Segmentation-based JPEG image artifacts reduction

摘要

A method for reducing ringing and blocking artifacts in a decompressed image models an image in a relatively small area as several smooth regions separated by edges. The method uses JPEG MxM pixel blocks and is compatible with JPEG decompression. To reduce ringing, a block is examined for uniformity (S20), segmented and smoothed (S24). Then, after a DCT transform (S26), a projection is performed (S28) to guarantee that the DCT coefficients of the resulting image block will be within the initial quantization interval. The resultant image is produced (S30) by an inverse DCT. To reduce blocking, the method is modified to employ a large outer window for uniformity checking, segmentation and smoothing and a small inner window for DCT projection.