colour.XYZ_to_hdr_CIELab#

colour.XYZ_to_hdr_CIELab(XYZ: ArrayLike, illuminant: ArrayLike = CCS_ILLUMINANTS['CIE 1931 2 Degree Standard Observer']['D65'], Y_s: FloatingOrArrayLike = 0.2, Y_abs: FloatingOrArrayLike = 100, method: Union[Literal['Fairchild 2011', 'Fairchild 2010'], str] = 'Fairchild 2011') ndarray[source]#

Convert from CIE XYZ tristimulus values to hdr-CIELAB colourspace.

Parameters:
  • XYZ (ArrayLike) – CIE XYZ tristimulus values.

  • illuminant (ArrayLike) – Reference illuminant CIE xy chromaticity coordinates or CIE xyY colourspace array.

  • Y_s (FloatingOrArrayLike) – Relative luminance \(Y_s\) of the surround.

  • Y_abs (FloatingOrArrayLike) – Absolute luminance \(Y_{abs}\) of the scene diffuse white in \(cd/m^2\).

  • method (Union[Literal['Fairchild 2011', 'Fairchild 2010'], str]) – Computation method.

Returns:

hdr-CIELAB colourspace array.

Return type:

numpy.ndarray

Notes

Domain

Scale - Reference

Scale - 1

XYZ

[0, 1]

[0, 1]

illuminant

[0, 1]

[0, 1]

Y_s

[0, 1]

[0, 1]

Range

Scale - Reference

Scale - 1

Lab_hdr

L_hdr : [0, 100]

a_hdr : [-100, 100]

b_hdr : [-100, 100]

L_hdr : [0, 1]

a_hdr : [-1, 1]

b_hdr : [-1, 1]

  • Conversion to polar coordinates to compute the chroma \(C_{hdr}\) and hue \(h_{hdr}\) correlates can be safely performed with colour.Lab_to_LCHab() definition.

  • Conversion to cartesian coordinates from the Lightness \(L_{hdr}\), chroma \(C_{hdr}\) and hue \(h_{hdr}\) correlates can be safely performed with colour.LCHab_to_Lab() definition.

References

[FW10], [FC11]

Examples

>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_hdr_CIELab(XYZ)  
array([ 51.8700206...,  60.4763385...,  32.1455191...])
>>> XYZ_to_hdr_CIELab(XYZ, method="Fairchild 2010")  
array([  31.9962111...,  128.0076303...,   48.7695230...])