Re: Chromatic adaptation -- original Von Kries ideas
Re: Chromatic adaptation -- original Von Kries ideas
- Subject: Re: Chromatic adaptation -- original Von Kries ideas
- From: edmund ronald <email@hidden>
- Date: Wed, 1 Jul 2009 13:28:29 +0900
There are two different issues here:
- Can we in simple cases for colored object found in nature compute
what a colorimeter would see when changing illuminant, when the before
and after illuinant is known? The answer seems to be supplied by the
Von Kries transforms.
- How does the brain decide which transform to apply?
Edmund
On Wed, Jul 1, 2009 at 8:10 AM, Roger<email@hidden> wrote:
> 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
>
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Colorsync-users mailing list (email@hidden)
> Help/Unsubscribe/Update your Subscription:
>
> This email sent to email@hidden
>
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden