@adam
You should have no problem with your workflow. It might be the copy-cut that is the problem. Like sallyanne says give the image an alpha channel and I advise not a cut but a copy.
Edit: It is the cut that is the issue, because the layer has no alpha channel (transparency) when you cut, the semi-transparent border pixels take the background colour, white but could be whatever colour is set. The pasted back-in-place edge is semi-transparent so the overlap shows white-ish.
Using a path is a great way to get your selection. Using your 'original' I get this
Sorry, all the gory detail, so 5 minute duration. Have a look and see where we differ.
You should have no problem with your workflow. It might be the copy-cut that is the problem. Like sallyanne says give the image an alpha channel and I advise not a cut but a copy.
Edit: It is the cut that is the issue, because the layer has no alpha channel (transparency) when you cut, the semi-transparent border pixels take the background colour, white but could be whatever colour is set. The pasted back-in-place edge is semi-transparent so the overlap shows white-ish.
Using a path is a great way to get your selection. Using your 'original' I get this
Sorry, all the gory detail, so 5 minute duration. Have a look and see where we differ.