According to edition.cnn, the image was found when art conservators took an X-ray of Van Gogh's 1885 "Head of a Peasant Woman" painting ahead of a forthcoming exhibition. They discovered the concealed image at the back of its canvas hidden by a sheet of cardboard, according to a press release from the National Galleries of Scotland (NGS).

Experts say the revealed artwork is believed to have been unknown until now.

"Moments like this are incredibly rare," said Frances Fowle, senior curator of French art at the NGS, in the press release Thursday. "We have discovered an unknown work by Vincent van Gogh, one of the most important and popular artists in the world."

The Dutch master often re-used canvases to save money, turning them around to work on the reverse side, the NGS said.

The underlying self-portrait is thought to have likely been made during a key moment in Van Gogh's career, when he was exposed to the work of the French impressionists after moving to Paris.

The "utterly compelling" X-ray image shows "a bearded sitter in a brimmed hat with a neckerchief loosely tied at the throat. He fixes the viewer with an intense stare, the right side of his face in shadow and his left ear clearly visible," according to the release.

While the condition of the actual self-portrait is unknown, if it can be uncovered, it is expected to help shed a new light on the renowned artist. Read more on this story here.

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