Hmmm I ussually don't recommend masking in these kind of cleninfg process....
there is a better method which I already mentioned in the tips, just use the rectangular selection for big areas, that'll save you a lot of time.... then you must end up with a somewhat cleaner image... then it is time to use the lasso tool, and you just zoom the image and start cleaning it little by litte..... it is a tedious and slow process, but trust me, it will give you a lot of control.
when you end up with a quite clean image but unfortunately it has this annoying rebroder which is hard to take out with either tool, then just select the clean part, the right click and then Selection>Grow, then you choose how many pixels you want the selection to grow. That must make the selection bigger, while keeping the border..... and then you clean it
it sounds complicated, but it is an easy trick... I'll explain it better in the next class
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