colour.polynomial_expansion

colour.polynomial_expansion(a: ArrayLike, method: Literal['Cheung 2004', 'Finlayson 2015', 'Vandermonde'] | str = 'Cheung 2004', **kwargs: Any) → NDArrayFloat

Perform polynomial expansion of the \(a\) array.

Parameters:

• a (ArrayLike) – Array to expand using polynomial expansion.

• method (Literal['Cheung 2004', 'Finlayson 2015', 'Vandermonde'] | str) – Computation method for the polynomial expansion.

• degree – {colour.characterisation.polynomial_expansion_Finlayson2015(), colour.characterisation.polynomial_expansion_Vandermonde()}, Expanded polynomial degree, must be one of [1, 2, 3, 4] for colour.characterisation.polynomial_expansion_Finlayson2015() definition.

• root_polynomial_expansion – {colour.characterisation.polynomial_expansion_Finlayson2015()}, Whether to use the root-polynomials set for the expansion.

• terms – {colour.characterisation.matrix_augmented_Cheung2004()}, Number of terms of the expanded polynomial.

• kwargs (Any)

Returns:

Polynomial-expanded \(a\) array.

Return type:

numpy.ndarray

References

[CWCR04], [FMH15], [WR04], [Wikipedia03f]

Examples

>>> RGB = np.array([0.17224810, 0.09170660, 0.06416938])
>>> polynomial_expansion(RGB)
array([0.1722481..., 0.0917066..., 0.0641693...])
>>> polynomial_expansion(RGB, "Cheung 2004", terms=5)
array([0.1722481..., 0.0917066..., 0.0641693..., 0.0010136..., 1...])