colour.models.rgb.rgb_colourspace Module

RGB Colourspace & Transformations

Defines the RGB_Colourspace class for the RGB colourspaces dataset from colour.models.dataset.aces_rgb, etc... and the following RGB colourspace transformations:

See also

RGB Colourspaces IPython Notebook

class colour.models.rgb.rgb_colourspace.RGB_Colourspace(name, primaries, whitepoint, illuminant=None, RGB_to_XYZ_matrix=None, XYZ_to_RGB_matrix=None, encoding_cctf=None, decoding_cctf=None)[source]

Bases: object

Implements support for the RGB colourspaces dataset from colour.models.dataset.aces_rgb, etc....

Parameters:
  • name (unicode) – RGB colourspace name.
  • primaries (array_like) – RGB colourspace primaries.
  • whitepoint (array_like) – RGB colourspace whitepoint.
  • illuminant (unicode, optional) – RGB colourspace whitepoint name as illuminant.
  • RGB_to_XYZ_matrix (array_like, optional) – Transformation matrix from colourspace to CIE XYZ tristimulus values.
  • XYZ_to_RGB_matrix (array_like, optional) – Transformation matrix from CIE XYZ tristimulus values to colourspace.
  • encoding_cctf (object, optional) – Encoding colour component transfer function (Encoding CCTF) / opto-electronic transfer function (OETF / OECF) that maps estimated tristimulus values in a scene to \(R'G'B'\) video component signal value.
  • decoding_cctf (object, optional) – Decoding colour component transfer function (Decoding CCTF) / electro-optical transfer function (EOTF / EOCF) that maps an \(R'G'B'\) video component signal value to tristimulus values at the display.
name
primaries
whitepoint
illuminant
RGB_to_XYZ_matrix
XYZ_to_RGB_matrix
encoding_cctf
decoding_cctf
RGB_to_XYZ_matrix

Property for self._to_XYZ private attribute.

Returns:self._to_XYZ.
Return type:array_like, (3, 3)
XYZ_to_RGB_matrix

Property for self._to_RGB private attribute.

Returns:self._to_RGB.
Return type:array_like, (3, 3)
decoding_cctf

Property for self._decoding_cctf private attribute.

Returns:self._decoding_cctf.
Return type:object
encoding_cctf

Property for self._encoding_cctf private attribute.

Returns:self._encoding_cctf.
Return type:object
illuminant

Property for self._illuminant private attribute.

Returns:self._illuminant.
Return type:unicode
name

Property for self._name private attribute.

Returns:self._name.
Return type:unicode
primaries

Property for self._primaries private attribute.

Returns:self._primaries.
Return type:array_like, (3, 2)
whitepoint

Property for self._whitepoint private attribute.

Returns:self._whitepoint.
Return type:array_like
colour.models.rgb.rgb_colourspace.XYZ_to_RGB(XYZ, illuminant_XYZ, illuminant_RGB, XYZ_to_RGB_matrix, chromatic_adaptation_transform=u'CAT02', encoding_cctf=None)[source]

Converts from CIE XYZ tristimulus values to given RGB colourspace.

Parameters:
  • XYZ (array_like) – CIE XYZ tristimulus values.
  • illuminant_XYZ (array_like) – CIE XYZ tristimulus values illuminant xy chromaticity coordinates or CIE xyY colourspace array.
  • illuminant_RGB (array_like) – RGB colourspace illuminant xy chromaticity coordinates or CIE xyY colourspace array.
  • XYZ_to_RGB_matrix (array_like) – Normalised primary matrix.
  • chromatic_adaptation_transform (unicode, optional) – {‘CAT02’, ‘XYZ Scaling’, ‘Von Kries’, ‘Bradford’, ‘Sharp’, ‘Fairchild’, ‘CMCCAT97’, ‘CMCCAT2000’, ‘CAT02_BRILL_CAT’, ‘Bianco’, ‘Bianco PC’}, Chromatic adaptation transform.
  • encoding_cctf (object, optional) – Encoding colour component transfer function (Encoding CCTF) or opto-electronic transfer function (OETF / OECF).
Returns:

RGB colourspace array.
Return type:

ndarray

Notes

  • Input CIE XYZ tristimulus values are in domain [0, 1].
  • Input illuminant_XYZ xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Input illuminant_RGB xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Output RGB colourspace array is in range [0, 1].

