Rediscovering text in the Yale Martellus map

A world map painted by Henricus Martellus c. 1491 is widely acknowledged to be of great importance in the history of cartography, but has been little studied since it came to the attention of scholars in 1959 because the pigments used to write the descriptive texts and place names has faded or flaked off of the surface. Spectral images of this map collected in August 2014 have been processed by several statistical methods, allowing much of the text to be recovered. The methods may be applied to other documents and for forensic applications.