Color Rendering Index, usually the general index Ra, the average fidelity score for eight pastel test colors compared with a reference illuminant of the same CCT. Incandescent and daylight score 100; typical commercial LEDs are 80 to 85 and high-quality ones 90 or more. Because it averages only eight unsaturated samples, a source can score well while rendering saturated reds poorly, so specs often add R9 or use TM-30.
Retail spec says CRI 90 minimum with R9 over 50, the 80 CRI version will make the produce look gray.
Also heard as
- Ra
- color rendering index
- CRI Ra
Do not mix it up with
- CCT: CCT is the color appearance of the light itself; CRI is how well it shows the colors of objects.
Related terms
R9
The color rendering score for a strong saturated red sample, not included in the general CRI average.
TM-30
A color rendition method that rates fidelity and saturation with 99 color samples, giving Rf, Rg and a color vector graphic.
CCT
Correlated Color Temperature: the warm-to-cool appearance of white light, stated in kelvin.
SPD
Spectral Power Distribution: a graph of how much power a light source emits at each wavelength.
Metamerism
The effect where two colors match under one light source but not under another, because their spectra differ.