Color-rendition analysis of light sources by a chromatic adaptation model based on the OSA-UCS system

摘要

The color rendering index is a debated quantity of the past few years and many indices with different meanings have been proposed and discussed. Today this concern is still open. This work considers the perceived surface colors as a function of the illuminant by applying a chromatic adaptation transform based on the Uniform Color Scale system of the Optical Society of America (OSA-UCS) with the request that the visual system works searching for color constancy. In general a change of illuminant alters the lightness, the chromatic content and the hue of a given object. An analysis made on the Munsell atlas using eight illuminants with very different spectral power distribution shows that these changes regard the two pairs of opponent hue regions. It follows that the color-rendering quality cannot be described by only one index because hue, lightness and chromatic gamut are different independent characteristics that cannot by synthetized in only one index. This work quantifies the variation of these characteristics produced by eight test illuminants with respect to the illuminant D65, chosen as reference, and does not judge the quality of the color rendition.