An oil painting thought to be created by the famous Italian artist Raphael features a face that he did not paint, according to scientists.
Researchers in the UK used artificial intelligence technology to analyse Madonna della Rosa (Madonna of the Rose), which was painted in early 16th century and is believed to be one of the many Madonnas painted by the Renaissance master.
It depicts Mary carrying an infant Jesus, Joseph on the left, a young John the Baptist, as well as a rose on the table from which the artwork got its title.
The painting, which currently hangs in the Museo del Prado (Prado Museum) in Madrid, Spain, has long been debated by art critics, with many suggesting Raphael’s pupil Giulio Romano may have been involved.
Some also believe the rose and the lower portion of the painting may have been created by another artist.
However, Professor Hassan Ugail, director of the Centre for Visual Computing and Intelligent Systems at the University of Bradford, said most of the painting is indeed by Raphael, except for the face of Joseph.
He said: “We used pictures of authenticated Raphael paintings to train the computer to recognise his style to a very detailed degree, from the brushstrokes, the colour palette, the shading and every aspect of the work.
“The computer sees far more deeply than the human eye, to microscopic level.”
Prof Ugail added: “When we tested the della Rosa as a whole, the results were not conclusive.
“So, then we tested the individual parts and while the rest of the picture was confirmed as Raphael, Joseph’s face came up as most likely not Raphael.”
The AI algorithm was developed by Prof Ugail who said it can recognise authentic works by Raphael with 98% accuracy.
Study author Howell Edwards, emeritus professor of molecular spectroscopy at the University of Bradford, said the della Rosa was regarded by early art connoisseurs as a Raphael autograph, meaning he painted 100% of it.
However, he said that during the 19th century, many art historians began to question whether pupils from Raphael’s workshop were also involved.
Prof Edwards said: “The attribution to Raphael’s workshop was gradually accepted later and attributed particularly to his pupil Giulio Romano and possibly also to Gianfrancesco Penni.
“In Spain the original attribution has never been questioned.
“Some connoisseurs regard the quality of the composition and painting for the Madonna, Child and Saint John as far exceeding that of Saint Joseph, whom they feel has been added at the workshop as somewhat of an afterthought.
“The AI programme analysis of our work has demonstrated conclusively that whereas the three figures of the Madonna, Christ Child and Saint John the Baptist are unequivocally painted by Raphael, that of Saint Joseph is not and has been painted by someone else – possibly by Romano.”
Although it is able to accurately identity a Raphael painting, the researchers say their AI system cannot be used as a sole authentication tool.
Study author David G Stork, who is adjunct professor of symbolic systems programmes at Stanford University in the US, said: “The current study’s results should not be taken as sufficient for an authentication decision, but a step toward improving overall authentication protocols.
“Some of the most successful computer studies of art have exploited large databases of art images to learn an artist’s style and other properties.
“As such databases grow, computer algorithms are refined, and most importantly, as humanistic art scholars criticise and refine computer methods, computer methods will improve and become widely used throughout art history and criticism.”
Raphael, whose full name is Raffaello Sanzio da Urbino, was born in Urbino, Italy in 1483.
He is widely considered one of the great masters of art from the High Renaissance period.
The findings have been published in the journal Heritage Science.