ICA based Image denoising for Single-Sensor Digital Cameras

MOST existing digital color cameras use a single sensor with a color filter array (CFA) to capture visual scenes in color. Since each sensor cell can record only one color value, the other two missing color components at each position need to be interpolated. The color interpolation process is usually called color demosaicking (CDM). The quality of demosaicked images is degraded due to the sensor noise introduced during the image acquisition process. The conventional solution of combating CFA sensor noise is demosaicking first, followed by a separate denoising processing. This strategy will generate many noise-caused color artifacts in the demosaicking process, which are hard to remove in the denoising process. Many advanced denoising algorithms, which are designed for monochromatic (or full color) images, are not directly applicable to CFA images due to the underlying mosaic structure of CFAs. A well designed “denoising first and demosaicking later” scheme can have advantages such as less noise-caused color artifacts and cost-effective implementation. In this paper, a single channel ICA based image denoising algorithm is proposed by constructing a noise image to as another observation signal for single channel noise reduction based on independent component analysis, thereby noise and original image can be separated through independent component analysis. Simulation result shows that much better denoising effect and signal-noise ratio can be obtained by using this algorithm.