MagickCore, C API for ImageMagick: Enhance an Image</title>
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164
165<div class="main">
166
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]167<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]168
169<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
170_8c.html" target="source" name="AutoGammaImage">AutoGammaImage</a></h2>
171<div class="doc-section">
172
173<p>AutoGammaImage() extract the 'mean' from the image and adjust the image to try make set its gamma appropriatally.</p></ol>
174
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]175<p>The format of the AutoGammaImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]176
177<pre class="code">
178 MagickBooleanType AutoGammaImage(Image *image)
179 MagickBooleanType AutoGammaImageChannel(Image *image,
180 const ChannelType channel)
181</pre>
182
183<p>A description of each parameter follows:</p></ol>
184
185<h5>image</h5>
186<ol><p>The image to auto-level</p></ol>
187
188<h5>channel</h5>
189<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>
190
191 </div>
192<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
193_8c.html" target="source" name="AutoLevelImage">AutoLevelImage</a></h2>
194<div class="doc-section">
195
196<p>AutoLevelImage() adjusts the levels of a particular image channel by scaling the minimum and maximum values to the full quantum range.</p></ol>
197
198<p>The format of the LevelImage method is:</p>
199
200<pre class="code">
201 MagickBooleanType AutoLevelImage(Image *image)
202 MagickBooleanType AutoLevelImageChannel(Image *image,
203 const ChannelType channel)
204</pre>
205
206<p>A description of each parameter follows:</p></ol>
207
208<h5>image</h5>
209<ol><p>The image to auto-level</p></ol>
210
211<h5>channel</h5>
212<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>
213
214 </div>
215<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy16ff93c2010-01-13 23:18:07 +0000[diff] [blame]216_8c.html" target="source" name="Use BrightnessContrastImage">Use BrightnessContrastImage</a></h2>
217<div class="doc-section">
218
219<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>
220
221<p>The format of the BrightnessContrastImage method is:</p>
222
223<pre class="code">
224 MagickBooleanType BrightnessContrastImage(Image *image,
225 const double brightness,const double contrast)
226 MagickBooleanType BrightnessContrastImageChannel(Image *image,
227 const ChannelType channel,const double brightness,
228 const double contrast)
229</pre>
230
231<p>A description of each parameter follows:</p></ol>
232
233<h5>image</h5>
234<ol><p>the image.</p></ol>
235
236<h5>channel</h5>
237<ol><p>the channel.</p></ol>
238
239<h5>brightness</h5>
240<ol><p>the brightness percent (-100 .. 100).</p></ol>
241
242<h5>contrast</h5>
243<ol><p>the contrast percent (-100 .. 100).</p></ol>
244
245 </div>
246<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]247_8c.html" target="source" name="ColorDecisionListImage">ColorDecisionListImage</a></h2>
248<div class="doc-section">
249
250<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>
251
252<pre class="text">
253 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
254 <ColorCorrection id="cc03345">
255 <SOPNode>
256 <Slope> 0.9 1.2 0.5 </Slope>
257 <Offset> 0.4 -0.5 0.6 </Offset>
258 <Power> 1.0 0.8 1.5 </Power>
259 </SOPNode>
260 <SATNode>
261 <Saturation> 0.85 </Saturation>
262 </SATNode>
263 </ColorCorrection>
264 </ColorCorrectionCollection>
265</pre>
266
267<p>which includes the slop, offset, and power for each of the RGB channels as well as the saturation.</p></ol>
268
269<p>The format of the ColorDecisionListImage method is:</p>
270
271<pre class="code">
272 MagickBooleanType ColorDecisionListImage(Image *image,
273 const char *color_correction_collection)
274</pre>
275
276<p>A description of each parameter follows:</p></ol>
277
278<h5>image</h5>
279<ol><p>the image.</p></ol>
280
281<h5>color_correction_collection</h5>
282<ol><p>the color correction collection in XML.</p></ol>
283
284 </div>
285<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
286_8c.html" target="source" name="ClutImage">ClutImage</a></h2>
287<div class="doc-section">
288
cristyeaedf062010-05-29 22:36:02 +0000[diff] [blame]289<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>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]290
291<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>
292
293<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>
294
295<p>The format of the ClutImage method is:</p>
296
297<pre class="code">
298 MagickBooleanType ClutImage(Image *image,Image *clut_image)
299 MagickBooleanType ClutImageChannel(Image *image,
