PARIS - Scientists are due to unveil some of the secrets behind Western art's most enigmatic smile this week, when they present the findings of the most extensive three dimensional scan ever undertaken on the Mona Lisa.

Leonardo da Vinci's 16th century masterpiece, perhaps the world's most famous painting, is considered a milestone in the art of portraiture and an icon of European culture.

A comprehensive examination of the work, painted at some time around 1503-06, was undertaken in 2004, using special 3D technology developed by scientists from Canada's National Research Council (NRC).

The scientists scanned the picture on both sides to obtain high resolution 3D image data of the whole painting which the NRC says will shed new light on the history and condition of the work, as well as on Leonardo da Vinci's technique.

The portrait itself will remain in the Louvre museum in Paris, where it has gazed inscrutably out at visitors since it was moved there after the French Revolution.

But the NRC, which will unveil its findings on Tuesday ahead of a public lecture in Ottawa, promises its model will allow both art history specialists and the general public to get closer than ever before without risking damage to the picture.

It will also reveal important details about Leonardo's technique, including the so-called "sfumato" method by which he created a delicate hazy effect which contributes much to the painting's general air of remote mystery.

The young woman with the ambiguous half smile has been identified as Lisa Gherardini, wife of a Florentine merchant named Francesco de Giocondo and her portrait has attracted admiration and curiosity since its creation 500 years ago.

Its popular status as Western art's most famous masterpiece was cemented in 1911 when it was stolen from the Louvre, sparking a massive hunt that saw even Pablo Picasso questioned by police before the painting turned up again two years later.