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<title>Apply a gamma correction to a GD image</title>
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<h1 class="refname">imagegammacorrect</h1>
<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">imagegammacorrect</span> — <span class="dc-title">Apply a gamma correction to a GD image</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.imagegammacorrect-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>imagegammacorrect</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$inputgamma</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$outputgamma</code></span>
)</div>
<p class="para rdfs-comment">
Applies gamma correction to the given gd <code class="parameter">image</code>
given an input and an output gamma.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.imagegammacorrect-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<code class="parameter">
image</code></dt>
<dd>
<p class="para">An image resource, returned by one of the image creation functions,
such as <span class="function"><a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a></span>.</p></dd>
<dt>
<code class="parameter">inputgamma</code></dt>
<dd>
<p class="para">
The input gamma.
</p>
</dd>
<dt>
<code class="parameter">outputgamma</code></dt>
<dd>
<p class="para">
The output gamma.
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.imagegammacorrect-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.imagegammacorrect-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3810">
<p><strong>Example #1 <span class="function"><strong>imagegammacorrect()</strong></span> usage</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Create image instance<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefromgif</span><span style="color: #007700">(</span><span style="color: #DD0000">'php.gif'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Correct gamma, out = 1.537<br /></span><span style="color: #0000BB">imagegammacorrect</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">1.0</span><span style="color: #007700">, </span><span style="color: #0000BB">1.537</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Save and free image<br /></span><span style="color: #0000BB">imagegif</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #DD0000">'./php_gamma_corrected.gif'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagedestroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
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