Hey Skywalker!
Thanks for showing all this.
I've just tried masking. I didn't have a picture with a green background. Instead I choose to outline the red horns on top the helmet of a knight standing in front of a black steck castle wall.
It worked perfectly though selecting the colours in the background was a bit tricky (because there were several shades of grey). Why do you say "invert selection" before we make the soft edges?
After that I used the outline option just to see what remained of the background, and the pictures was full or red spots! The remnants of the castle wall, all outline in red! So I re-selected the horns, copied them and pasted them. I now have the horns nicely outlined, but a small part of hte helmet still shows on the pic. Shall I make another mask? Is it really worth compared to just use the eraser?
Eager for your answer.
Arnaud