后来搜索发现如下 [quote]// 对jpeg图形设置隔行扫描
if('jpg'==$type || 'jpeg'==$type) imageinterlace($thumbImg,$interlace);

//$gray=ImageColorAllocate($thumbImg,255,0,0);
//ImageString($thumbImg,2,5,5,"ThinkPHP",$gray);
// 生成图片
$imageFun = 'image'.($type=='jpg'?'jpeg':$type);
$imageFun($thumbImg,$thumbname);
imagedestroy($thumbImg);
imagedestroy($srcImg);[/quote]

其中$imageFun($thumbImg,$thumbname);后面可以接参数设置缩略图质量，请官方对这个可配置