"http://en.wikipedia.org/wiki/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 or is emitted from a particular area, and falls within a given solid angle." . "L_v" . . . . . "\\(L_v = \\frac{dI_v}{dA}\\), where \\(dI_v\\) is the luminous intensity of an element of the surface with the area \\(dA\\) of the orthogonal projection of this element on a plane perpendicular to the given direction."^^ . . . . . "http://dbpedia.org/resource/Luminance"^^ . "Luminance"@en .