Abstract
Because of differences between how a human and a camera (or digital recording system) acquire and process information, a representation (e.g., a photograph) of a scene may vary in how accurately it portrays what a human would perceive, particularly at low illumination levels. Ayres (1996) described a methodology by which a representation can be matched to observations made at the scene. Central to this process is the utilization of a reference chart to validate the representation. The efficacy of the original chart has been documented empirically; however, its utility can be restricted under certain lighting and viewing conditions. The current paper introduces and tests new reference charts designed to offer a wider range of applicability and with finer gradations of contrast. The new charts were found to be useful at illumination levels ranging from approximately 0.05 to 10.0 footcandles. Potential applications for the charts, including forensic purposes, are discussed.
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