<?php
session_start(); 
$rand = rand(100000, 999999);
$_SESSION['image_random_value'] = md5($rand);
$image = imagecreate(60, 30);
$bgColor = imagecolorallocate ($image, 255, 255, 255); 
$textColor = imagecolorallocate ($image, 0, 0, 0); 
imagestring ($image, 5, 5, 8, $rand, $textColor); 
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); 
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); 
header("Cache-Control: no-store, no-cache, must-revalidate"); 
header("Cache-Control: post-check=0, pre-check=0", false); 
header("Pragma: no-cache"); 
header('Content-type: image/jpeg');
imagejpeg($image);
imagedestroy($image);
?>