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Re: [Phys-L] Color perception



Unfortunately the physics books give only a simple explanation of color
which is essentially the engineering explanation which is used in color
reproduction such as TV. The explanation for this phenomenon was given by
Land in the 60s as I recall at an APS meeting. Of course he used an
electronic network explanation, while the biological one is somewhat
different.

Essentially your eye-brain system perceives colors by comparing across
boundaries and the actual color balance is discarded. So the background
is very important. This also relates to why we can look at line drawings
and perceive the intended objects. We see difference rather than absolute
color balance. This tends to make our perception somewhat independent of
illumination. This is often referred to as color constancy. While the
Newtonian explanation works for fields of pure color it breaks down
completely in realistic situations.

Of course there is also some difference due to the number and type of
cones with some women having 4 different color cones.

Now something which is a bit different is that there is a 3D presentation
system which separates the 2 pictures by color. It splits each color band
(R,G,B) into 2 parts and then each picture occupies a slightly different
color space. The proponents correctly point out that this system produces
3D with no ghosting. But I may be an oddball because I found it to be
poor. I noticed that some colors were different between R & L eyes. I
found it disturbing. The same movie seen in a conventional circular
polarization 3D system was perfect.

I have never seen anyone commenting on this problem, so it is that my
perception of color is a bit different from "normal", but there may be
others like me. So color perception not only varies from person to person
but also between R&L eyes.

Anyone who has tried to match colors between R&L 3D views encounters big
problems. You can pick up a shade of brown in the R vies and try to fix a
defect in the L one which is also brown, but the result might look like
yellow, or blue, or red because the camera had slightly different color
balance between R&L.

It would be nice if the physics books would acknowledge that color is much
more complicated that the simplistic Newtonian interpretation. It should
point out that the Newtonian interpretation is just a simple model which
breaks down in realistic situations. In addition it should be noted that
some women may have 4 color vision which means they will perceive colors
which men will never be able to see, chimeras excepted.

John M. Clement
Houston, TX

There's a great controversy about color buzzing around the net.

This is a great opportunity to discuss the complexity of color vision.

<http://ktla.com/2015/02/26/what-color-is-this-dress-photo-posted-online-divides-users/>

<http://www.wired.com/2015/02/science-one-agrees-color-dress/>

<http://www.vox.com/2015/2/27/8119739/this-cartoon-is-the-simplest-explanation-of-the-color-changing-dress>