Images and PHP

Does anyone know where I can find tutorial(s) on how PHP can be used to generate images when it's passed some variables? For example at http://www.dvla-som.co.uk/search/ss...owtosearch.html if you search for a car registration plate then click on Preview Plate, a program called generate.pl gets passed the letters in the plate, like this: generate.pl?ALEX 1 and it creates a registration plate with those letters in the middle. It's not done with slices or anything: it's an actual GIF image. How can something like this be achieved?

Check this out:
http://hotwired.lycos.com/webmonkey/99/25/index3a.html?tw=programming

To modify images on the fly you'll need GD libary. But from version 1.6 there's no GIF support, but PNG support. I think that PHP 4.0 can communicate with GD and use PNG. Or you can grab pre 1.6 GD libary from some old forgotten ftps URL

You can use the Tool ImageMagick. It works with php, perl and apache! You can modify your images temporaly with powerfull functions.

Look at: http://www.wizards.dupont.com/cristy/ImageMagick.html