Adaptive Median Filtering of CCD Sensor Noise

With the advent of the inexpensive CCD (Charge-Coupled Device) on a chip, the wide-spread move from traditional 35mm film photography to digital photography is becoming increasingly apparent especially with journalists and professional photographers. This has prompted digital camera manufacturers to try to implement most of the legacy techniques common among traditional film cameras such as high -ISO film, long exposures, high-speed shutters...etc into digital cameras. One technique that is of utmost importance to a large community of photographers is the digital camera equivalent to the traditional high-speed silver-based film sensitivity, commonly known as the ISO sensitivity number. This paper focuses on the development of an adaptive window-based signal equalization median filtering system for removing sensor noise from images acquired using digital cameras at high ISO settings. The problem lies in the fact that the algorithm must deal with hardware-related sensor noise that affects certain color channels more than others and is thus non-uniform over all color channels. This work is an attempt at addressing the growing concern in the digital photography community about the reduced visual fidelity in images acquired by modern professional digital cameras at high-ISO settings.