#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
RGB Colourspace Transformations
===============================
Defines the *RGB* colourspace transformations:
- :func:`XYZ_to_RGB`
- :func:`RGB_to_XYZ`
- :func:`RGB_to_RGB`
See Also
--------
`RGB Colourspaces IPython Notebook
<http://nbviewer.ipython.org/github/colour-science/colour-ipython/blob/master/notebooks/models/rgb.ipynb>`_ # noqa
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.models import xy_to_XYZ
from colour.adaptation import chromatic_adaptation_matrix
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013 - 2014 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['XYZ_to_RGB',
'RGB_to_XYZ',
'RGB_to_RGB']
[docs]def XYZ_to_RGB(XYZ,
illuminant_XYZ,
illuminant_RGB,
to_RGB,
chromatic_adaptation_method='CAT02',
transfer_function=None):
"""
Converts from *CIE XYZ* colourspace to *RGB* colourspace using given
*CIE XYZ* colourspace matrix, *illuminants*, *chromatic adaptation* method,
*normalised primary matrix* and *transfer function*.
Parameters
----------
XYZ : array_like, (3,)
*CIE XYZ* colourspace matrix.
illuminant_XYZ : array_like
*CIE XYZ* colourspace *illuminant* *xy* chromaticity coordinates.
illuminant_RGB : array_like
*RGB* colourspace *illuminant* *xy* chromaticity coordinates.
to_RGB : array_like, (3, 3)
*Normalised primary matrix*.
chromatic_adaptation_method : unicode, optional
('XYZ Scaling', 'Bradford', 'Von Kries', 'Fairchild', 'CAT02')
*Chromatic adaptation* method.
transfer_function : object, optional
*Transfer function*.
Returns
-------
ndarray, (3,)
*RGB* colourspace matrix.
Notes
-----
- Input *CIE XYZ* colourspace matrix is in domain [0, 1].
- Input *illuminant_XYZ* *xy* chromaticity coordinates are in domain
[0, 1].
- Input *illuminant_RGB* *xy* chromaticity coordinates are in domain
[0, 1].
- Output *RGB* colourspace matrix is in domain [0, 1].
Examples
--------
>>> XYZ = np.array([0.1151847498, 0.1008, 0.0508937252])
>>> illuminant_XYZ = (0.34567, 0.35850)
>>> illuminant_RGB = (0.31271, 0.32902)
>>> chromatic_adaptation_method = 'Bradford'
>>> to_RGB = np.array([
... [3.24100326, -1.53739899, -0.49861587],
... [-0.96922426, 1.87592999, 0.04155422],
... [0.05563942, -0.2040112, 1.05714897]])
>>> XYZ_to_RGB(
... XYZ,
... illuminant_XYZ,
... illuminant_RGB,
... to_RGB,
... chromatic_adaptation_method) # doctest: +ELLIPSIS
array([ 0.1730350..., 0.0821103..., 0.0567249...])
"""
np.array([
[3.24100326, -1.53739899, -0.49861587],
[-0.96922426, 1.87592999, 0.04155422],
[0.05563942, -0.2040112, 1.05714897]])
cat = chromatic_adaptation_matrix(xy_to_XYZ(illuminant_XYZ),
xy_to_XYZ(illuminant_RGB),
method=chromatic_adaptation_method)
adapted_XYZ = np.dot(cat, XYZ)
RGB = np.dot(to_RGB.reshape((3, 3)), adapted_XYZ.reshape((3, 1)))
if transfer_function is not None:
RGB = np.array([transfer_function(x) for x in np.ravel(RGB)])
return np.ravel(RGB)
[docs]def RGB_to_XYZ(RGB,
illuminant_RGB,
illuminant_XYZ,
to_XYZ,
chromatic_adaptation_method='CAT02',
inverse_transfer_function=None):
"""
Converts from *RGB* colourspace to *CIE XYZ* colourspace using given
*RGB* colourspace matrix, *illuminants*, *chromatic adaptation* method,
*normalised primary matrix* and *transfer function*.
