# -*- coding: utf-8 -*-
"""
Viper Log Encoding
==================
Defines the *Viper Log* encoding:
- :func:`colour.models.log_encoding_ViperLog`
- :func:`colour.models.log_decoding_ViperLog`
See Also
--------
`RGB Colourspaces Jupyter Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/models/rgb.ipynb>`_
References
----------
- :cite:`SonyImageworks2012a` : 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.utilities import from_range_1, to_domain_1
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2019 - Colour Developers'
__license__ = 'New BSD License - https://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['log_encoding_ViperLog', 'log_decoding_ViperLog']
[docs]def log_encoding_ViperLog(x):
"""
Defines the *Viper Log* log encoding curve / opto-electronic transfer
function.
Parameters
----------
x : numeric or array_like
Linear data :math:`x`.
Returns
-------
numeric or ndarray
Non-linear data :math:`y`.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``x`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``y`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`SonyImageworks2012a`
Examples
--------
>>> log_encoding_ViperLog(0.18) # doctest: +ELLIPSIS
0.6360080...
"""
x = to_domain_1(x)
y = (1023 + 500 * np.log10(x)) / 1023
return from_range_1(y)
[docs]def log_decoding_ViperLog(y):
"""
Defines the *Viper Log* log decoding curve / electro-optical transfer
function.
Parameters
----------
y : numeric or array_like
Non-linear data :math:`y`.
Returns
-------
numeric or ndarray
Linear data :math:`x`.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``y`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``x`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`SonyImageworks2012a`
Examples
--------
>>> log_decoding_ViperLog(0.636008067010413) # doctest: +ELLIPSIS
0.1799999...
"""
y = to_domain_1(y)
x = 10 ** ((1023 * y - 1023) / 500)
return from_range_1(x)