Layer Modes, sometimes called Blending Modes, allow you to combine layers in a variety of ways. We continue with the Lighten Modes, except for Dodge which we will cover in the next tutorial along with Burn. These are the Layer Modes available on the latest (at the time I write this) version of GIMP, 2.10.24.

Links:

https://en.wikipedia.org/wiki/Luma_(video)

https://blog.johnnovak.net/2016/09/21/what-every-coder-should-know-about-gamma/

https://www.youtube.com/watch?v=Ijwb1R07aa0

https://docs.gimp.org/2.10/en/gimp-concepts-layer-modes.html

https://www.ahuka.com/gimp/lighten-layer-modes/