Since luminosity masks are all the rage, my own take on the subject.

Unlike the tutorial, and unlike most Gimp scripts based on this tutorial,

- The script creates only one mask at a time. This mask is immediately used to set the selection, thus saving several mouse clicks.
With the adequate shortcut(s) you can set a mask with a single keystroke.
- The mask is not created by addition/composition of other masks, but by applying directly the equivalent curve with the Curves tool.
- The script creates a mask using the current state of the layer. By contrast the tutorial and the scripts create all the masks once, usually on the initial state of the image, so when the masks are used successively, the pixels remain selected based on their initial luminosity and not on the luminosity they reached following the previous edits (unless you redo all the masks of course).

Script is here. Gimp 2.10 only for the time being (there is a compatibility problem with 2.8 that isn't solved yet).

Thanks ofnuts, your takes are always good. Tried it quickly, to change the hair color with DD and D.
Haven't played that much with luminosity masks, sometimes I use them to create better contrast for layer masks/background extraction.

After a quick try, I think this is a useful addition.
Because the selection/mask is available it can also be used as a basis for creating other masks.

david.

Uploaded a new version. Added feature: define your own mask(s) in a side file. Enjoy.

Impressive, I always wanted to learn how to do this with luminosity masking, but have no idea how to. I normally just use it to adjust brightness, shadow only. Can you teach me how or share the steps for this?

Thank you in advance.

It's nothing complex.
I used the plug-in from Menu. Select/luminosity/patdavid/Darks...DD
Then, a python plug-in called Layer via copy/cut by slybug.
You can do same with copy + paste as new layer in place in Gimp 2.10.
Repeated same with Darks...DDD for this pexels image, and merged them.



Used eraser to make sure eyes, nose, lips, chin and bikini straps are not affected.



Lot of ways to alter the hair color now. I think curves is the easiest and works well.
Changed the merged luminosity layer blending mode from normal to overlay and used red curve.

If anyone is interested, in the attachment I share the file with my curves that I edited to use with this script.

Thanks for the guide.