Infrared imaging techniques for the readability enhancement of Herculaneum papyri: A comparison between technical photography and high-resolution digital microscopy

The Herculaneum papyri are precious manuscripts containing unique witnesses about the ancient Greek philosophy and literature, preserved by carbonization after the Vesuvius eruption occurred in 79 AD. Despite the exceptional conservation processes resulting from the eruption, the textual readability of the papyri is very hard and often impossible with the naked eye owing to the difficult discrimination of the text made of carbon-black ink from charred papyrus support. Such complexity is an interesting challenge for both papyrologists and scientists and is one of the aims of the ERC Advanced Grant 885222-GreekSchools. In this project, advanced technologies and philological approaches are applied for the study of unrolled papyri aimed at reading the written texts and investigating among multiple layers and, so, achieving a deeper understanding of such manuscripts and providing new critical editions of them. This contribution presents a combined approach adopted for the analysis and the documentation of the Herculaneum papyrus collection by using technical photography and high-resolution digital microscopy. A comparison between the images obtained through both the two techniques is carried out, by focusing attention on the results in the infrared range (940-1000nm) in terms of details, resolution and images handling. Furthermore, an experimental study is performed through high resolution digital microscopy considering 3D profiling and morphology of the papyrus surface, with the aim of detecting and identifying letters among morphological accidents and understanding the thickness of papyrus layers.