AIC's 44th Annual Meeting

Multispectral imaging (MSI) has seen a rapid development within the field of conservation, thanks in part to its adaptation with digital imaging techniques. One recent advance in MSI is the use of visible-induced infrared luminescence (VIL) to map pigments that might otherwise be invisible to the naked eye. This technique, first published by Giovanni Verri (2009), involves the excitation of pigments on object surfaces with visible light, and the photographic capture of the resulting emission of infrared radiation. Specific pigments, including Egyptian blue, Han blue, Han purple, cadmium red and cadmium yellow, emit infrared radiation when excited in the visible range, creating visible-induced luminescence. The ways in which this phenomenon can be captured in an image involve a wide range of photographic equipment and associated techniques, which will be the focus of this paper. The authors will discuss their own experiences at the Metropolitan Museum of Art and the J. Paul Getty Museum Villa, where this technique has been used on a wide range of projects, including both in-lab and in-gallery imaging campaigns. Conservators have also tested the technique on archaeological excavations and have found that with the right equipment (battery-powered, durable) and the ability to limit ambient light, VIL can be successfully carried out in less controlled environments. This paper will provide a review of previous and current methodology, including a discussion of image capture and processing trade-offs, and also highlight areas for future development and experimentation.