Reduction of blocking artifact based on edge information in discrete cosine transform–coded images

Abstract

We propose new method for the reduction of blocking artifacts present in low bit-rate coded images. This algorithm performs the deblocking operation in two modes that are determined by the number of edge pixels around the block boundary. The number of edge pixels is calculated by applying the Roberts edge filter. An appropriate filtering operation is performed for each mode in both the horizontal and vertical directions. First, when the mode is associated with a smooth region, a strong filtering operation is applied because flat regions are more sensitive to the human visual system. In the second mode, an adaptive low-pass filter that is based on pixel behavior around the block boundaries is applied. This filter reduces the blocking artifact without introducing undesired blurring effects, while the original image edge is preserved. Although the proposed approach is simple and operates in the spatial domain, experimental results show that it improves both the subjective and objective qualities of the coded image with various features.