The two Mona Lisas staring out from the front page of the latest issue of Le Journal des Arts sum up the debate raging between art historians, museum curators and restorers. Should the world's most famous painting be freed of the build-up over centuries of yellowed varnish? Or is the risk, however small, of damaging the masterpiece too great?
On the left is the Mona Lisa we know, with her jaundiced face and mysterious smile, against a wallpaper-like backdrop.
On the right is a vibrant, fresh young woman with a delicate pink complexion. Her drab robes now have glints of deep gold. A blue lake stands out in the landscape behind her.
The new Mona Lisa is a computer projection by the Nicola restoration laboratory in Turin, and it shows how Leonardo da Vinci's portrait of Lisa de Noldo Gherardini, wife of the Florentine notable, Francesco de Giocondo, would look if the outer layers of varnish were gently dissolved.
Art historians know what colours the painting should be from a crack in its wooden base and from edges worn down by the frame. "Isn't it the mission of museums to present works in the closest state to that sought after by the artist?" the magazine's editor, Mr Emmanuel Fessy, asks.
The painting was purchased by King Francis I in the second quarter of the 16th century and remained part of the French royal collection thereafter. Because the portrait was so valued, it was regularly varnished for preservation. Old varnish would become cloudy so a new layer was added to restore transparency.
The portrait became shrouded in yellow mist, and by the 19th century art historians were (wrongly) claiming it had been painted in evening light during stormy weather.
Le Journal des Arts interviewed 11 experts worldwide about Mona Lisa. Mr Frederik Duparc, the director of the Mauritshuis museum in The Hague, was the most enthusiastic proponent of restoration.
"If the painting could be cleaned, our generation would have a chance to admire the true Mona Lisa," he said. "The varnish not only discoloured the painting, it altered the balance of shading, which would reappear."
Opponents fear restorers might damage the fragile, translucent glazes which da Vinci applied to the painting. "However it turns out, there'll always be somebody to say the painting is ruined," said Mr Federico Zeri, an art historian. He believes the Mona Lisa has entered our collective imagination as she is so it is better to leave her that way.
Mr Jean-Pierre Cuzin, the curator of the Louvre, which owns the painting, agrees with Mr Zeri. "There can be no question of restoring la Joconde," he says. Instead, the museum is building a new room for her with "perfect" lighting.
