colour.colorimetry.whiteness_Ganz1979

colour.colorimetry.whiteness_Ganz1979(xy, Y)[source]

Returns the whiteness index \(W\) and tint \(T\) of given sample xy chromaticity coordinates using Ganz and Griesser (1979) method.

Parameters:
  • xy (array_like) – Chromaticity coordinates xy of sample.
  • Y (numeric or array_like) – Tristimulus \(Y\) value of sample.
Returns:

Whiteness \(W\) and tint \(T\).
Return type:

ndarray

Warning

The input domain of that definition is non standard!

Notes

  • Input tristimulus \(Y\) value is in domain [0, 100].
  • The formula coefficients are valid for CIE Standard Illuminant D Series D65 and CIE 1964 10 Degree Standard Observer.
  • Positive output tint \(T\) values indicate a greener tint while negative values indicate a redder tint.
  • Whiteness differences of less than 5 Ganz units appear to be indistinguishable to the human eye.
  • Tint differences of less than 0.5 Ganz units appear to be indistinguishable to the human eye.

References

Examples

>>> xy = np.array([0.3167, 0.3334])
>>> whiteness_Ganz1979(xy, 100)  
array([ 85.6003766...,   0.6789003...])