Re: Neutral grey under different lighting
Re: Neutral grey under different lighting
- Subject: Re: Neutral grey under different lighting
- From: Marco Ugolini <email@hidden>
- Date: Mon, 03 Sep 2007 21:26:42 -0700
- Thread-topic: Neutral grey under different lighting
In a message dated 9/3/07 12:04 PM, Scott Martin wrote:
> Ah yes, yet another exhausting metamerism discussion.
I was hoping for "exhaustive", but... :-)
> I think everyone on this list is well versed on the topic.
I'm glad to hear that.
> Metameric failure is a better term to be used here, and more accurate.
No, Scott. We disagree. There are *two* samples in metameric matches or
failures. If the two samples match under one illuminant and not under
another one, we have *illuminant metamerism*. If the two samples appear to
match to one observer but not to another under the same illuminant, then we
are faced with issues of *observer metamerism*. The degree of match or
mismatch between the two samples is measured by means of a *metamerism
index* (or MI).
(You will find all of this explained in more detail in Roy Berns'
"Principles of Color Technology", pages 27-29 and passim)
> When communicating to common end users "metameric failure" might lead
> to more questions whereas "metamerism" gets the point across.
It may "get the point across", but at the cost of a degree of imprecision
that renders the information dubious.
> This is a tough situation for us because the term "metamerism" has become
> the commonly used term for "metameric failure".
Sorry. I disagree again. "Metamerism" has been used as equivalent to *color
inconstancy*. These two processes are not the same as one another: the
former deals with *two samples* of different spectra under one illuminant
(in the case of illuminant metamerism), the latter with *one sample* under
different illuminants.
> It drives me crazy that one can't mention metamerism without getting
> into an off topic discussion about the terminology even when all
> attendees know exactly what you are talking about.
"Off-topic"? It "drives you crazy"? You have no idea how crazy it drives
*me* to hear precise scientific language being used so inexactly... <g>
> So my apologies, Crystal Archive and (even more so) Kodak Endura are
> susceptible to metameric failure.
Suit yourself. It's a free country. :-)
Marco Ugolini
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