Is this a 3.2 Darktable bug?

Thank you for reporting it to developers team.

same ā€˜oneā€™ with and without VNG4 demosaic, any idea?

Man some of these glitches look cool :slight_smile:

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Are you sure this is due to the VNG4 demosaic?
Note that Iā€™m not doubting what you see, Iā€™m just not sure whether the VNG4 demosaic is the cause, or just making another bug visible. We canā€™t tell, as you donā€™t show the history stack or xmp fileā€¦

thank you for asking, here are the two associated xmp files ā€¦

I only know that resetting the demosaic module helps and the photo recovers ā€¦

What a psicodeliaā€¦
Remembers to the entry credits of a weekend program in late 70ā€™s I used to see. :laughing:

No, not only ocurs in VNG4, I use PPG only.

I have been editing another photo and problem raised again.

In my case it is clear that the prolem is the parametric luminosity mask.

I use it in color balance to create a vignette that darken borders but excluding extreme lights and shodows from darkening.

If I deactivate the parametric mask in color balance, the blownout disappear.

Ok but is that the only thing that makes it disappear? Unless color balance is the only module you have activated itā€™s hard to be certain that itā€™s the direct cause - something youā€™re doing in color balance could be causing a module further up the pipe to fail.

No, it is not.

But in different pictures it seems that what causes the problem is when I activate my vignette using color balance and activating the parametric mask to exclude extreme lights and shadows.

Of course it could be the sum of several causes.

I will try to reduce it down to the basic modules and as few as possible other modules to get the problem.

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It seems that the problem is the combination of mask parameters (mainly the negative contrast) and blend opacity that produces mask values outside the [0,1] interval. I made a Pull Request to make the mask values to stay inside the interval that should fix the issue.

Thank it is great that developers are aware of the problem

No doubt they will find the origin and a solution soon