"""
SMPTE 240M
==========
Defines 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 FloatingOrArrayLike, FloatingOrNDArray
from colour.utilities import (
as_float,
domain_range_scale,
from_range_1,
to_domain_1,
)
__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 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__ = [
"oetf_SMPTE240M",
"eotf_SMPTE240M",
]
[docs]def oetf_SMPTE240M(L_c: FloatingOrArrayLike) -> FloatingOrNDArray:
"""
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.floating` or :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: FloatingOrArrayLike) -> FloatingOrNDArray:
"""
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.floating` or :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))