GDEnhancer
What is GD Enhancer?
It is open source that everyone can use.
It is a class for PHP that offers an object oriented interface for images edit.
It is wrote by GD functions, so you have to install/turn on GD extension first. It is an alternative to GD library, but easier to use.
It is an image editor, not image creator. That means you have to edit an existing image not create an image from nothing.
My purpose to write GD Enhancer is to bulk edit images. Such as editing the images that users upload.
Features
Keeping GIF animation after editing.
Resizing images with fill, fit and stretch options.
Adding image/text watermark to images with 9 position options.
Rendering alpha channel when converting PNG to GIF.
You can find some good examples on website http://www.gdenhancer.com/