The PHP GD library is so powerful that it can perform a variety of image manipulations you would normally only find in a graphics program. In fact you could probably build quite an advanced image editor using them. This plug-in goes someway towards that by providing 14 different image transformations you can apply to your graphics.

The Figure shows just one of these, Edge Detect, in use.

This photograph has been modified by passing it through the Image Alter plug-in