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→Transfer function ("gamma"): The function being described is a power law, not an exponential. An exponential does not have any zero slope issues |
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The IEC specification indicates a reference display with a nominal [[gamma correction|gamma]] of 2.2 similar to the gamma response of [[cathode-ray tube|CRT]] displays (a more accurate value is 2.3<ref>{{Cite web |last=Roberts |first=A. |date=1992 |title=Measurements of display transfer characteristics using test pictures. BBC Research Department Report RD 1992/13 |url=http://downloads.bbc.co.uk/rd/pubs/reports/1992-13.pdf |access-date=10 August 2023}}</ref>). The ability to directly display sRGB images on a CRT without any lookup greatly helped sRGB's adoption. Gamma also conveniently places more numbers near the black, reducing visible [[Quantization (image processing)|quantization]] artifacts.
The standard further defines a nonlinear [[transfer functions in imaging|electro-optical transfer function]] (EOTF), which exactly defines the conversion from image data to output intensity. This curve is a slight tweaking of {{math|''x''{{sup|2.2}}}}.<ref>{{Cite web |last= |first= |date=2015-12-05 |title=The Importance of Terminology and sRGB Uncertainty |url=https://www.colour-science.org/posts/the-importance-of-terminology-and-srgb-uncertainty/ |access-date=2021-11-05 |website=Colour Science |language=en}}</ref> A linear section is near zero, in order to avoid an infinite or zero slope that
In practice a pure {{math|''x''{{sup|2.2}}}} may be used with sRGB data with very little difference, this is referred to as "simple sRGB" by Adobe, and also what happens when it is displayed unchanged on a CRT.
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