Patent ID: 8224109

Claim:
A method of automatically estimating white Gaussian noise that corrupts a digital image, comprising the steps of: a) subdividing the image to be processed in blocks; b) determining a maximum standard deviation of absolute values of differences among pixels of a block; c) for each pixel of the block, performing the steps of: c1) calculating absolute values of differences of intensities between the pixel and homogeneous pixels contained in a working window centered on the pixel; c2) comparing the absolute values of differences with a threshold based on the maximum standard deviation of the block; and c3) classifying the pixel as belonging to a homogeneous portion of the image if the absolute values of the differences are all smaller than the threshold; d) determining a standard deviation of noise for the block based on pixels classified as belonging to homogeneous portions of the image, wherein pixels which are not classified as homogeneous are not considered in determining the standard deviation of noise for the block; and e) setting a maximum standard deviation of differences between pixels for a successive block to be processed and repeating steps c) through d) for the successive block.