To demonstrate the new technique, researchers studied the painting “Madonna in Preghiera” from the workshop of 17th century Italian baroque painter Giovanni Battista Salvi da Sassoferrato. That's where the museum collaborators come in. The painting was borrowed from the Musée de la Cour d’Or, Metz Métropole in France.
Using the new terahertz scanning method, researchers generated a three-dimensional model of the painting, separating out the various layers, such as the canvas surface, the pictorial layer itself, and the imprimatura — the initial stain of neutral color used by painters to improve color quality. Analysis of the imaging data also revealed a previously unknown restoration of the varnish layer.
“An interesting thing about the project is that it involves people at Georgia Tech’s campus in Atlanta and at a French government laboratory located at Georgia Tech Lorraine — our European campus in Metz, France,” Citrin said. “In addition, we had important input from our collaborator Marcello Melis of Profilocolore, a multispectral imaging company in Rome, Italy.”
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ne-tune the technique, which was originally conceived and developed by graduate student Junliang Dong. The basic scanning technology has been around for a while.
“The equipment and the idea of terahertz imaging was developed for various general purposes,” Citrin said. “The fact that such commercial systems are now available means we could focus on the measurement and not on tweaking the system.”
The result of this unique collaboration among public and private groups, in several different countries, is that art historians worldwide now have a powerful new research tool. The terahertz imaging technique can be used on its own, or to supplement conventional art analysis techniques such as X-rays, nuclear magnetic resonance imaging, and optical imaging, Citrin said.
“I think it's important for the general public to see how science and engineering can be used to provide important information in the humanities.”
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