The brightness or luminance of an object is defined as the luminous flux emitted per unit area of the object into unit solid angle. 物体的亮度或发光率定义为物体面积发射到单位立体角内的光通量。
A luminance unit equal to 1 candle per square meter measured perpendicular to the rays from the source. 亮度单位等于每平方米新烛光。
A former luminance unit equal to one lumen per square foot. 旧制光的亮度单位等于每平方英尺流明。