colour.difference.Lab_to_metamerism_index#

colour.difference.Lab_to_metamerism_index(Lab_spl_t: Domain100, Lab_std_t: Domain100, Lab_spl_r: Domain100, Lab_std_r: Domain100, correction: str = 'Additive', method: LiteralDeltaEMethod | str = 'CIE 2000', *, additional_data: Literal[False] = False, **kwargs: Any) → NDArrayFloat[source]#

Compute the metamerism index \(M_{t}\) between four specified CIE L*a*b* colourspace arrays.

Before computing the metamerism index, apply either an additive or multiplicative correction. The correction is based on the difference between the colour sample and colour standard under the reference illuminant and is applied to the colour sample under the test illuminant. The correction is applied in CIE L*a*b* colourspace, which is then used to compute the metamerism index.

[InternationalOfStandardization24] recommends using additive correction in CIE L*a*b*.

Parameters:

Lab_spl_t (Domain100) – CIE L*a*b* colourspace array of the colour sample under the test illuminant.
Lab_std_t (Domain100) – CIE L*a*b* colourspace array of the colour standard under the test illuminant.
Lab_spl_r (Domain100) – CIE L*a*b* colourspace array of the colour sample under the reference illuminant.
Lab_std_r (Domain100) – CIE L*a*b* colourspace array of the colour standard under the reference illuminant.
correction (Literal['Additive', 'Multiplicative'] | str) – Correction method to apply, either 'Additive' or 'Multiplicative'.
method (LiteralDeltaEMethod | str) – Colour-difference method.
additional_data (bool) – Whether to output additional data.
c – {colour.difference.delta_E_CMC()}, Chroma weighting factor.
l – {colour.difference.delta_E_CMC()}, Lightness weighting factor.
textiles – {colour.difference.delta_E_CIE1994(), colour.difference.delta_E_CIE2000(), colour.difference.delta_E_DIN99()}, Textiles application specific parametric factors \(k_L=2,\ k_C=k_H=1,\ k_1=0.048,\ k_2=0.014,\ k_E=2,\ k_{CH}=0.5\) weights are used instead of \(k_L=k_C=k_H=1,\ k_1=0.045,\ k_2=0.015,\ k_E=k_{CH}=1.0\).
kwargs (Any)

Returns:

Metamerism index \(M_{t}\).

Return type:

numpy.ndarray or DeltaE_Specification

Notes

Domain	Scale - Reference	Scale - 1
`Lab_spl_t`	100	1
`Lab_std_t`	100	1
`Lab_spl_r`	100	1
`Lab_std_r`	100	1

References

[InternationalOfStandardization24]

Examples

>>> import numpy as np
>>> Lab_std_r = np.array([39.0908, -21.3269, 22.6657])
>>> Lab_std_t = np.array([38.17781, -17.4939, 21.0618])
>>> Lab_spl_r = np.array([38.83253, -19.8787, 20.0453])
>>> Lab_spl_t = np.array([37.9013, -19.56327, 16.9346])
>>> Lab_to_metamerism_index(
...     Lab_spl_t,
...     Lab_std_t,
...     Lab_spl_r,
...     Lab_std_r,
...     correction="Additive",
...     method="CIE 1976",
... )
np.float64(3.8267581...)
>>> Lab_to_metamerism_index(
...     Lab_spl_t,
...     Lab_std_t,
...     Lab_spl_r,
...     Lab_std_r,
...     correction="Multiplicative",
...     method="CIE 1976",
... )
np.float64(3.9842216...)

colour.difference.Lab_to_metamerism_index#

This Page