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From: alfter@nevada.edu (SCOTT ALFTER)
Newsgroups: comp.sys.apple2
Subject: Color Graphics Printing
Message-ID: <1991May1.173724.13975@nevada.edu>
Date: 1 May 91 17:37:24 GMT
Sender: news@nevada.edu (News Administrator)
Organization: University of Nevada, System Computing Services
Lines: 20

I have a whole bunch of color pictures I'd like to send to my
Imagewriter.  I can hack the routines together to do the actual
printing.  (Full-color printing on the Imagewriter would be done in
four passes with four ribbons--yellow, red, blue, black.)  The
problems I'm having relate to (1) separating the colors and (2)
halftoning.  First, the color information in the pictures gives you
red, green, and blue.  As I mentioned above, though, you print with
red, yellow, blue, and black.  What formulas should be applied to
generate the color separations?  After that, is there an efficient way
to generate a halfway-decent range of halftones?  A way to make 256
different shades would be especially nice, but I'll probably have to
settle for 64 shades (8x8 matrix for halftoning at 72x72 dpi).  Maybe
the GS system software gurus can help; they have to do the same stuff
in the Imagewriter II drivers, but any code examples must be usable on
8-bit machines (I'm writing the programs on my IIe).

Scott Alfter-----------------------------_/_----------------------------
Call the Skunk Works BBS (702) 896-2676 / v \ 6 PM-6 AM 300/1200/2400
Internet: alfter@uns-helios.nevada.edu (    ( Apple II:
   GEnie: S.ALFTER                      \_^_/ the power to be your best!