区别|缩略图
PHP的GD扩展提供了两个函数来缩放图像：
<SPAN lang=EN-US>ImageCopyResized(<TT><EM>dest</EM></TT>, <TT><EM>src</EM></TT>, <TT><EM>dx</EM></TT>, <TT><EM>dy</EM></TT>, <TT><EM>sx</EM></TT>, <TT><EM>sy</EM></TT>, <TT><EM>dw</EM></TT>, <TT><EM>dh</EM></TT>, <TT><EM>sw</EM></TT>, <TT><EM>sh</EM></TT>);<br/>ImageCopyResampled(<TT><EM>dest</EM></TT>, <TT><EM>src</EM></TT>, <TT><EM>dx</EM></TT>, <TT><EM>dy</EM></TT>, <TT><EM>sx</EM></TT>, <TT><EM>sy</EM></TT>, <TT><EM>dw</EM></TT>, <TT><EM>dh</EM></TT>, <TT><EM>sw</EM></TT>, <TT><EM>sh</EM></TT>);</SPAN> <br/>
<span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"><p><code><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"></span></span></span>
<span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"></span></span></span>ImageCopyResized( )函数在所有GD版本中有效，但其缩放图像的算法比较粗糙，可能会导致图像边缘的锯齿。GD 2.x中新增了一个ImageCopyResampled( )函数，其像素插值算法得到的图像边缘比较平滑（但该函数的速度比ImageCopyResized()慢）。<span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,0,187)"><?php <br/><br> $src </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">ImageCreateFromJPEG</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(221,0,0)">'php.jpg'</span><span style="COLOR: rgb(0,119,0)">); <br><br> </span><span style="COLOR: rgb(0,0,187)">$width </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">ImageSx</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(0,0,187)">$src</span><span style="COLOR: rgb(0,119,0)">); <br> </span><span style="COLOR: rgb(0,0,187)">$height </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">ImageSy</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(0,0,187)">$src</span><span style="COLOR: rgb(0,119,0)">); <br> </span><span style="COLOR: rgb(0,0,187)">$x </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">$width</span><span style="COLOR: rgb(0,119,0)">/</span><span style="COLOR: rgb(0,0,187)">2</span><span style="COLOR: rgb(0,119,0)">; </span><span style="COLOR: rgb(0,0,187)">$y </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">$height</span><span style="COLOR: rgb(0,119,0)">/</span><span style="COLOR: rgb(0,0,187)">2</span><span style="COLOR: rgb(0,119,0)">; <br> </span><span style="COLOR: rgb(0,0,187)">$dst </span><span style="COLOR: rgb(0,119,0)">= </span><span style="COLOR: rgb(0,0,187)">ImageCreateTrueColor</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(0,0,187)">$x</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$y</span><span style="COLOR: rgb(0,119,0)">); <br> </span><span style="COLOR: rgb(0,0,187)">ImageCopyResized</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(0,0,187)">$dst</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$src</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">0</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">0</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">0</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">0</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$x</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$y</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$width</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">$height</span><span style="COLOR: rgb(0,119,0)">); <br> </span><span style="COLOR: rgb(255,128,0)">//ImageCopyResampled($dst,$src,0,0,0,0,$x,$y,$width,$height); <br><br> </span><span style="COLOR: rgb(0,0,187)">header</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(221,0,0)">'Content-Type: image/jpeg'</span><span style="COLOR: rgb(0,119,0)">); <br> </span><span style="COLOR: rgb(0,0,187)">ImageJPEG</span><span style="COLOR: rgb(0,119,0)">(</span><span style="COLOR: rgb(0,0,187)">$dst</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(221,0,0)">''</span><span style="COLOR: rgb(0,119,0)">,</span><span style="COLOR: rgb(0,0,187)">100</span><span style="COLOR: rgb(0,119,0)">); <br></span><span style="COLOR: rgb(0,0,187)">?></span> <br><br>原图：<br><br><br>使用</span><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"></span><span style="COLOR: rgb(0,0,187)">ImageCopyResized</span><span style="COLOR: rgb(0,119,0)">()<span style="COLOR: rgb(0,0,0)">函数生成的结果：<br><br><br><br></span></span></span><span style="COLOR: rgb(0,0,0)">使用</span><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"></span><span style="COLOR: rgb(0,0,187)">ImageCopyResampled</span><span style="COLOR: rgb(0,119,0)">()<span style="COLOR: rgb(0,0,0)">函数生成的结果：</span></span></span><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"><br></span><br></span><span style="COLOR: rgb(0,0,187)"></span></span><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,0,187)">ImageCopyResampled</span><span style="COLOR: rgb(0,119,0)">()<span style="COLOR: rgb(0,0,0)">函数生成的结果比较平滑，效果较好。