Mine

<?php

Header("Content-Type: image/png");
session_start();
$random;
session_register('random');
$imagec = imagecreate(100, 100);

$white = imagecolorallocate($imagec, 255, 255, 255);
$black = imagecolorallocate($imagec, 0, 0, 0,);

srand((double)microtime()*10000000);

$string = md5(rand(0,99999));
$random = subtr($string, 17, 5);
imagefill($imagec, 0, 0, $black);
imagestring($imagec, 4, 70, 10, $random, $white);
imagepng($imagec, "verification.png");
imagedestroy($imagec);
?>


echo <img src=\"verification.png\">;
echo <br><br>;
echo Type the code you see in the image in the box below. (case sensitive);
echo  <form action=\"verify.php\" method=post>;
echo <input name=\"random\" type=\"text\" value=\"\">;
echo <input type=\"submit\">;


</form>