Man page 1 : g3topbm

g3topbm - convert a Group 3 fax file into a portable bitmap

g3topbm [ -kludge ] [ -reversebits ] [ -stretch ] [ g3file ]

Reads a Group 3 fax file as input. Produces a portable bitmap as output.

-kludge

    Tells g3topbmto ignore the first few lines of the file; sometimes fax files have some junk at the beginning.

-reversebits

    Tells g3topbmto interpret bits least-significant first, instead of the default most-significant first. Apparently some fax modems do it one way and others do it the other way. If you get a whole bunch of "bad code word" messages, try using this flag.

-stretch

    Tells g3topbmto stretch the image vertically by duplicating each row. This is for the low-quality transmission mode.

All flags can be abbreviated to their shortest unique prefix.

The standard for Group 3 fax is defined in CCITT Recommendation T.4.

Probably.

pbmtog3(1), pbm(5)

Copyright (C) 1989 by Paul Haeberli <>.