Noise reduction in digital images

As the popularity of digital cameras increases, some limitations of digital technology are becoming apparent. One limitation is the appearance of additive noise in images acquired using long exposure times. Long exposure times are necessary any time you need to take an image in conditions that have a low level of illumination. Pictures taken at night, in a large room such as an auditorium, or forensics images are examples of times when a long exposure time is necessary. This research project has resulted in the development of a technique to reduce the additive noise present in these images. The first step in this process is the characterization of an individual Charge-Coupled Device (CCD) array in a digital camera. This information is then used to selectively median filter individual color channels of images acquired using the characterized array. Experiments have shown this technique significantly reduces the additive noise in an image without noticeable loss of image sharpness