# Source code for colormath.color_diff

"""
The functions in this module are used for comparing two LabColor objects
using various Delta E formulas.
"""

import numpy

from colormath import color_diff_matrix

def _get_lab_color1_vector(color):
"""
Converts an LabColor into a NumPy vector.

:param LabColor color:
:rtype: numpy.ndarray
"""
if not color.__class__.__name__ == 'LabColor':
raise ValueError(
"Delta E functions can only be used with two LabColor objects.")
return numpy.array([color.lab_l, color.lab_a, color.lab_b])

def _get_lab_color2_matrix(color):
"""
Converts an LabColor into a NumPy matrix.

:param LabColor color:
:rtype: numpy.ndarray
"""
if not color.__class__.__name__ == 'LabColor':
raise ValueError(
"Delta E functions can only be used with two LabColor objects.")
return numpy.array([(color.lab_l, color.lab_a, color.lab_b)])

# noinspection PyPep8Naming
[docs]def delta_e_cie1976(color1, color2):
"""
Calculates the Delta E (CIE1976) of two colors.
"""
color1_vector = _get_lab_color1_vector(color1)
color2_matrix = _get_lab_color2_matrix(color2)
delta_e = color_diff_matrix.delta_e_cie1976(color1_vector, color2_matrix)[0]
return numpy.asscalar(delta_e)

# noinspection PyPep8Naming
[docs]def delta_e_cie1994(color1, color2, K_L=1, K_C=1, K_H=1, K_1=0.045, K_2=0.015):
"""
Calculates the Delta E (CIE1994) of two colors.

K_l:
0.045 graphic arts
0.048 textiles
K_2:
0.015 graphic arts
0.014 textiles
K_L:
1 default
2 textiles
"""
color1_vector = _get_lab_color1_vector(color1)
color2_matrix = _get_lab_color2_matrix(color2)
delta_e = color_diff_matrix.delta_e_cie1994(
color1_vector, color2_matrix, K_L=K_L, K_C=K_C, K_H=K_H, K_1=K_1, K_2=K_2)[0]
return numpy.asscalar(delta_e)

# noinspection PyPep8Naming
[docs]def delta_e_cie2000(color1, color2, Kl=1, Kc=1, Kh=1):
"""
Calculates the Delta E (CIE2000) of two colors.
"""
color1_vector = _get_lab_color1_vector(color1)
color2_matrix = _get_lab_color2_matrix(color2)
delta_e = color_diff_matrix.delta_e_cie2000(
color1_vector, color2_matrix, Kl=Kl, Kc=Kc, Kh=Kh)[0]
return numpy.asscalar(delta_e)

# noinspection PyPep8Naming
[docs]def delta_e_cmc(color1, color2, pl=2, pc=1):
"""
Calculates the Delta E (CMC) of two colors.

CMC values
Acceptability: pl=2, pc=1
Perceptability: pl=1, pc=1
"""
color1_vector = _get_lab_color1_vector(color1)
color2_matrix = _get_lab_color2_matrix(color2)
delta_e = color_diff_matrix.delta_e_cmc(
color1_vector, color2_matrix, pl=pl, pc=pc)[0]
return numpy.asscalar(delta_e)