How does he make them? I honestly have no idea, Im assuming he uses some sort of computer graphics design?
I'm a computer graphics major and my not-so-expert guess would be photoshop. You can actually do hardcore painting in there with a Wacom tablet and standard painting skills. Then he can put photoshop to its more well known uses to make those insane collages, distortions, and such.
He makes some awesome stuff, I don't know how he does that. I have to imagine it's some special program like you said, and maybe even some HTML coding involved...?
