It took me about 20 minutes to figure out how to get all of the appropriate libraries installed for PHP to recognize this little jewel-- but that was because of my lack of PHP-oriented knowledge. You just have to recompile PHP with GD and FreeType support and this script comes rocking out of the box!
I am happy that the developer allows so much customization in the way that your 'Security Code' looks ... and the code is easy to understand. So, if you are not happy with it as it comes, it's really easy to mold it into what you need.
Supports most colors and even supports image backgrounds. That's one of the coolest features (I am currently on the hunt for a fairly busy background)!
Excellent, A++, not much more to say. Thanks for keeping this 'Diamond in the Rough' FREE!