The color rendering index CRI stands for Color Rendering Index1 and indicates how well an artificial light source can reproduce the natural color of an object.
This specification has been of interest to consumers since the introduction of energy-saving lamps and LEDs, because unlike conventional incandescent lamps, these cannot reproduce colors as naturally as daylight.
The reference value is the sun or daylight with an Ra value2 of 100. A spectrometer can measure the reflected light from the test light source and compare it with specified reference values. This results in 8 R-values for different color spectra. The average value is formed from these values and the meaningful Ra value2 (a here stands for general) of the light source is obtained.
Ra ≥ 90 very good Ra ≤ 80 good Ra < 80 not recommended
Examples of Ra value2s for different light sources:
Incandescent lamp ≈ 100 Halogen lamp ≈ 98 White LEDs ≈ 70-95 Fluorescent lamp ≈ 50-90 Mercury vapor- High-pressure lamp ≈ 45-50 Black light ≈ 0
Understanding the Color Rendering Index (CRI) is crucial for choosing lighting that accurately reflects natural colors, enhancing visual comfort and aesthetics. ↩
Exploring how the Ra value is calculated helps in selecting the right lighting solutions that meet specific color accuracy needs for various applications. ↩