  A sketch, found in one of Leonardo da Vinci's notebooks and covered by the
written notes of this genius, has been recently restored. The restoration
reveals a possible self-portrait of the artist, drawn when he was young. Here,
we discuss the discovery of this self-portrait and the procedure used for
restoration. Actually, this is a restoration performed on the digital image of
the sketch, a procedure that can easily extended and applied to ancient
documents for studies of art and palaeography.
