> Here is a question for some of you. I remember seeing some demonstrations
> of experiments conducted by Dr. Edwin Land which seemed to indicate that
> only 2 colors are required for some full color applications. The program
> was several years ago, and I am not sure of all the details of the
> demonstration. As I recall, it had much to do with the brain's ability to
> add missing information to the scene. I do remember the full color
> reproductions of flowers made with during the demos. Anyone else remember
> this or can any of you provide some missing information?
>
> He also discussed depth perception and how it is not a big factor for
> people who have had stereoscopic vision at some point in their life, but
> lost an eye due to injury or disease. The brain creates the depth clues.
>
> RM
>
Bob,
Land's experiments were very interesting and in my opinion still
controversial and not very well known. The following is a quote from
the Discovery Magazine Article `COLOR PERCEPTION SEEING WITH THE BRAIN'
December 1988, Page 52 which I find to be concise.
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Land retested Maxwell's experiments which were the basis of Maxwell's
Tri-Color Theory. The experiment amounted to taking separation positives
(B&W Slides) and then superimposing their projected images with the proper
color filter for each negative. Blue filter slide (Short Wave Length)
projected through a blue filter, Green filtered slide (Medium Wave Length)
through a green filter and the Red filtered slide (Long Wave Length)
through a red filter.
HOWEVER, the blue filter accidentally fell off the projector. Land
noticed that the projected image's color was unchanged. This flys in the
face of the Tri Color theory. Further testing found that using white
light (unfilterd) through the Green filterd slide and Red filtered light
through the Red filterd slide produced a full color image.
Land theorized that the in addition to the three types of color senor
cones in our eyes, our brains process the amount of Red light present to
determine the actual color of an object. This explains why the color of
an object looks the same to our eyes at mid day or sunset but a photograph
shows them to look quite different in color.
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The last paragraph hits home to those who enjoy the light at sunrise and
sunset . . . I take most of my photos at those times. I find that I have
to overcome the compensation of my brain to visualize what the color image
will actually look like. Others may have a different approach.
In any event, Land's experiments are fascinating. I've done a little
testing and believe that this two color approach doesn't directly apply to
printed materials. Does anyone else out there have any testing to compare
notes?
Sincerely, Art
Art Chakalis
Columbus, Ohio, USA