Processing math: 100%

colour.temperature Package

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 Tcp and Δuv using given method.

Parameters:
  • CCT (numeric) – Correlated colour temperature Tcp.
  • Duv (numeric) – Δuv.
  • 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 0x102e0ccd0>)

Returns the CIE UCS colourspace uv chromaticity coordinates from given correlated colour temperature Tcp, Δuv and colour matching functions using Yoshi Ohno (2013) method.

Parameters:
  • CCT (numeric) – Correlated colour temperature Tcp.
  • Duv (numeric, optional) – Δuv.
  • 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 Tcp and Δuv using Robertson (1968) method.

Parameters:
  • CCT (numeric) – Correlated colour temperature Tcp.
  • Duv (numeric) – Δuv.
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 Tcp and Δuv 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 Tcp, Δuv.

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 0x102e0ccd0>, start=1000, end=100000, count=10, iterations=6)

Returns the correlated colour temperature Tcp and Δuv 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 Tcp, Δuv.

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 Tcp and Δuv 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 Tcp, Δuv.
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 Tcp using given method.

Parameters:
  • CCT (numeric) – Correlated colour temperature Tcp.
  • 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 Tcp using Kang, Moon, Hong, Lee, Cho and Kim (2002) method.

Parameters:CCT (numeric) – Correlated colour temperature Tcp.
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 Tcp of a CIE Illuminant D Series to the chromaticity of that CIE Illuminant D Series.

Parameters:CCT (numeric) – Correlated colour temperature Tcp.
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 Tcp 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 Tcp.

Return type:

numeric

colour.temperature.xy_to_CCT_mccamy1992(xy)

Returns the correlated colour temperature Tcp from given CIE XYZ colourspace xy chromaticity coordinates using McCamy (1992) method.

Parameters:xy (array_like) – xy chromaticity coordinates.
Returns:Correlated colour temperature Tcp.
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 Tcp 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 Tcp.
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...