Re: metamerism and metameric color - more
Re: metamerism and metameric color - more
- Subject: Re: metamerism and metameric color - more
- From: Peter MacLeod <email@hidden>
- Date: Wed, 20 Jun 2001 15:29:49 -0700
At 5:07 PM +0200 6/20/01, Rudy Vonk wrote:
[...]
> again we
> have to stick to the definition of metamerism ( two colors possesing the
> same trichromatic values but differ in the spectral distribution)
This cannot be a valid definition (with respect). Obviously, the two
objects *must* have different spectral distributions or they would
*always* look the same, so this part of the definition is merely stating
the obvious. The other part of the suggested definition fails to state
the essential: metamerism means that two objects produce the same
tristimulus values (to us, the signals interpreted by our brain from
three types of cones - to our computer, XYZ values or similar calculated
from reflectance power distribution measured in a spectrophotometer)
UNDER ONE ILLUMINANT and different tristimulus values under another. I
think it is worth while clarifying this..
According to Wyszecki and Stiles (1982) that is exactly the definition..
P. 184:
"Definition of Metamerism
Metameric color stimuli are color stimuli with the same tristimulus
values but different spectral radiant power distributions.
An equivalent definition states that metameric color stimuli are
color stimuli that have different spectral radiant power
distributions but match in color for a given observer."