One of the most famous paintings in French art history has undergone a sophisticated and careful restoration procedure, revealing new brightness and detail that demonstrates the artist's "true genius."

Many of his contemporaries thought Jean-Honoré Fragonard's The Swing, painted in 1767, was very risqué since it depicted a young lady offering a peek of her undergarments from her swing in a lush garden.

After removing a thick, yellowed, 100-year-old varnish and previous discolored retouches, the picture – dubbed "the most iconic painting of the entire rococo movement" – will return to the Wallace Collection in London next week.

The Wallace Collection's director, Xavier Bray, described the conservation work's outcomes as "amazing." "The true genius of Fragonard has been revealed."

The repair has uncovered layers of vegetation and restored depth. The girl now jumps out of the picture, her silk dress's lace is sharper, and her expression is more defined. A little dog in the bottom right corner has greater detail.

According to technical study, the artist did very little preparation work before beginning the painting. Most painters start with sketches or studies, but Fragonard seems to have worked straight on the canvas, according to the Wallace Collection.

"Removing the varnish has given it a new lease of life. It has been completely altered. The Wallace Collection's curator of French paintings, Yuriko Jackall, commented, "Fragonard's technical mastery is once again on display with very bold color contrasts reawakened, and little details that have always been there are now apparent again."

Although The Swing is one of the most well-known pieces of art, little is known about its beginnings. It is believed that the sponsor was a "gentleman of the court" who desired a painting of a "pretty child's legs." Some artists turned down the job because they thought it was indecent.

A young guy sitting underneath the swing in Fragonard's picture gets a clear look inside the girl's billowing skirts as one of her shoes soars into the air. As stone cherubs look on, an elderly guy drives the swing with a pair of ropes from behind her.

Through the prism of the twenty-first century, Jackall admitted that the painting may be difficult for some. "We need to think about how we're going to talk about it." But I believe [the young lady] has become a lot more vibrant and dynamic figure as a result of the treatment; she's zooming out of the canvas.

“She is the center of attention, which I believe gives her a certain amount of power. But it's an image with a certain amount of ambiguity, and it lends itself to a variety of interpretations."

Martin Wyld, a former director of conservation at the National Gallery, worked on the restoration for more than 40 years, repairing works by painters such as Leonardo da Vinci and Diego Velázquez.

Thanks to Harriet Sherwood at The Guardian whose reporting provided the original basis for this story.