Source code for colour.models.rgb.transfer_functions.smpte_240m

"""
SMPTE 240M
==========

Define the *SMPTE 240M* opto-electrical transfer function (OETF) and
electro-optical transfer function (EOTF):

-   :func:`colour.models.oetf_SMPTE240M`
-   :func:`colour.models.eotf_SMPTE240M`

References
----------
-   :cite:`SocietyofMotionPictureandTelevisionEngineers1999b` : Society of
    Motion Picture and Television Engineers. (1999). ANSI/SMPTE 240M-1995 -
    Signal Parameters - 1125-Line High-Definition Production Systems (pp. 1-7).
    http://car.france3.mars.free.fr/HD/INA-%2026%20jan%2006/\
SMPTE%20normes%20et%20confs/s240m.pdf
"""

from __future__ import annotations

import numpy as np

from colour.algebra import spow
from colour.hints import ArrayLike, NDArrayFloat
from colour.utilities import (
    as_float,
    domain_range_scale,
    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__ = [
    "oetf_SMPTE240M",
    "eotf_SMPTE240M",
]


[docs] def oetf_SMPTE240M(L_c: ArrayLike) -> NDArrayFloat: """ Define *SMPTE 240M* opto-electrical transfer function (OETF). Parameters ---------- L_c Light input :math:`L_c` to the reference camera normalised to the system reference white. Returns ------- :class:`numpy.ndarray` Video signal output :math:`V_c` of the reference camera normalised to the system reference white. Notes ----- +------------+-----------------------+---------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``L_c`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ +------------+-----------------------+---------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``V_c`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ References ---------- :cite:`SocietyofMotionPictureandTelevisionEngineers1999b` Examples -------- >>> oetf_SMPTE240M(0.18) # doctest: +ELLIPSIS 0.4022857... """ L_c = to_domain_1(L_c) V_c = np.where(L_c < 0.0228, 4 * L_c, 1.1115 * spow(L_c, 0.45) - 0.1115) return as_float(from_range_1(V_c))
[docs] def eotf_SMPTE240M(V_r: ArrayLike) -> NDArrayFloat: """ Define *SMPTE 240M* electro-optical transfer function (EOTF). Parameters ---------- V_r Video signal level :math:`V_r` driving the reference reproducer normalised to the system reference white. Returns ------- :class:`numpy.ndarray` Light output :math:`L_r` from the reference reproducer normalised to the system reference white. Notes ----- +------------+-----------------------+---------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``V_c`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ +------------+-----------------------+---------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``L_c`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ References ---------- :cite:`SocietyofMotionPictureandTelevisionEngineers1999b` Examples -------- >>> eotf_SMPTE240M(0.402285796753870) # doctest: +ELLIPSIS 0.1... """ V_r = to_domain_1(V_r) with domain_range_scale("ignore"): L_r = np.where( V_r < oetf_SMPTE240M(0.0228), V_r / 4, spow((V_r + 0.1115) / 1.1115, 1 / 0.45), ) return as_float(from_range_1(L_r))