Skip to content

Commit

Permalink
Add colour.difference.delta_e.intermediate_attributes_CIE2000 defin…
Browse files Browse the repository at this point in the history 
…ition.

References #1307.
  • Loading branch information
@KelSolaar
KelSolaar committed Nov 9, 2024
1 parent a685619 commit 37de33b
Show file tree
Hide file tree
Showing 2 changed files with 174 additions and 51 deletions.
192 changes: 141 additions & 51 deletions colour/difference/delta_e.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -45,11 +45,19 @@

from __future__ import annotations

from dataclasses import astuple, dataclass, field

import numpy as np

from colour.algebra import euclidean_distance
from colour.hints import ArrayLike, NDArrayFloat
from colour.utilities import as_float, to_domain_100, tsplit, zeros
from colour.utilities import (
MixinDataclassArithmetic,
as_float,
to_domain_100,
tsplit,
zeros,
)
from colour.utilities.documentation import (
DocstringFloat,
is_documentation_building,
Expand All @@ -66,6 +74,7 @@
"JND_CIE1976",
"delta_E_CIE1976",
"delta_E_CIE1994",
"intermediate_attributes_CIE2000",
"delta_E_CIE2000",
"delta_E_CMC",
"delta_E_ITP",
Expand Down Expand Up @@ -243,60 +252,57 @@ def delta_E_CIE1994(
return as_float(d_E)


def delta_E_CIE2000(
Lab_1: ArrayLike, Lab_2: ArrayLike, textiles: bool = False
) -> NDArrayFloat:
@dataclass
class Attributes_Specification_CIE2000(MixinDataclassArithmetic):
"""
Return the difference :math:`\\Delta E_{00}` between two given
*CIE L\\*a\\*b\\** colourspace arrays using *CIE 2000* recommendation.
Define the *CAM16* colour appearance model specification.
Parameters
----------
J
Correlate of *Lightness* :math:`J`.
C
Correlate of *chroma* :math:`C`.
h
*Hue* angle :math:`h` in degrees.
s
Correlate of *saturation* :math:`s`.
Q
Correlate of *brightness* :math:`Q`.
M
Correlate of *colourfulness* :math:`M`.
H
*Hue* :math:`h` quadrature :math:`H`.
HC
*Hue* :math:`h` composition :math:`H^C`.
"""

S_L: float | NDArrayFloat | None = field(default_factory=lambda: None)
S_C: float | NDArrayFloat | None = field(default_factory=lambda: None)
S_H: float | NDArrayFloat | None = field(default_factory=lambda: None)
delta_L_p: float | NDArrayFloat | None = field(default_factory=lambda: None)
delta_C_p: float | NDArrayFloat | None = field(default_factory=lambda: None)
delta_H_p: float | NDArrayFloat | None = field(default_factory=lambda: None)
R_T: float | NDArrayFloat | None = field(default_factory=lambda: None)


def intermediate_attributes_CIE2000(Lab_1: ArrayLike, Lab_2: ArrayLike) -> NDArrayFloat:
"""
Return the intermediate attributes to compute the difference
:math:`\\Delta E_{00}` between two given *CIE L\\*a\\*b\\** colourspace
arrays using *CIE 2000* recommendation.
Parameters
----------
Lab_1
*CIE L\\*a\\*b\\** colourspace array 1.
Lab_2
*CIE L\\*a\\*b\\** colourspace array 2.
textiles
Textiles application specific parametric factors.
:math:`k_L=2,\\ k_C=k_H=1` weights are used instead of
:math:`k_L=k_C=k_H=1`.
Returns
-------
:class:`numpy.ndarray`
Colour difference :math:`\\Delta E_{00}`.
Notes
-----
+------------+-----------------------+-------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===================+
| ``Lab_1`` | ``L_1`` : [0, 100] | ``L_1`` : [0, 1] |
| | | |
| | ``a_1`` : [-100, 100] | ``a_1`` : [-1, 1] |
| | | |
| | ``b_1`` : [-100, 100] | ``b_1`` : [-1, 1] |
+------------+-----------------------+-------------------+
| ``Lab_2`` | ``L_2`` : [0, 100] | ``L_2`` : [0, 1] |
| | | |
| | ``a_2`` : [-100, 100] | ``a_2`` : [-1, 1] |
| | | |
| | ``b_2`` : [-100, 100] | ``b_2`` : [-1, 1] |
+------------+-----------------------+-------------------+
- Parametric factors :math:`k_L=k_C=k_H=1` weights under
*reference conditions*:
- Illumination: D65 source
- Illuminance: 1000 lx
- Observer: Normal colour vision
- Background field: Uniform, neutral gray with :math:`L^*=50`
- Viewing mode: Object
- Sample size: Greater than 4 degrees
- Sample separation: Direct edge contact
- Sample colour-difference magnitude: Lower than 5.0
:math:`\\Delta E_{00}`
- Sample structure: Homogeneous (without texture)
Intermediate attributes to compute the difference :math:`\\Delta E_{00}`.
References
----------
Expand All @@ -306,19 +312,15 @@ def delta_E_CIE2000(
--------
>>> Lab_1 = np.array([48.99183622, -0.10561667, 400.65619925])
>>> Lab_2 = np.array([50.65907324, -0.11671910, 402.82235718])
>>> delta_E_CIE2000(Lab_1, Lab_2) # doctest: +ELLIPSIS
1.6709303...
>>> delta_E_CIE2000(Lab_1, Lab_2, textiles=True) # doctest: +ELLIPSIS
0.8412338...
>>> intermediate_attributes_CIE2000(Lab_1, Lab_2) # doctest: +ELLIPSIS
Attributes_Specification_CIE2000(S_L=1.0001021..., S_C=19.0782682..., \
S_H=4.7226695..., delta_L_p=1.6672370..., delta_C_p=2.1661609..., \
delta_H_p=0.0105030..., R_T=-3...)
"""

