Color rendering index: Difference between revisions

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'''Color rendering index''', or '''CRI''', is a measure of the quality of [[color]] [[light]], generally ranging from zero for a source like a low-pressure [[sodium vapor lamp]], which is monochromatic, to one hundred, for a source like an incandescent light bulb, which emits essentially [[blackbody radiation]]. It is related to [[color temperature]], in that the CRI measures for a pair of light sources can only be compared if they have the same color temperature. A standard "cool white" [[fluorescent lamp]] will have a CRI near 62.

CRI is a quantitatively measurable index, not a subjective one. A reference source, such as blackbody radiation, is defined as having a CRI of 100 (this is why incandescent lamps have that rating, as they are, in effect, blackbody radiators), and the test source with the same color temperature is compared against this. Both sources are used to illuminate several standard samples. The apparentperceived colorcolors under the reference and test illumination is(measured in [[International Commission on Illumination|CIE]] 1931 form) are compared inusing a particularstandard formula, and averaged over the number of samples taken (usually eight) to get the final CRI.

==External link==