#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
RED Log Encodings
=================
Defines the *RED* log encodings:
- :func:`log_encoding_REDLog`
- :func:`log_decoding_REDLog`
See Also
--------
`RGB Colourspaces IPython Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/models/rgb.ipynb>`_
References
----------
.. [1] Sony Imageworks. (2012). make.py. Retrieved November 27, 2014, from
https://github.com/imageworks/OpenColorIO-Configs/\
blob/master/nuke-default/make.py
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.models.rgb.transfer_functions import (
log_encoding_Cineon,
log_decoding_Cineon)
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2016 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['log_encoding_REDLog',
'log_decoding_REDLog',
'log_encoding_REDLogFilm',
'log_decoding_REDLogFilm']
[docs]def log_encoding_REDLog(x,
black_offset=10 ** ((0 - 1023) / 511)):
"""
Defines the *REDLog* log encoding curve / opto-electronic transfer
function.
Parameters
----------
x : numeric or array_like
Linear data :math:`x`.
black_offset : numeric or array_like
Black offset.
Returns
-------
numeric or ndarray
Non-linear data :math:`y`.
Examples
--------
>>> log_encoding_REDLog(0.18) # doctest: +ELLIPSIS
0.6376218...
"""
x = np.asarray(x)
return ((1023 +
511 * np.log10(x * (1 - black_offset) + black_offset)) / 1023)
[docs]def log_decoding_REDLog(y,
black_offset=10 ** ((0 - 1023) / 511)):
"""
Defines the *REDLog* log decoding curve / electro-optical transfer
function.
Parameters
----------
y : numeric or array_like
Non-linear data :math:`y`.
black_offset : numeric or array_like
Black offset.
Returns
-------
numeric or ndarray
Linear data :math:`x`.
Examples
--------
>>> log_decoding_REDLog(0.637621845988175) # doctest: +ELLIPSIS
0.1...
"""
y = np.asarray(y)
return (((10 **
((1023 * y - 1023) / 511)) - black_offset) /
(1 - black_offset))
[docs]def log_encoding_REDLogFilm(x,
black_offset=10 ** ((95 - 685) / 300)):
"""
Defines the *REDLogFilm* log encoding curve / opto-electronic transfer
function.
Parameters
----------
x : numeric or array_like
Linear data :math:`x`.
black_offset : numeric or array_like
Black offset.
Returns
-------
numeric or ndarray
Non-linear data :math:`y`.
Examples
--------
>>> log_encoding_REDLogFilm(0.18) # doctest: +ELLIPSIS
0.4573196...
"""
return log_encoding_Cineon(x, black_offset)
[docs]def log_decoding_REDLogFilm(y,
black_offset=10 ** ((95 - 685) / 300)):
"""
Defines the *REDLogFilm* log decoding curve / electro-optical transfer
function.
Parameters
----------
y : numeric or array_like
Non-linear data :math:`y`.
black_offset : numeric or array_like
Black offset.
Returns
-------
numeric or ndarray
Linear data :math:`x`.
Examples
--------
>>> log_decoding_REDLogFilm(0.457319613085418) # doctest: +ELLIPSIS
0.1799999...
"""
return log_decoding_Cineon(y, black_offset)