The LED color index is the parameter of the LED lamp's ability to restore color, which is mainly used to define the difference in color performance of different LED light sources. The lower the color index, the more distorted the color appears to the naked eye.
The color index is not unique to leds, but a parameter that all light sources have, namely the ability to restore color. Daylight has a color index of 100, incandescent light is also 100, energy-saving light is 80-90, and led is 70-90.
The color rendering ability of the light source to the object is called color rendering, which is compared with the appearance color of the object under the same color temperature reference or reference light source (incandescent lamp or painted light). The spectrum content emitted by the light determines the light color of the light source, but the same light color can be composed of many, a few or even just two monochromatic waves, and the color rendering of each color is also very different.
The light source with the same light color will have different spectral composition, and the light source with broad spectrum composition is more likely to provide better color quality. Color shift occurs when there is little or no reflected primary wave in the light source spectrum. The larger the color difference, the worse the color rendering of the light source.
The color index coefficient (Kaufman) is still a universal method for defining color rendering of light sources.