function.imagick-levelimage.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Adjusts the levels of an image</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagick-labelimage.html">Imagick::labelImage</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagick-linearstretchimage.html">Imagick::linearStretchImage</a></div> <div class="up"><a href="class.imagick.html">The Imagick class</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.imagick-levelimage" class="refentry"> <div class="refnamediv"> <h1 class="refname">Imagick::levelImage</h1> <p class="verinfo">(No version information available, might be only in CVS)</p><p class="refpurpose"><span class="refname">Imagick::levelImage</span> — <span class="dc-title">Adjusts the levels of an image</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><b><b>Imagick::levelImage</b></b></span> ( <span class="methodparam"><span class="type">float</span> <tt class="parameter">$blackPoint</tt></span> , <span class="methodparam"><span class="type">float</span> <tt class="parameter">$gamma</tt></span> , <span class="methodparam"><span class="type">float</span> <tt class="parameter">$whitePoint</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$channel</tt></span> ] )</div> <div class="warning"><b class="warning">Warning</b><p class="simpara">This function iscurrently not documented; only its argument list is available.</p></div> <p class="para"> Adjusts the levels of an image by scaling the colors falling between specified white and black points to the full available quantum range. The parameters provided represent the black, mid, and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. Mid point specifies a gamma correction to apply to the image. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">blackPoint</tt></i></span> <dd> <p class="para"> The image black point </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">gamma</tt></i></span> <dd> <p class="para"> The gamma value </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">whitePoint</tt></i></span> <dd> <p class="para"> The image white point </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">channel</tt></i></span> <dd> <p class="para"> Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channeltype constants using bitwise operators. Defaults to Imagick::CHANNEL_ALL. Refer to this list of <a href="imagick.constants.html#imagick.constants.channel" class="link">channel constants</a>. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <b><tt>TRUE</tt></b> on success. </p> </div> <div class="refsect1 errors"> <h3 class="title">Errors/Exceptions</h3> <p class="para"> Throws ImagickException on error. </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagick-labelimage.html">Imagick::labelImage</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagick-linearstretchimage.html">Imagick::linearStretchImage</a></div> <div class="up"><a href="class.imagick.html">The Imagick class</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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