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100 lines
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HTML
100 lines
5.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>将真彩色图像转换为调色板图像</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.imagetruecolortopalette" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">imagetruecolortopalette</h1>
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<p class="verinfo">(PHP 4 >= 4.0.6, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">imagetruecolortopalette</span> — <span class="dc-title">将真彩色图像转换为调色板图像</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.imagetruecolortopalette-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>imagetruecolortopalette</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
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, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$dither</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$ncolors</code></span>
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) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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<span class="function"><strong>imagetruecolortopalette()</strong></span>
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将一幅真彩色图像转换为调色板图像。本函数的代码原本是从独立的 JPEG
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小组库代码中提取出来的，非常出色。此代码被修改以在结果调色板中保留尽可能多的 alpha
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通道信息以及尽可能多的颜色。但并没有达到期望的效果。通常最好生成真彩色图像输出，这样可以保证得到最高的输出质量。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.imagetruecolortopalette-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">image</code></dt>
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<dd>
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<p class="para">由图象创建函数(例如<span class="function"><a href="imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a></span>)返回的图象资源。</p></dd>
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<dt>
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<code class="parameter">dither</code></dt>
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<dd>
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<p class="para">
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指明图像是否被抖动（dithered），如果为
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<strong><code>TRUE</code></strong> 则图像将被抖动使图像中的斑点更多但是颜色更接近。
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</p>
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</dd>
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<dt>
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<code class="parameter">ncolors</code></dt>
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<dd>
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<p class="para">
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设定调色板中被保留的颜色的最大数目。
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.imagetruecolortopalette-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.imagetruecolortopalette-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-3742">
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<p><strong>Example #1 Converting a true color image to a palette-based image</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Create a new true color image<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatetruecolor</span><span style="color: #007700">(</span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Convert to palette-based with no dithering and 255 colors<br /></span><span style="color: #0000BB">imagetruecolortopalette</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">, </span><span style="color: #0000BB">255</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Save the image<br /></span><span style="color: #0000BB">imagepng</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #DD0000">'./paletteimage.png'</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>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.imagetruecolortopalette-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数需要 GD 2.0.1 或更高版本(推荐 2.0.28 及更高版本)。</span></p></blockquote>
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</div>
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</div></div></div></body></html> |