This paper presents a new methodology for the reduction of sensor noise from images acquired using digital cameras at high-International Organization for Standardization (ISO) and long-exposure settings. The problem lies in the fact that the algorithm must deal with hardware-related noise that affects certain color channels more than others and is thus nonuniform over all color channels. A new adaptive center-weighted hybrid mean and median filter is formulated and used within a novel optimal-size windowing framework to reduce the effects of two types of sensor noise, namely blue-channel noise and JPEG blocking artifacts, common in high-ISO digital camera images. A third type of digital camera noise that affects long-exposure images and causes a type of sensor noise commonly known as "stuck-pixel" noise is dealt with by preprocessing the image with a new stuck-pixel prefilter formulation. Experimental results are presented with an analysis of the performance of the various filters in comparison with other standard noise reduction filters.
Tamer F. Rabie, Tamer F. Rabie,
"Adaptive hybrid mean and median filtering of high-ISO long-exposure sensor noise for digital photography," Journal of Electronic Imaging 13(2), (1 April 2004). https://doi.org/10.1117/1.1668279