L_1, a_1, b_1 = tsplit(to_domain_100(Lab_1))
L_2, a_2, b_2 = tsplit(to_domain_100(Lab_2))

k_L = 2 if textiles else 1
k_C = 1
k_H = 1

C_1_ab = np.hypot(a_1, b_1)
C_2_ab = np.hypot(a_2, b_2)

Expand Down Expand Up @@ -410,6 +412,94 @@ def delta_E_CIE2000(

R_T = -np.sin(np.deg2rad(2 * delta_theta)) * R_C

return Attributes_Specification_CIE2000(
S_L,
S_C,
S_H,
delta_L_p,
delta_C_p,
delta_H_p,
R_T,
)


def delta_E_CIE2000(
Lab_1: ArrayLike, Lab_2: ArrayLike, textiles: bool = False
) -> NDArrayFloat:
"""
Return the difference :math:`\\Delta E_{00}` between two given
*CIE L\\*a\\*b\\** colourspace arrays using *CIE 2000* recommendation.
Parameters
----------
Lab_1
*CIE L\\*a\\*b\\** colourspace array 1.
Lab_2
*CIE L\\*a\\*b\\** colourspace array 2.
textiles
Textiles application specific parametric factors.
:math:`k_L=2,\\ k_C=k_H=1` weights are used instead of
:math:`k_L=k_C=k_H=1`.
Returns
-------
:class:`numpy.ndarray`
Colour difference :math:`\\Delta E_{00}`.
Notes
-----
+------------+-----------------------+-------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===================+
| ``Lab_1`` | ``L_1`` : [0, 100] | ``L_1`` : [0, 1] |
| | | |
| | ``a_1`` : [-100, 100] | ``a_1`` : [-1, 1] |
| | | |
| | ``b_1`` : [-100, 100] | ``b_1`` : [-1, 1] |
+------------+-----------------------+-------------------+
| ``Lab_2`` | ``L_2`` : [0, 100] | ``L_2`` : [0, 1] |
| | | |
| | ``a_2`` : [-100, 100] | ``a_2`` : [-1, 1] |
| | | |
| | ``b_2`` : [-100, 100] | ``b_2`` : [-1, 1] |
+------------+-----------------------+-------------------+
- Parametric factors :math:`k_L=k_C=k_H=1` weights under
*reference conditions*:
- Illumination: D65 source
- Illuminance: 1000 lx
- Observer: Normal colour vision
- Background field: Uniform, neutral gray with :math:`L^*=50`
- Viewing mode: Object
- Sample size: Greater than 4 degrees
- Sample separation: Direct edge contact
- Sample colour-difference magnitude: Lower than 5.0
:math:`\\Delta E_{00}`
- Sample structure: Homogeneous (without texture)
References
----------
:cite:`Melgosa2013b`, :cite:`Sharma2005b`
Examples
--------
>>> Lab_1 = np.array([48.99183622, -0.10561667, 400.65619925])
>>> Lab_2 = np.array([50.65907324, -0.11671910, 402.82235718])
>>> delta_E_CIE2000(Lab_1, Lab_2) # doctest: +ELLIPSIS
1.6709303...
>>> delta_E_CIE2000(Lab_1, Lab_2, textiles=True) # doctest: +ELLIPSIS
0.8412338...
"""

S_L, S_C, S_H, delta_L_p, delta_C_p, delta_H_p, R_T = astuple(
intermediate_attributes_CIE2000(Lab_1, Lab_2)
)

k_L = 2 if textiles else 1
k_C = 1
k_H = 1

d_E = np.sqrt(
(delta_L_p / (k_L * S_L)) ** 2
+ (delta_C_p / (k_C * S_C)) ** 2
Expand Down
33 changes: 33 additions & 0 deletions colour/difference/tests/test_delta_e.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
delta_E_HyAB,
delta_E_ITP,
)
from colour.difference.delta_e import intermediate_attributes_CIE2000
from colour.utilities import domain_range_scale, ignore_numpy_errors

__author__ = "Colour Developers"
Expand Down Expand Up @@ -225,6 +226,38 @@ def test_nan_delta_E_CIE1994(self):
delta_E_CIE1994(cases, cases)


class TestIntermediateAttributes_CIE2000:
"""
Define :func:`colour.difference.delta_e.intermediate_attributes_CIE2000`
definition unit tests methods.
"""

def test_intermediate_attributes_CIE2000(self):
"""
Test :func:`colour.difference.delta_e.intermediate_attributes_CIE2000`
definition.
"""

np.testing.assert_allclose(
intermediate_attributes_CIE2000(
np.array([48.99183622, -0.10561667, 400.65619925]),
np.array([50.65907324, -0.11671910, 402.82235718]),
),
np.array(
[
1.00010211,
19.07826821,
4.72266955,
1.66723702,
2.16616092,
0.01050306,
-0.00000000,
]
),
atol=TOLERANCE_ABSOLUTE_TESTS,
)


class TestDelta_E_CIE2000:
"""
Define :func:`colour.difference.delta_e.delta_E_CIE2000` definition unit
Expand Down

0 comments on commit 37de33b

Please sign in to comment.