Source code for colour.characterisation.correction

# -*- coding: utf-8 -*-
"""
Colour Correction
=================

Defines various objects for colour correction, like colour matching two images:

-   :func:`colour.characterisation.augmented_matrix_Cheung2004` : Polynomial
    expansion using *Cheung, Westland, Connah and Ripamonti (2004)* method.
-   :func:`colour.characterisation.polynomial_expansion_Finlayson2015` :
    Polynomial expansion using *Finlayson, MacKiewicz and Hurlbert (2015)*
    method.
-   :func:`colour.characterisation.polynomial_expansion_Vandermonde` :
    Polynomial expansion using *Vandermonde* method.
-   :attr:`colour.POLYNOMIAL_EXPANSION_METHODS`: Supported polynomial expansion
    methods.
-   :func:`colour.polynomial_expansion`: Polynomial expansion of given
    :math:`a` array.
-   :func:`colour.characterisation.colour_correction_matrix_Cheung2004` :
    Colour correction matrix computation using *Cheung et al. (2004)* method.
-   :func:`colour.characterisation.colour_correction_matrix_Finlayson2015` :
    Colour correction matrix computation using *Finlayson et al. (2015)*
    method.
-   :func:`colour.characterisation.colour_correction_matrix_Vandermonde`
    Colour correction matrix computation using *Vandermonde* method.
-   :attr:`colour.COLOUR_CORRECTION_MATRIX_METHODS`: Supported colour
    correction matrix methods.
-   :func:`colour.colour_correction_matrix`: Colour correction matrix
    computation from given :math:`M_T` colour array to :math:`M_R` colour
    array.
-   :func:`colour.characterisation.colour_correction_Cheung2004` :
    Colour correction using *Cheung et al. (2004)* method.
-   :func:`colour.characterisation.colour_correction_Finlayson2015` :
    Colour correction using *Finlayson et al. (2015)* method.
-   :func:`colour.characterisation.colour_correction_Vandermonde` :
    Colour correction using *Vandermonde* method.
-   :attr:`colour.COLOUR_CORRECTION_METHODS`: Supported colour correction
    methods.
-   :func:`colour.colour_correction`: Colour correction of given *RGB*
    colourspace array using the colour correction matrix from given
    :math:`M_T` colour array to :math:`M_R` colour array.

References
----------
-   :cite:`Cheung2004` : Cheung, V., Westland, S., Connah, D., & Ripamonti, C.
    (2004). A comparative study of the characterisation of colour cameras by
    means of neural networks and polynomial transforms. Coloration Technology,
    120(1), 19-25. doi:10.1111/j.1478-4408.2004.tb00201.x
-   :cite:`Finlayson2015` : Finlayson, G. D., MacKiewicz, M., & Hurlbert, A.
    (2015). Color Correction Using Root-Polynomial Regression. IEEE
    Transactions on Image Processing, 24(5), 1460-1470.
    doi:10.1109/TIP.2015.2405336
-   :cite:`Westland2004` : Westland, S., & Ripamonti, C. (2004). Table 8.2. In
    Computational Colour Science Using MATLAB (1st ed., p. 137). John Wiley &
    Sons, Ltd. doi:10.1002/0470020326
-   :cite:`Wikipedia2003e` : Wikipedia. (2003). Vandermonde matrix. Retrieved
    May 2, 2018, from https://en.wikipedia.org/wiki/Vandermonde_matrix
"""

from __future__ import division, unicode_literals

import numpy as np

from colour.algebra import least_square_mapping_MoorePenrose
from colour.utilities import (CaseInsensitiveMapping, as_float_array, as_int,
                              closest, filter_kwargs, ones, tsplit, tstack)

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2020 - 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__ = [
    'augmented_matrix_Cheung2004', 'polynomial_expansion_Finlayson2015',
    'polynomial_expansion_Vandermonde', 'POLYNOMIAL_EXPANSION_METHODS',
    'polynomial_expansion', 'colour_correction_matrix_Cheung2004',
    'colour_correction_matrix_Finlayson2015',
