# colour.colorimetry.blackbody Module¶

Defines objects to compute the spectral radiance of a planckian radiator and its spectral power distribution.

Blackbody IPython Notebook colour.colorimetry.spectrum.SpectralPowerDistribution

colour.colorimetry.blackbody.planck_law(*args, **kwds)[source]

Returns the spectral radiance of a blackbody at thermodynamic temperature $$T[K]$$ in a medium having index of refraction $$n$$.

Notes

The following form implementation is expressed in term of wavelength. The SI unit of radiance is watts per steradian per square metre.

References

Parameters: wavelength (numeric) – Wavelength in meters. temperature (numeric) – Temperature $$T[K]$$ in kelvin degrees. c1 (numeric, optional) – The official value of $$c1$$ is provided by the Committee on Data for Science and Technology (CODATA), and is $$c1=3,741771x10.16\ W/m_2$$ (Mohr and Taylor, 2000). c2 (numeric, optional) – Since $$T$$ is measured on the International Temperature Scale, the value of $$c2$$ used in colorimetry should follow that adopted in the current International Temperature Scale (ITS-90) (Preston-Thomas, 1990; Mielenz et aI., 1991), namely $$c2=1,4388x10.2\ m/K$$. n (numeric, optional) – Medium index of refraction. For dry air at 15°C and 101 325 Pa, containing 0,03 percent by volume of carbon dioxide, it is approximately 1,00028 throughout the visible region although CIE 15:2004 recommends using $$n=1$$. Radiance in watts per steradian per square metre. numeric

Examples

>>> # Doctests ellipsis for Python 2.x compatibility.
>>> planck_law(500 * 1e-9, 5500)
20472701909806.5...


Returns the spectral radiance of a blackbody at thermodynamic temperature $$T[K]$$ in a medium having index of refraction $$n$$.

Notes

The following form implementation is expressed in term of wavelength. The SI unit of radiance is watts per steradian per square metre.

References

Parameters: wavelength (numeric) – Wavelength in meters. temperature (numeric) – Temperature $$T[K]$$ in kelvin degrees. c1 (numeric, optional) – The official value of $$c1$$ is provided by the Committee on Data for Science and Technology (CODATA), and is $$c1=3,741771x10.16\ W/m_2$$ (Mohr and Taylor, 2000). c2 (numeric, optional) – Since $$T$$ is measured on the International Temperature Scale, the value of $$c2$$ used in colorimetry should follow that adopted in the current International Temperature Scale (ITS-90) (Preston-Thomas, 1990; Mielenz et aI., 1991), namely $$c2=1,4388x10.2\ m/K$$. n (numeric, optional) – Medium index of refraction. For dry air at 15°C and 101 325 Pa, containing 0,03 percent by volume of carbon dioxide, it is approximately 1,00028 throughout the visible region although CIE 15:2004 recommends using $$n=1$$. Radiance in watts per steradian per square metre. numeric

Examples

>>> # Doctests ellipsis for Python 2.x compatibility.
>>> planck_law(500 * 1e-9, 5500)
20472701909806.5...

colour.colorimetry.blackbody.blackbody_spd(temperature, shape=SpectralShape(360, 830, 1), c1=3.741771e-16, c2=0.014388, n=1)[source]

Returns the spectral power distribution of the planckian radiator for given temperature $$T[K]$$.

Parameters: temperature (numeric) – Temperature $$T[K]$$ in kelvin degrees. shape (SpectralShape, optional) – Spectral shape used to create the spectral power distribution of the planckian radiator. c1 (numeric, optional) – The official value of $$c1$$ is provided by the Committee on Data for Science and Technology (CODATA), and is $$c1=3,741771x10.16\ W/m_2$$ (Mohr and Taylor, 2000). c2 (numeric, optional) – Since $$T$$ is measured on the International Temperature Scale, the value of $$c2$$ used in colorimetry should follow that adopted in the current International Temperature Scale (ITS-90) (Preston-Thomas, 1990; Mielenz et aI., 1991), namely $$c2=1,4388x10.2\ m/K$$. n (numeric, optional) – Medium index of refraction. For dry air at 15°C and 101 325 Pa, containing 0,03 percent by volume of carbon dioxide, it is approximately 1,00028 throughout the visible region although CIE 15:2004 recommends using $$n=1$$. Blackbody spectral power distribution. SpectralPowerDistribution

Examples

>>> from colour import STANDARD_OBSERVERS_CMFS
>>> cmfs = STANDARD_OBSERVERS_CMFS.get('CIE 1931 2 Degree Standard Observer')
>>> blackbody_spd(5000, cmfs.shape)
<colour.colorimetry.spectrum.SpectralPowerDistribution object at 0x...>