This conversation has been merged. Please reference the main conversation: Lightroom: Desaturate Highlights and Shadows
This would be a really useful and efficient addition for me and I suspect a lot of LR users for correcting saturation imbalances in different luminance ranges as well as creating some beautiful looks, without having to use local adjustments or export to PS with all the added time and storage space that involves.
Obviously I can use a brush with a saturation adjustment, but to do that for many images is very inefficient if what I really want is just to adjust saturation in shadows say (without affecting contrast - could just use curves if I wanted to change contrast along with saturation), especially if I want to do the same thing for a set of images under similar lighting.
The way I imagine it working is as a standard saturation control but effectively masked with a curve for a particular luminance range. Could be fixed curves for shadow, mid, highlight, or probably even better a user editable luminance/saturation curve.