CIE Lab - Colour Difference

cie_lab_colour_difference.py

import colour

# The two RGB triplets we want to measure the colour difference:
RGB = [(0.26, 0.42, 0.78), (0.25, 0.41, 0.79)]

# The reference illuminant/whitepoint.
D65 = colour.ILLUMINANTS['CIE 1931 2 Degree Standard Observer']['D65']

# Assuming sRGB IEC61966-2.1 encoded colours.
# - sRGB/BT.709 Primaries
# - D65 Whitepoint
# - sRGB OETF
XYZ = colour.sRGB_to_XYZ(RGB)

# Conversion to CIE Lab.
Lab = colour.XYZ_to_Lab(XYZ, D65)
Lab_1, Lab_2 = Lab

# Delta E ab computation.
d_E = {
    'CIE 1976': colour.delta_E_CIE1976(Lab_1, Lab_2),
    'CIE 1994': colour.delta_E_CIE1994(Lab_1, Lab_2),
    'CIE 2000': colour.delta_E_CIE2000(Lab_1, Lab_2)
}

print(d_E)

"""
{
    'CIE 1976': 34.986732014969455,
    'CIE 1994': 15.911944863134869,
    'CIE 2000': 11.722013662850278
}
"""