"""
Yrg Colourspace - Kirk (2019)
=============================
Define the *Kirk (2019)* *Yrg* colourspace:
- :func:`colour.models.LMS_to_Yrg`
- :func:`colour.models.Yrg_to_LMS`
- :func:`colour.XYZ_to_Yrg`
- :func:`colour.Yrg_to_XYZ`
References
----------
- :cite:`Kirk2019` : Kirk, R. A. (2019). Chromaticity coordinates for graphic
arts based on CIE 2006 LMS with even spacing of Munsell colours. Color and
Imaging Conference, 27(1), 215-219. doi:10.2352/issn.2169-2629.2019.27.38
"""
from __future__ import annotations
import numpy as np
from colour.algebra import sdiv, sdiv_mode, vecmul
from colour.hints import ArrayLike, NDArrayFloat
from colour.utilities import (
from_range_1,
to_domain_1,
tsplit,
tstack,
)
__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"
__all__ = [
"LMS_to_Yrg",
"Yrg_to_LMS",
"XYZ_to_Yrg",
"Yrg_to_XYZ",
]
MATRIX_XYZ_TO_LMS_KIRK2019: NDArrayFloat = np.array(
[
[0.257085, 0.859943, -0.031061],
[-0.394427, 1.175800, 0.106423],
[0.064856, -0.076250, 0.559067],
]
)
"""
*Kirk (2019)* matrix converting from *CIE XYZ* tristimulus values to *LMS*
colourspace.
"""
MATRIX_LMS_TO_XYZ_KIRK2019: NDArrayFloat = np.linalg.inv(MATRIX_XYZ_TO_LMS_KIRK2019)
"""
*Kirk (2019)* matrix converting from *LMS* colourspace to *CIE XYZ* tristimulus
values.
"""
[docs]
def LMS_to_Yrg(LMS: ArrayLike) -> NDArrayFloat:
"""
Convert from *LMS* colourspace to *Kirk (2019)* *Yrg* colourspace.
Parameters
----------
LMS
*LMS* colourspace values.
Returns
-------
:class:`numpy.ndarray`
*Kirk (2019)* *Yrg* :math:`Yrg` luminance, redness, and greenness.
Notes
-----
+------------+-----------------------+----------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``LMS`` | [0, 100] | [0, 1] |
+------------+-----------------------+----------------+
+------------+-----------------------+----------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``Yrg`` | ``Y`` : [0, 1] | ``Y`` : [0, 1] |
| | | |
| | ``r`` : [0, 1] | ``r`` : [0, 1] |
| | | |
| | ``g`` : [0, 1] | ``g`` : [0, 1] |
+------------+-----------------------+----------------+
References
----------
:cite:`Kirk2019`
Examples
--------
>>> import numpy as np
>>> LMS = np.array([0.15639195, 0.06741689, 0.03281398])
>>> LMS_to_Yrg(LMS) # doctest: +ELLIPSIS
array([ 0.1313780..., 0.4903764..., 0.3777739...])
"""
L, M, S = tsplit(to_domain_1(LMS))
Y = 0.68990272 * L + 0.34832189 * M
a = L + M + S
with sdiv_mode():
l = sdiv(L, a) # noqa: E741
m = sdiv(M, a)
r = 1.0671 * l - 0.6873 * m + 0.02062
g = -0.0362 * l + 1.7182 * m - 0.05155
Yrg = tstack([Y, r, g])
return from_range_1(Yrg)
[docs]
def Yrg_to_LMS(Yrg: ArrayLike) -> NDArrayFloat:
"""
Convert from *Kirk (2019)* *Yrg* colourspace to *LMS* colourspace.
Parameters
----------
Yrg
*Kirk (2019)* *Yrg* :math:`Yrg` luminance, redness, and greenness.
Returns
-------
:class:`numpy.ndarray`
*LMS* colourspace values.
Notes
-----
+------------+-----------------------+----------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``Yrg`` | ``Y`` : [0, 1] | ``Y`` : [0, 1] |
| | | |
| | ``r`` : [0, 1] | ``r`` : [0, 1] |
| | | |
| | ``g`` : [0, 1] | ``g`` : [0, 1] |
+------------+-----------------------+----------------+
+------------+-----------------------+----------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``LMS`` | [0, 100] | [0, 1] |
+------------+-----------------------+----------------+
References
----------
:cite:`Kirk2019`
Examples
--------
>>> import numpy as np
>>> Yrg = np.array([0.13137801, 0.49037644, 0.37777391])
>>> Yrg_to_LMS(Yrg) # doctest: +ELLIPSIS
array([ 0.1563929..., 0.0674150..., 0.0328213...])
"""
Y, r, g = tsplit(to_domain_1(Yrg))
l = 0.95 * r + 0.38 * g # noqa: E741
m = 0.02 * r + 0.59 * g + 0.03
a = Y / (0.68990272 * l + 0.34832189 * m)
L = l * a
M = m * a
S = (1 - l - m) * a
LMS = tstack([L, M, S])
return from_range_1(LMS)
[docs]
def XYZ_to_Yrg(XYZ: ArrayLike) -> NDArrayFloat:
"""
Convert from *CIE XYZ* tristimulus values to *Kirk (2019)* *Yrg*
colourspace.
Parameters
----------
XYZ
*CIE XYZ* tristimulus values values.
Returns
-------
:class:`numpy.ndarray`
*Kirk (2019)* *Yrg* :math:`Yrg` luminance, redness, and greenness.
Notes
-----
+------------+-----------------------+----------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``XYZ`` | [0, 100] | [0, 1] |
+------------+-----------------------+----------------+
+------------+-----------------------+----------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``Yrg`` | ``Y`` : [0, 1] | ``Y`` : [0, 1] |
| | | |
| | ``r`` : [0, 1] | ``r`` : [0, 1] |
| | | |
| | ``g`` : [0, 1] | ``g`` : [0, 1] |
+------------+-----------------------+----------------+
References
----------
:cite:`Kirk2019`
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_Yrg(XYZ) # doctest: +ELLIPSIS
array([ 0.1313780..., 0.4903764..., 0.3777738...])
"""
return LMS_to_Yrg(vecmul(MATRIX_XYZ_TO_LMS_KIRK2019, XYZ))
[docs]
def Yrg_to_XYZ(Yrg: ArrayLike) -> NDArrayFloat:
"""
Convert from *Kirk (2019)* *Yrg* colourspace to *CIE XYZ* tristimulus values.
Parameters
----------
Yrg
*Kirk (2019)* *Yrg* :math:`Yrg` luminance, redness, and greenness.
Returns
-------
:class:`numpy.ndarray`
*CIE XYZ* tristimulus values values.
Notes
-----
+------------+-----------------------+----------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``Yrg`` | ``Y`` : [0, 1] | ``Y`` : [0, 1] |
| | | |
| | ``r`` : [0, 1] | ``r`` : [0, 1] |
| | | |
| | ``g`` : [0, 1] | ``g`` : [0, 1] |
+------------+-----------------------+----------------+
+------------+-----------------------+----------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+================+
| ``XYZ`` | [0, 100] | [0, 1] |
+------------+-----------------------+----------------+
References
----------
:cite:`Kirk2019`
Examples
--------
>>> import numpy as np
>>> Yrg = np.array([0.13137801, 0.49037645, 0.37777388])
>>> Yrg_to_XYZ(Yrg) # doctest: +ELLIPSIS
array([ 0.2065468..., 0.1219717..., 0.0513819...])
"""
return vecmul(MATRIX_LMS_TO_XYZ_KIRK2019, Yrg_to_LMS(Yrg))
