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Reconstructed images in low bit-rate video coding often have visually annoying artifacts, such as blocking artifacts and corner outliers, usually due to block-based quantization and motion-compensated prediction. In this paper, we propose an adaptive deblocking algorithm based on local image characteristics. We remove ringing artifacts using a simple low-pass filter in the preprocessing. Among four filtering modes, an appropriate filter is selected adaptively, removing noticeable blocking artifacts in flat areas, while preserving details without blurring in highly complex areas. The proposed filter contains a non-symmetric filter a corner outlier removal filter. Simulation results show the effectiveness of the proposed deblocking algorithm in objective and subjective quality compared with those of the MPEG-4 deblocking filter. [ABSTRACT FROM AUTHOR]

A new fast motion estimation algorithm is presented. Our goal was to find the best block-matching results in a computation-limited and varying environment, and the conventional Diamond Search (DS) algorithm, though faster than most known algorithms, was found to be not very robust in terms of objective and subjective qualities for several sequences. The proposed algorithm, Enhanced Cross-Diamond Search (ECDS), employs a small cross search in the initial step. The large/small DS patterns are utilized as subsequent steps for fast block motion estimation. Experiment results show that the proposed algorithm outperforms other popular fast motion estimation algorithms in terms of PSNR and search speed, especially for sequences having random or fast motions. [ABSTRACT FROM AUTHOR]

Revealing the common underlying structure of data spread across multiple data sites by applying clustering techniques is the aim of collaborative clustering, a recent and innovative idea brought up on the basis of exchanging information granules instead of data patterns. The strength of the collaboration between each pair of data repositories is determined by a user-driven parameter, both in vertical and horizontal collaborative fuzzy clustering. In this study, Particle Swarm Optimization and Rough Set Theory are used for setting the most suitable values of the collaboration links between the data sites. Encouraging empirical results uncovered the deep impact observed at the individual clusters, allowing us to conclude that the overall effect of the collaboration has been improved. [ABSTRACT FROM AUTHOR]

To improve coding efficiency, the H.264/AVC video coding standard uses new coding tools, such as variable block size, quarter-pixel-accuracy motion estimation, multiple reference frames, intra prediction and a loop filter. Using these coding tools, H.264/AVC achieves significant improvement in coding efficiency compared with existing standards. However, the encoder complexity also increases tremendously. Among the tools, macroblock mode decision and motion estimation contribute most to total encoder complexity. This paper focuses on complexity reduction in macroblock mode decision. Of the macroblock modes which can be selected, inter8×8 and intra4×4 have the highest complexity. We propose three methods for complexity reduction, one for intra4×4 in intra-frames, one for inter8×8 in inter-frames, and one for intra4×4 in inter-frames. Simulation results show that the proposed methods save about 56.5% of total encoding time compared with the H.264/AVC reference implementation. Keywords: H.264/AVC video coding, macroblock mode decision, fast mode decision. [ABSTRACT FROM AUTHOR]

We propose a simple detection method and compensation filter in order to remove corner outlier artifacts. The corner outlier artifacts are detected based on the directions of edges going through a block corner and the characteristics of blocks around the edges. According to the detection results, we compensate the stair-shaped discontinuities, the so-called corner outlier artifacts, using the neighboring pixels of the artifacts in spatial domain. Simulation results show that the proposed method improves, when combined with a deblocking filter in particular, both objective and subjective visual quality. Keywords: Corner outlier artifact, deblocking filter, MPEG-4 video, low bit-rate video.This work was supported by Seoul Future Contents Convergence (SFCC) Cluster established by Seoul Industry-Academy-Research Cooperation Project. [ABSTRACT FROM AUTHOR]

To improve coding efficiency, the H.264 video coding standard uses new coding tools, such as variable block size, quarter-pixel-accuracy motion estimation, multiple reference frames, intra prediction and a loop filter. Using these coding tools, H.264 achieves significant improvement in coding efficiency compared with existing standards. However, encoder complexity also increases tremendously. Among the tools, macroblock mode selection and motion estimation contribute most to total encoder complexity. This paper focuses on complexity reduction in macroblock mode selection. Of the macroblock modes which can be selected, inter8×8 and intra4×4 have the highest complexity. We propose two methods for complexity reduction of inter8×8 and intra4×4 by using the costs of the other macroblock modes. Simulation results show that the proposed methods save about 53% of total encoding time compared with the H.264 reference implementation, whereas the average PSNR decreases less than 0.05 dB. [ABSTRACT FROM AUTHOR]