Examples

>>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
>>> illuminant_XYZ = np.array([0.34570, 0.35850])
>>> illuminant_RGB = np.array([0.31270, 0.32900])
>>> chromatic_adaptation_transform = 'Bradford'
>>> XYZ_to_RGB_matrix = np.array([
...     [3.24062548, -1.53720797, -0.49862860],
...     [-0.96893071, 1.87575606, 0.04151752],
...     [0.05571012, -0.20402105, 1.05699594]])
>>> XYZ_to_RGB(
...     XYZ,
...     illuminant_XYZ,
...     illuminant_RGB,
...     XYZ_to_RGB_matrix,
...     chromatic_adaptation_transform)  
array([ 0.0110015...,  0.1273504...,  0.1163271...])
colour.models.rgb.rgb_colourspace.RGB_to_XYZ(RGB, illuminant_RGB, illuminant_XYZ, RGB_to_XYZ_matrix, chromatic_adaptation_transform=u'CAT02', decoding_cctf=None)[source]

Converts from given RGB colourspace to CIE XYZ tristimulus values.

Parameters:
  • RGB (array_like) – RGB colourspace array.
  • illuminant_RGB (array_like) – RGB colourspace illuminant chromaticity coordinates or CIE xyY colourspace array.
  • illuminant_XYZ (array_like) – CIE XYZ tristimulus values illuminant chromaticity coordinates or CIE xyY colourspace array.
  • RGB_to_XYZ_matrix (array_like) – Normalised primary matrix.
  • chromatic_adaptation_transform (unicode, optional) – {‘CAT02’, ‘XYZ Scaling’, ‘Von Kries’, ‘Bradford’, ‘Sharp’, ‘Fairchild’, ‘CMCCAT97’, ‘CMCCAT2000’, ‘CAT02_BRILL_CAT’, ‘Bianco’, ‘Bianco PC’}, Chromatic adaptation transform.
  • decoding_cctf (object, optional) – Decoding colour component transfer function (Decoding CCTF) or electro-optical transfer function (EOTF / EOCF).
Returns:

CIE XYZ tristimulus values.
Return type:

ndarray

Notes

  • Input RGB colourspace array is in domain [0, 1].
  • Input illuminant_RGB xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Input illuminant_XYZ xy chromaticity coordinates or CIE xyY colourspace array are in domain [0, \(\infty\)].
  • Output CIE XYZ tristimulus values are in range [0, 1].

Examples

>>> RGB = np.array([0.01100154,  0.12735048,  0.11632713])
>>> illuminant_RGB = np.array([0.31270, 0.32900])
>>> illuminant_XYZ = np.array([0.34570, 0.35850])
>>> chromatic_adaptation_transform = 'Bradford'
>>> RGB_to_XYZ_matrix = np.array([
...     [0.41240000, 0.35760000, 0.18050000],
...     [0.21260000, 0.71520000, 0.07220000],
...     [0.01930000, 0.11920000, 0.95050000]])
>>> RGB_to_XYZ(
...     RGB,
...     illuminant_RGB,
...     illuminant_XYZ,
...     RGB_to_XYZ_matrix,
...     chromatic_adaptation_transform)  
array([ 0.0704953...,  0.1008    ,  0.0955831...])
colour.models.rgb.rgb_colourspace.RGB_to_RGB(RGB, input_colourspace, output_colourspace, chromatic_adaptation_transform=u'CAT02')[source]

Converts from given input RGB colourspace to output RGB colourspace using given chromatic adaptation method.

Parameters:
  • RGB (array_like) – RGB colourspace array.
  • input_colourspace (RGB_Colourspace) – RGB input colourspace.
  • output_colourspace (RGB_Colourspace) – RGB output colourspace.
  • chromatic_adaptation_transform (unicode, optional) – {‘CAT02’, ‘XYZ Scaling’, ‘Von Kries’, ‘Bradford’, ‘Sharp’, ‘Fairchild’, ‘CMCCAT97’, ‘CMCCAT2000’, ‘CAT02_BRILL_CAT’, ‘Bianco’, ‘Bianco PC’}, Chromatic adaptation transform.
Returns:

RGB colourspace array.
Return type:

ndarray

Notes

  • Input / output RGB colourspace arrays are in domain / range [0, 1].
  • Input / output RGB colourspace arrays are assumed to be representing linear light values.

Examples

>>> from colour import sRGB_COLOURSPACE, PROPHOTO_RGB_COLOURSPACE
>>> RGB = np.array([0.01103742, 0.12734226, 0.11632971])
>>> RGB_to_RGB(
...     RGB,
...     sRGB_COLOURSPACE,
...     PROPHOTO_RGB_COLOURSPACE)  
array([ 0.0643538...,  0.1157289...,  0.1158038...])