Raster is slowly getting support for CIE Lab color space. Eventually ops will be able to directly request data in this color space. You have to open the following images in different windows in the browser and switch between them to see the difference.
Old Duotone effect (left) where color compositing uses HSV space
where V is simply
MAX(MAX(r,g),b) vs. new Duotone effect
(right) where color compositing uses CIE Lab space: