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
Borel measure Borel measure In mathematics, specifically in measure theory, a Borel measure on a topological space is a measure that is defined on all open sets (and thus on all Borel sets). Some authors require additional restrictions on the measure, as described below. Let formula_1 be a locally compact Hausdorff space, and let formula_2 be the smallest σ-algebra that contains the open sets of formula_1; this is known as the σ-algebra of Borel sets. A Borel measure is any measure formula_4 defined on the σ-algebra of Borel sets. Some authors require in addition that formula_4 is locally compact, meaning that formula_6