(03-28-2020, 10:05 AM)Ofnuts Wrote: I see one explanation. In your file you have the initial white numbers under the colored ones, and this add a slight rim. Dependin on how you do the cut/paste for the brush this ends up in the brush. But you have only the anti-aliased layer it should be fine.
Thanks Ofnuts, but I am sure those layers are hidden when copying the image to make the clipboard brush (and removed completely when I generated the custom brush file).
Just having another look into this and I fairly certain now this is just default behaviour of Gimp. When using alpha in the brush, and their is anti aliasing in the alpha channel (ie image created from text tool, or paintbrush tool but not pencil tool), the edge sampling of the alpha channel is inconsistent between brush strokes (at any scale of the brush including its native size).
I know it's being picky but having an edge randomly covered with black pixels can be fairly undesirable depending on how much they clash with surrounding colours of the image. There is probably going to be issues with this sort of thing when downsizing or upsizing the image but if it was at least exactly consistent between strokes it would be more manageable. Even stranger is that on a number like 2, which has hard edges at the bottom there is a lot of these random artefacts on these edge too, even though the alpha and colour channels have hard edges as expected! The fact that it displays this sampling inconsistency even at the native size of the brush makes me think this is a bug.
It would be great if someone could recreate the simple case below to confirm they also see the same behaviour and I am not completely mad or something different with my installation.
1) make 256x256 image with alpha channel
2) use text tool to make one number (2 is good )
3) Ctrl C copy and pick the clipboard brush
4) new image 1000x1000 with transparency, paint on that background with the brush (using either paintbrush or pencil tool) at different scales
5) check the edges..
Its a can help to configure the grid as 1x1 pixel cells and turn it on to really accurately visualise the situation.
I attached my gimp file which has 3 layers, all with a number 2 image made from different methods.
1) text too
2) pencil tool
3) paintbrush tool
Do you think this is buggy behaviour worth reporting? Search function on the gimp bug database is not working for me at the moment.