FROM: Ben de Lange <b.lange@cerberus.dimes.tudelft.nl>
SUBJECT: Re: Hoeveel of Wat kunnen onze ogen zien ?
DATE: Wed, 13 Mar 2002 21:01:17 GMT
ORGANIZATION: Posted via Supernews, http://www.supernews.com
NEWSGROUPS: nl.foto

On Sun, 10 Mar 2002 16:52:55 +0100, "Paul Simons" <news@paul-simons.net> wrote:
> Misschien heb je wel exact gelijk, met 7,5 miljoen. Ik vind het tijd worden
> dat mensen die getalletjes noemen nu aangeven waar ze die vandaan hebben,
> want het wordt er niet duidelijker op.
> 
> Paul
> 
> "Maarten Callebert" <Maarten.Callebert@tijd.com> wrote in message
> news:3c8b6ffd$0$252$ba620e4c@news.skynet.be...
> > De mens zou een 7.5 miljoen kleuren of tinten kunnen onderscheiden.
> 
> 

Omdat ik dit wel een leuke discussie vind heb ik ook nog eens gezocht op het web en 
ben dit tegengekomen:
http://www.efg2.com/Lab/Library/UseNet/1999/1001b.txt
We moeten die vraag dus eigenlijk stellen in de groep
Sci.engr.color

Ben.

From: Mathew Brennesholtz <msb@philabs.research.philips.com>
Subject: Re: contrast of color
Date: 01 Oct 1999 00:00:00 GMT
Newsgroups: sci.engr.color

One intention of the L*a*b* formulation is that when you calculate:

    delta-E = sqrt((delta-L*)^2 + (delta-a*)^2 + (delta-b*)^2),

a delta-E = 1 should be just barely percievable to some viewers.  If you
want most people to be able to distinguish between two colors most of the
time, a delta-E = 3 is needed. Delta-E = 3 is called a MPCD (minimum
perceptible color difference) or a JND (just noticable difference) by
some authors.  Keep in mind that the L*a*b* space is not a perfectly
uniform space, so the delta-E value that is percievable depends on
location in x-y space and the direction between the two colors.

Using a delta-E = 1 threshold, M. R. Pointer (The Number of Discernible
Colours, Color Research and Application, 23:1 February 1998) calculated
that there are 2.28 million discernable color/luminance combinations.
Other studies (see references in Pointer) show that printing inks give
1.6 million colors and EBU phosphors give 1.35 million colors.  These are
far less than the 16 million colors claimed by 8 bit/color video cards,
never mind 10 or 12 bit video systems.  Obviously, some of these
color/luminance combinations are indistiguishable from each other.

Hope that helps.