The idea of examining a subject's pupil has been around for years. I've used a similar technique to reverse engineer lighting setups for portraits. See my frien

The idea of examining a subject's pupil has been around for years. I've used a similar technique to reverse engineer lighting setups for portraits. See my friend Mike's portrait of one of his children: http://www.flickr.com/photos/oatmeal2000/8545400550/sizes/o/ http://www.flickr.com/photos/oatmeal2000/8545400550/sizes/o/ You can clearly see that he uses one umbrella to the right of the camera. With higher resolution images and better focus you can sometimes determine the brand of lighting they use, but that's only if it has a very distinctive shape.