colour.colorimetry.whiteness_CIE2004

colour.colorimetry.whiteness_CIE2004(xy, Y, xy_n, observer='CIE 1931 2 Degree Standard Observer')[source]

Returns 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 (array_like) – Chromaticity coordinates CIE xy of sample.

  • Y (numeric or array_like) – Tristimulus \(Y\) value of sample.

  • xy_n (array_like) – Chromaticity coordinates xy_n of perfect diffuser.

  • observer (str, optional) – {‘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

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

[CIET14804i]

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...])