PHPImageWorkshop is an open source class using the GD library that helps you to manage images with PHP.
This class is thought like photo editing software (Photoshop, GIMP…): you can superpose many layers or even layer groups, each layer having a background image.
It makes the class the most flexible ever !
It is thought to do simple tasks like creating thumbnails or pasting watermarks and also to do more complex tasks (plural superspositions, images positions…).
Here is a none exhaustive list of what you can do with: pasting an image (or plural) on another one, cropping, moving, resizing, rotating, superposing, writing…