I thought that David Hockney's absurd assertions about the Old Masters were bad, but this is worse. The images that are supposedly so close as to prove tracing aren't remotely similar with the exception of the fact that they are different pictures of the same person and not even all that similar renderings.

It is also downright weird that the author claims that Van Gogh's paintings were realistic when they are so clearly not, in fact, his lack of realistic rendering is what some people prize his work for so much. Personally, I don't think there's much artistic value in his work at all. He just became famous for being mentally disturbed and now we are supposed to think that he was a genius somehow.

Anyway, this theory that the only way to create realistic images (which Van Gogh's certainly were not)is to use some kind of optical tracing device is false as can be seen by anyone who even looks at these images and as can be demonstrated by just looking at what actual contemporary realist artists do in their studios every day. I wrote a more detailed critique of the Hockney theory at http://www.artrenewal.org/articles/2004/Hockney/yoder1.asp and Dr. David Stork pretty much put the issue to bed in his own studies (including a nice piece in Scientific American) which you can look up at http://www.diatrope.com/stork/FAQs.html and
http://webexhibits.org/hockneyoptics/post/stork.html