#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
NTSC RGB Colourspace
====================
Defines the *NTSC RGB* colourspace:
- :attr:`NTSC_RGB_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] International Telecommunication Union. (1998). CONVENTIONAL TELEVISION
SYSTEMS. In Recommendation ITU-R BT.470-6 (pp. 1–36). Retrieved from
http://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf # noqa
"""
from __future__ import division, unicode_literals
import numpy as np
from colour.colorimetry import ILLUMINANTS
from colour.models import normalised_primary_matrix
from colour.models import RGB_Colourspace
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013 - 2014 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['NTSC_RGB_PRIMARIES',
'NTSC_RGB_ILLUMINANT',
'NTSC_RGB_WHITEPOINT',
'NTSC_RGB_TO_XYZ_MATRIX',
'XYZ_TO_NTSC_RGB_MATRIX',
'NTSC_RGB_TRANSFER_FUNCTION',
'NTSC_RGB_INVERSE_TRANSFER_FUNCTION',
'NTSC_RGB_COLOURSPACE']
NTSC_RGB_PRIMARIES = np.array(
[[0.67, 0.33],
[0.21, 0.71],
[0.14, 0.08]])
"""
*NTSC RGB* colourspace primaries.
NTSC_RGB_PRIMARIES : ndarray, (3, 2)
"""
NTSC_RGB_ILLUMINANT = 'C'
"""
*NTSC RGB* colourspace whitepoint name as illuminant.
NTSC_RGB_ILLUMINANT : unicode
"""
NTSC_RGB_WHITEPOINT = ILLUMINANTS.get(
'CIE 1931 2 Degree Standard Observer').get(NTSC_RGB_ILLUMINANT)
"""
*NTSC RGB* colourspace whitepoint.
NTSC_RGB_WHITEPOINT : tuple
"""
NTSC_RGB_TO_XYZ_MATRIX = normalised_primary_matrix(NTSC_RGB_PRIMARIES,
NTSC_RGB_WHITEPOINT)
"""
*NTSC RGB* colourspace to *CIE XYZ* colourspace matrix.
NTSC_RGB_TO_XYZ_MATRIX : array_like, (3, 3)
"""
XYZ_TO_NTSC_RGB_MATRIX = np.linalg.inv(NTSC_RGB_TO_XYZ_MATRIX)
"""
*CIE XYZ* colourspace to *NTSC RGB* colourspace matrix.
XYZ_TO_NTSC_RGB_MATRIX : array_like, (3, 3)
"""
def _ntsc_rgb_transfer_function(value):
"""
Defines the *NTSC RGB* value colourspace transfer function.
Parameters
----------
value : numeric
value.
Returns
-------
numeric
Companded value.
"""
return value ** (1 / 2.2)
def _ntsc_rgb_inverse_transfer_function(value):
"""
Defines the *NTSC RGB* value colourspace inverse transfer
function.
Parameters
----------
value : numeric
value.
Returns
-------
numeric
Companded value.
"""
return value ** 2.2
NTSC_RGB_TRANSFER_FUNCTION = _ntsc_rgb_transfer_function
"""
Transfer function from linear to *NTSC RGB* colourspace.
NTSC_RGB_TRANSFER_FUNCTION : object
"""
NTSC_RGB_INVERSE_TRANSFER_FUNCTION = _ntsc_rgb_inverse_transfer_function
"""
Inverse transfer function from *NTSC RGB* colourspace to linear.
NTSC_RGB_INVERSE_TRANSFER_FUNCTION : object
"""
NTSC_RGB_COLOURSPACE = RGB_Colourspace(
'NTSC RGB',
NTSC_RGB_PRIMARIES,
NTSC_RGB_WHITEPOINT,
NTSC_RGB_ILLUMINANT,
NTSC_RGB_TO_XYZ_MATRIX,
XYZ_TO_NTSC_RGB_MATRIX,
NTSC_RGB_TRANSFER_FUNCTION,
NTSC_RGB_INVERSE_TRANSFER_FUNCTION)
"""
*NTSC RGB* colourspace.
NTSC_RGB_COLOURSPACE : RGB_Colourspace
"""
Colour 0.3