Source code for colour.models.rgb.transfer_functions.viper_log
"""
Viper Log Encoding
==================
Defines the *Viper Log* encoding:
- :func:`colour.models.log_encoding_ViperLog`
- :func:`colour.models.log_decoding_ViperLog`
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 annotations
import numpy as np
from colour.hints import ArrayLike, NDArrayFloat
from colour.utilities import as_float, from_range_1, to_domain_1
__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"
__all__ = [
"log_encoding_ViperLog",
"log_decoding_ViperLog",
]
[docs]
def log_encoding_ViperLog(x: ArrayLike) -> NDArrayFloat:
"""
Define the *Viper Log* log encoding curve / opto-electronic transfer
function.
Parameters
----------
x
Linear data :math:`x`.
Returns
-------
:class:`numpy.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 as_float(from_range_1(y))
[docs]
def log_decoding_ViperLog(y: ArrayLike) -> NDArrayFloat:
"""
Define the *Viper Log* log decoding curve / electro-optical transfer
function.
Parameters
----------
y
Non-linear data :math:`y`.
Returns
-------
:class:`numpy.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 as_float(from_range_1(x))