Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!ames!amdcad!sun!kilowatt!raz
From: raz@kilowatt.uucp (Raz- Berry)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Color compression routines (4096 to 256) wanted.
Summary: argh, he got me. New iff2sun coming soon!
Keywords: HAM, 256 color, Amiga, Sun
Message-ID: <33752@kilowatt.uucp>
Date: 27 Apr 89 17:52:15 GMT
References: <33747@kilowatt.uucp> <11430@well.UUCP>
Reply-To: raz@sun.UUCP (Steve -Raz- Berry)
Organization: Sun Microsystems, Mountain View
Lines: 43

In article <11430@well.UUCP> ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab) writes:
)In article <33747@kilowatt.uucp> raz@kilowatt.uucp (Raz- Berry) writes:
)) I need a basic flowchart
)) on taking a 4096 color palette and converting it down to
)) 256. Initially I was thinking that:

)) [I take a first stab at a HAM conversion routine ... deleted]

)	Permit me to poke a hole in this.

) [Leo, armed with a short sword, makes swiss cheese out of my first pass]

)...  However, that white line is a
)prominent feature, because of its contrast with the rest of the image.  So
)picking colors for a reduced bitmap isn't all that simple.

Yeah, I had similar thoughts. I recognized the problem, I was hoping some
one could 'show me the way' to enlightened color mapping techniques. As
it turns out, a fellow named Tony Kennedy sent me some very interesting
conversion and dithering routines. Perhaps the version after the next release
will include dithering routines as well as HAM capability. So if I include
HAM conversion, you can all thank Tony.

BTW: I have included Extra-Half-Bright support to iff2sun and I will be
posting to Bob the new source soon. I am not too happy with the way
320x400 images look on a Sun color monitor though. There is a definate
elongation effect because of the different aspect ratio between the two
machines. So far the best results have been with 640 (or larger) x400
images 'rastrepl'ed once, to fit the Sun screen. I like the hires LION
that comes with PixMate... looks pretty good on mono.

)	I had to attack similar problems when writing some internal tools
)when we were developing Roger Rabbit.  I strongly recommend you get yourself
)a book on image processing (something I should have done).

Gee, I suppose sharing the RR code is out of the question huh? ;-)

)_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
)Leo L. Schwab -- The Guy in The Cape	INET: well!ewhac@ucbvax.Berkeley.EDU

-- 
Steve -Raz- Berry      Disclaimer: I didn't do nutin!
UUCP: sun!kilowatt!raz                    ARPA: raz%kilowatt.EBay@sun.com
"Fate, it protects little children, old women, and ships named Enterprize"