Path: utzoo!yunexus!ists!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcso!hpfcdj!myers
From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: comp.graphics
Subject: Re: VGA Colors
Message-ID: <17400013@hpfcdj.HP.COM>
Date: 14 Nov 89 18:48:35 GMT
Article-I.D.: hpfcdj.17400013
References: <824@uwm.edu>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 19

>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 ?

As a first approximation, this probably isn't too far off for most people,
at least within the confines of the average-sized computer display.  One
factor which affects the discrimination of the gray levels or colors is the
area involved; for example, the human eye has much poorer spatial resolution
for color than for monochrome images, meaning that you will be unable to
distinguish very small areas which are of different colors but similar in
apparent brightness.  On the other hand, those same details will be apparent
if they are rendered as differring in brightness.  This fact is used in the
NTSC color encoding process (and others), in which the color bandwidth is
purposely limited relative to the luminance bandwidth.


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers%hpfcla@hplabs.hp.com               |  sentient life-form on this planet.