FW: metamerism and metameric color - more
FW: metamerism and metameric color - more
- Subject: FW: metamerism and metameric color - more
- From: "Fred Bunting" <email@hidden>
- Date: Thu, 21 Jun 2001 14:57:24 -0700
- Thread-topic: metamerism and metameric color - more
Peter MacLeod wrote:
>
According to Wyszecki and Stiles (1982) that is exactly the
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definition..
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P. 184:
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"Definition of Metamerism
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Metameric color stimuli are color stimuli with the same
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tristimulus
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values but different spectral radiant power distributions.
Rudy Vonk replied:
>
>
I appreciate the post and realize that I am getting a little pedantic,
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but my personal impression is that the definition you quote is
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semantically "hollow".
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>
There are other definitions, and I personally find Fred Bunting's not
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only simpler and more practical, but also more accurate:
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>
> A relationship
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> between two color samples
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> whereby they appear to match in color
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> when viewed under certain conditions
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> (usually illuminant), but not under others.
:-) I actually started a post to this thread last night, but had to run
... so imagine my surprise this morning ...
While I appreciate Rudy's faith in my definition as simple and practical
(in the sense of describing how you detect when you are in the presence
of of the event, and why it matters), it troubles me to be cited as
"more accurate" than Wysecki and Stiles. They are the gospel, man. :-)
The fact is that the two definitions are pretty much equivalent for
purposes of giving a name to our pain (where the pain is a problem with
color matching under different illuminants). The two definitions are
just two ways to say the same thing. Each can be derived from the
other.
I think Rudy's point is valid ... the important feature of metamerism in
this thread (which goes way back to comparisons of print results from
two different printers) is the fragility of certain color matches to
changes in illuminant.
However, I would now have to defer to the formal W&S definition of
'metamerism' as stronger and more fundamental than mine. It explains
more about *why* the match fails under different illuminants ... many
spectra will produce the same tristimulus reaction. More importantly,
forget about the failure to match under different illuminants ... the
fact that two different spectra can produce a match at all is *very*
significant by itself. That's what lets us match a banana on a monitor
using red and green phosphors. That's metamerism too!
So metamerism is usually a good thing! But it can be a fragile thing.
And we talk about 'metamerism problems' when it breaks.
Fred Bunting