An article in a recent [PNAS (Proceedings of the National Academy of Sciences)](http://www.pnas.org/) describes the use of stylometry, the study of artwork through math and statistics, to analyze paintings in order to determine if they are authentic to the attributed master, to a student, or are a fake. The paper describes a technique called *sparse coding*, in which “analysts break down works of art into tiny patches and represent them as a series mathematical functions. By comparing the functions produced with authentic artwork to those from possible imitators, they can produce an objective measure of whether the piece in question is real or fake.” The [cover story on Ars Technica](http://arstechnica.com/science/news/2010/01/sparse-coding-technique-applied-to-art-authentication.ars) explains:
> Sparse coding was originally developed for studying how neurons in the brain responded to visuals. It works by breaking down an image—for simplicity’s sake, usually one in grayscale—into mathematical functions, pixel by pixel. The images that are broken down are just small patches of whole works, not much more than a dozen pixels square.