<?php
header("Content-type: image/jpeg");
$string=substr(md5($_GET[str]),-5);
$im    = imagecreatefromjpeg("gencode.jpg");
$red = imagecolorallocate($im, 255, 20, 136);
$font  = 'tempsitc.ttf';
imagettftext($im, 12, 3, 8, 15, $red, $font, $string);
imagejpeg($im);
imagedestroy($im);
?>