Adaptive Unsharp Masking for Contrast Enhancement

A new scheme of unsharp masking for image contrast enhancement is presented in this paper. An adaptive algorithm is introduced so that a sharpening action is performed only in locations where the image exhibits signiicant dynamics. Hence, the ampliication of noise in smooth areas is reduced. An adaptive directional l-tering is also performed so as to provide suitable emphasis to the diierent directional characteristics of the detail. Because it is capable of treating high-detail and medium-detail areas diierently, this algorithm also avoids unpleasant overshoot artifacts in regions of sharp transitions. Experimental results demonstrating the usefulness of the adaptive operator in an application involving preprocessing of images for enhancement prior to zooming are also included in the paper.