<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Adjusts the contrast of an image</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="imagick.shearimage.html">Imagick::shearImage</a></div> <div class="next" style="text-align: right; float: right;"><a href="imagick.sketchimage.html">Imagick::sketchImage</a></div> <div class="up"><a href="class.imagick.html">Imagick</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="imagick.sigmoidalcontrastimage" class="refentry"> <div class="refnamediv"> <h1 class="refname">Imagick::sigmoidalContrastImage</h1> <p class="verinfo">(PECL imagick 2.0.0)</p><p class="refpurpose"><span class="refname">Imagick::sigmoidalContrastImage</span> — <span class="dc-title">Adjusts the contrast of an image</span></p> </div> <div class="refsect1 description" id="refsect1-imagick.sigmoidalcontrastimage-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><strong>Imagick::sigmoidalContrastImage</strong></span> ( <span class="methodparam"><span class="type">bool</span> <code class="parameter">$sharpen</code></span> , <span class="methodparam"><span class="type">float</span> <code class="parameter">$alpha</code></span> , <span class="methodparam"><span class="type">float</span> <code class="parameter">$beta</code></span> [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$channel</code><span class="initializer"> = Imagick::CHANNEL_ALL</span></span> ] )</div> <p class="para rdfs-comment"> 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 <strong><code>TRUE</code></strong> to increase the image contrast otherwise the contrast is reduced. </p> </div> <div class="refsect1 parameters" id="refsect1-imagick.sigmoidalcontrastimage-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><em><code class="parameter">sharpen</code></em></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><em><code class="parameter">alpha</code></em></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><em><code class="parameter">beta</code></em></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><em><code class="parameter">channel</code></em></span> <dd> <p class="para"> </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-imagick.sigmoidalcontrastimage-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <strong><code>TRUE</code></strong> on success. </p> </div> <div class="refsect1 errors" id="refsect1-imagick.sigmoidalcontrastimage-errors"> <h3 class="title">Errors/Exceptions</h3> <p class="para"> Throws ImagickException on error. </p> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="imagick.shearimage.html">Imagick::shearImage</a></div> <div class="next" style="text-align: right; float: right;"><a href="imagick.sketchimage.html">Imagick::sketchImage</a></div> <div class="up"><a href="class.imagick.html">Imagick</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>