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From: osmoviita@cc.helsinki.fi
Newsgroups: comp.sys.sgi
Subject: Re: Who needs 24 bit colors
Message-ID: <1991Apr6.232435.5870@cc.helsinki.fi>
Date: 6 Apr 91 23:24:35 GMT
References: <1991Apr5.061410.22381@cunixf.cc.columbia.edu>
Organization: University of Helsinki
Lines: 32

In article <1991Apr5.061410.22381@cunixf.cc.columbia.edu>, shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) writes:
> OK, here's a question.  How many bits of color resolution can the human
> eye perceive?  I asked this question of a friend of mine who's a color
> scientist, and (to my surprise) he didn't know.
> 
12 bit color depth cann still be clearly distinguished from 16 color depth
when suitable images are shown. 14-15 bits grayscale is often considered as
sufficient when studying human vision. Some company published recently 
1,5 GHz 14 bit DAC (ECL) which would be used to make display system matching 
about the human visual system. If scenes varying between bright sunlight and 
dark night are animated perhaps even more bits is needed but this can be done
for example by altering gain in some amplifier.

> I suppose I could make the question more operational by asking, "how many
> segments would the color wheel need to have that even at high magnification
> it would not be possible to see a boundary anywhere?"
> 
This will imply to use indexed colors not direct RGB colors and is
inconvenient and heavy to use because of nonlinearities. To answer it is
nearly impossible because there is not such graphics systems that you can
measure it under 100 years work (guess). So we need 16 bit color depth and 
4 (maybe more) color channels and displays with pure spectral colors 
(laser/led based?) to get a clear answer. IMHO.

> 	-P.
> ************************f*u*cn*rd*ths*u*cn*gt*a*gd*jb**************************
> Peter S. Shenkin, Department of Chemistry, Barnard College, New York, NY  10027
> (212)854-1418  shenkin@cunixf.cc.columbia.edu(Internet)  shenkin@cunixf(Bitnet)
> ***"In scenic New York... where the third world is only a subway ride away."***

Kari Osmoviita, Deparment of Physiology, University of Helsinki, Finland
osmoviita@cc.helsinki.fi