Luminous intensity is abbreviated as luminosity, which refers  the brightness of the light source. It refers  the luminous flux emitted from a solid angle (unit: sr) of the light source, that is, the distribution density of the luminous flux emitted by the light source or lighting fixture in a selected direction in space, that is The physical quantity that represents the intensity of visible light radiation emitted by a light source in a certain direction and range, and the unit is candela (cd).

　　1cd = 1000mcd

　　1mcd = 1000μcd

　　The luminous intensity is for point light sources, or when the size of the luminous body is small compared  the irradiation distance, this quantity indicates the convergent ability of the luminous body  emit in space. It can be said that the luminous intensity describes the brightness of the light source, because it is a common description of light power and convergence ability. The greater the luminous intensity, the brighter the light source looks. At the same time, the brighter the object illuminated by the light source under the same conditions.