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From: tarolli@westcoast.esd.sgi.com (Gary Tarolli)
Newsgroups: comp.sys.sgi
Subject: Re: Who needs 24 bit colors
Summary: dithering 24 bit colors
Keywords: color
Message-ID: <95731@sgi.sgi.com>
Date: 5 Apr 91 21:39:44 GMT
References: <8009@eos.arc.nasa.gov> <95622@sgi.sgi.com> <1991Apr5.184742.1029@nas.nasa.gov>
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Organization: Silicon Graphics, Inc., Mountain View, CA
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In my last posting, when I was talking about dithering 24 bit colors,
I forgot to mention that what I was implying was that you iterate 
R,G,B using at least 12 bits (preferably a lot more) and then dither
down to 8 bits each.  I didn't mean taking a 24 bit image and then
dither it to 24 bits - this is a nop since the source picture has no
more info than the dest. picture.  Or you could take a 36 bit RGB image
and reduce it to 24 using dithering.  In either case you will lose a 
little spatial resolution, but like I said before, because of the number
of colors you have to choose from, its probably better to dither than
not dither.  Even if you had a full 36 bit video backend with 12 bit DACs
etc., you could iterate colors at 16 bits per component and then dither
them down to 12 bits.  I think the end result will be an improvement!

Unfortunately, I don't have the softare in place to simulate this, so
I won't be posting any pictures.  Maybe someone else can?

--------------------
	Gary Tarolli