Using a noninvasive technology that combines artificial intelligence and 3D imaging, researchers from France and Italy have discovered that Leonardo Da Vinci applied up to 30 layers of oil-based paint to create his most famous work of art, the Mona Lisa.

They found the pigments were blended so that they did not form a solid layer, which is why the painting has remained in such good condition.

The research, which was published in the journal Optics and Laser Technology, provides a new understanding of the techniques used by one of the most influential artists in history and could help restore other Renaissance paintings.

The research is the latest example of how scientific techniques can be used to study art, shedding light on the creative processes of some of history's greatest artists.