Suspecting that an Italian fresco at the Louvre contained hidden images, art specialists turned to body scanning technology:
To start, the researchers tried several techniques that included X-ray radiography, X-ray fluorescence imaging, infrared photography, infrared reflectometry and UV fluorescence. None of them showed anything unusual. Then they used terahertz spectroscopy, better known as the technology in modern airport body scanners.
“We could not believe our eyes as the image materialized on the screen,” Jackson told the American Chemical Society…. Underneath the folds in one of the men’s tunics the scientists saw an eye, a, nose, and a mouth. They think this mystery man was painted in a Roman fresco that dates back thousands of years. He just happened to be in the wall that was later used for the painting in the 1800s.