Diamond Gaussian Blur
GIMP version: 2.10.8
Operating System: Ubuntu 18.04.1
Description of the bug
Gaussian blur in gimp 2.10 produces a weird diamond effect.
The bug is entirely reproducible, though you have to use a fairly large image for it to be visually striking (I discovered it while working on a 3840x2160 wallpaper). If you use a smaller image you can still sort of see it but it's much less obvious.
- Create a new image, about 2000x2000 pixels.
- Fill the background with black.
- Create a new layer.
- Select a circle about 1/3 of the width in the center.
- Fill the circle with white.
- Select everything.
- Filters/Blur/Gaussian Blur. Set size X and size Y to be 100, filter to Auto, and Abyss to Clamp.
Expected result: The circle should be blurred evenly. Note that I did use a much higher radius value (600) for the 2.8 blur, to get a large enough effect that it would be visually obvious that it was working correctly. .
The problem doesn't occur in Gimp 2.8.