https://www.youtube.com/watch?v=F773Jfd6J0o 1. load image on Krita 2. use Bezier Curve Selection Tool and draw the border 3. put the mouse cursor in the image, then Ctrl+Shift+i to invert the selection area 4. push B key to select brush tool, 5. adjust brush size large enough to erase easier 6. set erase mode 7. erase the background (selected area by inverted selection)