colour.XYZ_to_RLAB

colour.XYZ_to_RLAB(XYZ: Annotated[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str], 100], XYZ_n: Annotated[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str], 100], Y_n: ArrayLike, sigma: ArrayLike = VIEWING_CONDITIONS_RLAB['Average'], D: ArrayLike = D_FACTOR_RLAB['Hard Copy Images']) → Annotated[CAM_Specification_RLAB, 360]

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

Parameters:

• XYZ (Annotated[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str], 100]) – CIE XYZ tristimulus values of test sample / stimulus.

• XYZ_n (Annotated[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str], 100]) – CIE XYZ tristimulus values of reference white.

• Y_n (ArrayLike) – Absolute adapting luminance in \(cd/m^2\).

• sigma (ArrayLike) – Relative luminance of the surround, see colour.VIEWING_CONDITIONS_RLAB for reference.

• D (ArrayLike) – Discounting-the-Illuminant factor normalised to domain [0, 1].

Returns:

RLAB colour appearance model specification.

Return type:

CAM_Specification_RLAB

Notes

Domain	Scale - Reference	Scale - 1
XYZ	100	1
XYZ_n	100	1

Range	Scale - Reference	Scale - 1
specification.h	360	1

References

[Fai96], [Fai13d]

Examples

>>> XYZ = np.array([19.01, 20.00, 21.78])
>>> XYZ_n = np.array([109.85, 100, 35.58])
>>> Y_n = 31.83
>>> sigma = VIEWING_CONDITIONS_RLAB["Average"]
>>> D = D_FACTOR_RLAB["Hard Copy Images"]
>>> XYZ_to_RLAB(XYZ, XYZ_n, Y_n, sigma, D)
CAM_Specification_RLAB(J=49.8347069..., C=54.8700585..., h=286.4860208..., s=1.1010410..., HC=None, a=15.5711021..., b=-52.6142956...)