Source code for colour.colorimetry.photometry

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

"""
Photometry
==========

Defines photometric quantities computation related objects.

See Also
--------
`Photometry IPython Notebook
<http://nbviewer.ipython.org/github/colour-science/colour-ipython/blob/master/notebooks/colorimetry/photometry.ipynb>`_  # noqa

References
----------
.. [1]  Wikipedia. (n.d.). Luminosity function. Retrieved October 20, 2014,
        from https://en.wikipedia.org/wiki/Luminosity_function#Details

.. [2]  Ohno, Y., & Davis, W. (2008). NIST CQS simulation 7.4. Retrieved from
        http://cie2.nist.gov/TC1-69/NIST CQS simulation 7.4.xls
"""

from __future__ import division, unicode_literals

import numpy as np

from colour.colorimetry import PHOTOPIC_LEFS
from colour.constants import K_M

__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__ = ['luminous_flux']


[docs]def luminous_flux(spd, lef=PHOTOPIC_LEFS.get( 'CIE 1924 Photopic Standard Observer'), K_m=K_M): """ Returns the *luminous flux* for given spectral power distribution using the given luminous efficiency function. Parameters ---------- spd : SpectralPowerDistribution test spectral power distribution lef : SpectralPowerDistribution, optional :math:`V(\lambda)` luminous efficiency function. Returns ------- numeric Luminous flux Examples -------- >>> from colour import LIGHT_SOURCES_RELATIVE_SPDS >>> spd = LIGHT_SOURCES_RELATIVE_SPDS.get('Neodimium Incandescent') >>> luminous_flux(spd) # doctest: +ELLIPSIS 23807.6555273... """ lef = lef.clone().align(spd.shape, left=0, right=0) spd = spd.clone() * lef flux = K_m * np.trapz(spd.values, spd.wavelengths) return flux