colour.complementary_wavelength¶
- colour.complementary_wavelength(xy: ArrayLike, xy_n: ArrayLike, cmfs: Optional[colour.colorimetry.spectrum.MultiSpectralDistributions] = None) Tuple[numpy.ndarray, numpy.ndarray, numpy.ndarray][source]¶
Return the complementary wavelength \(\lambda_c\) 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 dominant wavelength will be computed in lieu.
The dominant 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 dominant wavelength intersection coordinates with the spectral locus.
- Parameters
xy (ArrayLike) – Colour stimulus CIE xy chromaticity coordinates.
xy_n (ArrayLike) – Achromatic stimulus CIE xy chromaticity coordinates.
cmfs (Optional[colour.colorimetry.spectrum.MultiSpectralDistributions]) – Standard observer colour matching functions, default to the CIE 1931 2 Degree Standard Observer.
- Returns
Complementary wavelength, first intersection point CIE xy chromaticity coordinates, second intersection point CIE xy chromaticity coordinates.
- Return type
References
[CIET14804b], [Erdb]
Examples
Complementary wavelength computation:
>>> from colour.colorimetry import MSDS_CMFS >>> from pprint import pprint >>> cmfs = MSDS_CMFS['CIE 1931 2 Degree Standard Observer'] >>> xy = np.array([0.37605506, 0.24452225]) >>> xy_n = np.array([0.31270000, 0.32900000]) >>> pprint(complementary_wavelength(xy, xy_n, cmfs)) (array(509.0), array([ 0.0104096..., 0.7320745...]), array([ 0.0104096..., 0.7320745...]))
Dominant wavelength is returned if the first intersection is located on the line of purples:
>>> xy = np.array([0.54369557, 0.32107944]) >>> pprint(complementary_wavelength(xy, xy_n)) (array(492.0), array([ 0.0364795 , 0.3384712...]), array([ 0.0364795 , 0.3384712...]))