colour.XYZ_to_CIECAM02#

colour.XYZ_to_CIECAM02(XYZ: Domain100, XYZ_w: Domain100, L_A: ArrayLike, Y_b: ArrayLike, surround: InductionFactors_CIECAM02 = VIEWING_CONDITIONS_CIECAM02['Average'], discount_illuminant: bool = False, compute_H: bool = True) → Annotated[CAM_Specification_CIECAM02, 100, 100, 360, 100, 100, 100, 400][source]#

Compute the CIECAM02 colour appearance model correlates from the specified CIE XYZ tristimulus values.

Parameters:

  • XYZ (Domain100) – CIE XYZ tristimulus values of test sample / stimulus.

  • XYZ_w (Domain100) – CIE XYZ tristimulus values of reference white.

  • L_A (ArrayLike) – 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 (ArrayLike) – Luminous factor of background \(Y_b\) such as \(Y_b = 100 \times L_b / L_w\) 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) – Surround viewing conditions induction factors.

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

  • compute_H (bool) – Whether to compute Hue \(h\) quadrature \(H\). \(H\) is rarely used, and expensive to compute.

Returns:

CIECAM02 colour appearance model specification.

Return type:

colour.CAM_Specification_CIECAM02

Notes

Domain

Scale - Reference

Scale - 1

XYZ

100

1

XYZ_w

100

1

Range

Scale - Reference

Scale - 1

specification.J

100

1

specification.C

100

1

specification.h

360

1

specification.s

100

1

specification.Q

100

1

specification.M

100

1

specification.H

400

1

References

[Fai04], [LL13], [MFH+02], [Wikipedia07d]

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=np.float64(41.7310911...), C=np.float64(0.1047077...), h=np.float64(219.0484326...), s=np.float64(2.3603053...), Q=np.float64(195.3713259...), M=np.float64(0.1088421...), H=np.float64(278.0607358...), HC=None)
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