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

# -*- coding: utf-8 -*-
"""
Fujifilm F-Log Log Encoding
===========================

Defines the *Fujifilm F-Log* log encoding:

-   :func:`colour.models.log_encoding_FLog`
-   :func:`colour.models.log_decoding_FLog`

References
----------
-   :cite:`Fujifilm2016` : Fujifilm. (2016). F-Log Data Sheet Ver.1.0 (pp.
    1-4). https://www.fujifilm.com/support/digital_cameras/software/lut/pdf/\
F-Log_DataSheet_E_Ver.1.0.pdf
"""

from __future__ import division, unicode_literals

import numpy as np

from colour.models.rgb.transfer_functions import full_to_legal, legal_to_full
from colour.utilities import Structure, as_float, from_range_1, to_domain_1

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2020 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-developers@colour-science.org'
__status__ = 'Production'

__all__ = ['FLOG_CONSTANTS', 'log_encoding_FLog', 'log_decoding_FLog']

FLOG_CONSTANTS = Structure(
    cut1=0.00089,
    cut2=0.100537775223865,
    a=0.555556,
    b=0.009468,
    c=0.344676,
    d=0.790453,
    e=8.735631,
    f=0.092864)
"""
*Fujifilm F-Log* colourspace constants.

FLOG_CONSTANTS : Structure
"""


[docs]def log_encoding_FLog(in_r, bit_depth=10, out_normalised_code_value=True, in_reflection=True, constants=FLOG_CONSTANTS): """ Defines the *Fujifilm F-Log* log encoding curve / opto-electronic transfer function. Parameters ---------- in_r : numeric or array_like Linear reflection data :math`in`. bit_depth : int, optional Bit depth used for conversion. out_normalised_code_value : bool, optional Whether the non-linear *Fujifilm F-Log* data :math:`out` is encoded as normalised code values. in_reflection : bool, optional Whether the light level :math`in` to a camera is reflection. constants : Structure, optional *Fujifilm F-Log* constants. Returns ------- numeric or ndarray Non-linear data :math:`out`. Notes ----- +------------+-----------------------+---------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``in_r`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ +------------+-----------------------+---------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``out_r`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ References ---------- :cite:`Fujifilm2016` Examples -------- >>> log_encoding_FLog(0.18) # doctest: +ELLIPSIS 0.4593184... The values of *2-2. F-Log Code Value* table in :cite:`Fujifilm2016` are obtained as follows: >>> x = np.array([0, 18, 90]) / 100 >>> np.around(log_encoding_FLog(x, 10, False) * 100, 1) array([ 3.5, 46.3, 73.2]) >>> np.around(log_encoding_FLog(x) * (2 ** 10 - 1)).astype(np.int) array([ 95, 470, 705]) """ in_r = to_domain_1(in_r) if not in_reflection: in_r = in_r * 0.9 cut1 = constants.cut1 a = constants.a b = constants.b c = constants.c d = constants.d e = constants.e f = constants.f out_r = np.where( in_r < cut1, e * in_r + f, c * np.log10(a * in_r + b) + d, ) out_r = (out_r if out_normalised_code_value else legal_to_full(out_r, bit_depth)) return as_float(from_range_1(out_r))
[docs]def log_decoding_FLog(out_r, bit_depth=10, in_normalised_code_value=True, out_reflection=True, constants=FLOG_CONSTANTS): """ Defines the *Fujifilm F-Log* log decoding curve / electro-optical transfer function. Parameters ---------- out_r : numeric or array_like Non-linear data :math:`out`. bit_depth : int, optional Bit depth used for conversion. in_normalised_code_value : bool, optional Whether the non-linear *Fujifilm F-Log* data :math:`out` is encoded as normalised code values. out_reflection : bool, optional Whether the light level :math`in` to a camera is reflection. constants : Structure, optional *Fujifilm F-Log* constants. Returns ------- numeric or ndarray Linear reflection data :math`in`. Notes ----- +------------+-----------------------+---------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``out_r`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ +------------+-----------------------+---------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``in_r`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ References ---------- :cite:`Fujifilm2016` Examples -------- >>> log_decoding_FLog(0.45931845866162124) # doctest: +ELLIPSIS 0.1800000... """ out_r = to_domain_1(out_r) out_r = (out_r if in_normalised_code_value else full_to_legal(out_r, bit_depth)) cut2 = constants.cut2 a = constants.a b = constants.b c = constants.c d = constants.d e = constants.e f = constants.f in_r = np.where( out_r < cut2, (out_r - f) / e, (10 ** ((out_r - d) / c)) / a - b / a, ) if not out_reflection: in_r = in_r / 0.9 return as_float(from_range_1(in_r))