Reflectance transformation imaging (RTI) is an advanced imaging technique used to analyze the surface properties of objects. With this technique, the camera and object remain stationary, and an image is captured every time the angle of illumination changes. The images are then computationally combined to create a detailed and interactive representation of the object’s topography. In specialized viewing software, researchers can manipulate the light source’s position to virtually illuminate the object from any direction and also select different rendering modes. These manipulations can enhance the visibility of fine surface details (e.g., textures, inscriptions, and tool marks) that are not perceptible under normal lighting conditions.

The RTI Dome made by Involutech, Sp. z. o.o., is 35 cm in diameter and contains 50 LEDs that emit white light (specs). The dome can also illuminate the object with three discrete visible wavelengths (465 nm [blue], 520 nm [green], 630 nm [red]) at six light positions (high angle, low angle, and four types of directional light), as well as with 375 nm (UV) and 940 nm (IR) wavelengths at a high-angle light position. The dome can be placed directly over small objects, flush with the table, or it can be mounted on a tripod to hover over larger objects. Images are captured with a Sony Alpha 7 ILCE-7RM3A digital-back camera. The 42.4-megapixel, 35mm

CMOS RGB silicon sensor can capture color images with a maximum resolution of 7968×5320 pixels in 14-bit RAW file format. This camera is usually paired with a FE 2.8/50 MACRO lens. Images are processed in a dedicated RTI processor using the light positioning file. The resulting RTI files are displayed in the RTI Viewer software, available for free from Cultural Heritage Imaging (CHI). The RTI processor software requires files in a JPEG format and strict filenames 01–50.jpeg.