Video quality suffers significant degradation when transmitted over error-prone channel. In this paper, a novel error-resilient coding scheme based on the H.264/AVC standard is proposed to tackle this challenge. Unlik...
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Video quality suffers significant degradation when transmitted over error-prone channel. In this paper, a novel error-resilient coding scheme based on the H.264/AVC standard is proposed to tackle this challenge. Unlike traditional schemes using single and fixed tool, both intra refresh and reference selection (RS) refresh tools are dynamically adapted with consideration of more varying factors like transmission channel's packet loss state, bitrate, and expected distortion. To form a balance between coding efficiency and error-resilient capability, an approach to compute refresh locations, refresh mode, and reference picture selection according to scenarios will be presented. Experiments prove that it outperforms traditional refresh methods in a loss-probability-varying transmission channel environment.
A fast block selective motion estimation/compensation method is proposed. Motion indicators are used to determine the motion content of each frame on a block basis. These motion indicators are used in an MPEG-2 video ...
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A fast block selective motion estimation/compensation method is proposed. Motion indicators are used to determine the motion content of each frame on a block basis. These motion indicators are used in an MPEG-2 video coder implementation to decide whether to perform motion estimation on single macro blocks or not. It is shown that by using this approach, coding complexity and time consumption can be decreased and gracefully adjusted. PSNR quality is increased for high motion content videos at low to medium compression rates.
Synthetic aperture radar (SAR) is an imaging technique, which provides high-resolution images. The high resolution in the range direction is achieved by using large bandwidth signals and that in the azimuth direction ...
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Synthetic aperture radar (SAR) is an imaging technique, which provides high-resolution images. The high resolution in the range direction is achieved by using large bandwidth signals and that in the azimuth direction is achieved by synthesizing a large aperture antenna using platform motion. The unique data collection geometry of SAR system requires that huge amounts of raw data be processed before obtaining a viewable image. Therefore, performing some form of compression on SAR raw data provides an attractive option for SAR systems. In this paper, we present a transform coding approach for SAR raw data compression. Due to presence of large dynamic range of frequency content in SAR raw data we propose the usage of wavelet packet transform. Experimental results of the proposed method provide significant improvement in SNR results over standard block adaptive quantization (BAQ) and JPEG2000 techniques.
This paper proposes a fragile watermarking algorithm named compression watermarking algorithm (CWA) which provides compression and authentication functions to apply in MJPEG of video surveillance system. The watermark...
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This paper proposes a fragile watermarking algorithm named compression watermarking algorithm (CWA) which provides compression and authentication functions to apply in MJPEG of video surveillance system. The watermark information is embedded into every 8 times 8 block in the coefficient domain in encoding process and extracted watermark from each 8 times 8 block in the coefficient domain in decoding process. Simulation results show that the PSNR of embedded video is lower than non-embedded video, however, the loss of quality is hardly discernible. Furthermore, the results show that the scheme improves the coding efficiency and therefore reduces both the transmission time and the storage capacity.
This paper studies the idempotence of H.264 intraframe multi-generation coding. We analyze the H.264 transform and quantization and reveal that for some quantization parameters there always exists at least one clippin...
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This paper studies the idempotence of H.264 intraframe multi-generation coding. We analyze the H.264 transform and quantization and reveal that for some quantization parameters there always exists at least one clipping compensation matrix to make the H.264 intraframe multi-generation coding idempotent as long as the same prediction mode and the same quantization parameter are selected for each coding generation. In addition, an idempotent H.264 intraframe multi-generation coding procedure is presented.
This paper presents an information-theoretic approach for estimating the compression bounds of Wyner-Ziv frames in a distributed video coding system, taking into account the amount of motion in the captured video scen...
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This paper presents an information-theoretic approach for estimating the compression bounds of Wyner-Ziv frames in a distributed video coding system, taking into account the amount of motion in the captured video scene, as well as the transmission channel conditions. Simulation results show a comparable behavior between the practical system performance and the theoretical limits. Therefore, based on the analytical estimations, a suitable compression rate can be predicted for each frame without the need for a feedback channel, with a minor loss in the system's rate-distortion performance compared to the classical feedback-based coding system.
A new color image coding technique is proposed in this paper. The technique is based on the efficient grey-scaled wavelet-based image coding, the context adaptive wavelet difference reduction - CAWDR. The coder exploi...
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A new color image coding technique is proposed in this paper. The technique is based on the efficient grey-scaled wavelet-based image coding, the context adaptive wavelet difference reduction - CAWDR. The coder exploits not only compactness and self-similarities of wavelet transform in each color component, but also the dependency between the color components. The context adaptive arithmetic coder is implemented to the encoded bit stream. The significant coefficient quantizations for all color components are performed before the refinement pass in each bit-plane. This single bit stream of encoded image has embedded property and exact rate control without explicit information. The performance comparison is also presented in the paper. The proposed coder typically has 0.3 - 1 dB higher average PSNR than that of JPEG2000.
The conventional embedded wavelet image coder exploiting the adjacent neighbors is limited to efficiently compress the sign coefficients, since the wavelet coefficients are highly correlated along the dominant image f...
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The conventional embedded wavelet image coder exploiting the adjacent neighbors is limited to efficiently compress the sign coefficients, since the wavelet coefficients are highly correlated along the dominant image features, such as edges or contours. To solve the problem, in this paper, we propose the direction-adaptive sign context modeling by adaptively exploiting the neighbors suitable to the dominant image features. Experimental results show that the sign coding based on the proposed context modeling reduces the sign bits up to 5.5% compared to the conventional sign coding method.
Quantization in H.264 is achieved in the DCT domain using scalar quantizers, which assume a sum distortion constraint and often produce considerably larger distortions on block boundaries than inside a block in the pi...
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Quantization in H.264 is achieved in the DCT domain using scalar quantizers, which assume a sum distortion constraint and often produce considerably larger distortions on block boundaries than inside a block in the pixel domain. This biased distortion distribution degrades the rate distortion (RD) performance of H.264 intra coding whose prediction is exclusively based on boundary pixels. This paper considers the problem of designing balanced distortion quantizers (BDQs) in the DCT domain, which, in addition to the sum distortion constraint, require evenly distributed distortions in the pixel domain. In a special case where DCT coefficients are independent Gaussian, the problem is solved as a convex optimization problem. Using this approach, we design BDQs and apply them to improve H.264 intra coding. Experimental results on typical frames show that the improved intra coding scheme consistently outperforms its counterpart in H.264 main-profile, averaging 5-9% rate reduction for QCIF frames, and 7-12% for CIF frames with aligned distortions.
This paper proposes a multi-hypothesis based Wyner-Ziv (WZ) decoder for the multi-view distributed video coding (MDVC). Two hypotheses, the intra-view SI and the interview SI, are fed together into the WZ decoder in t...
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This paper proposes a multi-hypothesis based Wyner-Ziv (WZ) decoder for the multi-view distributed video coding (MDVC). Two hypotheses, the intra-view SI and the interview SI, are fed together into the WZ decoder in the proposed scheme. A multi-hypothesis based correlation model (MHBCM) is presented to fully exploit the redundancy between these two SI frames and the original frame. The MHBCM is also applied on the optimal minimum mean-square error reconstruction of the quantized samples. The simulation results show that the proposed algorithms are able to significantly improve the coding efficiency of the MDVC system.
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