Is it really a self-portrait of Leonardo da Vinci?  Is the Self Portrait Authentic?

Leonardo’s self-portrait, though a beloved work of art, has been at the center of controversy throughout history regarding it’s authenticity as a self-portrait. Although most scholars see a distinct connection between this drawing’s subject and Plato in Raphael’s The School of Athens (which was posed for by Leonardo, around the same time as the drawing), some scholars have doubts about whether the drawing is indeed a self-portrait of the famed Renaissance master...

"Last Supper" painting may include two Leonardo da Vinci self-portraits?
Leonardo da Vinci's "The Last Supper" may include two self-portraits of the legendary Renaissance artist, according to a British art expert. Ross King says the nose, beards and hairstyles of two of the apostles standing to the right of Jesus in the portrait, Thomas and James the Lesser, match a portrait of Leonardo that was made several years after he created his masterpiece. King told the Independent that while historians have long-suspected Leonardo placed images of himself in his works, no one has thoroughly researched "The Last Supper" for such evidence...

Going off scant descriptions of the 15th century artist as a younger man, some art historians have suggested Leonardo himself is his Vitruvian Man model. As Lester told NPR: "He was described as being very finely built, strong, very beautiful with locks of hair that curled and went down to his shoulders. There are a couple of possible renderings of him, one that survives in a sculpture from Florence and another that's in a fresco from Milan, and they both look a bit like that figure as well," but he admitted there's no way to know "for sure."

An image processing of a Raphael's portrait of Leonardo

In one of his paintings, the School of Athens, Raphael is depicting Leonardo da Vinci as the philosopher Plato.
Some image processing tools can help us in comparing this portrait with two Leonardo’s portraits, considered as self-portraits.