Iterative Ramp Sharpening for Structure/Signature-Preserving Simplification of Images

In this paper, we present a simple and heuristic ramp sharpening algorithm that achieves local contrast enhancement of vector-valued images. The proposed algorithm performs pixel wise comparisons of intensity values, gradient strength and directional information in order to locate transition ramps around true edges in the image. The sharpening is then applied only for those pixels found on the ramps. This way, the contrast between objects and regions separated by a ramp is enhanced correspondingly, avoiding ringing artifacts. It is found that applying this technique in an iterative manner on blurred imagery produces sharpening preserving both structure and signature of the image. The final approach reaches a good compromise between complexity and effectiveness for image simplfication, enhancing in an efficient manner the image details and maintaining the overall image appearance.