I might be totally off base here, but i think you're conflating lightness and luminance? HSL is hue, saturation, lightness luminance is sqrt( 0.299*R^2 + 0.587*G^2 + 0.114*B^2 )
I might be totally off base here, but i think you're conflating lightness and luminance?
HSL is hue, saturation, lightness
luminance is sqrt( 0.299R^2 + 0.587G^2 + 0.114*B^2 )