"""
DIN99 Colourspace and DIN99b, DIN99c, DIN99d Refined Formulas
=============================================================
Defines the *DIN99* colourspace and *DIN99b*, *DIN99c*, *DIN99d* refined
formulas transformations:
- :func:`colour.Lab_to_DIN99`
- :func:`colour.DIN99_to_Lab`
- :func:`colour.XYZ_to_DIN99`
- :func:`colour.DIN99_to_XYZ`
References
----------
- :cite:`ASTMInternational2007` : ASTM International. (2007). ASTM D2244-07 -
Standard Practice for Calculation of Color Tolerances and Color Differences
from Instrumentally Measured Color Coordinates: Vol. i (pp. 1-10).
doi:10.1520/D2244-16
- :cite:`Cui2002` : Cui, G., Luo, M. R., Rigg, B., Roesler, G., & Witt, K.
(2002). Uniform colour spaces based on the DIN99 colour-difference formula.
Color Research & Application, 27(4), 282-290. doi:10.1002/col.10066
"""
from __future__ import annotations
import numpy as np
from colour.algebra import spow
from colour.colorimetry import CCS_ILLUMINANTS
from colour.hints import ArrayLike, Floating, Literal, NDArray, Union
from colour.models import Lab_to_XYZ, XYZ_to_Lab
from colour.utilities import (
CaseInsensitiveMapping,
from_range_100,
tsplit,
tstack,
to_domain_100,
validate_method,
)
__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "New BSD License - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"
__all__ = [
"DIN99_METHODS",
"Lab_to_DIN99",
"DIN99_to_Lab",
"XYZ_to_DIN99",
"DIN99_to_XYZ",
]
DIN99_METHODS: CaseInsensitiveMapping = CaseInsensitiveMapping(
{
"ASTMD2244-07": np.array(
[105.509, 0.0158, 16.0, 0.7, 1, 9 / 200, 0.0, 9 / 200]
),
"DIN99": np.array(
[105.509, 0.0158, 16.0, 0.7, 1, 9 / 200, 0.0, 9 / 200]
),
"DIN99b": np.array([303.67, 0.0039, 26.0, 0.83, 23.0, 0.075, 26.0, 1]),
"DIN99c": np.array([317.65, 0.0037, 0.0, 0.94, 23.0, 0.066, 0.0, 1]),
"DIN99d": np.array([325.22, 0.0036, 50.0, 1.14, 22.5, 0.06, 50.0, 1]),
}
)
"""
*DIN99* colourspace methods, i.e. the coefficients for the *DIN99b*, *DIN99c*,
and *DIN99d* refined formulas according to *Cui et al. (2002)*.
References
----------
:cite:`ASTMInternational2007`, :cite:`Cui2002`
"""
[docs]def Lab_to_DIN99(
Lab: ArrayLike,
k_E: Floating = 1,
k_CH: Floating = 1,
method: Union[
Literal["ASTMD2244-07", "DIN99", "DIN99b", "DIN99c", "DIN99d"], str
] = "DIN99",
) -> NDArray:
"""
Convert from *CIE L\\*a\\*b\\** colourspace to *DIN99* colourspace or
one of the *DIN99b*, *DIN99c*, *DIN99d* refined formulas according
to *Cui et al. (2002)*.
Parameters
----------
Lab
*CIE L\\*a\\*b\\** colourspace array.
k_E
Parametric factor :math:`K_E` used to compensate for texture and other
specimen presentation effects.
k_CH
Parametric factor :math:`K_{CH}` used to compensate for texture and
other specimen presentation effects.
method
Computation method to choose between the :cite:`ASTMInternational2007`
formula and the refined formulas according to *Cui et al. (2002)*.
Returns
-------
:class:`numpy.ndarray`
*DIN99* colourspace array.
Notes
-----
+------------+------------------------+--------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+========================+====================+
| ``Lab`` | ``L`` : [0, 100] | ``L`` : [0, 1] |
| | | |
| | ``a`` : [-100, 100] | ``a`` : [-1, 1] |
| | | |
| | ``b`` : [-100, 100] | ``b`` : [-1, 1] |
+------------+------------------------+--------------------+
+------------+------------------------+--------------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+========================+====================+
| ``Lab_99`` | ``L_99`` : [0, 100] | ``L_99`` : [0, 1] |
| | | |
| | ``a_99`` : [-100, 100] | ``a_99`` : [-1, 1] |
| | | |
| | ``b_99`` : [-100, 100] | ``b_99`` : [-1, 1] |
+------------+------------------------+--------------------+
References
----------
:cite:`ASTMInternational2007`, :cite:`Cui2002`
Examples
--------
>>> import numpy as np
>>> Lab = np.array([41.52787529, 52.63858304, 26.92317922])
>>> Lab_to_DIN99(Lab) # doctest: +ELLIPSIS
array([ 53.2282198..., 28.4163465..., 3.8983955...])
"""
c_1, c_2, c_3, c_4, c_5, c_6, c_7, c_8 = DIN99_METHODS[
validate_method(str(method), DIN99_METHODS)
]
L, a, b = tsplit(to_domain_100(Lab))
cos_c = np.cos(np.radians(c_3))
sin_c = np.sin(np.radians(c_3))
e = cos_c * a + sin_c * b
f = c_4 * (-sin_c * a + cos_c * b)
G = spow(e**2 + f**2, 0.5)
h_ef = np.arctan2(f, e) + np.radians(c_7)
C_99 = c_5 * (np.log1p(c_6 * G)) / (c_8 * k_CH * k_E)
# Hue angle is unused currently.
# h_99 = np.degrees(h_ef)
a_99 = C_99 * np.cos(h_ef)
b_99 = C_99 * np.sin(h_ef)
L_99 = c_1 * (np.log1p(c_2 * L)) * k_E
Lab_99 = tstack([L_99, a_99, b_99])
return from_range_100(Lab_99)
[docs]def DIN99_to_Lab(
Lab_99: ArrayLike,
k_E: Floating = 1,
k_CH: Floating = 1,
method: Union[
Literal["ASTMD2244-07", "DIN99", "DIN99b", "DIN99c", "DIN99d"], str
] = "DIN99",
) -> NDArray:
"""
Convert from *DIN99* colourspace or one of the *DIN99b*, *DIN99c*,
*DIN99d* refined formulas according to *Cui et al. (2002)* to
*CIE L\\*a\\*b\\** colourspace.
Parameters
----------
Lab_99
*DIN99* colourspace array.
k_E
Parametric factor :math:`K_E` used to compensate for texture and other
specimen presentation effects.
k_CH
Parametric factor :math:`K_{CH}` used to compensate for texture and
other specimen presentation effects.
method
Computation method to choose between the :cite:`ASTMInternational2007`
formula and the refined formulas according to *Cui et al. (2002)*.
Returns
-------
:class:`numpy.ndarray`
*CIE L\\*a\\*b\\** colourspace array.
Notes
-----
+------------+------------------------+--------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+========================+====================+
| ``Lab_99`` | ``L_99`` : [0, 100] | ``L_99`` : [0, 1] |
| | | |
| | ``a_99`` : [-100, 100] | ``a_99`` : [-1, 1] |
| | | |
| | ``b_99`` : [-100, 100] | ``b_99`` : [-1, 1] |
+------------+------------------------+--------------------+
+------------+------------------------+--------------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+========================+====================+
| ``Lab`` | ``L`` : [0, 100] | ``L`` : [0, 1] |
| | | |
| | ``a`` : [-100, 100] | ``a`` : [-1, 1] |
| | | |
| | ``b`` : [-100, 100] | ``b`` : [-1, 1] |
+------------+------------------------+--------------------+
References
----------
:cite:`ASTMInternational2007`, :cite:`Cui2002`
Examples
--------
>>> import numpy as np
>>> Lab_99 = np.array([53.22821988, 28.41634656, 3.89839552])
>>> DIN99_to_Lab(Lab_99) # doctest: +ELLIPSIS
array([ 41.5278752..., 52.6385830..., 26.9231792...])
"""
c_1, c_2, c_3, c_4, c_5, c_6, c_7, c_8 = DIN99_METHODS[
validate_method(str(method), DIN99_METHODS)
]
L_99, a_99, b_99 = tsplit(to_domain_100(Lab_99))
cos = np.cos(np.radians(c_3))
sin = np.sin(np.radians(c_3))
h_99 = np.arctan2(b_99, a_99) - np.radians(c_7)
C_99 = np.sqrt(a_99**2 + b_99**2)
G = np.expm1((c_8 / c_5) * (C_99) * k_CH * k_E) / c_6
e = G * np.cos(h_99)
f = G * np.sin(h_99)
a = e * cos - (f / c_4) * sin
b = e * sin + (f / c_4) * cos
L = np.expm1(L_99 * k_E / c_1) / c_2
Lab = tstack([L, a, b])
return from_range_100(Lab)
[docs]def XYZ_to_DIN99(
XYZ: ArrayLike,
illuminant: ArrayLike = CCS_ILLUMINANTS[
"CIE 1931 2 Degree Standard Observer"
]["D65"],
k_E: Floating = 1,
k_CH: Floating = 1,
method: Union[
Literal["ASTMD2244-07", "DIN99", "DIN99b", "DIN99c", "DIN99d"], str
] = "DIN99",
) -> NDArray:
"""
Convert from *CIE XYZ* tristimulus values to *DIN99* colourspace or
one of the *DIN99b*, *DIN99c*, *DIN99d* refined formulas according
to *Cui et al. (2002)*.
