These are offered in modules that work in the RGB color space.
The grayscale value g is calculated as 0.3*R + 0.59*G + 0.11*B - that's a simple and rather common way of weighting the individual channels to get a grey image.
OTOH the L value is calculated out of a RGB -> HSL color space conversion. We could have left L out of the offered channels but as we anyhow wanted to allow users to select on Hue and Saturation the L channels came as a cheap add-on.
Ulrich Am 16.02.2017 um 17:38 schrieb David Vincent-Jones:
In some instances (for instance the channel mixer) the parametric masks offer scales in both 'g' (gray-scale) and 'L' (lightness). How do these scales differ?
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