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From: daveh@ccwf.cc.utexas.edu (Dave Huang)
Newsgroups: comp.sys.apple2
Subject: Re: Color Graphics Printing
Message-ID: <48260@ut-emx.uucp>
Date: 2 May 91 13:25:05 GMT
References: <1991May1.173724.13975@nevada.edu>
Sender: news@ut-emx.uucp
Reply-To: daveh@ccwf.cc.utexas.edu (Dave Huang)
Organization: The University of Texas at Austin
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In article <1991May1.173724.13975@nevada.edu> alfter@nevada.edu (SCOTT ALFTER) writes:
>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

The color separations are relatively easy, but they don't seem to come
out right... I think the problem is that the "real" names for the
subtractive primaries are cyan, magenta, and yellow. However, the
colors in IWIIs ribbon aren't exactly those colors, they're more like
blue, magenta, and yellow. This tends to turn things that should be
blue into a purplish color :(

Anyways,

C = 1 - R
M = 1 - G
Y = 1 - B

K = min(C,M,Y)  then C = C - K, M = M - K, Y = Y - K 
 
>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

I don't know about halftones though. 256 shades is definitely too much
for the IWII though, your pictures would be too chunky. I forgot how
many shades the GS/OS printer drivers do, but I think it's around 9
shades of one primary color... It's listed in the Toolbox Reference
Vol. 1, near the end, if you get a chance to look at one.

Anyone else have helpful comments??

>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!

-- 
David Huang                                 |
Internet: daveh@ccwf.cc.utexas.edu          | "One with a face made of metal
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