This is a simple exercise that creates a png image from a string, then stores that string information into a session variable for it to be verified using the form (captcha).

To make this happen, the class Getpng uses the PHP functions: imagecreate imagecolorallocate imagestring imagepng

The working copy of this simple script can be found at: http://rolymengual.com.ar/captcha_post_received.php