gimp-netpbm2gimp-plugins is a collection of over 200 GIMP plug-ins produced by running the source code of the Netpbm graphics filters through Netpbm2Gimp, which is described below. (Note: Think "GIMP" where the Netpbm graphics filter documentation says "PBM", "PGM", "PPM", "PNM", or "PAM".) There is a particular emphasis on load/save plug-ins for obscure graphics formats, but a number of miscellaneous and useful image filters and image generators are included as well.
Netpbm2Gimp is a tool for programmers that converts programs written using the easy-to-use Netpbm library into GIMP plug-ins. Netpbm2Gimp reimplements the Netpbm functions in terms of GIMP/GTK+ functions, thereby hiding much of the complexity of plug-in development. With Netpbm2Gimp, plug-in developers needn't worry about registering plug-ins with the GIMP core, displaying dialog boxes to request input from the user, displaying dialog boxes to present the user with status or error information, handling noninteractive usage (for the GIMP scripting interfaces), managing various GIMP data structures (images, layers, drawables, shadow buffers, the tile cache, etc.), updating the progress bar, controlling the undo stack, and performing the various other operations that are needed in the context of a graphical user interface. All of those features are handled automatically by Netpbm2Gimp.
The source code and Linux binaries for both Netpbm2Gimp and gimp-netpbm2gimp-plugins are available from the Netpbm2Gimp home page, http://netpbm2gimp.sourceforge.net/.