METHOD AND APPARATUS FOR NOISE REDUCTION

This invention is related to a multi-scale image processing algorithm for enhancing contrast to noise ratio in an electronic representation of an image represented by a) decomposing said digital image into a set of detail images at multiple resolution levels and a residual image at a resolution level lower than said multiple resolution levels, b) processing said detail images, c) computing a processed image by applying a reconstruction algorithm to the residual image and the processed detail images, said reconstruction algorithm being such that if it were applied to the residual image and the detail images without processing, then said digital image or a close approximation thereof would be obtained. The processing comprises the steps of: d) calculating a local variance value for at least one detail image pixel within a neighbourhood of said detail image pixel; e) enhancing or suppressing at least one detail image pixel as a function of said local variance value and said detail image pixel value.