A series of sketches and hand prints made by Leonardo Da Vinci, and hidden underneath one of his most famous paintings for more than 500 years, have been revealed for the first time.
Scientific analysis of "The Virgin of the Rocks," on display at London's National Gallery, has shown the original composition Leonardo started and then abandoned, before he painted the final product that has been admired for centuries.
Initial designs for the angel and Baby Jesus in the painting have been uncovered by the process, as well as hand prints where the artist or an assistant patted down paint on the canvas, London's National Gallery said.
The angle of the infant Christ's head was changed so that he was seen in profile, while some parts of the angel's curly hair were been removed.
"In the abandoned composition both figures are positioned higher up, while the angel, facing out, is looking down on the Infant Christ with what appears to be a much tighter embrace," the gallery explained in a press release.
"These new images were found because the drawings were made in a material that contained some zinc, so it could be seen in the macro x-ray fluorescence (MA-XRF) maps showing where this chemical element was present, and also through new infrared and hyperspectral imaging," it explained.
The revelations were made as the National Gallery announced a new exhibition on the artist, titled "Leonardo: Experience a Masterpiece," which will run from November.
The 500-year anniversary of Leonardo's death was commemorated earlier this year, and the artist, scientist and inventor remains one of the most enduring figures in Western history.
His surviving body of work as a painter is slim: Fewer than 20 artworks are universally attributed to him, although two of them -- the "Mona Lisa" and "The Last Supper" -- are easily among the most famous in the world.
Leonardo painted two versions of "The Virgin of the Rocks," which look similar overall but have crucial differences in the composition. The earlier, dating to around 1483, is on display at the Louvre in Paris. The National Gallery version was completed sometime between 1495 and 1508.
CNN's Jacopo Prisco contributed reporting.