#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Academy Color Encoding System - Log Encodings
=============================================
Defines the *Academy Color Encoding System* (ACES) log encodings:
- :func:`log_encoding_ACESproxy`
- :func:`log_decoding_ACESproxy`
- :func:`log_encoding_ACEScc`
- :func:`log_decoding_ACEScc`
- :func:'log_encoding_ACEScct'
- :func:'log_decoding_ACEScct'
See Also
--------
`RGB Colourspaces Jupyter Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/models/rgb.ipynb>`_
References
----------
.. [1] The Academy of Motion Picture Arts and Sciences, Science and
Technology Council, & Academy Color Encoding System (ACES) Project
Subcommittee. (n.d.). Academy Color Encoding System. Retrieved
February 24, 2014, from
http://www.oscars.org/science-technology/council/projects/aces.html
.. [2] The Academy of Motion Picture Arts and Sciences, Science and
Technology Council, & Academy Color Encoding System (ACES) Project
Subcommittee. (2014). Technical Bulletin TB-2014-004 - Informative
Notes on SMPTE ST 2065-1 – Academy Color Encoding Specification
(ACES). Retrieved from
https://github.com/ampas/aces-dev/tree/master/documents
.. [3] The Academy of Motion Picture Arts and Sciences, Science and
Technology Council, & Academy Color Encoding System (ACES) Project
Subcommittee. (2014). Specification S-2014-003 - ACEScc , A
Logarithmic Encoding of ACES Data for use within Color Grading
Systems. Retrieved from
https://github.com/ampas/aces-dev/tree/master/documents
.. [4] The Academy of Motion Picture Arts and Sciences, Science and
Technology Council, & Academy Color Encoding System (ACES) Project
Subcommittee. (2014). Specification S-2013-001 - ACESproxy , an
Integer Log Encoding of ACES Image Data. Retrieved from
https://github.com/ampas/aces-dev/tree/master/documents
.. [5] The Academy of Motion Picture Arts and Sciences. (2016).
Specification S-2016-001 - ACEScct, A Quasi-Logarithmic
Encoding of ACES Data for use within Color Grading Systems.
Retrieved October 10, 2016, from
https://github.com/ampas/aces-dev/tree/v1.0.3/documents
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.utilities import CaseInsensitiveMapping, Structure, as_numeric
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2017 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['ACES_PROXY_10_CONSTANTS',
'ACES_PROXY_12_CONSTANTS',
'ACES_PROXY_CONSTANTS',
'ACES_CCT_CONSTANTS',
'log_encoding_ACESproxy',
'log_decoding_ACESproxy',
'log_encoding_ACEScc',
'log_decoding_ACEScc',
'log_encoding_ACEScct',
'log_decoding_ACEScct']
ACES_PROXY_10_CONSTANTS = Structure(
CV_min=64,
CV_max=940,
steps_per_stop=50,
mid_CV_offset=425,
mid_log_offset=2.5)
"""
*ACESproxy* 10 bit colourspace constants.
ACES_PROXY_10_CONSTANTS : Structure
"""
ACES_PROXY_12_CONSTANTS = Structure(
CV_min=256,
CV_max=3760,
steps_per_stop=200,
mid_CV_offset=1700,
mid_log_offset=2.5)
"""
*ACESproxy* 12 bit colourspace constants.
ACES_PROXY_12_CONSTANTS : Structure
"""
ACES_PROXY_CONSTANTS = CaseInsensitiveMapping(
{'10 Bit': ACES_PROXY_10_CONSTANTS,
'12 Bit': ACES_PROXY_12_CONSTANTS})
"""
Aggregated *ACESproxy* colourspace constants.
ACES_PROXY_CONSTANTS : CaseInsensitiveMapping
**{'10 Bit', '12 Bit'}**
"""
ACES_CCT_CONSTANTS = Structure(
X_BRK=0.0078125,
Y_BRK=0.155251141552511,
A=10.5402377416545,
B=0.0729055341958355)
"""
*ACEScct* colourspace constants.
ACES_CCT_CONSTANTS : Structure
"""
[docs]def log_encoding_ACESproxy(lin_AP1, bit_depth='10 Bit'):
"""
Defines the *ACESproxy* colourspace log encoding curve / opto-electronic
transfer function.
Parameters
----------
lin_AP1 : numeric or array_like
*lin_AP1* value.
bit_depth : unicode, optional
**{'10 Bit', '12 Bit'}**,
*ACESproxy* bit depth.
Returns
-------
numeric or ndarray
*ACESproxy* non-linear value.
