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Path: utzoo!watmath!watnot!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.graphics
Subject: Re: Allocation of color map
Message-ID: <1974@watcgl.UUCP>
Date: Wed, 5-Jun-85 19:17:35 EDT
Article-I.D.: watcgl.1974
Posted: Wed Jun  5 19:17:35 1985
Date-Received: Thu, 6-Jun-85 03:23:34 EDT
References: <12800001@umn-cs.UUCP> <218@rti-sel.UUCP>
Reply-To: dmmartindale@watcgl.UUCP (Dave Martindale)
Organization: U of Waterloo, Ontario
Lines: 14

This is a hard problem, I think.  What you really want is to find a set
of 256 points in RGB space such that when the set of all colours present
in the image are each mapped to their nearest represented colour,
the sum of the errors are minimized.  And you probably want to weight
this sum according to the visibility to the eye of each error.
I think there was a paper presented at SIGGRAPH a year or two ago that
dealt with the subject; unfortunately my proceedings are still packed
somewhere.

What most people do with 8-bit frame buffers is just allocate 3 bits for
red, 3 bits for green, and 2 bits for blue.  The colour map is easy
to build, and encoding the pixels is easy.  If you want the image
to look realistic, don't forget to include gamma correction when
building the colour map.