Byzantine Sigillography and RTI: Insights from the DigiByzSeal Project in Cologne

This contribution discusses the application of Reflectance Transformation Imaging (RTI) in Byzantine sigillography, focusing on the experience of the DigiByzSeal project in Cologne. The project addresses the challenge of analyzing damaged or corroded Byzantine seals by employing RTI, an imaging technique that involves multiple captures with varying light positions in order to reveal epigraphic and iconographic features that are otherwise invisible.The paper also discusses the development of our RTI workflow, using an RTI Dome built at the Cologne Centre for eHumanities (CCeH), including capture preparation and determination of the optimal camera settings for each seal. Initially using darktable for tethered capturing, the project faced various issues and limitations, leading to the development of a custom capturing software. This software offers detailed control over camera configuration and streamlines the capture process, providing a user-friendly and efficient interface for capturing seals in a controlled environment. Further enhancements include the integration of Bluetooth connectivity to remotely control the RTI Dome, thereby fully automating the process. For the RTI processing part, RelightLab is presented as the software of choice, offering advantages over previously used tools in terms of user-friendliness and efficiency.Finally, it is discussed how the RTI images obtained have proved crucial for the analysis and interpretation of seals from the Robert Feind Collection, showing the potential of RTI for studying damaged artefacts and contributing to research on Byzantine sigillography.