Reflectance Transformation Imaging ( RTI ) in Conservation

Abstract

Reflectance transformation imaging (RTI) requires first capturing a series of digital images of an object. A computer algorithm then extracts data from the series to construct a new image type, which reveals surface information not visible in any of the single images or in the original object. With inexpensive equipment, free software, and active research leading to continuing improvements, RTI has become part of the standard toolkit of conservators. The enhanced surface morphology details visible in qualitative RTI reveal information about craft techniques and help conservators to document condition, assess effects of treatments, and monitor change. Quantitative RTI more accurately measures change over time on object surfaces. It requires care in arranging a repeatable photographic setup and use of reproducible methods very sensitive to detecting surface changes. Quantitative RTI can measure damage or deterioration over time, or the visual effects caused by the application of conservation materials or by treatment techniques.