colour.XYZ_to_Hunter_Rdab

colour.XYZ_to_Hunter_Rdab(XYZ, XYZ_n=array([ 95.02, 100., 108.82]), K_ab=array([ 172.3, 67.2]))[source]

Converts from CIE XYZ tristimulus values to Hunter Rd,a,b colour scale.

Parameters:
  • XYZ (array_like) – CIE XYZ tristimulus values.
  • XYZ_n (array_like, optional) – Reference illuminant tristimulus values.
  • K_ab (array_like, optional) – Reference illuminant chromaticity coefficients, if K_ab is set to None it will be computed using colour.XYZ_to_K_ab_HunterLab1966().
Returns:

Hunter Rd,a,b colour scale array.

Return type:

ndarray

Notes

Domain Scale - Reference Scale - 1
XYZ [0, 100] [0, 1]
XYZ_n [0, 100] [0, 1]
Range Scale - Reference Scale - 1
R_d_ab

R_d : [0, 100]

a_Rd : [-100, 100]

b_Rd : [-100, 100]

R_d : [0, 1]

a_Rd : [-1, 1]

b_Rd : [-1, 1]

References

[HunterLab2012a]

Examples

>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952]) * 100
>>> D65 = HUNTERLAB_ILLUMINANTS[
...     'CIE 1931 2 Degree Standard Observer']['D65']
>>> XYZ_to_Hunter_Rdab(XYZ, D65.XYZ_n, D65.K_ab)
... # doctest: +ELLIPSIS
array([ 12.197225 ...,  57.1253787...,  17.4624134...])