    'colour_correction_matrix_Vandermonde', 'COLOUR_CORRECTION_MATRIX_METHODS',
    'colour_correction_matrix', 'colour_correction_Cheung2004',
    'colour_correction_Finlayson2015', 'colour_correction_Vandermonde',
    'COLOUR_CORRECTION_METHODS', 'colour_correction'
]


[docs]def augmented_matrix_Cheung2004(RGB, terms=3): """ Performs polynomial expansion of given *RGB* colourspace array using *Cheung et al. (2004)* method. Parameters ---------- RGB : array_like *RGB* colourspace array to expand. terms : int, optional Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. Returns ------- ndarray Expanded *RGB* colourspace array. Notes ----- - This definition combines the augmented matrices given in :cite:`Cheung2004` and :cite:`Westland2004`. References ---------- :cite:`Cheung2004`, :cite:`Westland2004` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> augmented_matrix_Cheung2004(RGB, terms=5) # doctest: +ELLIPSIS array([ 0.1722481..., 0.0917066..., 0.0641693..., 0.0010136..., 1...]) """ R, G, B = tsplit(RGB) tail = ones(R.shape) existing_terms = np.array([3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]) closest_terms = as_int(closest(existing_terms, terms)) if closest_terms != terms: raise ValueError('"Cheung et al. (2004)" method does not define ' 'an augmented matrix with {0} terms, ' 'closest augmented matrix has {1} terms!'.format( terms, closest_terms)) if terms == 3: return RGB elif terms == 5: return tstack([R, G, B, R * G * B, tail]) elif terms == 7: return tstack([R, G, B, R * G, R * B, G * B, tail]) elif terms == 8: return tstack([R, G, B, R * G, R * B, G * B, R * G * B, tail]) elif terms == 10: return tstack( [R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, tail]) elif terms == 11: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, tail ]) elif terms == 14: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 3, G ** 3, B ** 3, tail ]) elif terms == 16: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 2 * G, G ** 2 * B, B ** 2 * R, R ** 3, G ** 3, B ** 3 ]) elif terms == 17: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 2 * G, G ** 2 * B, B ** 2 * R, R ** 3, G ** 3, B ** 3, tail ]) elif terms == 19: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 2 * G, G ** 2 * B, B ** 2 * R, R ** 2 * B, G ** 2 * R, B ** 2 * G, R ** 3, G ** 3, B ** 3 ]) elif terms == 20: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 2 * G, G ** 2 * B, B ** 2 * R, R ** 2 * B, G ** 2 * R, B ** 2 * G, R ** 3, G ** 3, B ** 3, tail ]) elif terms == 22: return tstack([ R, G, B, R * G, R * B, G * B, R ** 2, G ** 2, B ** 2, R * G * B, R ** 2 * G, G ** 2 * B, B ** 2 * R, R ** 2 * B, G ** 2 * R, B ** 2 * G, R ** 3, G ** 3, B ** 3, R ** 2 * G * B, R * G ** 2 * B, R * G * B ** 2 ])
[docs]def polynomial_expansion_Finlayson2015(RGB, degree=1, root_polynomial_expansion=True): """ Performs polynomial expansion of given *RGB* colourspace array using *Finlayson et al. (2015)* method. Parameters ---------- RGB : array_like *RGB* colourspace array to expand. degree : int, optional Expanded polynomial degree. root_polynomial_expansion : bool Whether to use the root-polynomials set for the expansion. Returns ------- ndarray Expanded *RGB* colourspace array. References ---------- :cite:`Finlayson2015` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> polynomial_expansion_Finlayson2015(RGB, degree=2) # doctest: +ELLIPSIS array([ 0.1722481..., 0.0917066..., 0.0641693..., 0.1256832..., \ 0.0767121..., 0.1051335...]) """ R, G, B = tsplit(RGB) # TODO: Generalise polynomial expansion. existing_degrees = np.array([1, 2, 3, 4]) closest_degree = as_int(closest(existing_degrees, degree)) if closest_degree != degree: raise ValueError('"Finlayson et al. (2015)" method does not define ' 'a polynomial expansion for {0} degree, ' 'closest polynomial expansion is {1} degree!'