Source code for colour.difference.din99
"""
:math:`\\Delta E_{99}` DIN99 - Colour Difference Formula
========================================================
Define the :math:`\\Delta E_{99}` *DIN99* colour difference formula:
- :func:`colour.difference.delta_E_DIN99`
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
"""
from __future__ import annotations
from colour.algebra import euclidean_distance
from colour.hints import ArrayLike, NDArrayFloat
from colour.models import Lab_to_DIN99
from colour.utilities import get_domain_range_scale
__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__ = [
"delta_E_DIN99",
]
[docs]
def delta_E_DIN99(
Lab_1: ArrayLike, Lab_2: ArrayLike, textiles: bool = False
) -> NDArrayFloat:
"""
Return the difference :math:`\\Delta E_{DIN99}` between two given
*CIE L\\*a\\*b\\** colourspace arrays using *DIN99* formula.
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_E=2,\\ k_{CH}=0.5` weights are used instead of
:math:`k_E=1,\\ k_{CH}=1`.
Returns
-------
:class:`numpy.ndarray`
Colour difference :math:`\\Delta E_{DIN99}`.
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] |
+------------+-----------------------+-------------------+
References
----------
:cite:`ASTMInternational2007`
Examples
--------
>>> import numpy as np
>>> Lab_1 = np.array([60.2574, -34.0099, 36.2677])
>>> Lab_2 = np.array([60.4626, -34.1751, 39.4387])
>>> delta_E_DIN99(Lab_1, Lab_2) # doctest: +ELLIPSIS
1.1772166...
"""
k_E = 2 if textiles else 1
k_CH = 0.5 if textiles else 1
factor = 100 if get_domain_range_scale() == "1" else 1
d_E = euclidean_distance(
Lab_to_DIN99(Lab_1, k_E, k_CH) * factor,
Lab_to_DIN99(Lab_2, k_E, k_CH) * factor,
)
return d_E
