colour.colorimetry.whiteness_CIE2004

colour.colorimetry.whiteness_CIE2004(xy: ArrayLike, Y: ArrayLike, xy_n: ArrayLike, observer: Literal['CIE 1931 2 Degree Standard Observer', 'CIE 1964 10 Degree Standard Observer'] = 'CIE 1931 2 Degree Standard Observer') → NDArrayFloat

Return the whiteness \(W\) or \(W_{10}\) and tint \(T\) or \(T_{10}\) of given sample CIE xy chromaticity coordinates using CIE 2004 method.

Parameters:

• xy (ArrayLike) – Chromaticity coordinates CIE xy of the sample.

• Y (ArrayLike) – Tristimulus \(Y\) value of the sample.

• xy_n (ArrayLike) – Chromaticity coordinates xy_n of a perfect diffuser.

• observer (Literal['CIE 1931 2 Degree Standard Observer', 'CIE 1964 10 Degree Standard Observer']) – CIE Standard Observer used for computations, tint \(T\) or \(T_{10}\) value is dependent on viewing field angular subtense.

Returns:

Whiteness \(W\) or \(W_{10}\) and tint \(T\) or \(T_{10}\) of given sample.

Return type:

numpy.ndarray

Notes

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

Range	Scale - Reference	Scale - 1
WT	[0, 100]	[0, 1]

• This method may be used only for samples whose values of \(W\) or \(W_{10}\) lie within the following limits: greater than 40 and less than 5Y - 280, or 5Y10 - 280.

• This method may be used only for samples whose values of \(T\) or \(T_{10}\) lie within the following limits: greater than -4 and less than +2.

• Output whiteness \(W\) or \(W_{10}\) values larger than 100 indicate a bluish white while values smaller than 100 indicate a yellowish white.

• Positive output tint \(T\) or \(T_{10}\) values indicate a greener tint while negative values indicate a redder tint.

References

[CIET14804d]

Examples

>>> import numpy as np
>>> xy = np.array([0.3167, 0.3334])
>>> xy_n = np.array([0.3139, 0.3311])
>>> whiteness_CIE2004(xy, 100, xy_n)  
array([ 93.85...,  -1.305...])