Restored painting illuminates da Vinci's work

After a year and a half of cleaning and restoration, art experts have unveiled new details about Leonardo da Vinci's famed painting Virgin of the Rocks.

The work returned to display with a new frame at the U.K.'s National Gallery in London on Wednesday and officials shared the findings of their 18-month restoration of the late 15th- to early-16th-century painting.

Restoration experts removed a layer of "badly discoloured varnish" — believed to have been applied sometime in 1948 or 1949 — that hid details of the painting, including subtle tones and shading in the work's darker areas.

Because some areas of the painting are unfinished, scholars have long debated about whether the painting was worked on by da Vinci as well as some assistants.

However, after the restoration, U.K. officials now believe Renaissance master likely painted the entire work himself and even intended it to remain unfinished.

An earlier version of Virgin of the Rocks is on display at the Louvre in Paris.

In 2005, a scan of the work revealed a different composition sketched in, hidden under the layers of paint. It is thought that da Vinci had considered embarking on a completely new arrangement of the figures but decided to stick with the original.