Text recovery from the ultraviolet-fluorescent spectrum for treatises of the Archimedes Palimpsest

Abstract

It has been reported previously that the readability of text in the original Archimedean treatises in the Archimedes Palimpsest is enhanced by spatially normalizing the images and rendering spectral differences in pseudocolor. Though this method worked well for some of the original texts in the palimpsest, the readability of the original text was improved little or not at all on leaves of a commentary on Aristotle's Categories by Alexander of Aphrodisias. This is not very surprising, since the various original works within the palimpsest were written by different scribes at various times and places, so the spectral responses of the inks in different manuscripts may be different. However, there is much scholarly interest in the readings from this text, so different image processing techniques were implemented. It was found that significant text information could be recovered from this manuscript by principal component analysis applied to color images of the fluorescence generated under ultraviolet illumination. This result indicates that useful text information is conveyed by the spectrum of the ultraviolet fluorescence. The success of this technique has changed the protocol used in image collections with other manuscripts.