.format( degree, closest_degree)) if degree == 1: return RGB elif degree == 2: if root_polynomial_expansion: return tstack([ R, G, B, (R * G) ** (1 / 2), (G * B) ** (1 / 2), (R * B) ** (1 / 2) ]) else: return tstack( [R, G, B, R ** 2, G ** 2, B ** 2, R * G, G * B, R * B]) elif degree == 3: if root_polynomial_expansion: return tstack([ R, G, B, (R * G) ** (1 / 2), (G * B) ** (1 / 2), (R * B) ** (1 / 2), (R * G ** 2) ** (1 / 3), (G * B ** 2) ** (1 / 3), (R * B ** 2) ** (1 / 3), (G * R ** 2) ** (1 / 3), (B * G ** 2) ** (1 / 3), (B * R ** 2) ** (1 / 3), (R * G * B) ** (1 / 3) ]) else: return tstack([ R, G, B, R ** 2, G ** 2, B ** 2, R * G, G * B, R * B, R ** 3, G ** 3, B ** 3, R * G ** 2, G * B ** 2, R * B ** 2, G * R ** 2, B * G ** 2, B * R ** 2, R * G * B ]) elif degree == 4: if root_polynomial_expansion: return tstack([ R, G, B, (R * G) ** (1 / 2), (G * B) ** (1 / 2), (R * B) ** (1 / 2), (R * G ** 2) ** (1 / 3), (G * B ** 2) ** (1 / 3), (R * B ** 2) ** (1 / 3), (G * R ** 2) ** (1 / 3), (B * G ** 2) ** (1 / 3), (B * R ** 2) ** (1 / 3), (R * G * B) ** (1 / 3), (R ** 3 * G) ** (1 / 4), (R ** 3 * B) ** (1 / 4), (G ** 3 * R) ** (1 / 4), (G ** 3 * B) ** (1 / 4), (B ** 3 * R) ** (1 / 4), (B ** 3 * G) ** (1 / 4), (R ** 2 * G * B) ** (1 / 4), (G ** 2 * R * B) ** (1 / 4), (B ** 2 * R * G) ** (1 / 4) ]) else: return tstack([ R, G, B, R ** 2, G ** 2, B ** 2, R * G, G * B, R * B, R ** 3, G ** 3, B ** 3, R * G ** 2, G * B ** 2, R * B ** 2, G * R ** 2, B * G ** 2, B * R ** 2, R * G * B, R ** 4, G ** 4, B ** 4, R ** 3 * G, R ** 3 * B, G ** 3 * R, G ** 3 * B, B ** 3 * R, B ** 3 * G, R ** 2 * G ** 2, G ** 2 * B ** 2, R ** 2 * B ** 2, R ** 2 * G * B, G ** 2 * R * B, B ** 2 * R * G ])
[docs]def polynomial_expansion_Vandermonde(a, degree=1): """ Performs polynomial expansion of given :math:`a` array using *Vandermonde* method. Parameters ---------- a : array_like :math:`a` array to expand. degree : int, optional Expanded polynomial degree. Returns ------- ndarray Expanded :math:`a` array. References ---------- :cite:`Wikipedia2003e` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> polynomial_expansion_Vandermonde(RGB) # doctest: +ELLIPSIS array([ 0.1722481 , 0.0917066 , 0.06416938, 1. ]) """ a = as_float_array(a) a_e = np.transpose(np.vander(np.ravel(a), degree + 1)) a_e = np.hstack(a_e.reshape(a_e.shape[0], -1, 3)) return np.squeeze(a_e[:, 0:a_e.shape[-1] - a.shape[-1] + 1])
POLYNOMIAL_EXPANSION_METHODS = CaseInsensitiveMapping({ 'Cheung 2004': augmented_matrix_Cheung2004, 'Finlayson 2015': polynomial_expansion_Finlayson2015, 'Vandermonde': polynomial_expansion_Vandermonde, }) POLYNOMIAL_EXPANSION_METHODS.__doc__ = """ Supported polynomial expansion methods. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` POLYNOMIAL_EXPANSION_METHODS : CaseInsensitiveMapping **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}** """
[docs]def polynomial_expansion(a, method='Cheung 2004', **kwargs): """ Performs polynomial expansion of given :math:`a` array. Parameters ---------- a : array_like, (3, n) :math:`a` array to expand. method : unicode, optional **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}**, Computation method. Other Parameters ---------------- degree : int {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`, :func:`colour.characterisation.polynomial_expansion_Vandermonde`}, Expanded polynomial degree, must be one of *[1, 2, 3, 4]* for :func:`colour.characterisation.polynomial_expansion_Finlayson2015` definition. terms : int {:func:`colour.characterisation.augmented_matrix_Cheung2004`}, Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. root_polynomial_expansion : bool {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`}, Whether to use the root-polynomials set for the expansion. Returns ------- ndarray, (3, n) Expanded :math:`a` array. