Mona Lisa replicas and reinterpretations
After restoration, the Prado's "Mona Lisa" revealed details covered by previous restorations and layers of varnish.
Furnishings and fabrics were enhanced, as well as landscape and facial features.
It is anticipated that such revelations may offer further insight into Leonardo's original.
Experts at the Louvre reportedly supported the Prado museum's findings.
The Prado replica was subsequently transported to the Louvre in 2012 to be displayed next to "Mona Lisa" as part of a temporary exhibition.
Two nude paintings bearing similarities to Leonardo da Vinci's original were part of a 2009 exhibition of artwork inspired by "Mona Lisa".
Displayed at the Museo Ideale in Leonardo's hometown of Vinci, near Florence, some believe one of the paintings – dating from Leonardo's time – to be the work of Leonardo himself, and it has at times been credited to him.
Other experts theorize the painting, one of at least six known to exist, may be just another copy painted by "followers" of Leonardo.
Scholarly dispute persists as to artist, subject and origin.
The nude in question, discovered behind a wall in a private library, reportedly belonged to an uncle of Napoleon Bonaparte, who owned another of Leonardo's paintings.
Facial features bear only vague resemblance, but landscape, compositional and technical details correspond to those of the "Mona Lisa" known worldwide today.
Cultural references to Leonardo da Vinci
No painting has been more imitated and satirised than the "Mona Lisa". Beginning possibly with a naked portrait of Diane de Poitiers by Clouet, the pose and expression have been freely adapted to many female portraits.
The avant-garde art world has made note of the undeniable fact of the "Mona Lisa's" popularity. Because of the painting's overwhelming stature, Dadaists and Surrealists often produce modifications and caricatures. Already in 1883, "Le rire," an image of a Mona Lisa smoking a pipe, by Sapeck (Eugène Bataille), was shown at the "Incoherents" show in Paris. In 1919, Marcel Duchamp, one of the most influential modern artists, created "L.H.O.O.Q.", a "Mona Lisa" parody made by adorning a cheap reproduction with a moustache and a goatee, as well as adding the rude inscription, when read out loud in French sounds like "Elle a chaud au cul" literally translated: "she has a hot ass". This is a manner of implying the woman in the painting is in a state of sexual excitement and availability. This was intended as a Freudian joke, referring to Leonardo's alleged homosexuality. According to Rhonda R. Shearer, the apparent reproduction is in fact a copy partly modelled on Duchamp's own face.