This is a compact (one-file only), lightweight, object-oriented image manipulation library written in and for PHP, that provides methods for performing several types of image manipulation operations. It doesn’t require any external libraries other than the GD2 extension (with which PHP usually comes pre-compiled with).
Zebra_Image‘s code is heavily commented and generates no warnings/errors/notices when PHP’s error reporting level is set to E_ALL.
With this library you can rescale, flip, rotate and crop images. It supports loading and saving images in the GIF, JPEG and PNG formats and preserves transparency for GIF, PNG and PNG24.
The cool thing about it is that it can re-size images to exact given width and height and still maintain aspect ratio!