Candela per square metre
Template:Short description Template:Redirect Template:Infobox Unit The candela per square metre (symbol: cd/m2) is the unit of luminance in the International System of Units (SI). The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area.
The nit (symbol: nt) is a deprecated non-SI name also used for this unit (1 nt = 1 cd/m2).<ref>Template:Cite book</ref> The term nit is believed to come from the Latin word Template:Wikt-lang, "to shine".<ref>Template:Cite book</ref>
As a measure of light emitted per unit area, this unit is frequently used to specify the brightness of a display device. The sRGB spec for monitors targets Template:Val.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Typically, monitors calibrated for SDR broadcast or studio color grading should have a brightness of Template:Val.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Most consumer desktop liquid crystal displays have luminances of 200 to 300 cd/m2.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> HDR displays range from around 400 to 2500 cd/m2.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Comparison with other units of luminance
One candela per square metre is equal to:
- 10−4 stilbs (the CGS unit of luminance)
- π×10−4 lamberts
- π apostilbs
- 0.292 foot-lamberts
- π×103 skots
- π×107 brils
- 1 nit
Template:Luminance conversions
See also
| Quantity | Unit | Dimension <ref group="{{#if:|{{{3}}}|nb}}" name="note-dimension-symbol">The symbols in this column denote dimensions; "L", "T" and "J" are for length, time and luminous intensity respectively, not the symbols for the units litre, tesla and joule.</ref> |
Notes | ||
|---|---|---|---|---|---|
| Name | Symbol<ref group="{{#if:|{{{3}}}|nb}}" name="note-suffix-v">Standards organizations recommend that photometric quantities be denoted with a subscript "v" (for "visual") to avoid confusion with radiometric or photon quantities. For example: USA Standard Letter Symbols for Illuminating Engineering USAS Z7.1-1967, Y10.18-1967</ref> | Name | Symbol | ||
| Luminous energy | Template:Math<ref group="{{#if:|{{{3}}}|nb}}" name="note-alternative-symbol-photometric">Alternative symbols sometimes seen: Template:Mvar for luminous energy, Template:Mvar or Template:Mvar for luminous flux, and Template:Mvar for luminous efficacy of a source.</ref> | lumen second | lm⋅s | T⋅J | The lumen second is sometimes called the talbot. |
| Luminous flux, luminous power | Template:Math<ref group="{{#if:|{{{3}}}|nb}}" name="note-alternative-symbol-photometric"></ref> | lumen (= candela steradian) | lm (= cd⋅sr) | J | Luminous energy per unit time |
| Luminous intensity | Template:Math | candela (= lumen per steradian) | cd (= lm/sr) | J | Luminous flux per unit solid angle |
| Luminance | Template:Math | candela per square metre | cd/m2 (= lm/(sr⋅m2)) | L−2⋅J | Luminous flux per unit solid angle per unit projected source area. The candela per square metre is sometimes called the nit. |
| Illuminance | Template:Math | lux (= lumen per square metre) | lx (= lm/m2) | L−2⋅J | Luminous flux incident on a surface |
| Luminous exitance, luminous emittance | Template:Math | lumen per square metre | lm/m2 | L−2⋅J | Luminous flux emitted from a surface |
| Luminous exposure | Template:Math | lux second | lx⋅s | L−2⋅T⋅J | Time-integrated illuminance |
| Luminous energy density | Template:Math | lumen second per cubic metre | lm⋅s/m3 | L−3⋅T⋅J | |
| Luminous efficacy (of radiation) | Template:Math | lumen per watt | lm/W | M−1⋅L−2⋅T3⋅J | Ratio of luminous flux to radiant flux |
| Luminous efficacy (of a source) | Template:Mvar<ref group="{{#if:|{{{3}}}|nb}}" name="note-alternative-symbol-photometric"></ref> | lumen per watt | lm/W | M−1⋅L−2⋅T3⋅J | Ratio of luminous flux to power consumption |
| Luminous efficiency, luminous coefficient | Template:Mvar | 1 | Luminous efficacy normalized by the maximum possible efficacy | ||
| See also: Template:Hlist | |||||
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