Application of Reflectance Transformation Imaging (RTI) to the study of ancient graffiti from Herculaneum, Italy

Abstract

This article discusses the application of Reflectance Transformation Imaging (RTI) to ancient graffiti from Herculaneum, Italy. RTI is a computational photography technique that makes it possible to digitally manipulate the light direction within a 2D image. This allows researchers to examine the graffiti (and individual details and letterforms) under a variety of lighting conditions. Furthermore, RTI is able to enhance the surface and color of the wall plaster on which the graffito was written. Several examples of this application to ancient graffiti show that RTI enables researchers to decipher graffiti, especially individual letterforms. RTI mimics the process of personal autopsy on site and allows scholars to reexamine the graffiti from anywhere in the world. In combination with other methods of archaeological documentation, RTI digitally preserves these inscriptions for the future.