colour.XYZ_to_OSA_UCS#

colour.XYZ_to_OSA_UCS(XYZ: ArrayLike) numpy.ndarray[source]#

Convert 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 (ArrayLike) – CIE XYZ tristimulus values under the CIE 1964 10 Degree Standard Observer.

Returns

OSA UCS \(Ljg\) lightness, jaune (yellowness), and greenness.

Return type

numpy.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

[CTS13], [Mor03]

Examples

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