A gradient-based image enhancement and restoration method and system which
applies an orientation-isotropy adaptive filter to the gradients of high
structured regions, and directly suppresses the gradients in the noise or
texture regions. A new gradient field is obtained from which image
reconstruction can progress using least mean squares. The method
generally comprises: inputting image data; calculating image gradients;
defining the gradients as having large or small coherence; filtering the
large coherence gradients for edge enhancement; suppressing the small
coherence gradients for noise reduction; assembling an enhanced gradient
field from the filtered large coherence and suppressed small coherence
gradients; and optimizing the assembled gradient field into a restored
image.