Hi all,

I have been suggesting to try Krita to virtually all my design students for a few years now... but for some reason never found the right time to start using it professionally myself. And I would like to change that.

So, coming from that other image editing software with the monthly subscription, I am first trying to find my way around. And I have to say, so far, I pretty much like the workflow. However, there's one thing that I seem to be misunderstanding...

Can anybody please help me understand, how to apply a mask to a filter layer to restrict the effect of that filter layer to a certain region? In my understanding, a filter layer is what I would be using instead of an adjustment layer and it affects all the layers underneath. And then there's the filter mask, which basically seems to be a filter layer combined with a mask, affecting only the layer that it is applied to. But how would I add a simple layer lask to a filter layer to have it affect specific regions of all layers beneath? Is that even possible? Or do I have to use a group for that?

Any help would be much appreciated. Thanks in advance.
Marcus

A filter layer actually has a grayscale mask already. You can erase pixels or add them using the normal painting tools and see the effect. I always forget, though, whether white or black masks out the effect of the filter.

Just use a brush you like (or rectangle tool etc.) and paint on the filter layer with, I believe, black (if it doesn't work, try white ) to mask out all the areas you don't want the filter to affect. or, alternatively, attach a Transparency Mask to the filter layer (it can be a better option for example if you already have this mask painted and you want to convert it into the filter layer mask).

Aaaaah... that makes sense. Just tried it, works well. I wouldn't have thought that the filter layer represents its own mask, so to speak. Sometimes it can help to forget, what you know.

By the way: Adding a transparency mask to a filter layer (not totally sure, if that idea makes sense at all) did not have to same effect: When I painted with black on that transparency mask, the whole image became transparent where I painted (as if I had painted on a transparency mask on the paint layer underneath) - instead of just removing the effect of the filter layer. (And some clicks later Krita crashed (4.2.7.1). So, it seems, this workflow is not intended?).

Um.... I want to know more about that crash. Which OS are you using?

I'm on Linux Mint 19.1 (based on Ubuntu Bionic), using the AppImage version of Krita 4.2.7.1. (2x8 Intel Xeon Processors; NVidia GTX 1070, OpenCL activated; unbearably slow without OpenCL)

Also... adding a filter mask to a filter layer (not that that would make much sense, but I tried it once) and deleting it again results in pretty weird screen artifacts.

Hm, we still haven't solved the backtrace problem with appimages Can you actually reproduce the crash? I'm not sure many people before have added transparency masks to filter layers. I'll have to play with that myself.

Yes, that is reproducible. It happens, when I play around with a transparency mask on a filter layer... somehow combined with a filter mask and clicking in the Undo History. Not sure, if it's related to transparency masks or filter masks, though. I will record a video of the crash for you...

Thanks, that would be awesome

Here's the screencast of the crash:

https://youtu.be/nJNWUGJP_IM

Hm... So that's both a filter mask and a transparency mask on a filter layer. I guess we do need a bug report on bugs.kde.org now, with the video. Would you mind making one?

Yes, in that case it was both masks. But I just managed to crash Krita by applying a transparency mask alone, clicking back and forth in the Undo History and then deleting the transparency mask again:

https://vimeo.com/371430316

Or just clicking back and forth in the Undo History:

https://vimeo.com/371431930

And Krita also crashes after repeatedly adding a transparency mask and deleting it again (without clicking in the Undo History):

https://vimeo.com/371431102

(By the way: YouTube doesn't seem to like these videos... they are kept unavailable for some reason. Do you know of another video hoster that keeps the videos unlisted? Vimeo makes them public by default.)

I can't induce a crash when applying/deleting a transparency mask to a gaussian blur filter layer, after many and complicated attempts.
I can quickly induce a crash if I use a colour adjustment layer, as Marcus has shown. I haven't tried other types of filter layer but this difference seems significant.

The weird screen artifacts are quite common when manipulating stacked and multiple filter/transform layers and masks and I think they're caused by the rendering process becoming confused and/or stuck in some way. I've found that you can 'recover' by turning off the layers and masks then turning them back on one by one.

Some filter layers/masks take quite a while to have their effect rendered (there's a progress bar under the layer box in the docker) and if you try to do anything significant during this time (such as add a transparency mask and paint on it) then that can cause the rendering to get stuck/confused as well.