Deblocking Algorithms with Edge Filters for DCT Compressed Images

Blocking artifacts occur in images and video streams that are compressed to low bit rates using block Discrete Cosine Transform (DCT)-based compression standards. It appears as artificial block boundaries between adjacent blocks of the compressed images. In this paper, new methods to reduce blocking effect are proposed. They were tested on different images and different compression ratios (quality factors), and they were evaluated using objective and subjective measures. In general, results of testing were obtained as expected. One technique, namely: The "two sides average+Sobel edge detector" achieved higher values for approximately all tested images in both, objective and subjective quality measures.