Here's an article adding to what Tim was saying about Pollack's fractals.

Jackson's fractals :
As recent articles in PASS Maths have shown, combining the computational powers of modern digital computers with the complex beauty of mathematical fractals has produced some entrancing artwork during the past two decades.
Intriguingly, recent research at the Physics Department of the University of New South Wales, Australia, has suggested that some works by the American artist Jackson Pollock also reflect a fractal structure.

Pollock created many of his works by dripping paint onto enormous canvases, leading to some riotously complex images. While Pollock himself felt that these works reflected "pure harmony", critics have dismissed them as "mere unorganised explosions of random energy". Having examined a number of such paintings produced between 1943 and 1952, the researchers are inclined to agree with Pollock, finding fractal relationships rather than "unorganised explosions" in the paint-drip works.
A feature of fractals is self-similarity on multiple scales: a small chunk of a fractal, scaled up, has similar features to a larger one. The researchers noticed this feature in the paint-splatter works, and analysed a quantity called the fractal dimension of the paintings.
Pollock's drip paintings became more complex over the years. In the early work of 1943, he used single dribbles of paint covering only about 20% of the canvas. By 1952, he was using multiple squiggles covering over 90%. Correspondingly, the researchers found that the fractal dimension of these works increased steadily from a low value close to 1 to a high value of 1.72.
Why is this interesting? Mignon Nixon, a lecturer in American art at London's Courtauld Institute, told the BBC's News Online service: "Mathematical models may be a way of attributing a kind of mastery and order, by shifting from an aesthetic, subjective mode of examination to a more objective, scientific one."
She said that scientific approaches can be useful in the study of art. "If you want to know how was a painting was made or how do we date it, then technical help is crucial. But the information you get that way is also useful for interpretation because you know more about how the thing was made."
Pollock Pic