colour.colorimetry.blackbody Module¶

Blackbody - Planckian Radiator¶

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

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

[1]	CIE 015:2004 Colorimetry, 3rd edition: Appendix E. Information on the Use of Planck”s Equation for Standard Air.

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 $n=1$.
Returns:	Radiance in watts per steradian per square metre.
Return type:	numeric

Examples

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

colour.colorimetry.blackbody.blackbody_spectral_radiance(*args, **kwds)¶

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

[1]	CIE 015:2004 Colorimetry, 3rd edition: Appendix E. Information on the Use of Planck”s Equation for Standard Air.

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 $n=1$.
Returns:	Radiance in watts per steradian per square metre.
Return type:	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 $n=1$.
Returns:	Blackbody spectral power distribution.
Return type:	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...>