Netpbm is a toolkit for conversion of images between a variety of
different formats, as well as to allow a few basic image operations.
Netpbm is based on the widely spread Pbmplus package (release: 10 Dec
91).  On top of that, a lot of improvements and additions have been
made. After the latest release of Pbmplus, a lot of additional filters
have been circulating on the net. The aim of Netpbm was, to collect
these and to turn them into a package. This work has been performed by
a group of programmers all over the world.

WWW: http://netpbm.sourceforge.net/