colour.plotting.diagrams.plot_spectral_locus(cmfs: Union[MultiSpectralDistributions, str, Sequence[Union[MultiSpectralDistributions, str]]] = 'CIE 1931 2 Degree Standard Observer', spectral_locus_colours: Optional[Union[ArrayLike, str]] = None, spectral_locus_opacity: Floating = 1, spectral_locus_labels: Optional[Sequence] = None, method: Union[Literal['CIE 1931', 'CIE 1960 UCS', 'CIE 1976 UCS'], str] = 'CIE 1931', **kwargs: Any) Tuple[plt.Figure, plt.Axes][source]

Plot the Spectral Locus according to given method.

  • cmfs (Union[MultiSpectralDistributions, str, Sequence[Union[MultiSpectralDistributions, str]]]) – Standard observer colour matching functions used for computing the spectral locus boundaries. cmfs can be of any type or form supported by the colour.plotting.filter_cmfs() definition.

  • spectral_locus_colours (Optional[Union[ArrayLike, str]]) – Colours of the Spectral Locus, if spectral_locus_colours is set to RGB, the colours will be computed according to the corresponding chromaticity coordinates.

  • spectral_locus_opacity (Floating) – Opacity of the Spectral Locus.

  • spectral_locus_labels (Optional[Sequence]) – Array of wavelength labels used to customise which labels will be drawn around the spectral locus. Passing an empty array will result in no wavelength labels being drawn.

  • method (Union[Literal[('CIE 1931', 'CIE 1960 UCS', 'CIE 1976 UCS')], str]) – Chromaticity Diagram method.

  • kwargs (Any) – {colour.plotting.artist(), colour.plotting.render()}, See the documentation of the previously listed definitions.


Current figure and axes.

Return type



>>> plot_spectral_locus(spectral_locus_colours='RGB')  
(<Figure size ... with 1 Axes>, <...AxesSubplot...>)