Anamorphosis is an image that the artist voluntarily distorts and that can be seen properly only with a special mirror or from a particular viewpoint. You can see two of these paintings on the first floor of the Convent of Trinità dei Monti. You will find the first one in the corridor and it depicts St. Francesco di Paola kneeling in prayer near a tree. If you look at the fresco frontally, the saint "disappears" and you will only see a bay surrounded by hills. The same thing happens with the fresco representing St. Giovanni Evangelista writing the Apocalypse who "disappears" and is "substituted" by the view of Patmos Island.