Netpbm

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 tools:
-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.