Chromatic adaptation -- original Von Kries ideas
Chromatic adaptation -- original Von Kries ideas
- Subject: Chromatic adaptation -- original Von Kries ideas
- From: Roger <email@hidden>
- Date: Tue, 30 Jun 2009 19:10:18 -0400
Hello folks,
I've been digging into the original concepts behind chromatic adaptation
lately and found myself returning to the Von Kries literature. His rules of
adaptation state that the cones spectral sensitivities are invariant (fixed)
and independent from each other. Chromatic adaptation is often presented in
the context of how to adapt some object color tristimulus values between two
sets of illumination or illuminants (D50 vs D65 as in ICC PCS). But I also
often find mention of this idea of 'Reference', as in Reference white. I
realize that the Reference white in question is the one to which the
observer is currently adapted. But could there be another notion of
Reference White where our that our brain has always access to? To which all
illuminations are always compared? Naturally? Possibly linked to the idea of
color constancy?
I don't find anything in the literature to substantiate this idea. Is this
too far-fetch an idea or could this make any sense conceptually? For
example, suppose I observe a red apple under direct sunlight. My brain has
no problem recognizing the apple from the combined apple spectral
reflectance and sunlight spectral energy. My cones, somehow, are adapted to
this "sunlight" and correctly infer the visual cues from the scene to adjust
the Von Kries Coefficients in my cones, so to speak, so that the red apple
appears like a red color I've learned to expect.
But suppose I now step indoor with my red apple, and I'm seeing it under
tungsten light. My question is : could it be argued that the "red" color
will appear red as though my brain has somehow adjust the gain sensitivities
of my cones to render the red to some abstract, possibly innate, notion of
"white", that would be independent of the scene? Maybe I'm trying to read
too much in chromatic adaptation?
Roger
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