colour.difference.delta_E_CIE1994

colour.difference.delta_E_CIE1994(Lab_1, Lab_2, textiles=False)[source]

Returns the difference \(\Delta E_{94}\) between two given CIE L*a*b* colourspace arrays using CIE 1994 recommendation.

Parameters:
  • Lab_1 (array_like) – CIE L*a*b* colourspace array 1.
  • Lab_2 (array_like) – CIE L*a*b* colourspace array 2.
  • textiles (bool, optional) – Textiles application specific parametric factors \(k_L=2,\ k_C=k_H=1,\ k_1=0.048,\ k_2=0.014\) weights are used instead of \(k_L=k_C=k_H=1,\ k_1=0.045,\ k_2=0.015\).
Returns:

Colour difference \(\Delta E_{94}\).

Return type:

numeric or 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]

  • CIE 1994 colour differences are not symmetrical: difference between Lab_1 and Lab_2 may not be the same as difference between Lab_2 and Lab_1 thus one colour must be understood to be the reference against which a sample colour is compared.

References

[Lindbloom2011a]

Examples

>>> Lab_1 = np.array([100.00000000, 21.57210357, 272.22819350])
>>> Lab_2 = np.array([100.00000000, 426.67945353, 72.39590835])
>>> delta_E_CIE1994(Lab_1, Lab_2)  # doctest: +ELLIPSIS
83.7792255...
>>> delta_E_CIE1994(Lab_1, Lab_2, textiles=True)  # doctest: +ELLIPSIS
88.3355530...