Re: Alternate Visual Systems

Wayne Throop wrote:

But remember, the fact that colors are "objective" is an elaborate
calculation done by the visual system; a calculation that attempts to
take account of the illumination; wildly differing spectra, which would
be taken to be completely different colors if displayed side-by-side, are
taken to be the same color when displayed in an appropriate background.

True.

If you have a white object and you ask people, in sunligth, what colour it is, they'll say white.

If you ask different people in a room illuminated by a mix of normal ligthbulbs and red ligthbulbs, they'll also say the object is white.

Yet, if you photograph the object at both locations, without changing the white-balance of your camera, and then compare the two photos in sunligth, you'll find that the photo taken indoors is, infact, not white, but pink.

Your brain does this for you automatically.

Clever digital cameras can be told to do the same, with my 350D for example, I can (under any light-conditions) photograph some object that is neutral grey/white and then tell the camera that *this* is a neutral color. Subsequent pictures taken in the same light will look the color they "are". The camera comes with pre-made profiles for common lightsources (sunligth, outdoor-shadow, tungsten, fluorescent, flash)



Eivind Kjørstad
.

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