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Abstract

User calibrated digital single-lens reflex (DSLR) cameras, utilizing an automated image calibration algorithm, are being used for glare evaluations as affordable alternatives to high-end luminance cameras calibrated by manufacturers. This study investigates the accuracy of luminance maps derived from HDR images captured with auto-calibrated DSLR cameras. More specifically, to compare the luminance values obtained with an auto-calibrated DSLR camera with a commercially available camera (that benefited from an absolute calibration) and a handheld luminance meter, considered as the reference. It was found that there are only small differences when luminance values estimated with auto-calibrated DSLR cameras are compared with those obtained for the commercially calibrated camera for low to mid-range luminance values (50 – 5000 cd/m 2 ). However, for higher luminance values (>5000 cd/m2 ), HDR images from the auto-calibrated camera show differences of up to 20 %, which could be problematic for glare investigations. More studies specifically focusing on high luminances are needed to determine more conclusively whether certain limitations should apply to the use of automatically calibrated DSLR cameras for glare evaluations.

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