Create Image Captcha in PHP <?php session_start(); 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"); function _generateRandom($length=6) { $_rand_src = array( array(48,57) //digits , array(97,122) //lowercase chars // , array(65,90) //uppercase chars ); srand ((double) microtime() * 1000000); $random_string = ""; for($i=0;$i<$length;$i++){ $i1=rand(0,sizeof($_rand_src)-1); $random_string .= chr(rand($_rand_src[$i1][0],$_rand_src[$i1][1])); } return $random_string; } $im = @imagecreatefromjpeg("captcha.jpg"); $rand = _generateRandom(3); $_SESSION['captcha'] = $rand; ImageString($im, 5, 2, 2, $rand[0].&qu