Source code for colour.colorimetry.illuminants

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Illuminants
===========

Defines *CIE* illuminants computation related objects.

See Also
--------
`Illuminants IPython Notebook
<http://nbviewer.ipython.org/github/colour-science/colour-ipython/blob/master/notebooks/colorimetry/illuminants.ipynb>`_  # noqa
colour.colorimetry.dataset.illuminants.d_illuminants_s_spds,
colour.colorimetry.spectrum.SpectralPowerDistribution
"""

from __future__ import division, unicode_literals

from colour.colorimetry import (
    D_ILLUMINANTS_S_SPDS,
    SpectralPowerDistribution)

__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__ = ['D_illuminant_relative_spd']


[docs]def D_illuminant_relative_spd(xy): """ Returns the relative spectral power distribution of given *CIE Standard Illuminant D Series* using given *xy* chromaticity coordinates. References ---------- .. [1] Wyszecki, G., & Stiles, W. S. (2000). CIE Method of Calculating D-Illuminants. In Color Science: Concepts and Methods, Quantitative Data and Formulae (pp. 145–146). Wiley. ISBN:978-0471399186 .. [2] Lindbloom, B. (2007). Spectral Power Distribution of a CIE D-Illuminant. Retrieved April 05, 2014, from http://www.brucelindbloom.com/Eqn_DIlluminant.html Parameters ---------- xy : array_like *xy* chromaticity coordinates. Returns ------- SpectralPowerDistribution *CIE Standard Illuminant D Series* relative spectral power distribution. Examples -------- >>> import numpy as np >>> xy = np.array([0.34567, 0.35850]) >>> D_illuminant_relative_spd(xy) # doctest: +ELLIPSIS <colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x...> """ M = 0.0241 + 0.2562 * xy[0] - 0.7341 * xy[1] M1 = (-1.3515 - 1.7703 * xy[0] + 5.9114 * xy[1]) / M M2 = (0.0300 - 31.4424 * xy[0] + 30.0717 * xy[1]) / M distribution = {} for i in D_ILLUMINANTS_S_SPDS.get('S0').shape: S0 = D_ILLUMINANTS_S_SPDS.get('S0').get(i) S1 = D_ILLUMINANTS_S_SPDS.get('S1').get(i) S2 = D_ILLUMINANTS_S_SPDS.get('S2').get(i) distribution[i] = S0 + M1 * S1 + M2 * S2 return SpectralPowerDistribution('CIE Standard Illuminant D Series', distribution)