A Flattery Index for Artificial Illuminants

Artificial illuminants are used for a large variety of purposes. Prominent among these are (1) to permit light-dark discrimination of objects, (2) critical examination of colored objects, and (3) appreciative viewing of colored objects.

The accepted way to appraise artificial illuminants for the first purpose is to measure lumen output of the light sources, or illuminance of the working plane for a lighting installation. The recommended way, rapidly becoming accepted, to appraise artificial illuminants for the second purpose is by general and special indices of color rendering. These indices of color rendering permit evaluation of the degree to which the artificial illuminant imparts to objects their "true" colors. No way has yet been developed to appraise artificial illuminants to be used for appreciative viewing of colored objects.

A lighting installation that promotes an optimistic viewpoint by flattery likewise performs a valuable service, so the purpose of this paper is to devise a way to evaluate the degree to which an artificial illuminant succeeds in flattering people and objects viewed under it.