Luminance while imaging luminance meters measure luminance in a way similar to the way a digital camera records color images. Luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted or reflected from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m). A non-SI term for the same unit is the nit. The CGS unit of luminance is the stilb, which is equal to one candela per square
Perfect measure Perfect measure In mathematics — specifically, in measure theory — a perfect measure (or, more accurately, a perfect measure space) is one that is “well-behaved” in some sense. Intuitively, a perfect measure "μ" is one for which, if we consider the pushforward measure on the real line R, then every measurable set is “"μ"-approximately a Borel set”. The notion of perfectness is closely related to tightness of measures: indeed, in metric spaces, tight measures are always perfect. A measure space ("X", Σ, "μ") is said to be perfect if, for every Σ-measurable function "f" : "X" → R and every