300 const ChannelType channel,Image *clut_image)
301</pre>
302
303<p>A description of each parameter follows:</p></ol>
304
305<h5>image</h5>
306<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
307
308<h5>clut_image</h5>
309<ol><p>the color lookup table image for replacement color values.</p></ol>
310
311<h5>channel</h5>
312<ol><p>the channel.</p></ol>
313
314 </div>
315<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
316_8c.html" target="source" name="ContrastImage">ContrastImage</a></h2>
317<div class="doc-section">
318
319<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>
320
321<p>The format of the ContrastImage method is:</p>
322
323<pre class="code">
324 MagickBooleanType ContrastImage(Image *image,
325 const MagickBooleanType sharpen)
326</pre>
327
328<p>A description of each parameter follows:</p></ol>
329
330<h5>image</h5>
331<ol><p>the image.</p></ol>
332
333<h5>sharpen</h5>
334<ol><p>Increase or decrease image contrast.</p></ol>
335
336 </div>
337<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
338_8c.html" target="source" name="The ContrastStretchImage">The ContrastStretchImage</a></h2>
339<div class="doc-section">
340
341<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>
342
343<p>The format of the ContrastStretchImage method is:</p>
344
345<pre class="code">
346 MagickBooleanType ContrastStretchImage(Image *image,
347 const char *levels)
348 MagickBooleanType ContrastStretchImageChannel(Image *image,
cristybb503372010-05-27 20:51:26 +0000[diff] [blame]349 const size_t channel,const double black_point,
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]350 const double white_point)
351</pre>
352
353<p>A description of each parameter follows:</p></ol>
354
355<h5>image</h5>
356<ol><p>the image.</p></ol>
357
358<h5>channel</h5>
359<ol><p>the channel.</p></ol>
360
361<h5>black_point</h5>
362<ol><p>the black point.</p></ol>
363
364<h5>white_point</h5>
365<ol><p>the white point.</p></ol>
366
367<h5>levels</h5>
368<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>
369
370 </div>
371<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
372_8c.html" target="source" name="EnhanceImage">EnhanceImage</a></h2>
373<div class="doc-section">
374
375<p>EnhanceImage() applies a digital filter that improves the quality of a noisy image.</p></ol>
376
377<p>The format of the EnhanceImage method is:</p>
378
379<pre class="code">
380 Image *EnhanceImage(const Image *image,ExceptionInfo *exception)
381</pre>
382
383<p>A description of each parameter follows:</p></ol>
384
385<h5>image</h5>
386<ol><p>the image.</p></ol>
387
388<h5>exception</h5>
389<ol><p>return any errors or warnings in this structure.</p></ol>
390
391 </div>
392<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
393_8c.html" target="source" name="EqualizeImage">EqualizeImage</a></h2>
394<div class="doc-section">
395
396<p>EqualizeImage() applies a histogram equalization to the image.</p></ol>
397
398<p>The format of the EqualizeImage method is:</p>
399
400<pre class="code">
401 MagickBooleanType EqualizeImage(Image *image)
402 MagickBooleanType EqualizeImageChannel(Image *image,
403 const ChannelType channel)
404</pre>
405
406<p>A description of each parameter follows:</p></ol>
407
408<h5>image</h5>
409<ol><p>the image.</p></ol>
410
411<h5>channel</h5>
412<ol><p>the channel.</p></ol>
413
414 </div>
415<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
416_8c.html" target="source" name="GammaImage">GammaImage</a></h2>
417<div class="doc-section">
418
419<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>
420
421<p>You can also reduce the influence of a particular channel with a gamma value of 0.</p></ol>
422
423<p>The format of the GammaImage method is:</p>
424
425<pre class="code">
426 MagickBooleanType GammaImage(Image *image,const double gamma)
427 MagickBooleanType GammaImageChannel(Image *image,
428 const ChannelType channel,const double gamma)
429</pre>
430
431<p>A description of each parameter follows:</p></ol>
432
433<h5>image</h5>
434<ol><p>the image.</p></ol>
435
436<h5>channel</h5>
437<ol><p>the channel.</p></ol>
438
439<h5>gamma</h5>
440<ol><p>the image gamma.</p></ol>
441
442 </div>
443<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
444_8c.html" target="source" name="HaldClutImage">HaldClutImage</a></h2>
445<div class="doc-section">
446
447<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>
448
449<p>The format of the HaldClutImage method is:</p>
450
451<pre class="code">
452 MagickBooleanType HaldClutImage(Image *image,Image *hald_image)
453 MagickBooleanType HaldClutImageChannel(Image *image,
454 const ChannelType channel,Image *hald_image)
