Narrow faces, haunting eyes, elongated necks … all well-known characteristics of an Amedeo Modigliani masterpiece. Less well known? The brains behind that brush. At the Barnes Foundation in Philadelphia, curators and conservators are using new technologies to unearth old secrets from beneath the canvas. Their findings are part of the exhibition "Modigliani Up Close."

"One of the really fun things was looking at some of the early paintings where he was painting over canvases that had already been painted upon – sometimes his own canvases, sometimes canvases that had been painted on by a different artist," said chief conservator Barbara Buckley.