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<title>Get the index of the closest color to the specified color + alpha</title>
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<h1 class="refname">imagecolorclosestalpha</h1>
<p class="verinfo">(PHP 4 >= 4.0.6, PHP 5)</p><p class="refpurpose"><span class="refname">imagecolorclosestalpha</span> — <span class="dc-title">Get the index of the closest color to the specified color + alpha</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.imagecolorclosestalpha-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">int</span> <span class="methodname"><strong>imagecolorclosestalpha</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$red</code></span>
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$green</code></span>
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$blue</code></span>
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$alpha</code></span>
)</div>
<p class="para rdfs-comment">
Returns the index of the color in the palette of the image which
is "closest" to the specified <acronym title="Red-Green-Blue">RGB</acronym> value and
<em><code class="parameter">alpha</code></em> level.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.imagecolorclosestalpha-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">
image</code></em></span><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>
<dt>
<span class="term"><em><code class="parameter">red</code></em></span>
<dd>
<p class="para">Value of red component.</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">green</code></em></span>
<dd>
<p class="para">Value of green component.</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">blue</code></em></span>
<dd>
<p class="para">Value of blue component.</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">alpha</code></em></span>
<dd>
<p class="para">
A value between <em>0</em> and <em>127</em>.
<em>0</em> indicates completely opaque while
<em>127</em> indicates completely transparent.
</p>
</dd>
</dt>
</dl>
The colors parameters are integers between 0 and 255 or hexadecimals
between 0x00 and 0xFF.
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.imagecolorclosestalpha-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the index of the closest color in the palette.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.imagecolorclosestalpha-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3188">
<p><strong>Example #1 Search for a set of colors in an image</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">// Start with an image and convert it to a palette-based image<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefrompng</span><span style="color: #007700">(</span><span style="color: #DD0000">'figures/imagecolorclosest.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagetruecolortopalette</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">, </span><span style="color: #0000BB">255</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Search colors (RGB)<br /></span><span style="color: #0000BB">$colors </span><span style="color: #007700">= array(<br /> array(</span><span style="color: #0000BB">254</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">154</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">153</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">188</span><span style="color: #007700">, </span><span style="color: #0000BB">127</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">153</span><span style="color: #007700">, </span><span style="color: #0000BB">90</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">255</span><span style="color: #007700">, </span><span style="color: #0000BB">137</span><span style="color: #007700">, </span><span style="color: #0000BB">92</span><span style="color: #007700">, </span><span style="color: #0000BB">84</span><span style="color: #007700">)<br />);<br /><br /></span><span style="color: #FF8000">// Loop through each search and find the closest color in the palette.<br />// Return the search number, the search RGB and the converted RGB match<br /></span><span style="color: #007700">foreach(</span><span style="color: #0000BB">$colors </span><span style="color: #007700">as </span><span style="color: #0000BB">$id </span><span style="color: #007700">=> </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorclosestalpha</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">3</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorsforindex</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #DD0000">"(</span><span style="color: #007700">{</span><span style="color: #0000BB">$result</span><span style="color: #007700">[</span><span style="color: #DD0000">'red'</span><span style="color: #007700">]}</span><span style="color: #DD0000">, </span><span style="color: #007700">{</span><span style="color: #0000BB">$result</span><span style="color: #007700">[</span><span style="color: #DD0000">'green'</span><span style="color: #007700">]}</span><span style="color: #DD0000">, </span><span style="color: #007700">{</span><span style="color: #0000BB">$result</span><span style="color: #007700">[</span><span style="color: #DD0000">'blue'</span><span style="color: #007700">]}</span><span style="color: #DD0000">, </span><span style="color: #007700">{</span><span style="color: #0000BB">$result</span><span style="color: #007700">[</span><span style="color: #DD0000">'alpha'</span><span style="color: #007700">]}</span><span style="color: #DD0000">)"</span><span style="color: #007700">;<br /><br /> echo </span><span style="color: #DD0000">"#</span><span style="color: #0000BB">$id</span><span style="color: #DD0000">: Search (</span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">]</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">]</span><span style="color: #DD0000">, </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">3</span><span style="color: #007700">]</span><span style="color: #DD0000">); Closest match: </span><span style="color: #0000BB">$result</span><span style="color: #DD0000">.\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">imagedestroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output
something similar to:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
#0: Search (254, 145, 154, 50); Closest match: (252, 150, 148, 0).
#1: Search (153, 145, 188, 127); Closest match: (148, 150, 196, 0).
#2: Search (153, 90, 145, 0); Closest match: (148, 90, 156, 0).
#3: Search (255, 137, 92, 84); Closest match: (252, 150, 92, 0).
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.imagecolorclosestalpha-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function requires GD 2.0.1 or later (2.0.28 or later is recommended).</span></p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.imagecolorclosestalpha-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.imagecolorexactalpha.html" class="function" rel="rdfs-seeAlso">imagecolorexactalpha()</a> - Get the index of the specified color + alpha</span></li>
<li class="member"> <span class="function"><a href="function.imagecolorclosest.html" class="function" rel="rdfs-seeAlso">imagecolorclosest()</a> - Get the index of the closest color to the specified color</span></li>
<li class="member"> <span class="function"><a href="function.imagecolorclosesthwb.html" class="function" rel="rdfs-seeAlso">imagecolorclosesthwb()</a> - Get the index of the color which has the hue, white and blackness</span></li>
</ul>
</p>
</div>
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