On a computer if you click and drag the image if the ghost image has a transparent bg you won't see the checkerboard. You can also save the file by dragging it to the location you wanna save it to.
Damn, where were you the other day when I got frustrated looking for a tool and wound up cutting out Odo's face by hand? It was tedious and came out a bit sloppy.
Easy way to tell (at least through Google) is that the background will show up as white on the images page, but upon selecting the image it will change to the checkered background