Magic wand tool, click on the 'inner' black area, hold the shift key and click on the 'outer' black area. Command+shift+I to invert the selection.
(Control+shift+I on PC)
If you want to re-use the selection later, just save the selection and load when needed.
OOPS! I think you mean the dotted selection on re-reading?
Oh well, you can use the above method when you want to isolate it from the background.