Adaptive hybrid mean and median filtering of high-ISO long-exposure sensor noise for digital photography

摘要

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.