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单词 luminance
释义

luminance


lu·mi·nance

L0286700 (lo͞o′mə-nəns)n.1. The condition or quality of being luminous.2. Physics The intensity of light per unit area of its source. Also called photometric brightness.

luminance

(ˈluːmɪnəns) n1. a state or quality of radiating or reflecting light2. (General Physics) a measure (in candelas per square metre) of the brightness of a point on a surface that is radiating or reflecting light. It is the luminous intensity in a given direction of a small element of surface area divided by the orthogonal projection of this area onto a plane at right angles to the direction. Symbol: L [C19: from Latin lūmen light]

lu•mi•nance

(ˈlu mə nəns)

n. 1. the state or quality of being luminous. 2. the quality or condition of radiating or reflecting light: the blinding luminance of the sun. 3. the quantitative measure of brightness of a light source or an illuminated surface, equal to luminous flux per unit solid angle emitted per unit projected area of the source or surface. [1875–80; < Latin lūmin- (see lumen) + -ance]
Thesaurus
Noun1.luminance - the quality of being luminousluminance - the quality of being luminous; emitting or reflecting light; "its luminosity is measured relative to that of our sun"brightness level, luminosity, luminousness, brightness, lightphysical property - any property used to characterize matter and energy and their interactionsilluminance, illumination - the luminous flux incident on a unit areaincandescence - light from heatglow, luminescence - light from nonthermal sources

luminance


Luminance

The luminous intensity of any surface in a given direction per unit of projected area of the surface viewed from that direction. The International Commission on Illumination defines it as the quotient of the luminous intensity in the given direction of an infinitesimal element of the surface containing the point under consideration, by the orthogonally projected area of the element on a plane perpendicular to the given direction. Simply, it is the luminous intensity per unit area. Luminance is also called photometric brightness.

Since the candela is the unit of luminous intensity, the luminance, or photometric brightness, of a surface may be expressed in candelas/cm2, candelas/in.2, and so forth.

The stilb is a unit of luminance (photometric brightness) equal to 1 candela/cm2. It is often used in Europe, but the practice in America is to use the term candela/cm2 in its place.

The apostilb is another unit of luminance sometimes used in Europe. It is equal to the luminance of a perfectly diffusing surface emitting or diffusing light at the rate of 1 lumen/m2. See Luminous intensity, Photometry

Luminance

The physical measure of brightness, or luminous intensity per unit of projected area of any surface, as measured from a specific direction. It is the amount of visible light. leaving a point on a surface in a given direction. This “surface” can be a physical surface or an imaginary plane, and the light leaving the surface can be due to reflection, transmission, and/or emission. The standard unit of luminance is candela per square meter (cd/m2).

Luminance

 

(L), a photometric quantity equal to the ratio of luminous flux d2ф and geometric factor dΩdA cos θ:

L = d2ф/dΩdA cos θ

where dΩ is the solid angle filled with radiation, dA is the area of the emitting or illuminated surface, and θ is the angle between the normal to the surface and the direction of the radiation.

Two special definitions of great practical interest follow from the general definition of luminance. First, luminance may be defined as the ratio of the luminous intensity I of a surface element and the area of the element’s projection perpendicular to a given direction: L = dI/dA cos θ. Second, luminance may be defined as the ratio of the illuminance E at a point of a plane that is perpendicular to the direction to the source and the unit solid angle occupied by the flux produced by the illuminance:

L = dE/dΩ cos θ.

Luminance is measured in candelas per m2. It is the photometric quantity that is most directly associated with visual sensations, because the illuminance of the image of an object on the retina is proportional to the luminance of the object.

In the system of radiometric quantities, the quantity that is analogous to luminance is called radiance. Radiance is measured in watts per steradian per m2.

D. N. LAZAREV

luminance

[′lü·mə·nəns] (optics) The ratio of the luminous intensity in a given direction of an infinitesimal element of a surface containing the point under consideration, to the orthogonally projected area of the element on a plane perpendicular to the given direction. Formerly known as brightness.

luminance

The luminous intensity of any surface in a given direction per unit of projected area of the surface, as viewed from that direction; a directional property of luminous radiation.

luminance

brightness

luminance

The amount of brightness, measured in lumens, that is given off by a pixel or area on a screen. For example, dark red and bright red would have the same chrominance, but a different luminance. Bright red and bright green could have the same luminance, but would always have a different chrominance. See luma.

luminance


lu·mi·nance

(lū'mi-nănts), The brightness of an object, expressed as the luminous flux per unit solid angle per unit projected area, measured in lamberts or in candelas per square meter. [L. lumino, to light up, fr. lumen, light]

lu·mi·nance

(lū'mi-năns) The brightness of an object, expressed as the luminous flux per unit solid angle per unit projected area, measured in lamberts or in candelas per square meter. [L. lumino, to light up, fr. lumen, light]

luminance

Photometric term characterizing the way in which a surface emits or reflects light in a given direction. It is equal to the luminous intensity measured in a given direction divided by the area of this surface projected on a perpendicular to the direction considered. Symbol: L. Units: candela per square metre (SI unit); footlambert; lambert, etc. See brightness; candela per square metre; footlambert; lambert; lightness; millilambert; nit; photometry; SI unit.
FinancialSeeLumaAcronymsSeeYCrCb

luminance


  • noun

Synonyms for luminance

noun the quality of being luminous

Synonyms

  • brightness level
  • luminosity
  • luminousness
  • brightness
  • light

Related Words

  • physical property
  • illuminance
  • illumination
  • incandescence
  • glow
  • luminescence
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