From closed testaments to books: Virtual X-ray Reading as an alternate digitization technology for fragile documents

In recent years, research and technology made considerable progress in increasing the speed and the safety of the entire digitization process of ancient collections. Despite this, imaging ancient, fragile or un-opened documents remains a formidable challenge. We employ an alternate digitization technique for handwritten documents, exploiting x-ray tomography: Virtual X-ray Reading. Thanks to the high penetration of x-rays, we can acquire 3-dimensional (3D) tomographic images of a multi-page document without opening it. The x-ray contrast necessary for the readability is produced by the chemical composition and the consequent strong x-ray absorption of the iron gall inks - largely used for European handwritten documents. We present the development of this technology, from the chemical investigations of the inks to the tomography of an unopened Venetian testament and of an 18th century, 200-page, handwritten book.