I changed the muscle structure a little and changed some of the lighting.
I actually don't know whether Von Lehmann is a professional or not. I was just looking up pictures of Batman and I found his. If he isn't a pro, his work is certainly of that caliber. The colored version of this picture, complete with background, is really amazing. He has his own website too, with a lot of other interesting drawings.
Either way, I liked his ink drawing a lot and decided to do a pencil version of it.
