colour.XYZ_to_LLAB¶

colour.XYZ_to_LLAB(XYZ, XYZ_0, Y_b, L, surround=LLAB_InductionFactors(D=1, F_S=3, F_L=1, F_C=1))[source]¶

Computes the LLAB(l:c) colour appearance model correlates.

Parameters:	XYZ (array_like) – CIE XYZ tristimulus values of test sample / stimulus in domain [0, 100]. XYZ_0 (array_like) – CIE XYZ tristimulus values of reference white in domain [0, 100]. Y_b (numeric or array_like) – Luminance factor of the background in \(cd/m^2\). L (numeric or array_like) – Absolute luminance \(L\) of reference white in \(cd/m^2\). surround (LLAB_InductionFactors, optional) – Surround viewing conditions induction factors.
Returns:	LLAB(l:c) colour appearance model specification.
Return type:	LLAB_Specification

Warning

The output range of that definition is non standard!

Notes

Input CIE XYZ tristimulus values are in domain [0, 100].
Input CIE XYZ_0 tristimulus values are in domain [0, 100].

References

Examples

>>> XYZ = np.array([19.01, 20.00, 21.78])
>>> XYZ_0 = np.array([95.05, 100.00, 108.88])
>>> Y_b = 20.0
>>> L = 318.31
>>> surround = LLAB_VIEWING_CONDITIONS['ref_average_4_minus']
>>> XYZ_to_LLAB(XYZ, XYZ_0, Y_b, L, surround)  
LLAB_Specification(J=37.3668650..., C=0.0089496..., h=270..., s=0.0002395..., M=0.0190185..., HC=None, a=..., b=-0.0190185...)