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From: jbm@Brahms.INSL.McGill.CA (John McCluskey)
Newsgroups: comp.os.msdos.misc
Subject: GhostScript 2.0 & SVGA256.BGI
Summary: Implementing a SuperVGA driver for Ghostscript
Keywords: Postscript,Ghostscript,SuperVGA,Borland
Message-ID: <1990Dec21.194023.7654@Brahms.INSL.McGill.CA>
Date: 21 Dec 90 19:40:23 GMT
Expires: January 7, 1991
Sender: jbm@brahms.insl.mcgill.ca
Followup-To: jbm%speedy.uucp@larry.mcrcim.mcgill.edu
Organization: INSL, McGill University, Montreal, Canada
Lines: 15

I've modified the GSDEVBGI.C Borland BGI device driver in Ghostscript 2.0
to work with the SVGA256.BGI driver recently posted, and I've run into a
little trouble implementing a greyscale mode.  In the device driver structure
there is a binary flag called has_color that actually seems to mean 
is_not_binary, because when I leave the flag cleared, and set max_color to
be 63 (meaning that there are 64 gray shades available), I get output as a
dithered black and white instead of true grayscale.  When I set the flag and
map the pallet with 6 shades for each primary color (6 x 6 x 6 = 216 colors),
then it seems to work just fine. (well, there are some odd transparency 
effects) Is it possible to define an output device which has grayscale
output?

I would appreciate if someone would forward this to gnu.ghostscript, if
such a newsgroup exists.  The Ghostscript documentation seems to omit any
network address of a maintainer or newsgroup mailing list.