Parameters
----------
XYZ
*CIE XYZ* tristimulus values.
illuminant
Reference *illuminant* *CIE xy* chromaticity coordinates or *CIE xyY*
colourspace array.
k_E
Parametric factor :math:`K_E` used to compensate for texture and other
specimen presentation effects.
k_CH
Parametric factor :math:`K_{CH}` used to compensate for texture and
other specimen presentation effects.
method
Computation method to choose between the :cite:`ASTMInternational2007`
formula and the refined formulas according to *Cui et al. (2002)*.
Returns
-------
:class:`numpy.ndarray`
*DIN99* colourspace array.
Notes
-----
+----------------+-----------------------+-----------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+================+=======================+=================+
| ``XYZ`` | [0, 1] | [0, 1] |
+----------------+-----------------------+-----------------+
| ``illuminant`` | [0, 1] | [0, 1] |
+----------------+-----------------------+-----------------+
+------------+------------------------+--------------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+========================+====================+
| ``Lab_99`` | ``L_99`` : [0, 100] | ``L_99`` : [0, 1] |
| | | |
| | ``a_99`` : [-100, 100] | ``a_99`` : [-1, 1] |
| | | |
| | ``b_99`` : [-100, 100] | ``b_99`` : [-1, 1] |
+------------+------------------------+--------------------+
References
----------
:cite:`ASTMInternational2007`
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_DIN99(XYZ) # doctest: +ELLIPSIS
array([ 53.2282198..., 28.4163465..., 3.8983955...])
"""
Lab = XYZ_to_Lab(XYZ, illuminant)
return Lab_to_DIN99(Lab, k_E, k_CH, method)
[docs]def DIN99_to_XYZ(
Lab_99: ArrayLike,
illuminant: ArrayLike = CCS_ILLUMINANTS[
"CIE 1931 2 Degree Standard Observer"
]["D65"],
k_E: Floating = 1,
k_CH: Floating = 1,
method: Union[
Literal["ASTMD2244-07", "DIN99", "DIN99b", "DIN99c", "DIN99d"], str
] = "DIN99",
) -> NDArray:
"""
Convert from *DIN99* colourspace or one of the *DIN99b*, *DIN99c*,
*DIN99d* refined formulas according to *Cui et al. (2002)* to *CIE XYZ*
tristimulus values.
Parameters
----------
Lab_99
*DIN99* colourspace array.
illuminant
Reference *illuminant* *CIE xy* chromaticity coordinates or *CIE xyY*
colourspace array.
k_E
Parametric factor :math:`K_E` used to compensate for texture and other
specimen presentation effects.
k_CH
Parametric factor :math:`K_{CH}` used to compensate for texture and
other specimen presentation effects.
method
Computation method to choose between the :cite:`ASTMInternational2007`
formula and the refined formulas according to *Cui et al. (2002)*.
Returns
-------
:class:`numpy.ndarray`
*CIE XYZ* tristimulus values.
Notes
-----
+----------------+------------------------+--------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+================+========================+====================+
| ``Lab_99`` | ``L_99`` : [0, 100] | ``L_99`` : [0, 1] |
| | | |
| | ``a_99`` : [-100, 100] | ``a_99`` : [-1, 1] |
| | | |
| | ``b_99`` : [-100, 100] | ``b_99`` : [-1, 1] |
+----------------+------------------------+--------------------+
| ``illuminant`` | [0, 1] | [0, 1] |
+----------------+------------------------+--------------------+
+----------------+-----------------------+---------------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+================+=======================+=====================+
| ``XYZ`` | [0, 1] | [0, 1] |
+----------------+-----------------------+---------------------+
References
----------
:cite:`ASTMInternational2007`
Examples
--------
>>> import numpy as np
>>> Lab_99 = np.array([53.22821989, 28.41634656, 3.89839552])
>>> DIN99_to_XYZ(Lab_99) # doctest: +ELLIPSIS
array([ 0.2065400..., 0.1219722..., 0.0513695...])
"""
Lab = DIN99_to_Lab(Lab_99, k_E, k_CH, method)
return Lab_to_XYZ(Lab, illuminant)