READING LAND’S SCIENTIFIC AMERICAN PAPER “EXPERIMENTS IN COLOR VISION” IS INSTRUCTIVE

by Gerald Huth on May 13, 2010

It occurs to me that the reader, perhaps conditioned  over the years to disregard Edwin Land’s color vision work, might read the piece in the May 1959 issue of Scientific American “Experiments in Color Vision” written by Land.  Characteristic of all of Land’s writings, the piece lucidly summarizes his color vision experiments and the overall concept.

Subsequent papers on the same subject appeared in the Proceedings of the National Academy of Sciences: “Color Vision and the Natural Image. Parts I and II”, Vol. 45, No. 1, January 1959, although these do not contain color plates and are more difficult to wade through.

(I would be remiss if I did not note the article that was referred to me that, in the words of someone who should know,  ”put Land’s work to bed”!  That  paper  is titled “LAND! LAND!”  (Physiological Bulletin, Vol 37,No.1 1960) authored by Gordon Walls. The first page (p.29) sets the tenor for the entire piece noting that Land, although a genius, was an inventor (read “not  a scientist”) and that, anyway, it had all been thought of before.)

In reading Land beware of the charge often made that he was proposing a “two color” basis for color vision in violation of the recognized trichromicity of vision. He was not saying this!

A few take away points from the Scientific American article:

Page.5: “Is something “wrong” with classical theory? This long line of great investigators cannot have been mistaken, The answer is that their work had very little to do with color as we normally see it. They dealt with spots of light, and particularly with pairs of spots, trying to match one to another”

Page.6: (the crucial finding) “It appears, therefore, that colors in images arise not from the choice of wavelength but from the interplay of longer and shorter wavelengths over the entire scene.” (underline is mine).

Page.13: “If the eye perceives color by comparing longer and shorter wavelengths, it must establish a balance point or fulcrum somewhere in between, so that all wavelengths on one side of it are taken as long and all on the other side as short”.

Page.13: “Where is the fulcrum in the ordinary sunlit world? Experiments on a large number of subjects indicate that it is at a wavelength of 588 millimicrons”.

Pages 13-14: “Our eyes are always ready to receive at any frequency in the visible spectrum. And they have the miraculous ability to distinguish the longer record from the shorter, whatever the frequencies and the band-widths. Somehow they establish a fulcrum and divide the incoming carrier waves into longs and shorts around that point.”

This work, from the finding of a geometrically determined the exact mid-band “fulcrum” wavelength to an explanation for the simultaneous detection of three wavelength bands and the “entire scene” in heretofore unconsidered regions of time and space seem to validate Land’s experiments.

GCH

Ojai, CA

Revised 5.14.10

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