Re: Metamerism vs Color Constancy
Re: Metamerism vs Color Constancy
- Subject: Re: Metamerism vs Color Constancy
- From: Graeme Gill <email@hidden>
- Date: Tue, 20 Sep 2005 23:17:21 +1000
Marco Ugolini wrote:
I am bringing this up because my poor insufficiently scientifically-trained
mind is trying to comprehend whether the term "metamerism" is currently
being used improperly in color management circles.
When we refer to inkjet prints as being "metameric" (a common buzzword these
days among the initiated to the growing sect of inkjet printing), do we
actually mean, instead, that they lack color constancy?
Metamers are colors that have different spectra, but subjectively are
the same color. This is sometimes referred to as a "metameric match".
The basis of almost all commercial color reproduction systems relies
on creating metamers, since it is rare for the combined spectra of
the color reproduction system primaries, to match that of original,
real world colors.
I guess if you have two colors that don't match, then you could
call them a "metameric mismatch", but that's not saying much. There
are an infinite number of color mismatches !
If two colors match under one illuminant, and not under another,
then what you've proven is that they aren't a spectral match,
and also don't happen to have spectra that are metamers under both
those illuminants. This would be a remarkable property for
two colors composed of different spectra, and may be achievable,
but doesn't seem easy to do.
If I was trying to be accurate, I'd tend to say that two prints
that match under one illuminant, but not well enough under another,
are "not sufficiently good spectral matches".
A print that had a grey balance that varied unacceptably in hue
under different illuminants, might be referred to as having
an "insufficiently robust grey spectra".
Graeme Gill.
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