[] V

The index of the lightness of perceived object color defined in terms of the luminance factor (Y) for CIE Standard Illuminant C and the CIE 1931 Standard Observer.*

Note: The exact definition gives Y as a fifth-power function of V, so that tabular or iterative methods are needed to find V as a function of Y. However, V can be estimated within ± 0.1 by  V=11.6 (Y/100)1/3 – 1.6, or within ± 0.6  by V=Y1/2, where Y is the luminance factor expressed in percent.


* Newhall SM, Nickerson D, Judd DB. Final Report of the O.S.A. Subcommittee on the Spacing of the Munsell Colors. Journal of the Optical Society of America. Jul 1943;33:385.

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