<br><br></span></span></span><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"><code><span style="COLOR: rgb(0,0,0)"><span style="COLOR: rgb(0,119,0)"><span style="COLOR: rgb(0,0,0)"><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false;"><FONT size=2>顺便贴一个效果，用ASCII表示图像。ImageColorAt()有一个很有趣的用处，它可以循环检查<br/></FONT><FONT size=2>图像中的每一个像素的颜色，然后对该颜色数据进行操作。</FONT></PRE>登录后复制</div><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false;"><FONT face=宋体 size=2><SPAN style="FONT-SIZE: 12pt">源代码：<br/></SPAN></FONT><FONT face="Courier New"><html></FONT></PRE>登录后复制</div><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false;"><FONT face="Courier New"><body bgcolor="#000000" style="line-height:6pt"> </FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,0,187)"><?php <br/> $im </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagecreatefromjpeg</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(221,0,0)">'test1.jpg'</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">); <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">$dx </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagesx</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$im</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">); <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">$dy </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagesy</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$im</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">); <br/> for(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$y </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">0</SPAN><SPAN style="COLOR: rgb(0,119,0)">; </SPAN><SPAN style="COLOR: rgb(0,0,187)">$y </SPAN><SPAN style="COLOR: rgb(0,119,0)">< </SPAN><SPAN style="COLOR: rgb(0,0,187)">$dy</SPAN><SPAN style="COLOR: rgb(0,119,0)">; </SPAN><SPAN style="COLOR: rgb(0,0,187)">$y</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">++) { <br/> for(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$x</SPAN><SPAN style="COLOR: rgb(0,119,0)">=</SPAN><SPAN style="COLOR: rgb(0,0,187)">0</SPAN><SPAN style="COLOR: rgb(0,119,0)">; </SPAN><SPAN style="COLOR: rgb(0,0,187)">$x </SPAN><SPAN style="COLOR: rgb(0,119,0)">< </SPAN><SPAN style="COLOR: rgb(0,0,187)">$dx</SPAN><SPAN style="COLOR: rgb(0,119,0)">; </SPAN><SPAN style="COLOR: rgb(0,0,187)">$x</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">++) { <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">$col </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagecolorat</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$im</SPAN><SPAN style="COLOR: rgb(0,119,0)">, </SPAN><SPAN style="COLOR: rgb(0,0,187)">$x</SPAN><SPAN style="COLOR: rgb(0,119,0)">, </SPAN><SPAN style="COLOR: rgb(0,0,187)">$y</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">); <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">$rgb </SPAN><SPAN style="COLOR: rgb(0,119,0)">= </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagecolorsforindex</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$im</SPAN><SPAN style="COLOR: rgb(0,119,0)">,</SPAN><SPAN style="COLOR: rgb(0,0,187)">$col</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">); <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">printf</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(221,0,0)">'<font color=#%02x%02x%02x>*</font>'</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">, <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">$rgb</SPAN><SPAN style="COLOR: rgb(0,119,0)">[</SPAN><SPAN style="COLOR: rgb(221,0,0)">'red'</SPAN><SPAN style="COLOR: rgb(0,119,0)">],</SPAN><SPAN style="COLOR: rgb(0,0,187)">$rgb</SPAN><SPAN style="COLOR: rgb(0,119,0)">[</SPAN><SPAN style="COLOR: rgb(221,0,0)">'green'</SPAN><SPAN style="COLOR: rgb(0,119,0)">],</SPAN><SPAN style="COLOR: rgb(0,0,187)">$rgb</SPAN><SPAN style="COLOR: rgb(0,119,0)">[</SPAN><SPAN style="COLOR: rgb(221,0,0)">'blue'</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">]); <br/> } <br/> echo </SPAN><SPAN style="COLOR: rgb(221,0,0)">"<br>\n"</SPAN></FONT><FONT face="Courier New"><SPAN style="COLOR: rgb(0,119,0)">; <br/> } <br/> </SPAN><SPAN style="COLOR: rgb(0,0,187)">imagedestroy</SPAN><SPAN style="COLOR: rgb(0,119,0)">(</SPAN><SPAN style="COLOR: rgb(0,0,187)">$im</SPAN></FONT><SPAN style="COLOR: rgb(0,119,0)"><FONT face="Courier New">); <br/></FONT></SPAN><FONT face="Courier New"><SPAN style="COLOR: rgb(0,0,187)">?> <br/></SPAN></body></html> </FONT></PRE>登录后复制</div><p><br></p>
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</span></span></span>很有趣吧，呵呵..
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