colour.temperature Package¶

Sub-Modules¶

Module Contents¶

colour.temperature.CCT_to_uv(CCT, Duv=0, method=u'Ohno 2013', **kwargs)¶

Returns the CIE UCS colourspace uv chromaticity coordinates from given correlated colour temperature \(T_{cp}\) and \(\Delta_{uv}\) using given method.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\). Duv (numeric) – \(\Delta_{uv}\). method (unicode) – (‘Ohno 2013’, ‘Robertson 1968’) Computation method. **kwargs (**) – Keywords arguments.
Returns:	CIE UCS colourspace uv chromaticity coordinates.
Return type:	tuple
Raises:	ValueError – If the computation method is not defined.

Examples

>>> from colour import STANDARD_OBSERVERS_CMFS
>>> cmfs = 'CIE 1931 2 Degree Standard Observer'
>>> cmfs = STANDARD_OBSERVERS_CMFS.get(cmfs)
>>> CCT = 6507.4342201047066
>>> Duv = 0.003223690901512735
>>> CCT_to_uv(CCT, Duv, cmfs=cmfs)  
(0.1978003..., 0.3122005...)

colour.temperature.CCT_to_uv_ohno2013(CCT, Duv=0, cmfs=<colour.colorimetry.cmfs.XYZ_ColourMatchingFunctions object at 0x102cf5c10>)¶

Returns the CIE UCS colourspace uv chromaticity coordinates from given correlated colour temperature \(T_{cp}\), \(\Delta_{uv}\) and colour matching functions using Yoshi Ohno (2013) method.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\). Duv (numeric, optional) – \(\Delta_{uv}\). cmfs (XYZ_ColourMatchingFunctions, optional) – Standard observer colour matching functions.
Returns:	CIE UCS colourspace uv chromaticity coordinates.
Return type:	tuple

References

[4]	Yoshi Ohno, Practical Use and Calculation of CCT and Duv, DOI: https://doi.org/10.1080/15502724.2014.839020

Examples

>>> from colour import STANDARD_OBSERVERS_CMFS
>>> cmfs = 'CIE 1931 2 Degree Standard Observer'
>>> cmfs = STANDARD_OBSERVERS_CMFS.get(cmfs)
>>> CCT = 6507.4342201047066
>>> Duv = 0.003223690901512735
>>> CCT_to_uv_ohno2013(CCT, Duv, cmfs)  
(0.1978003..., 0.3122005...)

colour.temperature.CCT_to_uv_robertson1968(CCT, Duv=0)¶

Returns the CIE UCS colourspace uv chromaticity coordinates from given correlated colour temperature \(T_{cp}\) and \(\Delta_{uv}\) using Robertson (1968) method.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\). Duv (numeric) – \(\Delta_{uv}\).
Returns:	CIE UCS colourspace uv chromaticity coordinates.
Return type:	tuple

References

[7]	Wyszecki & Stiles, Color Science - Concepts and Methods Data and Formulae - Second Edition, Wiley Classics Library Edition, published 2000, ISBN-10: 0-471-39918-3, page 227.

[8]	Adobe DNG SDK 1.3.0.0: dng_sdk_1_3/dng_sdk/source/dng_temperature.cpp: dng_temperature::xy_coord.

Examples

>>> CCT = 6500.0081378199056
>>> Duv = 0.0083333312442250979
>>> CCT_to_uv_robertson1968(CCT, Duv)  
(0.1937413..., 0.3152210...)

colour.temperature.uv_to_CCT(uv, method=u'Ohno 2013', **kwargs)¶

Returns the correlated colour temperature \(T_{cp}\) and \(\Delta_{uv}\) from given CIE UCS colourspace uv chromaticity coordinates using given method.

Parameters:	uv (array_like) – CIE UCS colourspace uv chromaticity coordinates. method (unicode) – (‘Ohno 2013’, ‘Robertson 1968’) Computation method. **kwargs (**) – Keywords arguments.
Returns:	Correlated colour temperature \(T_{cp}\), \(\Delta_{uv}\).
Return type:	tuple
Raises:	ValueError – If the computation method is not defined.

Examples

>>> from colour import STANDARD_OBSERVERS_CMFS
>>> cmfs = 'CIE 1931 2 Degree Standard Observer'
>>> cmfs = STANDARD_OBSERVERS_CMFS.get(cmfs)
>>> uv_to_CCT((0.1978, 0.3122), cmfs=cmfs)  
(6507.5470349..., 0.0032236...)

colour.temperature.uv_to_CCT_ohno2013(uv, cmfs=<colour.colorimetry.cmfs.XYZ_ColourMatchingFunctions object at 0x102cf5c10>, start=1000, end=100000, count=10, iterations=6)¶

Returns the correlated colour temperature \(T_{cp}\) and \(\Delta_{uv}\) from given CIE UCS colourspace uv chromaticity coordinates, colour matching functions and temperature range using Yoshi Ohno (2013) method.

The iterations parameter defines the calculations precision: The higher its value, the more planckian tables will be generated through cascade expansion in order to converge to the exact solution.

