In photoshop, use the magic wand tool to select white - with a tolerance of 1. Once selected the white area can be deleted.

You can't be me, I'm taken

It would be useful to retain the labels on the graph, otherwise it's not clear what the joke is about, and the serious point of the cartoon is lost.

Of all the ways of organizing banking, the worst is the one we have today — Mervyn King, 25 October 2010