Source code for colour.models.rgb.transfer_functions.viper_log

# -*- coding: utf-8 -*-
"""
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
"""

import numpy as np

from colour.utilities import from_range_1, to_domain_1

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2021 - 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__ = ['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)