Image above: Table in our room with two small portraits of us, a poster from Martin-Gropius-Bau Museum in Berlin and another mask made by Marc.

In this case I want to put a small feather on the selection before we mask as even though I want a crisp line, it's very rare that you don't need at least a small amount of feathering.

I have just tried different Numbers for the last part of the subnet mask, until the small graphical interface tool finally showed my IP in the status bar.