"""
Huang et al. (2015) Power-Functions
===================================
Define the *Huang, Cui, Melgosa, Sanchez-Maranon, Li, Luo and Liu (2015)*
power-functions improving the performance of colour-difference formulas:
- :func:`colour.difference.power_function_Huang2015`
References
----------
- :cite:`Huang2015` : Huang, M., Cui, G., Melgosa, M., Sanchez-Maranon, M.,
Li, C., Luo, M. R., & Liu, H. (2015). Power functions improving the
performance of color-difference formulas. Optical Society of America,
23(1), 597-610. doi:10.1364/OE.23.000597
- :cite:`Li2017` : Li, C., Li, Z., Wang, Z., Xu, Y., Luo, M. R., Cui, G.,
Melgosa, M., Brill, M. H., & Pointer, M. (2017). Comprehensive color
solutions: CAM16, CAT16, and CAM16-UCS. Color Research & Application,
42(6), 703-718. doi:10.1002/col.22131
"""
from __future__ import annotations
import typing
import numpy as np
if typing.TYPE_CHECKING:
from colour.hints import ArrayLike, Literal, NDArrayFloat
from colour.utilities import CanonicalMapping, tsplit, validate_method
__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__ = [
"power_function_Huang2015",
]
COEFFICIENTS_HUANG2015: CanonicalMapping = CanonicalMapping(
{
"CIE 1976": np.array([1.26, 0.55]),
"CIE 1994": np.array([1.41, 0.70]),
"CIE 2000": np.array([1.43, 0.70]),
"CMC": np.array([1.34, 0.66]),
"CAM02-LCD": np.array([1.00, 0.85]),
"CAM02-SCD": np.array([1.45, 0.75]),
"CAM02-UCS": np.array([1.30, 0.75]),
"CAM16-UCS": np.array([1.41, 0.63]),
"DIN99d": np.array([1.28, 0.74]),
"OSA": np.array([3.32, 0.62]),
"OSA-GP-Euclidean": np.array([1.52, 0.76]),
"ULAB": np.array([1.17, 0.69]),
}
)
COEFFICIENTS_HUANG2015.__doc__ = """
*Huang et al. (2015)* power-functions coefficients.
References
----------
:cite:`Huang2015`, :cite:`Li2017`
Notes
-----
- :cite:`Li2017` does not give the coefficients for the *CAM16-LCD* and
*CAM16-SCD* colourspaces. *Ronnie Luo* has been contacted to know if they
have been computed.
Aliases:
- 'cie1976': 'CIE 1976'
- 'cie1994': 'CIE 1994'
- 'cie2000': 'CIE 2000'
"""
COEFFICIENTS_HUANG2015["cie1976"] = COEFFICIENTS_HUANG2015["CIE 1976"]
COEFFICIENTS_HUANG2015["cie1994"] = COEFFICIENTS_HUANG2015["CIE 1994"]
COEFFICIENTS_HUANG2015["cie2000"] = COEFFICIENTS_HUANG2015["CIE 2000"]
[docs]
def power_function_Huang2015(
d_E: ArrayLike,
coefficients: (
Literal[
"CIE 1976",
"CIE 1994",
"CIE 2000",
"CMC",
"CAM02-LCD",
"CAM02-SCD",
"CAM16-UCS",
"DIN99d",
"OSA",
"OSA-GP-Euclidean",
"ULAB",
]
| str
) = "CIE 2000",
) -> NDArrayFloat:
"""
Improve the performance of the :math:`\\Delta E` value for given
coefficients using
*Huang, Cui, Melgosa, Sanchez-Maranon, Li, Luo and Liu (2015)*
power-function: :math:`d_E^{\\prime}=a*d_{E^b}`.
Parameters
----------
d_E
Computed colour difference array :math:`\\Delta E`.
coefficients
Coefficients for the power-function.
Returns
-------
:class:`numpy.ndarray`
Improved math:`\\Delta E` value.
References
----------
:cite:`Huang2015`, :cite:`Li2017`
Examples
--------
>>> d_E = np.array([2.0425, 2.8615, 3.4412])
>>> power_function_Huang2015(d_E) # doctest: +ELLIPSIS
array([ 2.3574879..., 2.9850503..., 3.3965106...])
"""
coefficients = validate_method(
coefficients,
tuple(COEFFICIENTS_HUANG2015),
'"{0}" coefficients are invalid, they must be one of {1}!',
)
a, b = tsplit(COEFFICIENTS_HUANG2015[coefficients])
return a * d_E**b
