Color Rendering Index

The color rendering index (CRI), sometimes called color rendition index, is a quantitative measure of the ability of a light source to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. Light sources with a high CRI are desirable in color-critical applications such as photography and cinematography. It is defined by the International Commission on Illumination as follows:

Color rendering: Effect of an illuminant on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant

The CRI of a light source does not indicate the apparent color of the light source; that information is under the rubric of the correlated color temperature (CCT).

CRI's ability to predict color appearance has been criticized in favor of measures based on color appearance models, such as CIECAM02 and, for daylight simulators, the CIE Metamerism Index. CRI is not a good indicator for use in visual assessment, especially for sources below 5000 kelvin (K).

A newer version of the CRI, R96a, has been developed, but it has not replaced the better-known Ra general color rendering index.

Read more about Color Rendering Index:  History, Test Method, R96a Method, Example, Typical Values, Criticism and Resolution, Film and Video High-CRI LED Lighting Incompatibility

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