colour.difference.delta_E_CMC

colour.difference.delta_E_CMC(Lab_1: ArrayLike, Lab_2: ArrayLike, l: float = 2, c: float = 1) → NDArrayFloat

Return the difference \(\Delta E_{CMC}\) between two given CIE L*a*b* colourspace arrays using Colour Measurement Committee recommendation.

The quasimetric has two parameters: Lightness (l) and chroma (c), allowing the users to weight the difference based on the ratio of l:c. Commonly used values are 2:1 for acceptability and 1:1 for the threshold of imperceptibility.

Parameters:

• Lab_1 (ArrayLike) – CIE L*a*b* colourspace array 1.

• Lab_2 (ArrayLike) – CIE L*a*b* colourspace array 2.

• l (float) – Lightness weighting factor.

• c (float) – Chroma weighting factor.

Returns:

Colour difference \(\Delta E_{CMC}\).

Return type:

numpy.ndarray

Notes

Domain	Scale - Reference	Scale - 1
Lab_1	L_1 : [0, 100] a_1 : [-100, 100] b_1 : [-100, 100]	L_1 : [0, 1] a_1 : [-1, 1] b_1 : [-1, 1]
Lab_2	L_2 : [0, 100] a_2 : [-100, 100] b_2 : [-100, 100]	L_2 : [0, 1] a_2 : [-1, 1] b_2 : [-1, 1]

References

[Lin09b]

Examples

>>> Lab_1 = np.array([48.99183622, -0.10561667, 400.65619925])
>>> Lab_2 = np.array([50.65907324, -0.11671910, 402.82235718])
>>> delta_E_CMC(Lab_1, Lab_2)  
0.8996999...