455</pre>
456
457<p>A description of each parameter follows:</p></ol>
458
459<h5>image</h5>
460<ol><p>the image, which is replaced by indexed CLUT values</p></ol>
461
462<h5>hald_image</h5>
463<ol><p>the color lookup table image for replacement color values.</p></ol>
464
465<h5>channel</h5>
466<ol><p>the channel.</p></ol>
467
468 </div>
469<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
470_8c.html" target="source" name="LevelImage">LevelImage</a></h2>
471<div class="doc-section">
472
473<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>
474
475<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>
476
477<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>
478
479<p>Gamma specifies a gamma correction to apply to the image.</p></ol>
480
481<p>The format of the LevelImage method is:</p>
482
483<pre class="code">
484 MagickBooleanType LevelImage(Image *image,const char *levels)
485</pre>
486
487<p>A description of each parameter follows:</p></ol>
488
489<h5>image</h5>
490<ol><p>the image.</p></ol>
491
492<h5>levels</h5>
493<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>
494
495 </div>
496<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]497_8c.html" target="source" name="LevelizeImage">LevelizeImage</a></h2>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]498<div class="doc-section">
499
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]500<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]501
502<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>
503
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]504<p>The format of the LevelizeImage method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]505
506<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]507 MagickBooleanType LevelizeImage(Image *image,const double black_point,
508 const double white_point,const double gamma)
509 MagickBooleanType LevelizeImageChannel(Image *image,
510 const ChannelType channel,const double black_point,
511 const double white_point,const double gamma)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]512</pre>
513
514<p>A description of each parameter follows:</p></ol>
515
516<h5>image</h5>
517<ol><p>the image.</p></ol>
518
519<h5>channel</h5>
520<ol><p>the channel.</p></ol>
521
522<h5>black_point</h5>
523<ol><p>The level which is to be mapped to zero (black)</p></ol>
524
525<h5>white_point</h5>
526<ol><p>The level which is to be mapped to QuantiumRange (white)</p></ol>
527
528<h5>gamma</h5>
529<ol><p>adjust gamma by this factor before mapping values. use 1.0 for purely linear stretching of image color values</p></ol>
530
531 </div>
532<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
533_8c.html" target="source" name="LevelizeImageChannel">LevelizeImageChannel</a></h2>
534<div class="doc-section">
535
536<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>
537
538<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>
539
540<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>
541
542<p>The format of the LevelizeImageChannel method is:</p>
543
544<pre class="code">
545 MagickBooleanType LevelizeImageChannel(Image *image,
546 const ChannelType channel,const char *levels)
547</pre>
548
549<p>A description of each parameter follows:</p></ol>
550
551<h5>image</h5>
552<ol><p>the image.</p></ol>
553
554<h5>channel</h5>
555<ol><p>the channel.</p></ol>
556
557<h5>black_point</h5>
558<ol><p>The level to map zero (black) to.</p></ol>
559
560<h5>white_point</h5>
561<ol><p>The level to map QuantiumRange (white) to.</p></ol>
562
563<h5>gamma</h5>
564<ol><p>adjust gamma by this factor before mapping values.</p></ol>
565
566 </div>
567<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
568_8c.html" target="source" name="LevelImageColor">LevelImageColor</a></h2>
569<div class="doc-section">
570
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]571<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]572
573<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>
574
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]575<p>The format of the LevelColorsImageChannel method is:</p>
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]576
577<pre class="code">
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]578 MagickBooleanType LevelColorsImage(Image *image,
cristye7f8fdd2009-09-20 14:43:12 +0000[diff] [blame]579 const MagickPixelPacket *black_color,
580 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy5cadd612009-09-21 19:33:41 +0000[diff] [blame]581 MagickBooleanType LevelColorsImageChannel(Image *image,
582 const ChannelType channel,const MagickPixelPacket *black_color,
583 const MagickPixelPacket *white_color,const MagickBooleanType invert)
