colour.CAM16_to_XYZ(CAM16_specification, XYZ_w, L_A, Y_b, surround=CAM16_InductionFactors(F=1.0, c=0.69, N_c=1.0), discount_illuminant=False)[source]

Converts CAM16 specification to CIE XYZ tristimulus values.

This is the reverse implementation.

  • CAM16_specification (CAM16_Specification) – CAM16 colour appearance model specification. Correlate of Lightness \(J\), correlate of chroma \(C\) or correlate of colourfulness \(M\) and hue angle \(h\) in degrees must be specified, e.g. \(JCh\) or \(JMh\).
  • XYZ_w (array_like) – CIE XYZ tristimulus values of reference white.
  • L_A (numeric or array_like) – Adapting field luminance \(L_A\) in \(cd/m^2\), (often taken to be 20% of the luminance of a white object in the scene).
  • Y_b (numeric or array_like) – Relative luminance of background \(Y_b\) in \(cd/m^2\).
  • surround (CAM16_InductionFactors, optional) – Surround viewing conditions.
  • discount_illuminant (bool, optional) – Discount the illuminant.

XYZCIE XYZ tristimulus values.

Return type:



ValueError – If neither C or M correlates have been defined in the CAM16_specification argument.


The output range of that definition is non standard!


  • CAM16_specification can also be passed as a compatible argument colour.utilities.as_namedtuple() definition.
  • Input CIE XYZ_w tristimulus values are in domain [0, 100].
  • Output CIE XYZ tristimulus values are in range [0, 100].



>>> specification = CAM16_Specification(J=41.718025051415616,
...                                     C=11.941344635245843,
...                                     h=210.38389558131118)
>>> XYZ_w = np.array([95.05, 100.00, 108.88])
>>> L_A = 318.31
>>> Y_b = 20.0
>>> CAM16_to_XYZ(specification, XYZ_w, L_A, Y_b)  
array([ 19.01...,  20...  ,  21.78...])