Discontinuity enhancement using fuzziness in DCT blocks

Abstract

Though there have been many methods to detect features in spatial domain, in the case of a compressed image it has to be decoded, processed and encoded again. Alternatively, we can manipulate a compressed image directly in the Discrete Cosine Transform (DCT) domain that has been used for compressing videos or images in the standards like MPEG and JPEG, and we have proposed a model-based discontinuity evaluation technique in the DCT domain that has problems in the rotated or non-ideal discontinuities. In this paper, 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. © Springer-Verlag Berlin Heidelberg 2004.