Abstract

In any system which defines color on the basis of the non-spatial, non-temporal properties of light it is shown that white, gray, and black are not colors. The perception of white is shown to be caused by a physical property of the object not associated with its selectivity. This property is the diffusion of light. White is shown to be one extreme of a series starting at clear and passing through various degrees of pale white to a maximum. Gray is shown to be the perception of the relative visual effectiveness of the light from two areas and cannot be seen unless at least two areas are present. Black is considered the extreme in lack of relative effectiveness.

© 1949 Optical Society of America

Some Variables Influencing Vernier AcuityI. Illumination and Exposure TimeII. Wave-Length of Illumination*

Katherine Eleanor Baker
J. Opt. Soc. Am. 39(7) 567-576 (1949)

The Color Perceptions of Deuteranopic and Protanopic Observers

Deane B. Judd
J. Opt. Soc. Am. 39(3) 252-256 (1949)

Sunlight and Skylight as Determinants of Photographic Exposure. II. Scene Structure, Directional Index, Photographic Efficiency of Daylight, Safety Factors, and Evaluation of Camera Exposure

Loyd A. Jones and H. R. Condit
J. Opt. Soc. Am. 39(2) 94-135 (1949)

The Apparent Colors of Surfaces of Small Subtense—A Preliminary Report*

W. E. Knowles Middleton and Marian C. Holmes
J. Opt. Soc. Am. 39(7) 582-592 (1949)

The Emission Characteristics of Fluorescent Pigments

C. E. Barnett and L. D. Grady
J. Opt. Soc. Am. 39(8) 663-669 (1949)