Xref: utzoo alt.fax:560 comp.dcom.modems:5331 biz.comp.telebit:38
Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!rutgers!bellcore!att!cbnewsh!wcs
From: wcs@cbnewsh.ATT.COM (Bill Stewart 201-949-0705 erebus.att.com!wcs)
Newsgroups: alt.fax,comp.dcom.modems,biz.comp.telebit
Subject: Fax Standards Question
Message-ID: <8456@cbnewsh.ATT.COM>
Date: 26 Feb 90 05:29:55 GMT
Reply-To: wcs@cbnewsh.ATT.COM (Bill Stewart 201-949-0705 erebus.att.com!wcs)
Organization: AT&T Bell Labs - Government Communications
Lines: 23

I've got a question about the Huffman-ish codes used in G3 fax.
(It's been long enough since I've seen the standards that I've
forgotten whether G3 translates fixed-length source bit strings to
variable-length coded, or variable source to fixed coded, or
variable to variable.)  Anyway, is it possible to generate correct
G3 fax for which the source bitmaps are always the same width?
I'm trying to find efficient ways to translate ASCII to fax, and
this would let you store a font as a collection of G3 output bitmaps,
so you could output the characters directly instead of generating a
bitmap from the text and then bit-hacking it into G3.

A standard 10-pitch 6-lpi font corresponds to a character size of
20 pixels wide and 16+ or 33+ lines tall, for 100x200 or 200x200 res.
The bitmap for the 16-line occupies about 10K for a 256-character font,
which is small enough to be practical on a fax board or modem 
(e.g. a Telebit or similar).  A G3 version would be a bit smaller,
though you need to store widths and may not save anything.

-- 
# Bill Stewart AT&T Bell Labs 4M312 Holmdel NJ 201-949-0705 erebus.att.com!wcs
# Fax 949-4876.  Sometimes found at Somerset 201-271-4712
# He put on the goggles, waved his data glove, and walked off into cyberspace.
# Wasn't seen again for days.