How can we evaluate the quality of a light source?

The evaluation indicators of the light source include: color temperature, color rendering index, Spd (spectral energy distribution), and CIE same color spectral index.

1. color temperature

Color temperature definition: It is determined by comparing its color with the theoretical hot black body radiation. The kairen temperature when the colors of the radiant body and the light source match. (The trajectory of the black body radiation on the CIE-XY color chart is as follows: 1)

Figure 1

Generally, the color temperature of K is yellow, and the color temperature of K is blue. Figure 1 shows that the low color temperature is yellow, and the high color temperature is blue.

2. color rendering index

The color index indicates the color reproduction ability of the light source to the object. The system defines the color rendering index (value range: 0-100) by calculating the position of the tested light source and the reference light source moving in the eight specific middle colors of the CIE color space ).

In China's National Standard "light source color assessment method GB5702-85", it is required to use the radiation body (color temperature less than 5000 K) and the combination daylight (color temperature higher than 5000 K) as the reference light source.

The color index is used to calculate the color difference between the light source to be tested and the reference light source. The larger the color index, the better the color of the light source to be tested.

The color index simplifies the calculation process, for example, 2: △ei, that is, color shift.

Figure 2

For general light source Ra color index reference:

Figure 3

3. Spd (spectral energy distribution)

The relationship between the spectral radiation degree (or spectral radiation brightness or spectral radiation intensity or spectral radiation flux) of the light source and the wavelength is called "spectral energy distribution ".

The SPD introduced the same-color spectral phenomenon 4:

Figure 4

4. CIE same-color SPECTRAL INDEX

CIE proposed the calculation method of the "Special Same Color spectral index", that is, the color difference between two colors caused by the test of illumination body with different relative spectral power distribution. (MI = deltaE)

The smaller the same color spectral index of different light sources, the better the performance.

Refer:

Http://baike.baidu.cn/view/618844.htm

Http://www.color-gl.com/Article/ArticleShow.asp? ArticleID = 120

Http://www.canyilight.com/info_more.asp? PID = 3 & parentid = 36 & categoryid = 36

Http://zh.wikipedia.org/wiki/%E5%85%89%E8%B0%B1%E8%83%BD%E9%87%8F%E5%88%86%E5%B8%83

Http://wenku.baidu.com/view/1eb06b1114791711cc7917ac.html