Colour Rendering Index
A score out of 100 describing how faithfully a light source reveals the colours of objects compared with a reference illuminant.
Measured in
CRI (Ra)
In depth
The standard figure averages performance across eight desaturated test colours, which is why a light can score 95 and still render saturated reds badly — the extended R9 value for strong red is the number to check. Anything below about 90 is unsuitable for photographic work, and the metric was designed for architectural lighting rather than cameras.
Examples in practice
An LED panel quoting CRI 96 but R9 of only 20 will still render lipstick and skin unconvincingly.