Old Masters, New Tricks

By Philip Elmer-DeWitt

Critics scoffed when computers were first enlisted to help restore Michelangelo's magnificent frescoes in the Sistine Chapel. What could an electronic filing system in some Vatican basement contribute to the painstaking, labor-intensive task of liberating one of the world's largest and most famous paintings from nearly 500 years of accumulated grime and murky glue? But the computer -- an Apollo workstation programmed to map every curve and crack down to the last millimeter -- proved so indispensable that it was installed 20 meters (65 ft.) above the ground, on the main scaffold, where it put a wealth of data about the frescoes at the master restorer's fingertips. Today man and machine labor side by side, only an arm's length from Michelangelo's original brushstrokes.

The Sistine Chapel project was a breakthrough that made believers of the skeptics. Even the Vatican's chief restorer, Gianluigi Colalucci, concedes that future computers will recall in an instant visual information that used to require years of research, including, he adds with a laugh, "the errors we are making now." But more important, the restoration marked the beginning of the Italian art establishment's love affair with technology. Nowadays, computers linked up to gamma-ray detectors, infrared cameras and thermographic sensors are turning up in art-restoration projects all across Italy, from the vast ruins of Pompeii to the crowded workshops of Venice. In tasks ranging from simple cataloging to advanced image processing, the new technology not only is making restoration more manageable but also is helping solve some of the oldest mysteries of art history.

In the past, technological advances in art have moved from the new world to the old, as when computer techniques developed by NASA to enhance satellite photos were adapted for use on the works of the old masters. That flow has, to some extent, been reversed. With a major portion of the world's ancient art treasures located inside its borders, Italy has become the capital of high- tech restoration. Experts from such citadels of art as the Louvre, the Getty Museum and the Metropolitan Museum of Art are making pilgrimages to Italy to see how it is done in Rome, not to mention Venice, Milan and Florence.

The technology that most fascinates visitors is a method for peering below the surface of a finished artwork and analyzing the various layers of paint it contains. The technique, computerized infrared reflectoscopy, is based on the fact that some pigments that reflect light in the visible range (like cadmium red) are more or less transparent to infrared light. By looking through these layers, art historians can catch glimpses of the artist's original handiwork: rough sketches, repaintings and the occasional erasure. Other techniques, notably X-ray analysis, had been used in the past. The major advantage of using a computer with a video display screen is that the artwork can be superimposed over the infrared image, making the slightest differences easily visible.

CIS has become a veritable third eye for restorers and art historians. Paolo Spezzani, a Venetian radiologist who pioneered the technique with Olivetti, has applied it to hundreds of familiar paintings, sometimes with startling results. In one case, an examination of Titian's Albertini Madonna and Child turned up a praying saint hiding under the baby's chubby legs. In another instance, the procedure helped prove that the so-called Sketchbook of Raphael, long thought to be a 17th century copy, actually did contain early 16th century drawings from Raphael's Umbrian school that had been later covered over in ink.

Sometimes the simplest application of the computer, as an electronic archive, is the most effective. At Pompeii, experts from Fiat and IBM, aided by more than 100 young workers, cataloged thousands of frescoes and mosaics scattered over 36,000 hectares (89,000 acres) of the Vesuvius valley. Result: + a computerized map that makes a great deal of art history instantly accessible. Says Aldo Todini, IBM's operating director for the project: "If you see a house on the map, you can go into that house, go right up to a wall, ask the computer what's painted on it and see the fresco in living color."

Computer operators at the Sistine Chapel can call up a vast library of information for every square meter of fresco, from the location of weakening areas to the curves of the artist's underlying sketches. On the screen, green lines mark the beginning and end of each day's work for Michelangelo, providing historians with a graphic record of his progress as he struggled to master the art of painting face upward in soft plaster. It took him an exhausting 29 days to do 15 square meters (18 sq. yds.) of The Flood, even with several helpers. By the time he reached The Creation of the Sun and Moon, however, he could cover the same space in seven days without any help at all.

Art-restoration computers in Italy have become nearly as ubiquitous as masterpieces. In Bologna's Church of Santa Maria della Vita, a computer analysis of body postures showed art historians how to piece together a disassembled 15th century terra-cotta sculpture of Christ and six grieving figures. In Rome a computer has created a perfect electronic "mold" of the bronze statue of Marcus Aurelius. Says Giorgio Accardo, head of the physics lab at Italy's Central Institute for Restoration: "The idea is to put Italy's artworks on a computer disk so that if somebody chops off an arm or a leg, we can re-create it."

But even the smartest computer cannot decide what to do with the information it gathers. An analysis of Tintoretto's Paradiso uncovered a coat of arms that had been painted over with a cloud, presumably by new owners. The decision to remove or not to remove was one that had to be made by art historians. (In the end, they decided to bring the coat of arms back to light.) The loincloths in the Sistine Chapel pose a trickier problem. Michelangelo's nude figures in The Last Judgment so offended the prelates of the 16th century that they ordered papal artists to cover the bodies with strips of cloth. An analysis of the underlying layers makes it unlikely that the outerwear will be removed, however. Before the loincloths were added, Michelangelo's original painting was physically scraped away.

With reporting by Cathy Booth/Rome