colour.XYZ_to_OSA_UCS

colour.XYZ_to_OSA_UCS(XYZ)[source]

Converts from CIE XYZ tristimulus values under the CIE 1964 10 Degree Standard Observer to OSA UCS colourspace.

The lightness axis, L is usually in range [-9, 5] and centered around middle gray (Munsell N/6). The yellow-blue axis, j is usually in range [-15, 15]. The red-green axis, g is usually in range [-20, 15].

Parameters:XYZ (array_like) – CIE XYZ tristimulus values under the CIE 1964 10 Degree Standard Observer.
Returns:OSA UCS \(Ljg\) lightness, jaune (yellowness), and greenness.
Return type:ndarray

Notes

Domain Scale - Reference Scale - 1
XYZ [0, 100] [0, 1]
Range Scale - Reference Scale - 1
Ljg

L : [-100, 100]

j : [-100, 100]

g : [-100, 100]

L : [-1, 1]

j : [-1, 1]

g : [-1, 1]

  • OSA UCS uses the CIE 1964 10 Degree Standard Observer.

References

[Cao2013], [Moroney2003]

Examples

>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952]) * 100
>>> XYZ_to_OSA_UCS(XYZ)  # doctest: +ELLIPSIS
array([-3.0049979...,  2.9971369..., -9.6678423...])