PUBLICATIONS

2002

The Prime Colors of Human Vision; Their Prescription for Illumination, Color Printing,Color Photography, Color Television, and Visual Clarity
William A. Thornton
Prime-Color Inc. (USA)

Abstract:

Since before 1700 the notion was abroad among mankind that three particular colors of light have special significance to human vision.For a long time inchoate, the notion gathered some substance by 1800,and identification of the particular colors,as red,green and violet,began to be clear.Then around 1900 both the notion of three particular colors,and the identity of those colors,fell again into obscurity due to the sudden popularity of a competing notion represented by "transformability of primaries."1 However,in the last 30 years,the validity of transformation of primaries has been questioned,and evidence adduced suggesting such transformation to be inadvisable,if not meaningless. Meanwhile,the three particular colors of light have been identified with considerable precision,and their function in human vision has become clearer.These matters underlie the present paper.

Palmer (1777)attributed trichromacy to "particles of three different kinds"in the retina,rather than to something in the light itself,as did all forerunners.The three kinds of particles respond,Palmer proposed,to three different kinds of light rays,red,yellow and blue.Wunsch (1792)promoted red,green and violet,instead,as best serving to compose all other colors.Young (1802)also proposed three types of retinal particles,each associated with one of the "three principle colours,red,yellow,and blue...”but in 1803 substituted red,green,and violet as the principal colors.Lang writes 2 (1983)"These formulations (of Young's,in the 1803 paper)express very clearly the fundamental difference between his and all earlier trichromatic theories:He did not assume three different kinds of physical rays,but three kinds of sensitive elements in the retina.There is no longer an isomorphism between rays and colors,but an isomorphism between the three kinds of sensitive elements in the retina and the three fundamental color sensations.In other words:The three principal colors do not exist in the outside world of physical radiation,but only in the world of human color sensation.Their existence has its roots in the organization of our visual system...So Young's priority did not lie in his choice of the additive primaries red,green,violet --here he was anticipated by Wunsch --nor in the hypothesis of three kinds of sensitive particles in the retina --this was stated before him by Palmer --but in the discovery of the fact that trichromacy is uniquely a consequence of the organization of the human visual system."

I wish (1)to transpose Thomas Young's conceptualization from retina to visual system as a whole, (2)to propose isomorphism between the three spectral sensitivities of the normal human visual system and what have been called the three fundamental color sensations, and (3)to stipulate (a)that the "three principal colors"do exist in the outside world of physical radiation,(b)that they are to be identified with the three spectral lights I have termed the prime colors for 30 years (namely,near 450 nm in the blue-violet,near 530 nm in the green,and near 610 nm in the orange-red),(c)that the wavelengths of these three spectral lights mark the maxima of the three independent spectral sensitivities of the normal human visual system,and (d)that it is in those spectral sensitivities that "trichromacy is uniquely a consequence of the organization of the human visual system"(Young). In this context I wish also to review some of the problems in current colorimetry,and to give evidence that (in colorimetry)various shifts toward the prime-color wavelengths and the prime-color construct are alleviating those problems.

William A.Thornton received a BS in Physics from the University of Buffalo in 1949 and was Phi Beta Kappa. He received the MS and PhD in Physics from Yale in 1949 and 1951.He was with the GE Research Laboratory to 1956;Westinghouse Lamp Divisions to 1983;and Research-Engineering Consultant.He has 45 patents,80 articles,Westinghouse’highest honor,the Order of Merit 1978.He received the US National “Inventor of the Year” 1979.He is a Fellow of IESNA,Past Director of ISCC, and President Prime-Color Inc.He lead eight researchers in improving international measurement of light and color

The First European Conference on Color in Graphics, Imaging and Vision (CGIV)
Poitiers, France;April 2002; p. 56-60; ISBN / ISSN: 0-89208-239-9