colour.colorimetry.lefs Module

Luminous Efficiency Functions Spectral Power Distributions

Defines luminous efficiency functions computation related objects.

See also

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

References

[1]Wikipedia. (n.d.). Mesopic weighting function. Retrieved June 20, 2014, from http://en.wikipedia.org/wiki/Mesopic_vision#Mesopic_weighting_function
colour.colorimetry.lefs.mesopic_weighting_function(wavelength, Lp, source=u'Blue Heavy', method=u'MOVE', photopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x2b437a9a0f50>, scotopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x2b437a9a9150>)[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, optional) – {‘Blue Heavy’, ‘Red Heavy’}, Light source colour temperature.
  • method (unicode, optional) – {‘MOVE’, ‘LRC’}, Method to calculate the weighting factor.
  • photopic_lef (SpectralPowerDistribution, optional) – \(V(\lambda)\) photopic luminous efficiency function.
  • scotopic_lef (SpectralPowerDistribution, optional) – \(V^\prime(\lambda)\) scotopic luminous efficiency function.
Returns:

Mesopic weighting function factor.
Return type:

numeric
Raises:

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 0x2b437a9a0f50>, scotopic_lef=<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x2b437a9a9150>)[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, optional) – {‘Blue Heavy’, ‘Red Heavy’}, Light source colour temperature.
  • method (unicode, optional) – {‘MOVE’, ‘LRC’}, Method to calculate the weighting factor.
  • photopic_lef (SpectralPowerDistribution, optional) – \(V(\lambda)\) photopic luminous efficiency function.
  • scotopic_lef (SpectralPowerDistribution, optional) – \(V^\prime(\lambda)\) scotopic luminous efficiency function.
Returns:

Mesopic luminous efficiency function \(V_m(\lambda)\).
Return type:

SpectralPowerDistribution

Examples

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