Issue with the opacity of drawn masks

Hi everyone, I have noticed an odd behavior with my drawn masks in darktable recently (using dt 4).

Whenever I draw a mask, its opacity is set at 35%. I never had a problem before using masks, but the other day it just started behaving like this, which is kind of annoying since I have to raise the opacity of every mask I draw, especially when I’m using several masks. Maybe I did something wrong and didn’t notice? I didn’t find anything in the manual that could explain this.
Does anyone know what could have caused this behavior, and how can I reset the standard opacity of drawn masks to 100%?

I also had this in the past, but not recently. The setting is defined in darktablerc, which is a plain text file. Try searching it for opacity or mask.
Sorry, I’m not at the computer at the moment.



in darktablerc


Accidently using ctrl + scroll can reduce opacity of the mask. I have done this in the past when I intended to use shift + scroll to alter the feathering radius.

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Ya that is fine…the setting just seems to become global sometimes and becomes the new default for all objects… no idea. I hadn’t had it in a really long time and then it happened the other day…

From notes I have made:

The mask is drawn to exclude the sky from the parametric selection. I expect it to completely exclude the sky, but there is a low opacity selection. Something else I have noticed in mask manager: the percentage to the right of the path name. What does that mean? Is it related to the low opacity selection in the sky?

That figure is the opacity of the drawn shape, and is why you’re getting the issues.

Select that mask in the mask manager, hover over the drawn mask with your mouse, hold ctrl and scroll up until this number changes to 100%.

If you want to change it permanently

(so that an opacity of 100% applies to all new shapes by default), draw another defined, not path, shape and ctrl-scroll-up before you place (left-click on) it.

Edit: changed right-click to left-click :upside_down_face:

Thanks, changing that solved it!

If it happens again, I’ll try to take note of what I was doing, so maybe we can find out why it happens.

Opened Remove plugins/darkroom/masks/opacity from darktablerc · Issue #13037 · darktable-org/darktable · GitHub

If you read the user manual you will see why. Adjust things before you place the shape, and you’re setting defaults, adjust things after and you only affect the shape concerned. This is working as designed and, for me, this is useful behaviour.


I understand that it’s useful to keep the opacity the same when placing several shapes. But should this really be permanent, kept between images and even sessions?

Thing is, it’s used for a lot of other shape parameters as well (like size, feathering) which it really can be useful to retain between images/sessions. For example, I most commonly use retouch for removing dust spots and only very rarely change the default start point (size, feather) for a circle mask, once I’ve set it. To single out just one of the many shape parameters and say “this one works differently” seems worse.

(Edit: stuff like this is why I spent months rewriting the user manual but unfortunately I can’t make people read it)


Shape and size are properties that i can see you want to remain from image to image/session. Opacity does not seem to fit and i think it should default to 100.

It would seem to me that image to image something like selective copy and pasting would be how you would propagate something/features like this and not to make it a persistent setting for any image going forward. This would make it an intentional decision rather than a consequence of a previous edit…