Luminosity Masks by Saul Goode & Patrick David for Gimp-2.10
Create Luminosity Masks for an image.
Originally authored by Patrick David re-coded by Saul Goode to honor selection and layer offsets will isolate light, mid, and dark tones in an image as channel masks.
Adapted from tutorial by Tony Kuyper (originally for PS).
If you want to understand the use of masks, you should absolutely read: Getting Around in GIMP - Luminosity Masks Revisited [also in the attachment].
Author: Saul Goode
In menu: Layer / Mask / Luminosity Masks (Saul Goode)
Author: Patrick David
In menu: Layer / Mask / Luminosity Masks (Pat David)
Pdf - Luminosity Masks Revisited by Patrick David: