colour.models.cie_lab Module

CIE Lab Colourspace

Defines the CIE Lab colourspace transformations:

See also

CIE Lab Colourspace IPython Notebook

References

[1]Wikipedia. (n.d.). Lab color space. Retrieved February 24, 2014, from http://en.wikipedia.org/wiki/Lab_color_space
colour.models.cie_lab.XYZ_to_Lab(XYZ, illuminant=(0.34567, 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 domain [0, 100].

References

[2]Lindbloom, B. (2003). XYZ to Lab. Retrieved February 24, 2014, from http://www.brucelindbloom.com/Eqn_XYZ_to_Lab.html

Examples

>>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
>>> XYZ_to_Lab(XYZ)  
array([ 37.9856291..., -23.6230288...,  -4.4141703...])
colour.models.cie_lab.Lab_to_XYZ(Lab, illuminant=(0.34567, 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 domain [0, 1].

References

[3]Lindbloom, B. (2008). Lab to XYZ. Retrieved February 24, 2014, from http://www.brucelindbloom.com/Eqn_Lab_to_XYZ.html

Examples

>>> Lab = np.array([37.98562910, -23.62302887, -4.41417036])
>>> 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].

References

[4]Lindbloom, B. (2007). Lab to LCH(ab). Retrieved February 24, 2014, from http://www.brucelindbloom.com/Eqn_Lab_to_LCH.html

Examples

>>> Lab = np.array([37.98562910, -23.62302887, -4.41417036])
>>> Lab_to_LCHab(Lab)  
array([  37.9856291...,   24.0319036...,  190.5841597...])
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].

References

[5]Lindbloom, B. (2006). LCH(ab) to Lab. Retrieved February 24, 2014, from http://www.brucelindbloom.com/Eqn_LCH_to_Lab.html

Examples

>>> LCHab = np.array([37.98562910, 24.03190365, 190.58415972])
>>> LCHab_to_Lab(LCHab)  
array([ 37.9856291..., -23.6230288...,  -4.4141703...])