Patent ID: 7317842

Claim:
A method for reducing noise in a digital image formed from a plurality of pixels including a given pixel, the method comprising the steps of: computing global statistics from the image; computing local statistics for the given pixel; configuring a local filter using the local and global statistics; filtering the given pixel using the local filter to reduce image noise; wherein the step of computing the local statistics for the given pixel further includes the steps of: selecting a window containing the given pixel and a plurality of neighboring pixels; computing a 2-D local variance of the given pixel based on information related to the pixels in the window; computing a plurality of 1-D local variances along multiple directions through the given pixel in the window; and detecting a local edge direction by selecting one of the directions with the smallest 1-D local variance, wherein the step of configuring the local filter using the local and global statistics includes the steps of: selecting the detected local edge direction L as the direction of the local filter; for the detected local edge direction L, computing a 1-D filter strength as a function of a square root of a local variance and a global noise standard deviation; computing a 2-D filter strength as a function of the local variance and the global noise standard deviation; and configuring the local filter for the detected local edge direction L based on the 1-D and 2-D filter strengths.