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

# -*- coding: utf-8 -*-
"""
Panalog Encoding
================

Defines the *Panalog* encoding:

-   :func:`colour.models.log_encoding_Panalog`
-   :func:`colour.models.log_decoding_Panalog`

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_Panalog', 'log_decoding_Panalog']


[docs]def log_encoding_Panalog(x, black_offset=10 ** ((64 - 681) / 444)): """ Defines the *Panalog* 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`. Warnings -------- These are estimations known to be close enough, the actual log encoding curves are not published. 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_Panalog(0.18) # doctest: +ELLIPSIS 0.3745767... """ x = to_domain_1(x) y = (681 + 444 * np.log10(x * (1 - black_offset) + black_offset)) / 1023 return from_range_1(y)
[docs]def log_decoding_Panalog(y, black_offset=10 ** ((64 - 681) / 444)): """ Defines the *Panalog* 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`. Warnings -------- These are estimations known to be close enough, the actual log encoding curves are not published. 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_Panalog(0.374576791382298) # doctest: +ELLIPSIS 0.1... """ y = to_domain_1(y) x = (10 ** ((1023 * y - 681) / 444) - black_offset) / (1 - black_offset) return from_range_1(x)