<?php

$src = '02.jpg';

    $info = getimagesize($src);

    $type = image_type_to_extension($info[2],false);

   $fun = "imagecreatefrom{$type}";

   $image = $fun($src);

   $font = "simhei.ttf";

   $content = "你好，美女";

   $color = imagecolorallocatealpha($image,255,0,0,50);

   imagettftext($image,20,0,20,30,$color,$font,$content);

   header("Content-type:".$info['mime']);

   $func = "image{$type}";

   $func($image);

   imagedestroy($image);

?>