skimage2.color.xyz2lab#

skimage2.color.xyz2lab(xyz, illuminant='D65', observer='2', *, channel_axis=-1)[source]#

XYZ to CIE-LAB color space conversion.

Parameters:

xyzarray_like of shape (…, C=3, …): The image in XYZ format. By default, the final dimension denotes channels.
illuminant{“A”, “B”, “C”, “D50”, “D55”, “D65”, “D75”, “E”}, optional: The name of the illuminant (the function is NOT case sensitive).
observer{“2”, “10”, “R”}, optional: One of: 2-degree observer, 10-degree observer, or ‘R’ observer as in R function grDevices::convertColor.
channel_axisint, optional: This parameter indicates which axis of the array corresponds to channels.

Added in version 0.19: channel_axis was added in 0.19.

Returns:

outndarray of shape (…, C=3, …): The image in CIE-LAB format. Same dimensions as input.

Raises:

ValueError: If xyz is not at least 2-D with shape (…, C=3, …).
ValueError: If either the illuminant or the observer angle is unsupported or unknown.

Notes

By default Observer=”2”, Illuminant=”D65”. CIE XYZ tristimulus values x_ref=95.047, y_ref=100., z_ref=108.883. See function xyz_tristimulus_values() for a list of supported illuminants.

References

[1]

http://www.easyrgb.com/en/math.php

[2]

https://en.wikipedia.org/wiki/CIELAB_color_space

Examples

>>> from _skimage2 import data
>>> from _skimage2.color import rgb2xyz, xyz2lab
>>> img = data.astronaut()
>>> img_xyz = rgb2xyz(img)
>>> img_lab = xyz2lab(img_xyz)