#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
V-Gamut Colourspace
===================
Defines the *V-Gamut* colourspace:
- :attr:`V_GAMUT_COLOURSPACE`.
See Also
--------
`RGB Colourspaces IPython Notebook
<http://nbviewer.ipython.org/github/colour-science/colour-ipython/blob/master/notebooks/models/rgb.ipynb>`_ # noqa
References
----------
.. [1] Panasonic. (2014). VARICAM V-Log/V-Gamut. Retrieved from
http://pro-av.panasonic.net/en/varicam/common/pdf/VARICAM_V-Log_V-Gamut.pdf # noqa
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.colorimetry import ILLUMINANTS
from colour.models import RGB_Colourspace
from colour.utilities import Structure
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013 - 2015 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['V_GAMUT_PRIMARIES',
'V_GAMUT_ILLUMINANT',
'V_GAMUT_WHITEPOINT',
'V_GAMUT_TO_XYZ_MATRIX',
'XYZ_TO_V_GAMUT_MATRIX',
'V_LOG_CONSTANTS',
'V_LOG_TRANSFER_FUNCTION',
'V_LOG_INVERSE_TRANSFER_FUNCTION',
'V_GAMUT_COLOURSPACE']
V_GAMUT_PRIMARIES = np.array(
[[0.730, 0.280],
[0.165, 0.840],
[0.100, -0.030]])
"""
*V-Gamut* colourspace primaries.
V_GAMUT_PRIMARIES : ndarray, (3, 2)
"""
V_GAMUT_ILLUMINANT = 'D65'
"""
*V-Gamut* colourspace whitepoint name as illuminant.
V_GAMUT_WHITEPOINT : unicode
"""
V_GAMUT_WHITEPOINT = ILLUMINANTS.get(
'CIE 1931 2 Degree Standard Observer').get(V_GAMUT_ILLUMINANT)
"""
*V-Gamut* colourspace whitepoint.
V_GAMUT_WHITEPOINT : tuple
"""
V_GAMUT_TO_XYZ_MATRIX = np.array(
[[0.679644, 0.152211, 0.118600],
[0.260686, 0.774894, -0.035580],
[-0.009310, -0.004612, 1.102980]])
"""
*V-Gamut* colourspace to *CIE XYZ* tristimulus values matrix.
V_GAMUT_TO_XYZ_MATRIX : array_like, (3, 3)
"""
XYZ_TO_V_GAMUT_MATRIX = np.linalg.inv(
V_GAMUT_TO_XYZ_MATRIX)
"""
*CIE XYZ* tristimulus values to *V-Gamut* colourspace matrix.
XYZ_TO_V_GAMUT_MATRIX : array_like, (3, 3)
"""
V_LOG_CONSTANTS = Structure(cut1=0.01,
cut2=0.181,
b=0.00873,
c=0.241514,
d=0.598206)
"""
*V-Log* colourspace constants.
V_LOG_CONSTANTS : Structure
"""
def _linear_to_v_log(value):
"""
Defines the *linear* to *V-Log* conversion function.
Parameters
----------
value : numeric or array_like
Value.
Returns
-------
numeric or ndarray
Companded value.
"""
value = np.asarray(value)
cut1 = V_LOG_CONSTANTS.cut1
b = V_LOG_CONSTANTS.b
c = V_LOG_CONSTANTS.c
d = V_LOG_CONSTANTS.d
value = np.where(value < cut1,
5.6 * value + 0.125,
c * np.log10(value + b) + d)
return value
def _v_log_to_linear(value):
"""
Defines the *V-Log* to *linear* conversion function.
Parameters
----------
value : numeric or array_like
Value.
Returns
-------
numeric or ndarray
Companded value.
"""
value = np.asarray(value)
cut2 = V_LOG_CONSTANTS.cut2
b = V_LOG_CONSTANTS.b
c = V_LOG_CONSTANTS.c
d = V_LOG_CONSTANTS.d
value = np.where(value < cut2,
(value - 0.125) / 5.6,
np.power(10, ((value - d) / c)) - b)
return value
V_LOG_TRANSFER_FUNCTION = _linear_to_v_log
"""
Transfer function from linear to *V-Log*.
V_LOG_TRANSFER_FUNCTION : object
"""
V_LOG_INVERSE_TRANSFER_FUNCTION = _v_log_to_linear
"""
Inverse transfer function from *V-Log* to linear.
V_LOG_INVERSE_TRANSFER_FUNCTION : object
"""
V_GAMUT_COLOURSPACE = RGB_Colourspace(
'V-Gamut',
V_GAMUT_PRIMARIES,
V_GAMUT_WHITEPOINT,
V_GAMUT_ILLUMINANT,
V_GAMUT_TO_XYZ_MATRIX,
XYZ_TO_V_GAMUT_MATRIX,
V_LOG_TRANSFER_FUNCTION,
V_LOG_INVERSE_TRANSFER_FUNCTION)
"""
*V-Gamut* colourspace.
V_GAMUT_COLOURSPACE : RGB_Colourspace
"""
Colour 0.3