colour.dominant_wavelength¶
-
colour.
dominant_wavelength
(xy, xy_n, cmfs=XYZ_ColourMatchingFunctions(name='CIE 1931 2 Degree Standard Observer', ...), reverse=False)[source]¶ Returns the dominant wavelength \(\lambda_d\) for given colour stimulus \(xy\) and the related \(xy_wl\) first and \(xy_{cw}\) second intersection coordinates with the spectral locus.
In the eventuality where the \(xy_wl\) first intersection coordinates are on the line of purples, the complementary wavelength will be computed in lieu.
The complementary wavelength is indicated by a negative sign and the \(xy_{cw}\) second intersection coordinates which are set by default to the same value than \(xy_wl\) first intersection coordinates will be set to the complementary dominant wavelength intersection coordinates with the spectral locus.
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.
- reverse (bool, optional) – Reverse the computation direction to retrieve the complementary wavelength.
Returns: Dominant wavelength, first intersection point xy chromaticity coordinates, second intersection point xy chromaticity coordinates.
Return type: References
Examples
Dominant wavelength computation:
>>> from pprint import pprint >>> xy = np.array([0.54369557, 0.32107944]) >>> xy_n = np.array([0.31270000, 0.32900000]) >>> cmfs = CMFS['CIE 1931 2 Degree Standard Observer'] >>> pprint(dominant_wavelength(xy, xy_n, cmfs)) # doctest: +ELLIPSIS (array(616...), array([ 0.6835474..., 0.3162840...]), array([ 0.6835474..., 0.3162840...]))
Complementary dominant wavelength is returned if the first intersection is located on the line of purples:
>>> xy = np.array([0.37605506, 0.24452225]) >>> pprint(dominant_wavelength(xy, xy_n, cmfs)) # doctest: +ELLIPSIS (array(-509.0), array([ 0.4572314..., 0.1362814...]), array([ 0.0104096..., 0.7320745...]))