Parameters:	uv (array_like) – CIE UCS colourspace uv chromaticity coordinates. cmfs (XYZ_ColourMatchingFunctions, optional) – Standard observer colour matching functions. start (numeric, optional) – Temperature range start in kelvins. end (numeric, optional) – Temperature range end in kelvins. count (int, optional) – Temperatures count in the planckian tables. iterations (int, optional) – Number of planckian tables to generate.
Returns:	Correlated colour temperature \(T_{cp}\), \(\Delta_{uv}\).
Return type:	tuple

References

[3]	Yoshi Ohno, Practical Use and Calculation of CCT and Duv, DOI: https://doi.org/10.1080/15502724.2014.839020

Examples

>>> from colour import STANDARD_OBSERVERS_CMFS
>>> cmfs = 'CIE 1931 2 Degree Standard Observer'
>>> cmfs = STANDARD_OBSERVERS_CMFS.get(cmfs)
>>> uv_to_CCT_ohno2013((0.1978, 0.3122), cmfs)  
(6507.5470349..., 0.0032236...)

colour.temperature.uv_to_CCT_robertson1968(uv)¶

Returns the correlated colour temperature \(T_{cp}\) and \(\Delta_{uv}\) from given CIE UCS colourspace uv chromaticity coordinates using Robertson (1968) method.

Parameters:	uv (array_like) – CIE UCS colourspace uv chromaticity coordinates.
Returns:	Correlated colour temperature \(T_{cp}\), \(\Delta_{uv}\).
Return type:	tuple

References

[5]	Wyszecki & Stiles, Color Science - Concepts and Methods Data and Formulae - Second Edition, Wiley Classics Library Edition, published 2000, ISBN-10: 0-471-39918-3, page 227.

[6]	Adobe DNG SDK 1.3.0.0: dng_sdk_1_3/dng_sdk/source/dng_temperature.cpp: dng_temperature::Set_xy_coord.

Examples

>>> uv = (0.19374137599822966, 0.31522104394059397)
>>> uv_to_CCT_robertson1968(uv)  
(6500.0162879..., 0.0083333...)

colour.temperature.CCT_to_xy(CCT, method=u'Kang 2002')¶

Returns the CIE XYZ colourspace xy chromaticity coordinates from given correlated colour temperature \(T_{cp}\) using given method.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\). method (unicode (‘Kang 2002’, ‘CIE Illuminant D Series’)) – Computation method.
Returns:	xy chromaticity coordinates.
Return type:	tuple

colour.temperature.CCT_to_xy_kang2002(CCT)¶

Returns the CIE XYZ colourspace xy chromaticity coordinates from given correlated colour temperature \(T_{cp}\) using Kang, Moon, Hong, Lee, Cho and Kim (2002) method.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\).
Returns:	xy chromaticity coordinates.
Return type:	tuple
Raises:	ValueError – If the correlated colour temperature is not in appropriate domain.

References

[11]	Design of Advanced Color - Temperature Control System for HDTV Applications

Examples

>>> CCT_to_xy_kang2002(6504.38938305)  
(0.3134259..., 0.3235959...)

colour.temperature.CCT_to_xy_illuminant_D(CCT)¶

Converts from the correlated colour temperature \(T_{cp}\) of a CIE Illuminant D Series to the chromaticity of that CIE Illuminant D Series.

Parameters:	CCT (numeric) – Correlated colour temperature \(T_{cp}\).
Returns:	xy chromaticity coordinates.
Return type:	tuple
Raises:	ValueError – If the correlated colour temperature is not in appropriate domain.

References

[12]	Wyszecki & Stiles, Color Science - Concepts and Methods Data and Formulae - Second Edition, Wiley Classics Library Edition, published 2000, ISBN-10: 0-471-39918-3, page 145.

Examples

>>> CCT_to_xy_illuminant_D(6504.38938305)  
(0.3127077..., 0.3291128...)

colour.temperature.xy_to_CCT(xy, method=u'McCamy 1992', **kwargs)¶

Returns the correlated colour temperature \(T_{cp}\) from given CIE XYZ colourspace xy chromaticity coordinates using given method.

Parameters:	xy (array_like) – xy chromaticity coordinates. method (unicode (‘McCamy 1992’, ‘Hernandez 1999’)) – Computation method. **kwargs (**) – Keywords arguments.
Returns:	Correlated colour temperature \(T_{cp}\).
Return type:	numeric

colour.temperature.xy_to_CCT_mccamy1992(xy)¶

Returns the correlated colour temperature \(T_{cp}\) from given CIE XYZ colourspace xy chromaticity coordinates using McCamy (1992) method.

Parameters:	xy (array_like) – xy chromaticity coordinates.
Returns:	Correlated colour temperature \(T_{cp}\).
Return type:	numeric

References

[9]	http://en.wikipedia.org/wiki/Color_temperature#Approximation (Last accessed 28 June 2014)

Examples

>>> xy_to_CCT_mccamy1992((0.31271, 0.32902))  
6504.3893830...

colour.temperature.xy_to_CCT_hernandez1999(xy)¶

Returns the correlated colour temperature \(T_{cp}\) from given CIE XYZ colourspace xy chromaticity coordinates using Hernandez-Andres, Lee & Romero (1999) method.

Parameters:	xy (array_like) – xy chromaticity coordinates.
Returns:	Correlated colour temperature \(T_{cp}\).
Return type:	numeric

References

[10]	Calculating correlated color temperatures across the entire gamut of daylight and skylight chromaticities, DOI: https://doi.org/10.1364/AO.38.005703

Examples

>>> xy_to_CCT_hernandez1999((0.31271, 0.32902))  
6500.0421533...