#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
:math:`\Delta E'` - Delta E Colour Difference - Luo, Cui and Li (2006)
======================================================================
Defines :math:`\Delta E'` colour difference computation objects based on
*Luo et al. (2006)* *CAM02-LCD*, *CAM02-SCD*, and *CAM02-UCS* colourspaces:
The following objects are available:
- :func:`delta_E_CAM02LCD`
- :func:`delta_E_CAM02SCD`
- :func:`delta_E_CAM02UCS`
See Also
--------
`CAM02-LCD, CAM02-SCD, and CAM02-UCS Colourspaces Jupyter Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/models/ucs_luo2006.ipynb>`_
References
----------
.. [1] Luo, R. M., Cui, G., & Li, C. (2006). Uniform Colour Spaces Based on
CIECAM02 Colour Appearance Model. Color Research and Application,
31(4), 320–330. doi:10.1002/col.20227
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.utilities import tsplit
from colour.models.ucs_luo2006 import COEFFICIENTS_UCS_LUO2006
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2017 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = [
'delta_E_Luo2006', 'delta_E_CAM02LCD', 'delta_E_CAM02SCD',
'delta_E_CAM02UCS'
]
[docs]def delta_E_Luo2006(Jpapbp_1, Jpapbp_2, coefficients):
"""
Returns the difference :math:`\Delta E'` between two given
*Luo et al. (2006)* *CAM02-LCD*, *CAM02-SCD*, or *CAM02-UCS* colourspaces
:math:`J'a'b'` arrays.
Parameters
----------
Jpapbp_1 : array_like
Standard / reference *Luo et al.* (2006) *CAM02-LCD*, *CAM02-SCD*, or
*CAM02-UCS* colourspaces :math:`J'a'b'` array.
Jpapbp_2 : array_like
Sample / test *Luo et al. (2006)* *CAM02-LCD*, *CAM02-SCD*, or
*CAM02-UCS* colourspaces :math:`J'a'b'` array.
coefficients : array_like
Coefficients of one of the *Luo et al. (2006)* *CAM02-LCD*,
*CAM02-SCD*, or *CAM02-UCS* colourspaces.
Returns
-------
numeric or ndarray
Colour difference :math:`\Delta E'`.
Examples
--------
>>> Jpapbp_1 = np.array([54.90433134, -0.08450395, -0.06854831])
>>> Jpapbp_2 = np.array([54.90433134, -0.08442362, -0.06848314])
>>> delta_E_Luo2006( # doctest: +ELLIPSIS
... Jpapbp_1, Jpapbp_2, COEFFICIENTS_UCS_LUO2006['CAM02-LCD'])
0.0001034...
"""
J_p_1, a_p_1, b_p_1 = tsplit(Jpapbp_1)
J_p_2, a_p_2, b_p_2 = tsplit(Jpapbp_2)
K_L, c_1_, c_2_ = tsplit(coefficients)
d_E = np.sqrt(((J_p_1 - J_p_2) / K_L) ** 2 + (a_p_1 - a_p_2) ** 2 +
(b_p_1 - b_p_2) ** 2)
return d_E
[docs]def delta_E_CAM02LCD(Jpapbp_1, Jpapbp_2):
"""
Returns the difference :math:`\Delta E'` between two given
*Luo et al. (2006)* *CAM02-LCD* colourspaces :math:`J'a'b'` arrays.
Parameters
----------
Jpapbp_1 : array_like
Standard / reference *Luo et al.* (2006) *CAM02-LCD* colourspaces
:math:`J'a'b'` array.
Jpapbp_2 : array_like
Sample / test *Luo et al.* (2006) *CAM02-LCD* colourspaces
:math:`J'a'b'` array.
Returns
-------
numeric or ndarray
Colour difference :math:`\Delta E'`.
Examples
--------
>>> Jpapbp_1 = np.array([54.90433134, -0.08450395, -0.06854831])
>>> Jpapbp_2 = np.array([54.90433134, -0.08442362, -0.06848314])
>>> delta_E_CAM02LCD(Jpapbp_1, Jpapbp_2) # doctest: +ELLIPSIS
0.0001034...
"""
return delta_E_Luo2006(Jpapbp_1, Jpapbp_2,
COEFFICIENTS_UCS_LUO2006['CAM02-LCD'])
[docs]def delta_E_CAM02SCD(Jpapbp_1, Jpapbp_2):
"""
Returns the difference :math:`\Delta E'` between two given
*Luo et al. (2006)* *CAM02-SCD* colourspaces :math:`J'a'b'` arrays.
Parameters
----------
Jpapbp_1 : array_like
Standard / reference *Luo et al.* (2006) *CAM02-SCD* colourspaces
:math:`J'a'b'` array.
Jpapbp_2 : array_like
Sample / test *Luo et al.* (2006) *CAM02-SCD* colourspaces
:math:`J'a'b'` array.
Returns
-------
numeric or ndarray
Colour difference :math:`\Delta E'`.
Examples
--------
>>> Jpapbp_1 = np.array([54.90433134, -0.08450395, -0.06854831])
>>> Jpapbp_2 = np.array([54.90433134, -0.08442362, -0.06848314])
>>> delta_E_CAM02SCD(Jpapbp_1, Jpapbp_2) # doctest: +ELLIPSIS
0.0001034...
"""
return delta_E_Luo2006(Jpapbp_1, Jpapbp_2,
COEFFICIENTS_UCS_LUO2006['CAM02-SCD'])
[docs]def delta_E_CAM02UCS(Jpapbp_1, Jpapbp_2):
"""
Returns the difference :math:`\Delta E'` between two given
*Luo et al. (2006)* *CAM02-UCS* colourspaces :math:`J'a'b'` arrays.
Parameters
----------
Jpapbp_1 : array_like
Standard / reference *Luo et al.* (2006) *CAM02-UCS* colourspaces
:math:`J'a'b'` array.
Jpapbp_2 : array_like
Sample / test *Luo et al.* (2006) *CAM02-UCS* colourspaces
:math:`J'a'b'` array.
Returns
-------
numeric or ndarray
Colour difference :math:`\Delta E'`.
Examples
--------
>>> Jpapbp_1 = np.array([54.90433134, -0.08450395, -0.06854831])
>>> Jpapbp_2 = np.array([54.90433134, -0.08442362, -0.06848314])
>>> delta_E_CAM02UCS(Jpapbp_1, Jpapbp_2) # doctest: +ELLIPSIS
0.0001034...
"""
return delta_E_Luo2006(Jpapbp_1, Jpapbp_2,
COEFFICIENTS_UCS_LUO2006['CAM02-UCS'])