xyz2lab

xyz2lab

skimage.color.xyz2lab(xyz, illuminant='D65', observer='2') [source]

XYZ to CIE-LAB color space conversion.

Parameters:	xyz : array_like The image in XYZ format, in a 3- or 4-D array of shape (.., ..,[ ..,] 3). illuminant : {“A”, “D50”, “D55”, “D65”, “D75”, “E”}, optional The name of the illuminant (the function is NOT case sensitive). observer : {“2”, “10”}, optional The aperture angle of the observer.
Returns:	out : ndarray The image in CIE-LAB format, in a 3- or 4-D array of shape (.., ..,[ ..,] 3).
Raises:	ValueError If xyz is not a 3-D array of shape (.., ..,[ ..,] 3). ValueError If either the illuminant or the observer angle is unsupported or unknown.

Notes

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

References

[R56]

http://www.easyrgb.com/index.php?X=MATH&H=07#text7

[R57]

http://en.wikipedia.org/wiki/Lab_color_space

Examples

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