Re: Metamerism vs Color Inconstancy, again
Re: Metamerism vs Color Inconstancy, again
- Subject: Re: Metamerism vs Color Inconstancy, again
- From: Graeme Gill <email@hidden>
- Date: Tue, 22 Jun 2010 09:47:28 +1000
Marco Ugolini wrote:
"Related to metamerism is COLOR CONSTANCY, the tendency of an object to
maintain its color despite changes in illuminating conditions. Each object
forming a metameric pair has a different DEGREE OF COLOR INCONSTANCY. For
example, the right-hand square [of two squares viewed under one illuminant
-- MU] will turn pinkish when illuminated by incandescent illumination,
whereas the left-hand square tends to remain grayish. Although both samples
match under daylight and are thus a metameric pair, only one sample of the
pair exhibits objectionable color inconstancy. If both formulations [both
specimens -- MU] are candidates as a color standard, the sample that
minimizes the degree of color inconstancy would be preferred."
Roy Berns, "Billmeyer and Saltzman's Principles of Color Technology", Third
Edition, Wiley & Sons, 2000, page 29
It's all there: the distinct notions of metamerism vs color
constancy/inconstancy, and their correlations too.
I think you are reading far too much into this. Color constancy
is not related solely to metamerism, but is a far wider topic,
mainly to do with human vision and perception. Naturally a color that
remains close to a metameric match under different lighting
conditions is going to be more perceptually constant in color
(which is what Roy Berns is saying above), but the reverse is not
necessarily the case. You may well have a situation in which a
change in lighting induces large metameric failures (compared
to the target colors), but perceptually remains a constant color.
So to say that a failure of a color to match a target due to a
change in lighting conditions is "color inconstancy" is not
being very specific as to the cause. Color inconstancy can be
due to many other things than metameric failures.
"Metameric failure" is being specific, and isn't confusing
the situation by dragging in unrelated phenomena.
For a broader view on color constancy, take a look at the
work of some of the primary researchers in this area, e.g.
McCann <http://web.me.com/mccanns/Color/Color_Constancy.html>.
You'll notice that the emphasis is on many aspects of vision,
but has little directly to do with metamerism.
Graeme Gill.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden