Ink detection from surface topography of the Herculaneum papyri (opens in new tab)

Reading the Herculaneum papyri is challenging because both the scrolls and the ink, which is carbon-based, are carbonized. In X-ray radiography and tomography, ink detection typically relies on density- or composition-driven contrast, but carbon ink on carbonized papyrus provides little attenuation contrast. Building on earlier X-ray phase contrast tomographic and microscopic observations suggesting that relief contributes to letter visibility, we show that surface morphology of written regio...