Luminance 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 centimetre or 10 kcd/m. Luminance is often used to characterize emission or reflection from flat, diffuse surfaces. The luminance
Perfect measure "A" ⊆ R with "f"("A") ∈ Σ, there exist Borel subsets "A" and "A" of R such that 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,