Image enhancement via transform amplitude sharpening

A new frequency-domain based image edge enhancement technique is described. In the proposed method, the magnitude of the transform of an image is modified using a novel amplitude change function with the phase kept invariant, which is followed by an inverse transform resulting in the crispening of the edge. The new method is somewhat similar to the alpha-rooting method but does not suffer from certain objectionable artifacts associated with the latter, and also exhibits less degradation due to noise. A post-processing of the enhanced image generated using the proposed transform amplitude sharpening method via histogram modification has been found to improve the image quality. Images enhanced with the proposed method are included to illustrate the method.