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> polynomial_expansion(RGB) # doctest: +ELLIPSIS array([ 0.1722481..., 0.0917066..., 0.0641693...]) >>> polynomial_expansion(RGB, 'Cheung 2004', terms=5) # doctest: +ELLIPSIS array([ 0.1722481..., 0.0917066..., 0.0641693..., 0.0010136..., 1...]) """ function = POLYNOMIAL_EXPANSION_METHODS[method] return function(a, **filter_kwargs(function, **kwargs))
[docs]def colour_correction_matrix_Cheung2004(M_T, M_R, terms=3): """ Computes a colour correction from given :math:`M_T` colour array to :math:`M_R` colour array using *Cheung et al. (2004)* method. Parameters ---------- M_T : array_like, (3, n) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (3, n) Reference array the array :math:`M_T` will be colour fitted against. terms : int, optional Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. Returns ------- ndarray, (3, n) Colour correction matrix. References ---------- :cite:`Cheung2004`, :cite:`Westland2004` Examples -------- >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_matrix_Cheung2004(M_T, M_R) # doctest: +ELLIPSIS array([[ 1.0526376..., 0.1378078..., -0.2276339...], [ 0.0739584..., 1.0293994..., -0.1060115...], [ 0.0572550..., -0.2052633..., 1.1015194...]]) """ return least_square_mapping_MoorePenrose( augmented_matrix_Cheung2004(M_T, terms), M_R)
[docs]def colour_correction_matrix_Finlayson2015(M_T, M_R, degree=1, root_polynomial_expansion=True): """ Computes a colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array using *Finlayson et al. (2015)* method. Parameters ---------- M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. degree : int, optional Expanded polynomial degree. root_polynomial_expansion : bool Whether to use the root-polynomials set for the expansion. Returns ------- ndarray, (n, 3) Colour correction matrix. References ---------- :cite:`Finlayson2015` Examples -------- >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_matrix_Finlayson2015(M_T, M_R) # doctest: +ELLIPSIS array([[ 1.0526376..., 0.1378078..., -0.2276339...], [ 0.0739584..., 1.0293994..., -0.1060115...], [ 0.0572550..., -0.2052633..., 1.1015194...]]) """ return least_square_mapping_MoorePenrose( polynomial_expansion_Finlayson2015(M_T, degree, root_polynomial_expansion), M_R)
[docs]def colour_correction_matrix_Vandermonde(M_T, M_R, degree=1): """ Computes a colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array using *Vandermonde* method. Parameters ---------- M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. degree : int, optional Expanded polynomial degree. Returns ------- ndarray, (n, 3) Colour correction matrix. References ---------- :cite:`Wikipedia2003e` Examples -------- >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_matrix_Vandermonde(M_T, M_R) # doctest: +ELLIPSIS array([[ 1.0300256..., 0.1141770..., -0.2621816..., 0.0418022...], [ 0.0670209..., 1.0221494..., -0.1166108..., 0.0128250...], [ 0.0744612..., -0.1872819..., 1.1278078..., -0.0318085...]]) """ return least_square_mapping_MoorePenrose( polynomial_expansion_Vandermonde(M_T, degree), M_R)
COLOUR_CORRECTION_MATRIX_METHODS = CaseInsensitiveMapping({ 'Cheung 2004': colour_correction_matrix_Cheung2004, 'Finlayson 2015': colour_correction_matrix_Finlayson2015, 'Vandermonde': colour_correction_matrix_Vandermonde, }) COLOUR_CORRECTION_MATRIX_METHODS.__doc__ = """ Supported colour correction matrix methods. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` POLYNOMIAL_EXPANSION_METHODS : CaseInsensitiveMapping **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}** """
