Small lighting knowledge | what is brightness? - China lighting network

A shiny surface and light irradiation on the surface of the object by the light bright degree, can be directly feel the human eye, but feel the bright degree of the human eye, called luminosity ( 亮度) Subjective brightness, or it may be to observe the influence of environment and some factors of the light source itself. Subjective feeling also because of the different eyes adapt to the situation and there is a considerable difference. In photometry with brightness ( Luminance) This quantity to represent the shiny surface and by the light irradiation on the surface of the liquid level. As a professional term, brightness is defined as a point light source surface bin luminous intensity in a given direction is divided by the surface element in the direction perpendicular to a given orthographic projection area of the business. The brightness of the si units is CD/m2 ( Candela per square meter) 。 The brightness can be bright enough, also can be surfaces under the light reflection or transmission the brightness of the light, the brightness of the light source is the time. In general, the brightness of the different parts on the surface is different, the brightness of the same parts also changes according to the observation direction. Describing and measuring the brightness, therefore, should be clear position and direction. YanZhiXiang

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