Glitch/Bug?!? Some cropped brush strokes show up in exported PNG


In my GIMP project, I painted some Yellow and then cropped a circle using the circle select + Layer mask.

However, when I export it to PNG - I get some ugly line that I had drawn before and should be masked/cropped out…

I tried applying the layer mask … selecting and clearing, restarting GIMP - but the problem persists…


What am I missing?!?

Did you flatten all the layers before exporting? I’m not a GIMP expert - just a thought.

I tried that also … doesn’t help … and keeps on acting strange…
Now it exports a white background even though it should be transparent. (and I am exporting as PNG with default settings)

I am not a GIMP newbie … this is very strange…
Never had bug issues…

What is the image mode and precision? Can you attach the XCF (or put it somewhere and post the URL)?

Not sure about the mode and precision

Works for me. This said the image is color-indexed (see title bar) so you are exporting a color-indexed PNG, which despite being part of the standard, is not always well supported. You can change your image to plain RGB mode (Image > Mode> RGB) to export a regular PNG.

Also, on my first export, it tried to export a JPEG and not a PNG (it also has JPEG-related “parasite” data(*)) so this could the remnants an attempt to export as JPG on your side.

(*) this is just the name Gimp uses for metadata it attaches to various things; image, layers, etc…

Thanks for the check! So maybe it’s some sort of memory leak or something and it needs a complete restart to my PC… I will do that later and check.

Nope … I restarted my PC - and reloaded the project - and it still exports it with the scribble… :frowning:

I thought to try and reinstall GIMP… (I am running the latest version)

How do you go about it without losing your brushes?
Do you uninstall and reinstall - or just reinstall/upgrade over the old one?

Do you have any idea about how to solve this?

Changing the color mode solved it…

I have no idea why and it doesn’t make sense to me… :slight_smile:

When you uninstall Gimp, your current Gimp profile is not removed, and is reused by a later installation. So:

  1. You don’t lose any add-ons (brushes, patterns, scripts, plug(ins…) if you installed them properly (in your profile and not in the Gimp install tree)
  2. un-install/re-install rarely fixes things (only the cases where the Gimp install itself is damaged, which isn’t that frequent).
  3. There are however several places in the Preference where you can restore Gimp to factory settings.
  4. In the dire cases you can just rename your profile. Gimp won’t find a profile, so it will recreate a clean one. You can then copy stuff from the old profile.

Some more details here: Managing tool options and window positions

Thank you very much for the detailed explanation and the help!

The indexed color mode is quite special. It is really designed to mimic GIF behavior. In particular it handles transparency differently, as an all-or-nothing characteristic. A side effect of this is that you get jagged edges:


This is because proper anti-aliasing relies on partially transparent pixels that blend with the background, producing the required intermediate colors:


(reddish background added for contrast)


Yeah, the file type was messed with a bit.

Though it was really weird because I “hard”-cleared the area - but still pixels showed up there… very bizarre…