Discontinuity filtering in the compressed domain using height and direction fuzziness

Abstract

There have been many techniques that manipulate a compressed image in the discrete cosine transform (DCT) domain for MPEG and JPEG standards, and we have proposed a model-based discontinuity evaluation technique in the DCT domain that has problems with rotated or nonideal discontinuities. To enhance the effectiveness of the discontinuity detection method in the DCT domain while preserving the advantage of efficiency, we propose a fuzzy filtering technique that consists of height fuzzification, direction fuzzification, and fuzzy filtering of discontinuities. The enhancement achieved by the fuzzy filtering includes the linking, thinning, and smoothing of discontinuities in the DCT domain. Although the detected discontinuities are rough in a low-resolution image for the size (8×8 pixels) of the DCT block, experimental results show that this technique is fast and stable to enhance the quality of discontinuities.