Path: utzoo!utgpu!watserv1!watmath!att!rutgers!usc!jarthur!nntp-server.caltech.edu!jjfeiler
From: jjfeiler@nntp-server.caltech.edu (John Jay Feiler)
Newsgroups: comp.sys.amiga
Subject: Re: 24/32 Bit Color
Message-ID: <1990Oct17.220307.3750@nntp-server.caltech.edu>
Date: 17 Oct 90 22:03:07 GMT
References: <33786@nigel.ee.udel.edu>
Organization: California Institute of Technology, Pasadena
Lines: 24

byrne@muppet.dnet.ge.com writes:
>I think I need some education.  I was under the (false?) assumption that the
>human eye could not distinguish 16 million colors (24 bit).  I assumed 24 bits
>was decided as number because it was an even multiple of a byte given the 3
>color components (RGB).  Since most displays don't have 16 million pixels, this
>gives you a great big palette.  But why 32 bit?  Is 32 bit color used because
>it is the word size of most of the popular high performance microprocessors
>(i.e 68020+)?  I don't see it buying you anything from a color stand point
>because who could distinguish adjacent colors from either 24 or 32 bit
>palettes?  Does it help in shading or is it just for data movement speed?
>Seems like overkill.  Thanks,

>                        -FB

The human eye can only distinguish about 4 million colors, but the colors are
not distributed evenly across the RGB spectrum.  It is much easier to add extra
bitplanes, and have more colors than we can distinguish, than it is to have
a nonlinear bits-to-colors conversion.  All one needs is 24bits, and we 
have all the colors we could want.  Usually, if a system has more than 24
bits, they are used for text overlay, shadowing, blurring, double-buffering,
and a gadzillion of other fun graphics things.  I have heard of systems that
actually have as many as 268 bitplanes!!

	John (not an expert) Feiler