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]584</pre>
585
586<p>A description of each parameter follows:</p></ol>
587
588<h5>image</h5>
589<ol><p>the image.</p></ol>
590
591<h5>channel</h5>
592<ol><p>the channel.</p></ol>
593
594<h5>black_color</h5>
595<ol><p>The color to map black to/from</p></ol>
596
597<h5>white_point</h5>
598<ol><p>The color to map white to/from</p></ol>
599
600<h5>invert</h5>
601<ol><p>if true map the colors (levelize), rather than from (level)</p></ol>
602
603 </div>
604<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
605_8c.html" target="source" name="The LinearStretchImage">The LinearStretchImage</a></h2>
606<div class="doc-section">
607
608<p>The LinearStretchImage() discards any pixels below the black point and above the white point and levels the remaining pixels.</p></ol>
609
610<p>The format of the LinearStretchImage method is:</p>
611
612<pre class="code">
613 MagickBooleanType LinearStretchImage(Image *image,
614 const double black_point,const double white_point)
615</pre>
616
617<p>A description of each parameter follows:</p></ol>
618
619<h5>image</h5>
620<ol><p>the image.</p></ol>
621
622<h5>black_point</h5>
623<ol><p>the black point.</p></ol>
624
625<h5>white_point</h5>
626<ol><p>the white point.</p></ol>
627
628 </div>
629<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
630_8c.html" target="source" name="ModulateImage">ModulateImage</a></h2>
631<div class="doc-section">
632
633<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>
634
635<p>The format of the ModulateImage method is:</p>
636
637<pre class="code">
638 MagickBooleanType ModulateImage(Image *image,const char *modulate)
639</pre>
640
641<p>A description of each parameter follows:</p></ol>
642
643<h5>image</h5>
644<ol><p>the image.</p></ol>
645
646<h5>modulate</h5>
647<ol><p>Define the percent change in brightness, saturation, and hue.</p></ol>
648
649 </div>
650<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
651_8c.html" target="source" name="NegateImage">NegateImage</a></h2>
652<div class="doc-section">
653
654<p>NegateImage() negates the colors in the reference image. The grayscale option means that only grayscale values within the image are negated.</p></ol>
655
656<p>The format of the NegateImageChannel method is:</p>
657
658<pre class="code">
659 MagickBooleanType NegateImage(Image *image,
660 const MagickBooleanType grayscale)
661 MagickBooleanType NegateImageChannel(Image *image,
662 const ChannelType channel,const MagickBooleanType grayscale)
663</pre>
664
665<p>A description of each parameter follows:</p></ol>
666
667<h5>image</h5>
668<ol><p>the image.</p></ol>
669
670<h5>channel</h5>
671<ol><p>the channel.</p></ol>
672
673<h5>grayscale</h5>
674<ol><p>If MagickTrue, only negate grayscale pixels within the image.</p></ol>
675
676 </div>
677<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
678_8c.html" target="source" name="The NormalizeImage">The NormalizeImage</a></h2>
679<div class="doc-section">
680
681<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>
682
683<p>The format of the NormalizeImage method is:</p>
684
685<pre class="code">
686 MagickBooleanType NormalizeImage(Image *image)
687 MagickBooleanType NormalizeImageChannel(Image *image,
688 const ChannelType channel)
689</pre>
690
691<p>A description of each parameter follows:</p></ol>
692
693<h5>image</h5>
694<ol><p>the image.</p></ol>
695
696<h5>channel</h5>
697<ol><p>the channel.</p></ol>
698
699 </div>
700<h2><a href="http://www.imagemagick.org/api/MagickCore/enhance
701_8c.html" target="source" name="SigmoidalContrastImage">SigmoidalContrastImage</a></h2>
702<div class="doc-section">
703
704<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>
705
706<p>The format of the SigmoidalContrastImage method is:</p>
707
708<pre class="code">
709 MagickBooleanType SigmoidalContrastImage(Image *image,
710 const MagickBooleanType sharpen,const char *levels)
711 MagickBooleanType SigmoidalContrastImageChannel(Image *image,
712 const ChannelType channel,const MagickBooleanType sharpen,
713 const double contrast,const double midpoint)
714</pre>
715
716<p>A description of each parameter follows:</p></ol>
717
718<h5>image</h5>
719<ol><p>the image.</p></ol>
720
721<h5>channel</h5>
722<ol><p>the channel.</p></ol>
723
724<h5>sharpen</h5>
725<ol><p>Increase or decrease image contrast.</p></ol>
726
727<h5>contrast</h5>
728<ol><p>control the "shoulder" of the contast curve.</p></ol>
729
730<h5>midpoint</h5>
731<ol><p>control the "toe" of the contast curve.</p></ol>
732
733 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]734
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