"magic wanding" with the bitmap class

I've got some .jpgs that are just white with some black line shapes that I'm bringing in via a Loader() object.

Is there a way using threshold() or something that I can alpha out the outer white (negative space) pixels without touching the white pixels enclosed in the line work?

Try this:

bmd.floodFill(0,0, 0x00000000);

Thanks. That's the right track but fudging with the tolerance is going to take too many operations. I think I'll just bring these in as .pngs