In Honor of Dan Rather

News on the forgery beat:

A new digital technique has been developed that can identify whether two works of art are by the same artist. It can help to reveal fakes, and even discern if an artist used talented students to help with the painting process.

While most forensic work requires a paint sample, the scientists behind the new technique do not even have to touch the masterpiece.

"We just walk around with a nice camera and take photos," says Hany Farid of Dartmouth College in Hanover, New Hampshire, US. A computer program then looks for statistical patterns in the digital image, based on the pressure, orientation or length of the brush stroke and the evenness of the paint.

When these characteristics are plotted in three-dimensions, the paintings of one artist will lie in a tight cluster of "signature" coordinates, while the oeuvre of another artist will cluster elsewhere on the plot. Comparing a suspected forgery with a genuine painting can therefore help identify it as authentic or fake.

Imitators beware

Farid and his colleagues digitally analysed a series of eight drawings by the Flemish artist Pieter Bruegel and five drawings that are known to be imitations of his style. When they plotted the points from the drawings, the authentic points lay close together within a ball, while the fake points all lay outside of the ball.

The team also examined the Italian painter Pietro Perugino's Madonna with Child, painted around 1500. Many experts believe that Perugino's students, which included Raphael, contributed to the painting. The computer analysis shows that three of the six heads in the painting were probably the work of one artist, perhaps Perugino himself, while the other heads were painted by three different people.