Metamerism (was Re: photogravures)
Metamerism (was Re: photogravures)
- Subject: Metamerism (was Re: photogravures)
- From: Wire Moore <email@hidden>
- Date: Wed, 24 Oct 2001 17:42:33 -0700
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If your on-screen image is one sample, your inkjet print is the
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second sample, and they match under one lighting condition but not
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another, then you have a metameric pair -- a pure example of
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metamerism with no quotes required.
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When you're comparing the print under one lighting condition to the
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print under another, it's more questionable as to whether you're
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dealing with two samples (though certainly both the spectral response
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curve and the tristimulus values will be different for the two
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conditions), hence the quotes.
Thank you for clarifying this, Bruce. I didn't notice while writing that my
explanation over generalized this important point.
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But in either case, it's the property of eyes that allows two
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different spectra to create the same color appearance that lies at
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the heart of the problem. The metamerism part of the equation is that
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under some lighting condition, the print has the desired appearance.
Yikes! You just pulled me out of the swamp and we're standing there, safely
taking in a broad view of those pesky alligators, then you just go and jump
right back into the swamp!
As you just pointed out a paragraph ago, you need two samples to compare.
I'll rephrase your last sentence above: 'The metamerism part is that two
prints, say one from an Epson 3000 and an another from an Epson 2000p, match
in a light booth, but not in daylight on the street outside my office.' We
would say that in the light booth there is a metameric match. Or metamerism,
for short. And, as you mentioned above, an inkjet print in the light booth
and a monitor display of the same image may match. Again, metamerism. But
without a match, we just have a case of a print that either looks appealing
or not depending on the lighting conditions. I'd say this is not about
metamerism, but I see my position as tilting against a windmill... The color
industry meme is just too powerful :)
[Continuing just for fun...]
It seems that the term metamerism shares properties with the phenomenon it
meant to describe: e.g., the term has multiple usages and meanings that
appear to agree in some contexts but not in others. Spiffy!
A couple of tangential thoughts (forgive me):
I am struck by how issues of determining color fidelity seem very similar to
issues of determining meaning of language. We can formally reconcile color
in terms of physics, while it's much harder to do so in terms of sensations.
Language is similar: we can reconcile language in terms of words, but not so
easily in terms of meanings.
For example, when I say 'smoking green grass' a variety of sensations and
meanings may come to mind of which we may hardly agree, or which we may say
we agree even though we have different thoughts, or upon which we may agree
completely...
It's seems marvelous there's so much agreement to be found in our affairs!
And not so surprising to me that as we again carry ourselves across the
threshold of a communication revolution, we are shaken by the throws of
cultural upheaval.
(Did someone say 'smoking grass'? Ooop...:)
Wire