colour.models.cie_lab Module¶

CIE Lab Colourspace¶

Defines the CIE Lab colourspace transformations:

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 colourspace to CIE Lab colourspace.

Parameters: XYZ (array_like, (3,)) – CIE XYZ colourspace matrix. illuminant (array_like, optional) – Reference illuminant chromaticity coordinates. CIE Lab colourspace matrix. ndarray, (3,)

Notes

• Input CIE XYZ is in domain [0, 1].
• Input illuminant chromaticity coordinates are in domain [0, 1].
• 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, 0.1008, 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 colourspace.

Parameters: Lab (array_like, (3,)) – CIE Lab colourspace matrix. illuminant (array_like, optional) – Reference illuminant chromaticity coordinates. CIE XYZ colourspace matrix. ndarray, (3,)

Notes

• Input Lightness $$L^*$$ is in domain [0, 100].
• Input illuminant chromaticity coordinates are in domain [0, 1].
• Output CIE XYZ colourspace matrix is 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([37.9856291, -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, (3,)) – CIE Lab colourspace matrix. CIE LCHab colourspace matrix. ndarray, (3,)

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([37.9856291, -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, (3,)) – CIE LCHab colourspace matrix. CIE Lab colourspace matrix. ndarray, (3,)

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