Patent ID: 6990252

Claim:
A method of analyzing noise content in a digital image, the method comprising: identifying regions of approximately constant pixel value within the digital image; selecting a predetermined number of said identified regions based on pixel value variances within each said identified region; analyzing said selected regions to generate a mathematical model of noise present in the digital image, wherein said analyzing said selected regions to generate a mathematical model of the noise present in the digital image comprises: processing each selected region to remove a mean pixel value from each pixel in the selected region and obtain an approximation of the noise in each selected region, analyzing the power spectral density (PSD) of the noise in said selected regions, generating a parametric model of the noise present in the digital image based on said PSD of the noise in said selected regions, wherein said generating a parametric model of the noise present in the digital image based on said PSD for each selected region comprises: taking a discrete Fourier transform of each noise sample, and squaring each resulting frequency component to produce a periodogram, averaging together the periodograms; and selecting a best-fit linear combination of a small set of predefined PSDs.