Standards for illumination of digital prints and photographs

Abstract

Standards for illuminating digital prints and photographs have a number of quite different applications. In the graphic arts industry, the main applications are defined as appraisal and critical comparison, for which 500lux and 2000lux are specified in ISO 3664. In the museum world much lower levels of illumination are imposed when artefacts are considered to be prone to damage from such exposure. For display and storage of photographic prints, BS 5454:2000 is applicable and specifies maximum levels of 50 lux and 200 lux respectively. While these standards provide recommendations for exposure to radiant energy with the goal of limiting damage to materials and maximising visual discrimination, there is a need for more data on the radiative damage spectrum for the materials used in digital prints and photographs and other artefacts, and on the viewing conditions which can maximise visual performance for specific tasks. It is recommended that radiative exposure is measured in watts per square metre instead of lux to give a better indication of the propensity for radiative damage of a given illumination source.