[docs]def colour_correction_matrix(M_T, M_R, method='Cheung 2004', **kwargs): """ Computes a colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array. The resulting colour correction matrix is computed using multiple linear or polynomial regression using given method. The purpose of that object is for example the matching of two *ColorChecker* colour rendition charts together. Parameters ---------- M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. method : unicode, optional **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}**, Computation method. Other Parameters ---------------- degree : int {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`, :func:`colour.characterisation.polynomial_expansion_Vandermonde`}, Expanded polynomial degree, must be one of *[1, 2, 3, 4]* for :func:`colour.characterisation.polynomial_expansion_Finlayson2015` definition. terms : int {:func:`colour.characterisation.augmented_matrix_Cheung2004`}, Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. root_polynomial_expansion : bool {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`}, Whether to use the root-polynomials set for the expansion. Returns ------- ndarray, (n, 3) Colour correction matrix. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` Examples -------- >>> M_T = np.array( ... [[0.17224810, 0.09170660, 0.06416938], ... [0.49189645, 0.27802050, 0.21923399], ... [0.10999751, 0.18658946, 0.29938611], ... [0.11666120, 0.14327905, 0.05713804], ... [0.18988879, 0.18227649, 0.36056247], ... [0.12501329, 0.42223442, 0.37027445], ... [0.64785606, 0.22396782, 0.03365194], ... [0.06761093, 0.11076896, 0.39779139], ... [0.49101797, 0.09448929, 0.11623839], ... [0.11622386, 0.04425753, 0.14469986], ... [0.36867946, 0.44545230, 0.06028681], ... [0.61632937, 0.32323906, 0.02437089], ... [0.03016472, 0.06153243, 0.29014596], ... [0.11103655, 0.30553067, 0.08149137], ... [0.41162190, 0.05816656, 0.04845934], ... [0.73339206, 0.53075188, 0.02475212], ... [0.47347718, 0.08834792, 0.30310315], ... [0.00000000, 0.25187016, 0.35062450], ... [0.76809639, 0.78486240, 0.77808297], ... [0.53822392, 0.54307997, 0.54710883], ... [0.35458526, 0.35318419, 0.35524431], ... [0.17976704, 0.18000531, 0.17991488], ... [0.09351417, 0.09510603, 0.09675027], ... [0.03405071, 0.03295077, 0.03702047]] ... ) >>> M_R = np.array( ... [[0.15579559, 0.09715755, 0.07514556], ... [0.39113140, 0.25943419, 0.21266708], ... [0.12824821, 0.18463570, 0.31508023], ... [0.12028974, 0.13455659, 0.07408400], ... [0.19368988, 0.21158946, 0.37955964], ... [0.19957425, 0.36085439, 0.40678123], ... [0.48896605, 0.20691688, 0.05816533], ... [0.09775522, 0.16710693, 0.47147724], ... [0.39358649, 0.12233400, 0.10526425], ... [0.10780332, 0.07258529, 0.16151473], ... [0.27502671, 0.34705454, 0.09728099], ... [0.43980441, 0.26880559, 0.05430533], ... [0.05887212, 0.11126272, 0.38552469], ... [0.12705825, 0.25787860, 0.13566464], ... [0.35612929, 0.07933258, 0.05118732], ... [0.48131976, 0.42082843, 0.07120612], ... [0.34665585, 0.15170714, 0.24969804], ... [0.08261116, 0.24588716, 0.48707733], ... [0.66054904, 0.65941137, 0.66376412], ... [0.48051509, 0.47870296, 0.48230082], ... [0.33045354, 0.32904184, 0.33228886], ... [0.18001305, 0.17978567, 0.18004416], ... [0.10283975, 0.10424680, 0.10384975], ... [0.04742204, 0.04772203, 0.04914226]] ... ) >>> colour_correction_matrix(M_T, M_R) # doctest: +ELLIPSIS array([[ 0.6982266..., 0.0307162..., 0.1621042...], [ 0.0689349..., 0.6757961..., 0.1643038...], [-0.0631495..., 0.0921247..., 0.9713415...]]) """ function = COLOUR_CORRECTION_MATRIX_METHODS[method] return function(M_T, M_R, **filter_kwargs(function, **kwargs))
