I'd like to be able to determine a luminosity mask for the adjustment brush, to make it more targeted and powerful than it already is.
The interface could be as simple as having two sliders on a small histogram, representing the in and out points of the mask.
It's been three years since an Adobe engineer has acknowledged luminosity masking to be something under consideration for Lightroom and Camera Raw. I hope this is still on Adobe’s to-do list.
In addition to the existing Graduated Filter, Radial Filter,
and Adjustment Brush I would like to see a new Luminosity Mask feature that
generates a luminosity mask (or its inversion) and have this mask be applied
for localized edits. In addition the mask should be editable with a brush.