Testing the GD Library

The GD library allows a server to render simple graphics. It’s not photoshop, but it is highly useful. Especially for CAPTCHA pages, a typical feature which I am in the middle of developing for traffic exchanges.

CAPTCHA stands for ‘Completely Automated Public Turing test to tell Computers and Humans Apart‘, and typically uses the GD library to create a graphic with a random string or word, sometimes distorted, that a human can decipher and input back to the server but bots can not.

There are many other uses for the GD library, but this is an extremely common one these days.

When developing a script which uses image rendering through the GD library sometimes (usually) you get to a point where you have to check if the library is installed on the server. It’s a big plus to a developer if the code he’s writing can actually work.

So I was really pleased when I found a simple script by Dagon Design that tells you straight out that GD is installed. You can look at phpinfo() to find this info, but I find this nicer and more to the point.

Perhaps this will be as useful to you as it will be to me:
Script: Checking for GD support on your server