Mona Lisa
Modern analysis

In the early 21st century, French scientist Pascal Cotte hypothesized a hidden portrait underneath the surface of the painting. He analyzed the painting in the Louvre with reflective light technology beginning in 2004, and produced circumstantial evidence for his theory. Cotte admits that his investigation was carried out only in support of his hypotheses and should not be considered as definitive proof. The underlying portrait appears to be of a model looking to the side, and lacks flanking columns, but does not fit with historical descriptions of the painting. Both Vasari and Gian Paolo Lomazzo describe the subject as smiling, unlike the subject in Cotte's supposed portrait. In 2020, Cotte published a study alleging that the painting has an underdrawing, transferred from a preparatory drawing via the spolvero technique.
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