Fast loop filtering using separable characteristics of the integer 2-D discrete cosine transform

Abstract

When an image is highly compressed, video coding using the discrete cosine transform (DCT) and quantization produces noticeable image degradations, such as blocking artifacts and ringing noise. In order to reduce the degradations, a loop filtering algorithm is proposed, which consists of simple deblocking filtering and a fast decision rule for ringing and blocking conditions. The proposed method utilizes a four-point integer DCT for detecting blocking and ringing conditions. It also adopts an early termination policy during detection of the blocking and ringing conditions in the DCT domain. This policy speeds up computation of the filtering. The proposed method is compared with the loop filtering of the Joint Video Team (JVT) codec. As an experimental result, the computation time of the proposed method is approximately 20% faster than that of the JVT loop filtering, while the PSNR is almost the same. (C) 2003 Society of Photo-Optical Instrumentation Engineers.