Candela per square metre

The candela per square metre (cd/m2) is the derived SI unit of luminance. The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area. Nit (nt) is a deprecated non-SI name also used for this unit (1 nit = 1 cd/m2).[1]

Most consumer desktop liquid crystal displays have luminances of 200 to 300 cd/m2;[2] the sRGB spec for monitors targets 80 cd/m2.[3] HDTVs range from 450 to about 1000 cd/m2.

Nit is believed to come from the Latin nitere, to shine.[4]

Contents

Comparison to other units of luminance

One candela per square metre is equal to:

See also

'
Quantity Symbol[nb 1] SI unit Symbol Dimension Notes
Luminous energy Qv [nb 2] lumen second lm⋅s T⋅J units are sometimes called talbots
Luminous flux Φv [nb 2] lumen (= cd⋅sr) lm J also called luminous power
Luminous intensity Iv candela (= lm/sr) cd J [nb 3] an SI base unit, luminous flux per unit solid angle
Luminance Lv candela per square metre cd/m2 L−2⋅J units are sometimes called nits
Illuminance Ev lux (= lm/m2) lx L−2⋅J used for light incident on a surface
Luminous emittance Mv lux (= lm/m2) lx L−2⋅J used for light emitted from a surface
Luminous exposure Hv lux second lx⋅s L−2⋅T⋅J
Luminous energy density ωv lumen second per metre3 lm⋅s⋅m−3 L−3⋅T⋅J
Luminous efficacy η [nb 2] lumen per watt lm/W M−1⋅L−2⋅T3⋅J ratio of luminous flux to radiant flux
Luminous efficiency V 1 also called luminous coefficient
See also: SI · Photometry · Radiometry
  1. ^ Standards organizations recommend that photometric quantities be denoted with a suffix "v" (for "visual") to avoid confusion with radiometric or photon quantities.
  2. ^ a b c Alternative symbols sometimes seen: W for luminous energy, P or F for luminous flux, and ρ or K for luminous efficacy.
  3. ^ "J" is the recommended symbol for the dimension of luminous intensity in the International System of Units.

References

  1. ^ Pierre Buser and Michel Imbert (1992). Vision. MIT Press. p. 53. ISBN 9780262023368. http://books.google.com/books?id=NSZvt8Ld2-8C&pg=PA53&dq=nit+luminance. 
  2. ^ "PC Perspective". http://www.pcper.com/article.php?aid=907&type=expert&pid=3. 
  3. ^ "IEC 61966-2-1:1999 Multimedia systems and equipment - Colour measurement and management - Part 2-1: Colour management - Default RGB colour space - sRGB". International Electrotechnical Commission. http://webstore.iec.ch/webstore/webstore.nsf/artnum/025408. 
  4. ^ R. L. F. Boyd (ed.) (1992). Astronomical Photometry. Springer. p. 9. ISBN 9780792316534. http://books.google.com/books?id=ojzepXhy9DIC&pg=PA9&dq=nitere+nit+luminance. 

External links