This program is part of Netpbm.
xpbtoppm reads an X11 pixmap (XPM version 1 or 3) as input and produces a PPM image as output.
If you specify - as the filename, xpmtoppm writes the alpha output to Standard Output and discards the image.
See pamcomp for one way to use the alpha output file.
xpmtoppm can't handle a line longer than 8K characters in the the XPM input. If an input line exceeds this limit, xpmtoppm quits with an error message to that effect. Before Netpbm 10.30 (October 2005), the limit was 2K.
The recogized XPM version 3 features are limited. Comments can only be single lines and there must be for every pixel a default colorname for a color type visual.
Copyright (C) 1991 by Jef Poskanzer.
Upgraded to work with XPM version 3 by Arnaud Le Hors <lehors@mirsa.inria.fr>, Tue Apr 9 1991.