colour.excitation_purity¶
-
colour.
excitation_purity
(xy, xy_n, cmfs=XYZ_ColourMatchingFunctions(name='CIE 1931 2 Degree Standard Observer', ...))[source]¶ Returns the excitation purity \(P_e\) for given colour stimulus \(xy\).
Parameters: - xy (array_like) – Colour stimulus xy chromaticity coordinates.
- xy_n (array_like) – Achromatic stimulus xy chromaticity coordinates.
- cmfs (XYZ_ColourMatchingFunctions, optional) – Standard observer colour matching functions.
Returns: Excitation purity \(P_e\).
Return type: numeric or array_like
References
Examples
>>> xy = np.array([0.54369557, 0.32107944]) >>> xy_n = np.array([0.31270000, 0.32900000]) >>> cmfs = CMFS['CIE 1931 2 Degree Standard Observer'] >>> excitation_purity(xy, xy_n, cmfs) # doctest: +ELLIPSIS 0.6228856...