Examples
--------
>>> log_encoding_ACESproxy(0.18)
426
"""
lin_AP1 = np.asarray(lin_AP1)
constants = ACES_PROXY_CONSTANTS[bit_depth]
CV_min = np.resize(constants.CV_min, lin_AP1.shape)
CV_max = np.resize(constants.CV_max, lin_AP1.shape)
def float_2_cv(x):
"""
Converts given numeric to code value.
"""
return np.maximum(CV_min, np.minimum(CV_max, np.round(x)))
output = np.where(lin_AP1 > 2 ** -9.72,
float_2_cv((np.log2(lin_AP1) +
constants.mid_log_offset) *
constants.steps_per_stop +
constants.mid_CV_offset),
np.resize(CV_min, lin_AP1.shape))
return as_numeric(output, int)
[docs]def log_decoding_ACESproxy(ACESproxy, bit_depth='10 Bit'):
"""
Defines the *ACESproxy* colourspace log decoding curve / electro-optical
transfer function.
Parameters
----------
ACESproxy : numeric or array_like
*ACESproxy* non-linear value.
bit_depth : unicode, optional
**{'10 Bit', '12 Bit'}**,
*ACESproxy* bit depth.
Returns
-------
numeric or ndarray
*lin_AP1* value.
Examples
--------
>>> log_decoding_ACESproxy(426) # doctest: +ELLIPSIS
0.1792444...
"""
ACESproxy = np.asarray(ACESproxy).astype(np.int)
constants = ACES_PROXY_CONSTANTS[bit_depth]
return (2 ** (((ACESproxy - constants.mid_CV_offset) /
constants.steps_per_stop - constants.mid_log_offset)))
[docs]def log_encoding_ACEScc(lin_AP1):
"""
Defines the *ACEScc* colourspace log encoding / opto-electronic transfer
function.
Parameters
----------
lin_AP1 : numeric or array_like
*lin_AP1* value.
Returns
-------
numeric or ndarray
*ACEScc* non-linear value.
Examples
--------
>>> log_encoding_ACEScc(0.18) # doctest: +ELLIPSIS
0.4135884...
"""
lin_AP1 = np.asarray(lin_AP1)
output = np.where(lin_AP1 < 0,
(np.log2(2 ** -15 * 0.5) + 9.72) / 17.52,
(np.log2(2 ** -16 + lin_AP1 * 0.5) + 9.72) / 17.52)
output = np.where(lin_AP1 >= 2 ** -15,
(np.log2(lin_AP1) + 9.72) / 17.52,
output)
return as_numeric(output)
[docs]def log_decoding_ACEScc(ACEScc):
"""
Defines the *ACEScc* colourspace log decoding / electro-optical transfer
function.
Parameters
----------
ACEScc : numeric or array_like
*ACEScc* non-linear value.
Returns
-------
numeric or ndarray
*lin_AP1* value.
Examples
--------
>>> log_decoding_ACEScc(0.413588402492442) # doctest: +ELLIPSIS
0.1799999...
"""
ACEScc = np.asarray(ACEScc)
output = np.where(ACEScc < (9.72 - 15) / 17.52,
(2 ** (ACEScc * 17.52 - 9.72) - 2 ** -16) * 2,
2 ** (ACEScc * 17.52 - 9.72))
output = np.where(ACEScc >= (np.log2(65504) + 9.72) / 17.52,
65504,
output)
return as_numeric(output)
[docs]def log_encoding_ACEScct(lin_AP1):
"""
Defines the *ACEScct* colourspace log encoding / opto-electronic transfer
function.
Parameters
----------
lin_AP1 : numeric or array_like
*lin_AP1* value.
Returns
-------
numeric or ndarray
*ACEScct* non-linear value.
Examples
--------
>>> log_encoding_ACEScct(0.18) # doctest: +ELLIPSIS
0.4135884...
"""
constants = ACES_CCT_CONSTANTS
lin_AP1 = np.asarray(lin_AP1)
output = np.where(lin_AP1 <= constants.X_BRK,
constants.A * lin_AP1 + constants.B,
(np.log2(lin_AP1) + 9.72) / 17.52)
return as_numeric(output)
[docs]def log_decoding_ACEScct(ACEScct):
"""
Defines the *ACEScct* colourspace log decoding / electro-optical transfer
function.
Parameters
----------
ACEScct : numeric or array_like
*ACEScct* non-linear value.
Returns
-------
numeric or ndarray
*lin_AP1* value.
Examples
--------
>>> log_decoding_ACEScct(0.413588402492442) # doctest: +ELLIPSIS
0.1799999...
"""
constants = ACES_CCT_CONSTANTS
ACEScct = np.asarray(ACEScct)
output = np.where(ACEScct > constants.Y_BRK,
2 ** (ACEScct * 17.52 - 9.72),
(ACEScct - constants.B) / constants.A)
return as_numeric(output)