colour.XYZ_to_CIECAM02

colour.XYZ_to_CIECAM02(XYZ, XYZ_w, L_A, Y_b, surround=InductionFactors_CIECAM02(F=1, c=0.69, N_c=1), discount_illuminant=False)[source]

Computes the CIECAM02 colour appearance model correlates from given CIE XYZ tristimulus values.

This is the forward implementation.

Parameters
  • XYZ (array_like) – CIE XYZ tristimulus values of test sample / stimulus.

  • 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) – Luminous factor of background \(Y_b\) such as \(Y_b = 100 x L_b / L_w\) where \(L_w\) is the luminance of the light source and \(L_b\) is the luminance of the background. For viewing images, \(Y_b\) can be the average \(Y\) value for the pixels in the entire image, or frequently, a \(Y\) value of 20, approximate an \(L^*\) of 50 is used.

  • surround (InductionFactors_CIECAM02, optional) – Surround viewing conditions induction factors.

  • discount_illuminant (bool, optional) – Truth value indicating if the illuminant should be discounted.

Returns

CIECAM02 colour appearance model specification.

Return type

CAM_Specification_CIECAM02

Notes

Domain

Scale - Reference

Scale - 1

XYZ

[0, 100]

[0, 1]

XYZ_w

[0, 100]

[0, 1]

Range

Scale - Reference

Scale - 1

CAM_Specification_CIECAM02.J

[0, 100]

[0, 1]

CAM_Specification_CIECAM02.C

[0, 100]

[0, 1]

CAM_Specification_CIECAM02.h

[0, 360]

[0, 1]

CAM_Specification_CIECAM02.s

[0, 100]

[0, 1]

CAM_Specification_CIECAM02.Q

[0, 100]

[0, 1]

CAM_Specification_CIECAM02.M

[0, 100]

[0, 1]

CAM_Specification_CIECAM02.H

[0, 400]

[0, 1]

References

[Fai04], [LL13], [MFH+02], [Wikipedia07b]

Examples

>>> XYZ = np.array([19.01, 20.00, 21.78])
>>> XYZ_w = np.array([95.05, 100.00, 108.88])
>>> L_A = 318.31
>>> Y_b = 20.0
>>> surround = VIEWING_CONDITIONS_CIECAM02['Average']
>>> XYZ_to_CIECAM02(XYZ, XYZ_w, L_A, Y_b, surround)  
CAM_Specification_CIECAM02(J=41.7310911..., C=0.1047077..., h=219.0484326..., s=2.3603053..., Q=195.3713259..., M=0.1088421..., H=278.0607358..., HC=None)