Beneath some of Picasso's iconic paintings, researchers are finding new details about hidden portraits and compositions.

Why it matters: The discoveries, being presented in a new exhibition, offer clues about the artist's materials and process early in his career — and how to better conserve his work.

"The technical studies were able to inform art historical research at a new level," says Patricia Favero, an associate conservator at the Phillips Collection in Washington, D.C.

What's new: Combining data from X-radiography, infrared (IR) reflectance imaging spectroscopy, and X-ray fluorescence mapping, a team of researchers from the Phillips, the National Gallery of Art and other institutions were able to see a portrait of a man, indicators of the brush and strokes, and the pigments the artist used. For example, the presence of mercury suggests he was painting with vermilion.

With IR reflectance spectroscopy, the researchers could see forms beneath the right shoulder and forearm of the woman in "Crouching Beggarwoman" (1902).

A map of the elements in the paint of "The Soup" (1903) suggests Picasso changed the shape of the bowl being offered to a child by a woman and that he altered the woman's gesture and how her hair fell from her forehead.

The bottom line: "There is still more to learn from some of the world's most studied paintings," Favero says.