Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!midway!mimsy!mojo!russotto
From: russotto@eng.umd.edu (Matthew T. Russotto)
Newsgroups: comp.sys.mac.system
Subject: Re: Color Look Up Table: Apple folks, please read!
Keywords: CLUT, APPLE
Message-ID: <1991Jun3.190609.23552@eng.umd.edu>
Date: 3 Jun 91 19:06:09 GMT
References: <4053@ssc-bee.ssc-vax.UUCP>
Sender: news@eng.umd.edu (C-News)
Distribution: usa
Organization: College of Engineering, Maryversity of Uniland, College Park
Lines: 25

In article <4053@ssc-bee.ssc-vax.UUCP> howie@ssc-vax.UUCP (The Humbug Wizard @ The Emerald City) writes:
>This is aimed primarily at any of the Cupertino folks who frequent the
>net, though if anyone else has an answer, it will be welcome.
>
>I took a class last week which included a section on "stack" design
>and layout, with some Art Theory thrown in for good measure.  The question
>came up during the lecture on "why is the Color Look Up Table organized
>the way it is?"  That is, why are the colors arranged on it the way they are?
>
>I have a copy of the "Human Interface Guidelines" book and it doesn't say
>anything about it that I could see.
>
>Does anyone have an answer and can tell it?

I can't tell you why-- I suspect it was ease of calculating the table, but
that's just cynicism....  Up to index D6, the blue value is
$FFFF - $3333 * (index mod 6), the green value is $FFFF - $3333 * (index/6
mod 6), and the red value is $FFFF - $3333 * (index/36 mod 6)-- that is, all
three values cycle downward $3333 at a time, at different rates.  After that,
the pure reds that weren't caught by that algorithm are there, in decreasing
order of intensity, followed by the pure greens, followed by the pure blues.

--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
     .sig under construction, like the rest of this campus.