Path: utzoo!attcan!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-sdd!ucsdhub!celit!hutch
From: hutch@fps.com (Jim Hutchison)
Newsgroups: comp.graphics
Subject: Color perception (Was another @#*! VGA article)
Message-ID: <3667@celit.fps.com>
Date: 14 Nov 89 17:21:58 GMT
References: <824@uwm.edu> <391@ucsvc.ucs.unimelb.edu.au>
Sender: daemon@fps.com
Reply-To: hutch@fps.com (Jim Hutchison)
Organization: FPS Computing
Lines: 26

In <391@ucsvc.ucs.unimelb.edu.au> U5569462@ucsvc.ucs.unimelb.edu (DAVID CLUNIE):
[contemplation of 6 bit DAC input/output deleted]
>Which brings me to the point that I have read somewhere recently (can't
>remember where) that the human eye CAN'T distinguish any more than 64 different
>shades of grey. Is this so ? Do people beleive it ?

Nope, I don't believe it.  Smoothly shaded surfaces will develop visible
banding, shadows will have little definition, highlights will be boring.
These are all the nifty things you will get with a limited color space.
64 is not all that bad though, much nicer than 32 or 16.

Try comparing 64 to 256 shades on shaded spheres or high quality digitized
flesh tones.  I mention the need for high quality digitization because if
you already lost the shades in the input you'll never get a chance to see
them in the output.

We could venture into biology.  Since my experience has been with seeing
and not sight, you will have to hit those books on your own.  There seems
no good reason to stop at 8 bits either, 10 may be appropriate.  There
probably isn't a monitor yet for projecting an average scene on a sunny
day (near blinding sunlight and dark shadows under rocky outcroppings).

Just for kicks, good b&w film at 30-40 bits of grey.
--
/*    Jim Hutchison   		{dcdwest,ucbvax}!ucsd!celerity!hutch  */
/*    Disclaimer:  I am not an official spokesman for FPS computing   */