colour.Hunter_Rdab_to_XYZ

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

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

Parameters:
  • R_d_ab (array_like) – Hunter Rd,a,b colour scale array.
  • 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:

CIE XYZ tristimulus values.

Return type:

ndarray

Notes

Domain 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]

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

References

[HunterLab2012a]

Examples

>>> import numpy as np
>>> R_d_ab = np.array([12.19722500, 57.12537874, 17.46241341])
>>> D65 = HUNTERLAB_ILLUMINANTS[
...     'CIE 1931 2 Degree Standard Observer']['D65']
>>> Hunter_Rdab_to_XYZ(R_d_ab, D65.XYZ_n, D65.K_ab)
array([ 20.654008,  12.197225,   5.136952])