[docs]def colour_correction_Cheung2004(RGB, M_T, M_R, terms=3): """ Performs colour correction of given *RGB* colourspace array using the colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array using *Cheung et al. (2004)* method. Parameters ---------- RGB : array_like, (n, 3) *RGB* colourspace array to colour correct. M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. terms : int, optional Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. Returns ------- ndarray Colour corrected *RGB* colourspace array. References ---------- :cite:`Cheung2004`, :cite:`Westland2004` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_Cheung2004(RGB, M_T, M_R) # doctest: +ELLIPSIS array([ 0.1793456..., 0.1003392..., 0.0617218...]) """ RGB = as_float_array(RGB) shape = RGB.shape RGB = np.reshape(RGB, (-1, 3)) RGB_e = augmented_matrix_Cheung2004(RGB, terms) CCM = colour_correction_matrix_Cheung2004(M_T, M_R, terms) return np.reshape(np.transpose(np.dot(CCM, np.transpose(RGB_e))), shape)
[docs]def colour_correction_Finlayson2015(RGB, M_T, M_R, degree=1, root_polynomial_expansion=True): """ Performs colour correction of given *RGB* colourspace array using the colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array using *Finlayson et al. (2015)* method. Parameters ---------- RGB : array_like, (n, 3) *RGB* colourspace array to colour correct. M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. degree : int, optional Expanded polynomial degree. root_polynomial_expansion : bool Whether to use the root-polynomials set for the expansion. Returns ------- ndarray Colour corrected *RGB* colourspace array. References ---------- :cite:`Finlayson2015` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_Finlayson2015(RGB, M_T, M_R) # doctest: +ELLIPSIS array([ 0.1793456..., 0.1003392..., 0.0617218...]) """ RGB = as_float_array(RGB) shape = RGB.shape RGB = np.reshape(RGB, (-1, 3)) RGB_e = polynomial_expansion_Finlayson2015(RGB, degree, root_polynomial_expansion) CCM = colour_correction_matrix_Finlayson2015(M_T, M_R, degree, root_polynomial_expansion) return np.reshape(np.transpose(np.dot(CCM, np.transpose(RGB_e))), shape)
[docs]def colour_correction_Vandermonde(RGB, M_T, M_R, degree=1): """ Performs colour correction of given *RGB* colourspace array using the colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array using *Vandermonde* method. Parameters ---------- RGB : array_like, (n, 3) *RGB* colourspace array to colour correct. M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. degree : int, optional Expanded polynomial degree. Returns ------- ndarray Colour corrected *RGB* colourspace array. References ---------- :cite:`Wikipedia2003e` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> prng = np.random.RandomState(2) >>> M_T = prng.random_sample((24, 3)) >>> M_R = M_T + (prng.random_sample((24, 3)) - 0.5) * 0.5 >>> colour_correction_Vandermonde(RGB, M_T, M_R) # doctest: +ELLIPSIS array([ 0.2128689..., 0.1106242..., 0.036213 ...]) """ RGB = as_float_array(RGB) shape = RGB.shape RGB = np.reshape(RGB, (-1, 3)) RGB_e = polynomial_expansion_Vandermonde(RGB, degree) CCM = colour_correction_matrix_Vandermonde(M_T, M_R, degree) return np.reshape(np.transpose(np.dot(CCM, np.transpose(RGB_e))), shape)
COLOUR_CORRECTION_METHODS = CaseInsensitiveMapping({ 'Cheung 2004': colour_correction_Cheung2004, 'Finlayson 2015': colour_correction_Finlayson2015, 'Vandermonde': colour_correction_Vandermonde, }) COLOUR_CORRECTION_METHODS.__doc__ = """ Supported colour correction methods. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` COLOUR_CORRECTION_METHODS : CaseInsensitiveMapping **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}** """
