Calibration assessment of CMOS photo cameras for roadways luminance measurements at night

This paper presents a practical method for calibrating CMOS-based photographic cameras to ensure accurate luminance measurements. The calibration process involves calculating XYZ tristimulus values by processing 14-bit RAW data files captured from different camera positions to fully utilize the camera sensor. Subsequently, a multivariable polynomial fit is employed to determine a three-dimensional surface of luminance weighting factors. The regression method used in this study quantifies the luminance error associated with each of the three evaluated camera. It was observed that camera C3 exhibited an error of less than 6% compared to a calibrated luminance meter. Overall, the evaluation of camera performance suggests that all three cameras, despite their distinct brands and technologies, are suitable devices for measuring luminance levels.