Equal Luminosity Masks [eq_lum_mask.py].
Author: David Marsden
In menu: Layer / Mask / Equal Luminosity Masks...
Create 10 Luminosity Masks - discussed: here & pdf: here.
The plugin checks if there is a pre-existing selection and if so, saves it to a channel.
It then makes a copy of the image, equalizes the copy and desaturates it.
Using a series of 10 equally spaced spline curves it creates 10 channels named Lum 0 to Lum 9.
These are used to make 10 layers (Lum 0 to Lum 9) each of which has a mask controlling the range of luminosity that can be adjusted in that layer.
Layer 0 permits adjustment of the darkest regionsand layer 9 the lightest.