Patent ID: 8582916

Claim:
A method of reducing noise in an image, comprising: a) for each pixel being examined in the image, selecting a set of search pixels; b) calculating a value of at least a first feature of a first neighborhood of each search pixel, and a value of a corresponding feature of a corresponding neighborhood of the pixel being examined; c) calculating a value of at least a second feature of a second neighborhood of each search pixel, the same as or different from the first neighborhood, and a value of a corresponding feature of a corresponding neighborhood of the pixel being examined; d) calculating a reduced noise grey value for each pixel being examined, based on raw or transformed grey values of the search pixels of each pixel being examined, with greater sensitivity to those with one or more feature values similar to those of the pixel being examined; e) assigning a patch of pixels in the image, represented as a vector of grey levels, to one out of a plurality of clusters in a vector space of the plurality of clusters; f) approximating the patch of pixels as a function of a reduced set of independent parameters, fewer than the number pixels in the patch of pixels, associated with said one cluster; and g) correcting a grey level of a pixel of the patch of pixels according to a difference between actual grey levels of the patch of pixels and the approximation of the patch of pixels as a function of the reduced set of independent parameters; wherein calculating the value of at least the first feature comprises calculating a characteristic of a distribution of raw or transformed grey values of pixels in the neighborhood, other than a mean grey value of all pixels in the neighborhood, and calculating the value of at least the second feature comprises evaluating a transform of the image in the neighborhood, or an effect of a filter on the image in the neighborhood, that preferentially selects structures of a range of scales intermediate between the size of the neighborhood and a few pixels, or of some orientations over other orientations, or both.