colour.RGB_luminance

colour.RGB_luminance(RGB: ArrayLike, primaries: ArrayLike, whitepoint: ArrayLike) → Annotated[ndarray[tuple[Any, ...], dtype[float16 | float32 | float64]], 1]

Calculate the luminance \(Y\) of the specified RGB components using the specified primaries and whitepoint chromaticity coordinates.

Parameters:

• RGB (ArrayLike) – RGB colour components array.

• primaries (ArrayLike) – Primaries \(xy\) chromaticity coordinates array.

• whitepoint (ArrayLike) – Illuminant / whitepoint \(xy\) chromaticity coordinates.

Returns:

Luminance \(Y\).

Return type:

numpy.ndarray

Notes

Range	Scale - Reference	Scale - 1
Y	1	1

Examples

>>> RGB = np.array([0.21959402, 0.06986677, 0.04703877])
>>> p = np.array([0.73470, 0.26530, 0.00000, 1.00000, 0.00010, -0.07700])
>>> whitepoint = np.array([0.32168, 0.33767])
>>> RGB_luminance(RGB, p, whitepoint)
0.1230145...