Notebook

Notebook, 1993- RELATIONSHIPS

Brightness

Brightness is a purely psychological concept. It is a sensation of the observer and cannot be measured by instruments. The ability of the eye to judge absolute values of brightness is very poor due to its great powers of adaptation. The eye is a very sensitive detector of brightness differences, however, provided the two fields of view are presented simultaneously. The measurement of light by visual comparision is the basis of the science of photometry . . . . Brightness is associated with the amount of the light stimulus. It is the visual sensation corresponding to the perception of luminance. [p. 32]

NOTE: Lightness is a term used by an observer to distinguish between lightness and darkness of colored objects, as between light blue and a dark blue paint. It should not be confused with brightness. The observer's perception of lightness is also a recognition of a difference in whiteness or grayness between objects. It is a comparative term referring to the amount of diffusely reflected light coming to the observer's eye from a surface. [p. 32]

[Rainwater, Clarence [Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim]. Light and Color. Golden Press, NY, Western Publishing Company, Inc., 1971.]

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