The color rendering ability of a light source to an object is called chromaticity, which is compared with the color of the object under the same reference color or reference light source (incandescent lamp or light). The spectral content emitted by light determines the light color of the light source, but the same light color can be made by a few, or even only two monochromatic light waves, and the color rendering of each color is also different. The same light source will have different spectral composition, and the more widely distributed light source is likely to provide better color quality. When there is little or no main wave reflected by the object under the reference light source, the color color shift will be produced. The greater the chromatic aberration, the worse the color rendering of the light source. The chromatic index coefficient (Kaufman) is still a general method to evaluate the color rendering of light sources.