# colour.colorimetry.lefs Module¶

## Luminous Efficiency Functions Spectral Power Distributions¶

Defines luminous efficiency functions computation related objects.

Luminous Efficiency Functions IPython Notebook colour.colorimetry.dataset.lefs, colour.colorimetry.spectrum.SpectralPowerDistribution

References

 [1] http://en.wikipedia.org/wiki/Mesopic#Mesopic_weighting_function (Last accessed 20 June 2014)
colour.colorimetry.lefs.mesopic_weighting_function(wavelength, Lp, source=u'Blue Heavy', method=u'MOVE', photopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x102e320d0>, scotopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x102e32290>)[source]

Calculates the mesopic weighting function factor at given wavelength $$\lambda$$ using the photopic luminance $$L_p$$.

Parameters: wavelength (numeric) – Wavelength $$\lambda$$ to calculate the mesopic weighting function factor. Lp (numeric) – Photopic luminance $$L_p$$. source (unicode) – (‘Blue Heavy’, ‘Red Heavy’), Light source colour temperature. method (unicode) – (‘MOVE’, ‘LRC’), Method to calculate the weighting factor. photopic_lef (SpectralPowerDistribution) – $$V(\lambda)$$ photopic luminous efficiency function. scotopic_lef (SpectralPowerDistribution) – $$V^\prime(\lambda)$$ scotopic luminous efficiency function. Mesopic weighting function factor. numeric KeyError – If wavelength $$\lambda$$ is not available in either luminous efficiency function.

Examples

>>> mesopic_weighting_function(500, 0.2)
0.7052200...

colour.colorimetry.lefs.mesopic_luminous_efficiency_function(Lp, source=u'Blue Heavy', method=u'MOVE', photopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x102e320d0>, scotopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x102e32290>)[source]

Returns the mesopic luminous efficiency function $$V_m(\lambda)$$ for given photopic luminance $$L_p$$.

Parameters: Lp (numeric) – Photopic luminance $$L_p$$. source (unicode) – (‘Blue Heavy’, ‘Red Heavy’), Light source colour temperature. method (unicode) – (‘MOVE’, ‘LRC’), Method to calculate the weighting factor. photopic_lef (SpectralPowerDistribution) – $$V(\lambda)$$ photopic luminous efficiency function. scotopic_lef (SpectralPowerDistribution) – $$V^\prime(\lambda)$$ scotopic luminous efficiency function. Mesopic luminous efficiency function $$V_m(\lambda)$$. SpectralPowerDistribution

Examples

>>> mesopic_luminous_efficiency_function(0.2)
<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x...>