Identifying portraits

The left-hand portrait above is of Galileo Galilei, one of history’s most famous physicists. But the right-hand one? Its identity divides scholars. Some think it is also Galileo; others disagree. Disputes like this are common in art history. Amit Roy-Chowdhury of the University of California, Riverside, in collaboration with Conrad Rudolph, an art historian, has applied face-recognition technology to see if it can solve such questions. He fed 271 known portraits, by 36 artists, into an algorithm developed for the purpose, together with 20 others whose subject’s identity is in question. A careful scientist, Dr Roy-Chowdhury emphasises that the results are probabilistic, not deterministic. Nevertheless, 12 of the 20 seemed to match portraits of known identity (the pictures above among them). Even more intriguingly, two of the unknowns matched each other. They had the same subject, according to the algorithm, but who she was remains a mystery.