colour.models.cie_lab Module

CIE Lab Colourspace

Defines the CIE Lab colourspace transformations:

References

[1]CIE TC 1-48. (2004). CIE 1976 uniform colour spaces. In CIE 015:2004 Colorimetry, 3rd Edition (p. 24). ISBN:978-3-901-90633-6
colour.models.cie_lab.XYZ_to_Lab(XYZ, illuminant=array([ 0.3457, 0.3585]))[source]

Converts from CIE XYZ tristimulus values to CIE Lab colourspace.

Parameters:
  • XYZ (array_like) – CIE XYZ tristimulus values.
  • illuminant (array_like, optional) – Reference illuminant xy chromaticity coordinates or CIE xyY colourspace array.
Returns:

CIE Lab colourspace array.

Return type:

ndarray

Notes

  • Input CIE XYZ tristimulus values are in domain [0, 1].
  • Input illuminant xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Output Lightness \(L^*\) is in range [0, 100].

Examples

>>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
>>> XYZ_to_Lab(XYZ)  
array([ 37.9856291..., -23.6290768...,  -4.4174661...])
colour.models.cie_lab.Lab_to_XYZ(Lab, illuminant=array([ 0.3457, 0.3585]))[source]

Converts from CIE Lab colourspace to CIE XYZ tristimulus values.

Parameters:
  • Lab (array_like) – CIE Lab colourspace array.
  • illuminant (array_like, optional) – Reference illuminant xy chromaticity coordinates or CIE xyY colourspace array.
Returns:

CIE XYZ tristimulus values.

Return type:

ndarray

Notes

  • Input Lightness \(L^*\) is in domain [0, 100].
  • Input illuminant xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Output CIE XYZ tristimulus values are in range [0, 1].

Examples

>>> Lab = np.array([37.98562910, -23.62907688, -4.41746615])
>>> Lab_to_XYZ(Lab)  
array([ 0.0704953...,  0.1008    ,  0.0955831...])
colour.models.cie_lab.Lab_to_LCHab(Lab)[source]

Converts from CIE Lab colourspace to CIE LCHab colourspace.

Parameters:Lab (array_like) – CIE Lab colourspace array.
Returns:CIE LCHab colourspace array.
Return type:ndarray

Notes

  • Lightness \(L^*\) is in domain [0, 100].

Examples

>>> Lab = np.array([37.98562910, -23.62907688, -4.41746615])
>>> Lab_to_LCHab(Lab)  
array([  37.9856291...,   24.0384542...,  190.5892337...])
colour.models.cie_lab.LCHab_to_Lab(LCHab)[source]

Converts from CIE LCHab colourspace to CIE Lab colourspace.

Parameters:LCHab (array_like) – CIE LCHab colourspace array.
Returns:CIE Lab colourspace array.
Return type:ndarray

Notes

  • Lightness \(L^*\) is in domain [0, 100].

Examples

>>> LCHab = np.array([37.98562910, 24.03845422, 190.58923377])
>>> LCHab_to_Lab(LCHab)  
array([ 37.9856291..., -23.6290768...,  -4.4174661...])