Edit: Just realised the issue: Free select around around a foreground shape, the background is white (or some other colour) and cutting the selection leaves a thin perimeter line from the background. This is a very common problem
The usual way is:
Make your selection as close as possible to the foreground shape.
Shrink the selection by 2 or 3 pixels (depends on the size of the image) Select -> Shrink
Invert the selection
Clear (or Cut) the selection. If necessary follow up with the eraser if you were not so good with the initial selection
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If you make a selection free / rectangular / ellipical to swop from inside selection to outside selection use Select -> Invert Then use clear or delete.
A safer way is make your selection then Edit -> Copy followed by Edit -> Paste as -> New Image and that saves the original, just in case.
The usual way is:
Make your selection as close as possible to the foreground shape.
Shrink the selection by 2 or 3 pixels (depends on the size of the image) Select -> Shrink
Invert the selection
Clear (or Cut) the selection. If necessary follow up with the eraser if you were not so good with the initial selection
---------------------
If you make a selection free / rectangular / ellipical to swop from inside selection to outside selection use Select -> Invert Then use clear or delete.
A safer way is make your selection then Edit -> Copy followed by Edit -> Paste as -> New Image and that saves the original, just in case.