CRI — Colour Rendering Index
Definition
The colour rendering index (CRI), defined by the CIE, rates on a scale of 0 to 100 how faithfully a light source renders colours compared with a reference source of the same colour temperature. The general index Ra is the average of eight test colours (R1 to R8). Values of 90 and above are commonly required for broadcast, film and fashion work, and 80 to 90 is generally accepted for live events. Below 80, colour rendering is generally regarded as poor, and colours, skin tones included, look desaturated and dull. The special index R9 (saturated red) is one of the most revealing for LED sources, yet it is not part of the Ra average.
In the field
For broadcast or close camera work, the R9 value is requested explicitly when LED fixtures are selected. A fixture can show a CRI of 85 with an R9 of 0, which gives poor reds that broadcast cameras reveal immediately.
Related lessons
Sources
- CIE 13.3-1995, Method of measuring and specifying colour rendering properties of light sources : Ra = moyenne de R1 à R8, R9 hors moyenne · cie.co.at
- Wikipédia (pointeur secondaire), Color rendering index : calcul de Ra, indices particuliers R9 à R14 · en.wikipedia.org
- Waveform Lighting, Does color rendering matter? 80 CRI vs 90 CRI vs 95 CRI : sous 80, rendu jugé médiocre et couleurs désaturées · waveformlighting.com
- VELLO, CRI in stage lighting : plus de 80 pour les visages des artistes, 90 et plus pour les projecteurs vus à l'image et 95 et plus en télévision · vellolight.com
- JEL Products, Colour rendering and CRI : un Ra de 80 peut s'accompagner d'un rendu des rouges très médiocre, d'où l'examen séparé du R9 · jelproducts.nl