<?
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-cache, must-revalidate");
header("Pragma: no-cache"); 
header("Content-type: image/png");

$fd = fopen("images/".$img, "r");
$contents = fread( $fd, filesize("images/".$img) );
echo $contents;
fclose($fd);
?>