What is the difference between illuminance and brightness?

2024-04-20

Brightness refers to the intensity of led light reflected by the illuminated object and entered into the human eye, the unit is (cd/m2); and illuminance refers to how much light shines on the illuminated object, the unit is (lm/m2)

Brightness is directly related to the reflectivity of the object being illuminated. Objects with smooth surfaces have high reflectivity. Under the same illumination, the brightness we feel when shining on objects with different reflectivity is also different.

In practice, it is obviously unrealistic to use brightness as a measurement standard to specify the brightness of each object surface. We need to set a general range and judge the lighting quality based on this premise. Therefore, we assume that the books are white, the blackboard is black, and the desk is smooth. Under this premise, we can simply measure the amount of light shining on them to evaluate a suitable reading environment.For example, the average illumination in a general classroom is around 300lx, which can meet basic reading needs. However, in extreme cases, if black walls, blackboards, and black desks are used, the light absorption is very strong. In this case, we need to increase the illumination. Reading comfort can be improved by reaching 500lx.

Therefore, in home lighting design, in order to achieve ideal lighting effects and improve comfort, we must not only design according to standard illumination requirements, but also fully consider factors such as materials and glossiness used in the overall home decoration.