[docs]def colour_correction(RGB, M_T, M_R, method='Cheung 2004', **kwargs): """ Performs colour correction of given *RGB* colourspace array using the colour correction matrix from given :math:`M_T` colour array to :math:`M_R` colour array. Parameters ---------- RGB : array_like, (n, 3) *RGB* colourspace array to colour correct. M_T : array_like, (n, 3) Test array :math:`M_T` to fit onto array :math:`M_R`. M_R : array_like, (n, 3) Reference array the array :math:`M_T` will be colour fitted against. method : unicode, optional **{'Cheung 2004', 'Finlayson 2015', 'Vandermonde'}**, Computation method. Other Parameters ---------------- degree : int {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`, :func:`colour.characterisation.polynomial_expansion_Vandermonde`}, Expanded polynomial degree, must be one of *[1, 2, 3, 4]* for :func:`colour.characterisation.polynomial_expansion_Finlayson2015` definition. terms : int {:func:`colour.characterisation.augmented_matrix_Cheung2004`}, Number of terms of the expanded polynomial, must be one of *[3, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22]*. root_polynomial_expansion : bool {:func:`colour.characterisation.polynomial_expansion_Finlayson2015`}, Whether to use the root-polynomials set for the expansion. Returns ------- ndarray Colour corrected *RGB* colourspace array. References ---------- :cite:`Cheung2004`, :cite:`Finlayson2015`, :cite:`Westland2004`, :cite:`Wikipedia2003e` Examples -------- >>> RGB = np.array([0.17224810, 0.09170660, 0.06416938]) >>> M_T = np.array( ... [[0.17224810, 0.09170660, 0.06416938], ... [0.49189645, 0.27802050, 0.21923399], ... [0.10999751, 0.18658946, 0.29938611], ... [0.11666120, 0.14327905, 0.05713804], ... [0.18988879, 0.18227649, 0.36056247], ... [0.12501329, 0.42223442, 0.37027445], ... [0.64785606, 0.22396782, 0.03365194], ... [0.06761093, 0.11076896, 0.39779139], ... [0.49101797, 0.09448929, 0.11623839], ... [0.11622386, 0.04425753, 0.14469986], ... [0.36867946, 0.44545230, 0.06028681], ... [0.61632937, 0.32323906, 0.02437089], ... [0.03016472, 0.06153243, 0.29014596], ... [0.11103655, 0.30553067, 0.08149137], ... [0.41162190, 0.05816656, 0.04845934], ... [0.73339206, 0.53075188, 0.02475212], ... [0.47347718, 0.08834792, 0.30310315], ... [0.00000000, 0.25187016, 0.35062450], ... [0.76809639, 0.78486240, 0.77808297], ... [0.53822392, 0.54307997, 0.54710883], ... [0.35458526, 0.35318419, 0.35524431], ... [0.17976704, 0.18000531, 0.17991488], ... [0.09351417, 0.09510603, 0.09675027], ... [0.03405071, 0.03295077, 0.03702047]] ... ) >>> M_R = np.array( ... [[0.15579559, 0.09715755, 0.07514556], ... [0.39113140, 0.25943419, 0.21266708], ... [0.12824821, 0.18463570, 0.31508023], ... [0.12028974, 0.13455659, 0.07408400], ... [0.19368988, 0.21158946, 0.37955964], ... [0.19957425, 0.36085439, 0.40678123], ... [0.48896605, 0.20691688, 0.05816533], ... [0.09775522, 0.16710693, 0.47147724], ... [0.39358649, 0.12233400, 0.10526425], ... [0.10780332, 0.07258529, 0.16151473], ... [0.27502671, 0.34705454, 0.09728099], ... [0.43980441, 0.26880559, 0.05430533], ... [0.05887212, 0.11126272, 0.38552469], ... [0.12705825, 0.25787860, 0.13566464], ... [0.35612929, 0.07933258, 0.05118732], ... [0.48131976, 0.42082843, 0.07120612], ... [0.34665585, 0.15170714, 0.24969804], ... [0.08261116, 0.24588716, 0.48707733], ... [0.66054904, 0.65941137, 0.66376412], ... [0.48051509, 0.47870296, 0.48230082], ... [0.33045354, 0.32904184, 0.33228886], ... [0.18001305, 0.17978567, 0.18004416], ... [0.10283975, 0.10424680, 0.10384975], ... [0.04742204, 0.04772203, 0.04914226]] ... ) >>> colour_correction(RGB, M_T, M_R) # doctest: +ELLIPSIS array([ 0.1334872..., 0.0843921..., 0.0599014...]) """ function = COLOUR_CORRECTION_METHODS[method] return function(RGB, M_T, M_R, **filter_kwargs(function, **kwargs))