Graphics Processor
From Just Solve the File Format Problem
Graphics Processor is a file format for the Atari ST.
pg1
files are 16 colors and 320x200
pg2
files are 4 colors and 640x400
pg3
files are mono and 640x400
Identification
The test files I have located are all exactly 32331 bytes long. Not sure if this is always the case or not.