colour.colorimetry.intermediate_lightness_function_CIE1976

colour.colorimetry.intermediate_lightness_function_CIE1976(Y, Y_n=100)[source]

Returns the intermediate value \(f(Y/Yn)\) in the Lightness \(L^*\) computation for given luminance \(Y\) using given reference white luminance \(Y_n\) as per CIE 1976 recommendation.

Parameters:
  • Y (numeric or array_like) – luminance \(Y\).
  • Y_n (numeric or array_like, optional) – White reference luminance \(Y_n\).
Returns:

Intermediate value \(f(Y/Yn)\).

Return type:

numeric or array_like

Notes

Domain Scale - Reference Scale - 1
Y [0, 100] [0, 100]
Range Scale - Reference Scale - 1
f_Y_Y_n [0, 1] [0, 1]

References

[CIETC1-482004m], [Wyszecki2000bd]

Examples

>>> intermediate_lightness_function_CIE1976(12.19722535)
... # doctest: +ELLIPSIS
0.4959299...
>>> intermediate_lightness_function_CIE1976(12.19722535, 95)
... # doctest: +ELLIPSIS
0.5044821...