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Luminance
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<p>Luminance is a <a href="/facts/Photometry_(optics)/eo6J7qj3">photometric</a> measure of the <a href="/facts/Luminous_intensity/uUSDSAKR">luminous intensity</a> per <a href="/facts/Units_of_measurement/pvTpWbmC">unit area</a> of <a href="/facts/Light/jeofpMn4">light</a> travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls within a given <a href="/facts/Solid_angle/se8IXufg">solid angle</a>. </p><p>The procedure for conversion from spectral <a href="/facts/Radiance/5kS1FhpD">radiance</a> to luminance is standardized by the <a href="/facts/International_Commission_on_Illumination/46q6W1zk">CIE</a> and <a href="/facts/International_Organization_for_Standardization/IacYR7Yg">ISO</a>. </p><p><a href="/facts/Brightness/e93R5I4b">Brightness</a> is the <a href="/facts/Terminology/1tfqvX1h">term</a> for the <i>subjective</i> impression of the <i>objective</i> luminance measurement standard (see <a href="/facts/Objectivity_(science)/dvNQI5a9">Objectivity (science) § Objectivity in measurement</a> for the importance of this contrast). </p><p>The <a href="/facts/SI_base_unit/M7PsTWg4">SI unit</a> for luminance is <a href="/facts/Candela_per_square_metre/9CaTeynY">candela per square metre</a> (cd/m2). A non-SI term for the same unit is the <a href="/facts/Nit_(unit)/9CaTeynY">nit</a>. The unit in the <a href="/facts/Centimetre%25E2%2580%2593gram%25E2%2580%2593second_system_of_units/qbHxv78q">Centimetre–gram–second system of units (CGS)</a> (which predated the SI system) is the <a href="/facts/Stilb_(luminance)/hQwPU9VG">stilb</a>, which is equal to one candela per square centimetre or 10 kcd/m2. </p>