Recent applications of digital imaging in painting conservation: transportation, colour change and infrared reflectographic studies

Abstract

In recent years digital imaging has proved to be a useful tool for documenting and examining paintings. These techniques can yield permanent records that are potentially more accurate than photographic images. The key applications in which digital imaging is superior to other techniques are those where short- or long-term changes are measured. The paper describes the imaging systems developed in a ten-year collaboration between the National Gallery, London and the Doemer- Institut, Munich and the geometric transformation algorithms which have allowed accurate comparisons of ‘before’ and ‘after’ images to be made. Recent results obtained from a long-term study of colour changes caused by display in the museum and short-term changes caused by transportation to loan exhibitions are presented. Improvements made to the procedure for acquiring, processing and presenting infrared reflectogram mosaics are also detailed. Finally, other conservationrelated and archival uses for the colour-accurate, high-resolution digital images are discussed.