This program is part of Netpbm.
ppmtorgb3 reads a PPM image as input and writes three PGM images as
output, one each for red, green, and blue.
ppmtorgb3 constructs the output filenames by taking the input file-
name, stripping off any extension, and appending .red, .grn, .blu.
For example, separating lenna.ppm would result in lenna.red,
lenna.grn, and lenna.blu. If the input comes from stdin, the names
are noname.red, noname.grn, and noname.blu.
rgb3toppm, pamchannel, ppmtopgm, pgmtoppm, ppm, pgm
Copyright (C) 1991 by Jef Poskanzer.
netpbm documentation 10 January 1991 Ppmtorgb3 User Manual(0)