This photographic technique makes use of the fact that certain elements found in pigments will emit infrared radiation when irradiated by a blue-green light source. Terminology is defined, and the difference between visible fluorescence excited by ultraviolet radiation and invisible infrared luminescence excited by blue-green light is explained. Methods are given for obtaining the blue-green exciting illumination and for the necessary filtration at the camera. Faint chips and paintings photographed by the well-known ultraviolet technique and by the infrared luminescence technique are compared. Infrared luminescence may find major applications in the examination of heavily varnished paintings which are difficult to see or photograph under ultraviolet light. Other possible applications to the study of art materials are discussed.