Editing Luminous efficiency function (section)

==Improvements to the standard==
The CIE 1924 photopic ''V''(''λ'') luminosity function,<ref name="CIE1926" group=cie/> which is included in the CIE 1931 color-matching functions as the {{overline|''y''}}(''λ'') function, has long been acknowledged to underestimate the contribution of the blue end of the spectrum to perceived luminance. There have been numerous attempts to improve the standard function, to make it more representative of human vision. Judd in 1951,<ref name="Judd1975"/> improved by Vos in 1978,<ref name="Vos1978"/> resulted in a function known as CIE ''V''<sub>M</sub>(''λ'').<ref name="Stiles1955"/> More recently, Sharpe, Stockman, Jagla & Jägle (2005) developed a function consistent with the [[LMS color space#Stockman & Sharpe (2000)|Stockman & Sharpe cone fundamentals]];<ref name="Sharpe2005"/> their curves are plotted in the figure above.

Stockman & Sharpe has subsequently produced an improved function in 2011, taking into account the effects of [[chromatic adaptation]] ''under daylight''.<ref name="S&S2011">{{cite journal |last1=Sharpe |first1=L.T. |last2=Stockman |first2=A. |display-authors=etal|date=February 2011 |title=A Luminous Efficiency Function, V*D65(&lambda;), for Daylight Adaptation: A Correction |journal=COLOR Research and Application |volume=36 |issue=1 |pages=42–46 |doi=10.1002/col.20602 |doi-access=free }}</ref> Their work in 2008<ref>{{cite journal |last1=Stockman |first1=A |last2=Jägle |first2=H |last3=Pirzer |first3=M |last4=Sharpe |first4=LT |title=The dependence of luminous efficiency on chromatic adaptation. |journal=Journal of Vision |date=15 December 2008 |volume=8 |issue=16 |pages=1.1–26 |doi=10.1167/8.16.1 |pmid=19146268 |doi-access=free}}</ref> has revealed that "luminous efficiency or V(l) functions change dramatically with chromatic adaptation".<ref name="Stockman2019">{{cite journal |last1=Stockman |first1=Andrew|date=December 2019 |title=Cone fundamentals and CIE standards |url=http://www.cvrl.org/people/Stockman/pubs/2019%20Cone%20fundamentals%20CIE%20S.pdf |journal=Current Opinion in Behavioral Sciences |volume=30 |issue= |pages=87–93 |doi= 10.1016/j.cobeha.2019.06.005|s2cid=199544026 |access-date=27 October 2023}}</ref>

===ISO standard===
The ISO standard is ISO/CIE FDIS 11664-1. The standard provides an incremental table by nm of each value in the visible range for the CIE 1924 function.<ref>{{cite web |url=https://www.iso.org/standard/74164.html |title=Colorimetry -- Part 1: CIE standard colorimetric observers|access-date=December 9, 2018}}</ref><ref>{{cite web|url=http://www.kayelaby.npl.co.uk/general_physics/2_5/2_5_3.html|title=Kay & Laby;tables of physical & chemical constants;General physics;SubSection: 2.5.3 Photometry|publisher=National Physical Laboratory; UK|access-date=December 9, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20190501164428/http://www.kayelaby.npl.co.uk/general_physics/2_5/2_5_3.html |archive-date=May 1, 2019}}</ref>