Abstract
The successful commercialization of solid-state lighting for general illumination will require an effective method to characterize the color quality of these sources. The distinctive spectral characteristics of solid-state lighting sources present both unique challenges and opportunities with regards to color quality. Color quality is difficult to define, much less measure. Several aspects of color quality, including color fidelity (rendering), chromatic discrimination, and general population preferences must be considered. In some instances, these factors are contradictory. For example, observers tend to prefer lamps that increase object color chroma (vividness), though such chroma increases are deviations from color fidelity. In addition to devising a way to balance the influence of these different dimensions of color quality, consideration must be given to ways of communicating color quality in a simple way, which permits comparison between products. At NIST we're approaching this problem by developing a computational method that takes inspiration from the Color Rendering Index (CRI), but incorporates other aspects of color quality. The output of this Color Quality Scale (CQS) is a composite score incorporating a lamp's ability to accurately render object colors, permit precise discrimination between different colors, and display object colors in a way that is visually pleasing to typical consumers. Visual experimentation will be vital to improve and validate this method, which was initially developed with colorimetric simulations. Preliminary experimentation has begun, focusing on the issues most relevant to the development of commercial standards for color quality.
