1. A method for modifying an image comprising: (a) receiving an image having a first bit depth; (b) modifying said image using a Sieve filter performing a summation operation that replaces the value of a target pixel with the value of central pixel in said summation operation when said target pixel differs from said central pixel by a value larger than a threshold to create a modified image resulting in a second bit depth different than said first bit depth in such a manner that the higher frequency content with respect to the lower frequency content of said image is attenuated, and attenuating the lower amplitude content of said higher frequency content with respect to the higher amplitude content of said higher frequency content; (c) modifying said modified image based upon said modified image and said lower frequency content of said image.