请问，php base64 的字符编码怎么设置，我现在把一张图片读取后编码是这样 
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
这是utf8的 但是我想弄成gbk，gb2312的 我试了 header 没用，请问我该怎么做
附上图片
回复讨论(解决方案)   $thefilename='split.gif';
  $psize = filesize($thefilename);
  $imgbinary = fread(fopen($thefilename, rb), filesize($thefilename));
  $base64=base64_encode ($imgbinary); 
这是我的代码 
图片与字符编码毫无关系
那我怎么得到 其他形式的 base64 编码 
我在c#中写了一个 base64读取的例子 得到的字符串就不一样  
内容不同，base64码值就不同