This paper proposes that every color sensation be represented by a vector, in three-space, whose length indicates the color’s luminance and whose direction indicates its chromaticness. The color sensation produced by a mixture of component colors is represented by the vector resultant of the vectors representing the sensations of the component colors—as if the component vectors were forces. The construction of this color space, using the 2° color mixture data of Stiles and Burch and the 2° CIE luminosity data, is reported. The primaries are axes oblique to each other, the angles between the axes being specified by the present investigation. When color-matching data for the spectral color sensations are plotted in this frame, it is found that the lengths of the resultant vectors closely approximate the CIE luminosities, except in the extreme violet. Introduction of an arbitrary orthogonal frame into the configuration shows that the values on one axis are followed by (-1)<sup>½</sup>, tentatively suggesting that one color construct may be an inhibitor while the remaining two are excitors.
JOZEF COHEN and W. A. GIBSON, "Vector Model for Color Sensations," J. Opt. Soc. Am. 52, 692-697 (1962)