colour.xy_to_xyY

colour.xy_to_xyY(xy, Y=1)[source]

Converts from CIE xy chromaticity coordinates to CIE xyY colourspace by extending the array last dimension with given \(Y\) luminance.

xy argument with last dimension being equal to 3 will be assumed to be a CIE xyY colourspace array argument and will be returned directly by the definition.

Parameters:
  • xy (array_like) – CIE xy chromaticity coordinates or CIE xyY colourspace array.
  • Y (numeric, optional) – Optional \(Y\) luminance value used to construct the CIE xyY colourspace array, the default \(Y\) luminance value is 1.
Returns:

CIE xyY colourspace array.

Return type:

ndarray

Notes

Domain Scale - Reference Scale - 1
xy [0, 1] [0, 1]
Range Scale - Reference Scale - 1
xyY [0, 1] [0, 1]
  • This definition is a convenient object provided to implement support of illuminant argument luminance value in various colour.models package objects such as colour.Lab_to_XYZ() or colour.Luv_to_XYZ().

References

[Wikipedia2005]

Examples

>>> xy = np.array([0.54369557, 0.32107944])
>>> xy_to_xyY(xy)  # doctest: +ELLIPSIS
array([ 0.5436955...,  0.3210794...,  1.        ])
>>> xy = np.array([0.54369557, 0.32107944, 1.00000000])
>>> xy_to_xyY(xy)  # doctest: +ELLIPSIS
array([ 0.5436955...,  0.3210794...,  1.        ])
>>> xy = np.array([0.54369557, 0.32107944])
>>> xy_to_xyY(xy, 100)  # doctest: +ELLIPSIS
array([   0.5436955...,    0.3210794...,  100.        ])