skimage2.color.lch2lab#

skimage2.color.lch2lab(lch, *, channel_axis=-1)[source]#

Convert image in CIE-LCh to CIE-LAB color space.

CIE-LCh is the cylindrical representation of the CIE-LAB (Cartesian) color space.

Parameters:

lcharray_like of shape (…, C=3, …): The input image in CIE-LCh color space. Unless channel_axis is set, the final dimension denotes the CIE-LAB channels. The L* values range from 0 to 100; the C values range from 0 to 100; the h values range from 0 to 2*pi.
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, of same shape as input.

Raises:

ValueError: If lch does not have at least 3 channels (i.e., L*, C, and h).

See also

lab2lch

Notes

The h channel (i.e., hue) is expressed as an angle in range (0, 2*pi).

References

[1]

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

[2]

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

[3]

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

Examples

>>> from _skimage2 import data
>>> from _skimage2.color import rgb2lab, lch2lab, lab2lch
>>> img = data.astronaut()
>>> img_lab = rgb2lab(img)
>>> img_lch = lab2lch(img_lab)
>>> img_lab2 = lch2lab(img_lch)