Netpbm is a toolkit for manipulation of graphic images, including conversion of images between a variety of different formats. There are over 300 separate tools in the package including converters for about 100 graphics formats.
Examples of the sort of image manipulation we're talking about are:
- Shrinking an image by 10%
- Cutting the top half off of an image
- Making a mirror image
- Creating a sequence of images that fade from one image to another