Re: metamerism and metameric color - more
Re: metamerism and metameric color - more
- Subject: Re: metamerism and metameric color - more
- From: Samer Mady <email@hidden>
- Date: Tue, 19 Jun 2001 09:50:39 +0200
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In response to a question Mr. Tobie provides a definition of metamerism (my
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interpretation reading between the lines) as two objets that match under
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one light but do not match under another light.
metamerism happens when two colours have the same trichromatic values but
different spectral distributions.
this metameric colour match is unstable, when changing the Illumination the
colours will not match anymore.
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Then he cites an example of a print that shows a certain color balance
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under one light condition and a different color balance under another light
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condition. (What is lacking in this second example is two objects - instead
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we only have one).
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If this second case is not "metamerism" - what is it an example of?
this is not an example of metametism but an example of chromatic adaptation.
chromatic adaptation will always happen even if two colours have the same
spectral distribution. they will look different when the illumination
changes but the colour match is retained.
chromatich adaptation consists of two components. sensory mechanisms and
cognetive mechanisms. sensory mechanisms relate to the change of the
sensitivity of the cones when the Illuminaition changes. sensory mechanisms
can be modeled by using the von Kries transformation. cognetive mechanisms
happen when looking at a known object. a red apple will look red no matter
what the colour of the illumination is. becouse we know that this object is
red.
samer mady