This class can generate images for use in CAPTCHA based validation tests.
It generates an image of a given width and height with a sequence of random hexadecimal digits over a set of random lines.
The digits and the lines are rendered with the same foreground color. The foreground and background colors are generated randomly. The background color is always darker than the foreground color to assure high contrast.
The generated image is a PHP file.
The verification digits are stored in a session variable for posterior verification.
It also supports relaoding the Image without need to reload the base page. The link used to initiate the reload may be customized to any text or even image or button. Now in version 2.5 a loading gif indicator is rendered till the new Captcha image is downloaded.