Parameters
----------
RGB : array_like, (3,)
*RGB* colourspace matrix.
illuminant_RGB : array_like
*RGB* colourspace *illuminant* chromaticity coordinates.
illuminant_XYZ : array_like
*CIE XYZ* colourspace *illuminant* chromaticity coordinates.
to_XYZ : array_like, (3, 3)
*Normalised primary matrix*.
chromatic_adaptation_method : unicode, optional
('XYZ Scaling', 'Bradford', 'Von Kries', 'Fairchild', 'CAT02')
*Chromatic adaptation* method.
inverse_transfer_function : object, optional
*Inverse transfer function*.
Returns
-------
ndarray, (3,)
*CIE XYZ* colourspace matrix.
Notes
-----
- Input *RGB* colourspace matrix is in domain [0, 1].
- Input *illuminant_RGB* *xy* chromaticity coordinates are in domain
[0, 1].
- Input *illuminant_XYZ* *xy* chromaticity coordinates are in domain
[0, 1].
- Output *CIE XYZ* colourspace matrix is in domain [0, 1].
Examples
--------
>>> RGB = np.array([0.17303501, 0.08211033, 0.05672498])
>>> illuminant_RGB = (0.31271, 0.32902)
>>> illuminant_XYZ = (0.34567, 0.35850)
>>> chromatic_adaptation_method = 'Bradford'
>>> to_XYZ = np.array([
... [0.41238656, 0.35759149, 0.18045049],
... [0.21263682, 0.71518298, 0.0721802],
... [0.01933062, 0.11919716, 0.95037259]])
>>> RGB_to_XYZ(
... RGB,
... illuminant_RGB,
... illuminant_XYZ,
... to_XYZ,
... chromatic_adaptation_method) # doctest: +ELLIPSIS
array([ 0.1151847..., 0.1008 , 0.0508937...])
"""
if inverse_transfer_function is not None:
RGB = np.array([inverse_transfer_function(x)
for x in np.ravel(RGB)])
XYZ = np.dot(to_XYZ.reshape((3, 3)), RGB.reshape((3, 1)))
cat = chromatic_adaptation_matrix(
xy_to_XYZ(illuminant_RGB),
xy_to_XYZ(illuminant_XYZ),
method=chromatic_adaptation_method)
adapted_XYZ = np.dot(cat, XYZ.reshape((3, 1)))
return np.ravel(adapted_XYZ)
[docs]def RGB_to_RGB(RGB,
input_colourspace,
output_colourspace,
chromatic_adaptation_method='CAT02'):
"""
Converts from given input *RGB* colourspace to output *RGB* colourspace
using given *chromatic adaptation* method.
Parameters
----------
RGB : array_like, (3,)
*RGB* colourspace matrix.
input_colourspace : RGB_Colourspace
*RGB* input colourspace.
output_colourspace : RGB_Colourspace
*RGB* output colourspace.
chromatic_adaptation_method : unicode, optional
('XYZ Scaling', 'Bradford', 'Von Kries', 'Fairchild', 'CAT02')
*Chromatic adaptation* method.
ndarray, (3,)
*RGB* colourspace matrix.
Notes
-----
- *RGB* colourspace matrices are in domain [0, 1].
Examples
--------
>>> from colour import sRGB_COLOURSPACE, PROPHOTO_RGB_COLOURSPACE
>>> RGB = np.array([0.35521588, 0.41, 0.24177934])
>>> RGB_to_RGB(
... RGB,
... sRGB_COLOURSPACE,
... PROPHOTO_RGB_COLOURSPACE) # doctest: +ELLIPSIS
array([ 0.3579334..., 0.4007138..., 0.2615704...])
"""
cat = chromatic_adaptation_matrix(
xy_to_XYZ(input_colourspace.whitepoint),
xy_to_XYZ(output_colourspace.whitepoint),
chromatic_adaptation_method)
trs_matrix = np.dot(output_colourspace.to_RGB,
np.dot(cat, input_colourspace.to_XYZ))
return np.dot(trs_matrix, RGB)
Colour 0.3