The Zend Developer Zone has a new tutorial from Vikram Vaswani on working with GraphicsMagik to create and manipulate images in your PHP scripts.
Based on the robust, multi-threaded GraphicsMagick library, aka the "Swiss Army knife of image processing", PHP's GraphicsMagick extension allows developers to add street cred to their image (sorry, I couldn't resist!) with some fairly powerful API methods. This article discusses the extension in detail, introducing you to its key functions and showing you how to rotate, resample, transform, crop, carve, and otherwise mangle your images until they roll over and beg for mercy.
The tutorial looks at how to get the package installed (both from source or as a pecl package) and how to check and make sure it's up and working. The sample scripts included show you how to grab the info about an image, resize it, write it out to a file, rotate/flip it and do a few other fun tricks (including using built-in filters).