A method of sharpening a digital image having image pixels according to its material
content, includes the steps of: generating a subject matter belief map corresponding
spatially to the image pixels, having belief values indicating the likelihood that
respective image pixels are representative of a particular subject matter, generating
a noisy pixel belief map corresponding spatially to the image pixels having belief
values indicating the likelihood that the modulation about respective pixels are
due to system noise; generating gain map from the subject matter belief map and
the noisy pixel belief map having values that indicate the degree of sharpening
to be applied to the image pixels; and using the gain map to sharpen the image.
