1. A method for finding an area of interest in an input image, comprising the steps of: (a) filtering said input image with a two-dimensional filter to generate a filtered image, wherein at least part of the filter is applied to each entire row of the input image before any part of the filter is applied to any pixels of the next row of the input image; (b) determining the location of an artifact in said filtered image; and (c) determining the location of said area of interest in said input image according to said location of said artifact in said filtered image, wherein step (a) comprises the steps of: (1) filtering the input image with a (4.times.4) compression filter to generate a first compressed image, wherein at least part of the (4.times.3) compression filter is applied to each entire row of the input image before any part of the (4.times.4) compression filter is applied to any pixels of the next row of the input image; (2) filtering the first compressed image with a first (2.times.2) compression filter to generate a second compressed image, wherein at least part of the first (2.times.2) compression filter is applied to each entire row of the first compressed image before any part of the first (2.times.2) compression filter is applied to any pixels of the next row of the first compressed image; (3) filtering the second compressed image with a second (2.times.2) compression filter to generate a third compressed image, wherein at least part of the second (2.times.2) compression filter is applied to each entire row of the second compressed image before any part of the second (2.times.2) compression filter is applied to any pixels of the next row of the second compressed image; and (4) optionally filtering the third compressed image with a third (2.times.2) compression filter to generate a fourth compressed image, wherein at least part of the third (2.times.2) compression filter is applied to each entire row of the third compressed image before any part of the third (2.times.2) compression filter is applied to any pixels of the next row of the third compressed image, wherein: the first (2.times.2) compression filter is applied to at least part of the first compressed image before the (4.times.4) compression filter is completely applied to the input image; the second (2.times.2) compression filter is applied to at least part of the second compressed image before the first (2.times.2) filter is completely applied to the first compressed image; the third (2.times.2) compression filter is optionally applied to at least part of the third compressed image before the second (2.times.2) compression filter is completely applied to the second compressed image; and if the third (2.times.2) compression filter is applied, then the filtered image comprises the fourth compressed image; otherwise, the filtered image comprises the third compressed image.