Rotation center shifts by half a pixel the second time you do a 180 degrees rotation
GIMP 2.10.6 on Windows 7 here.
Someone complained that doing a 180 degrees rotation of an image twice demonstrates a serious loss of sharpness. While testing this, I discovered the following:
- Open a 5760x3840px large image.
- Shift+R to switch to Rotate tool.
- Input 180 degrees instead of the default 0 degrees.
- Rotation center is at 2880x1920px as expected.
- Click on the image to rotate again.
- Rotate tool defaults to 0 degrees again, but the X position of the rotation center is now 2879,50 instead of 2880.
This means the resulted image (after 2x180 deg rotation) is shifted horizontally.
I tried using 45, 90, 150, and 179 degrees for the first rotation to see if I can reproduce this, and nope. Only happens when the first rotation is 180 degrees.