GIMP Version: 2.10.4
Operating System: Windows
GIMP Experience: Intermediate Level

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I have some problem with Add Layer Mask->Add Layer Mask in Gimp 2.10.4.

I don't know if it's a bug, a new planned program behavior, some setting problem in greyscale conversion, etc... But using Add Layer Mask->Add Layer Mask and Invert mask give me a Layer Mask too "bright". Add Layer Mask->Add Layer Mask in Gimp 2.10.4 give quite the same result in 2.8, the problem seem to be only with the Invert mask checked.

Some images will explain the problem better than words.

Original image



Add Layer Mask->Add Layer Mask+Invert mask in Gimp 2.8



Add Layer Mask->Add Layer Mask+Invert mask in Gimp 2.10.4

My opinion, might be a bug, or probably the default (non-legacy) modes kicking in.

Generate the mask, but do not enable Invert mask (1) Instead use Colours -> Invert on the layer mask (2)



That should give a mask as required.



EDIT:
Replicating the Gimp 2.10 very light mask
Make copy
Mode -> Greyscale
Colours -> Linear Invert

Yes, with this i obtain same resunts os the "Invert Mask" in 2.8, but it is a slowing down of the workflow .



So they would seem to have changed the way the default inversion occurs in the Layer Mask, from "Value Invert" to "Linear Invert". I'm wondering if this can not break the functioning of some scripts that used the "Add Layer Mask-> Add Layer Mask" + "Invert mask" expecting the old mode of operation.

You could write a bug report. https://gitlab.gnome.org/GNOME/gimp/issues but do not expect too much and even if it is 'adjusted' it will be in a future release.

To speed things up maybe a couple of keyboard shortcuts.

1. Brings up the add mask dialogue, then once that is applied
2. Inverts the mask using plain color -> invert



Use keys that are convenient to you. Not many single free keys remaining so whatever you choose will replace existing.