rgb2gray

rgb2gray

skimage.color.rgb2gray(rgb) [source]

Compute luminance of an RGB image.

Parameters:	rgb : array_like The image in RGB format, in a 3-D array of shape (.., .., 3), or in RGBA format with shape (.., .., 4).
Returns:	out : ndarray The luminance image, a 2-D array.
Raises:	ValueError If rgb2gray is not a 3-D array of shape (.., .., 3) or (.., .., 4).

Notes

The weights used in this conversion are calibrated for contemporary CRT phosphors:

Y = 0.2125 R + 0.7154 G + 0.0721 B

If there is an alpha channel present, it is ignored.

References

[R48]

http://www.poynton.com/PDFs/ColorFAQ.pdf

Examples

>>> from skimage.color import rgb2gray
>>> from skimage import data
>>> img = data.astronaut()
>>> img_gray = rgb2gray(img)