This program is part of Netpbm.
pjtoppm reads an HP PaintJet file as input and converts it into a PPM image. This was a quick hack to save some trees, and it only handles a small subset of the paintjet commands. In particular, it will only handle enough commands to convert most raster image files.
There are no command line options defined specifically for pjtoppm, but it recognizes the options common to all programs based on libnetpbm (See Common Options.)