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Robust multiple description image coding over wireless networks based on wavelet tree coding, error resilient entropy coding, and error concealment

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2008年第5期19卷 311-319页

作者： Song, Daewon Cao, Lei Chen, Chang Wen SUNY Buffalo Buffalo NY 14260 USA LG Dacom Res Inst Technol IPTV Team Taejon 303350 South Korea Univ Mississippi Dept EE University MS 38677 USA

In this paper, we propose an integrated robust multiple description coding (MDC) scheme for compressed still images over error-prone channels with both packet loss and random bit errors. Multiple descriptions are first generated independently by using multiple description scalar quantizer (MDSQ). To achieve an excellent error resilient capability for each description, multiple bitstreams are then generated based on wavelet trees along the spatial orientations. The spatial orientation trees in the wavelet domain are individually encoded using SPIHT. Error propagation is thus limited within each bitstreams. However, synchronization words are usually needed to avoid error propagation across multiple independent bitstreams. In order to maintain high compression efficiency robust synchronization, we adopt error resilient entropy coding (EREC) to re-organize these variable-length bitstreams into fixed-length data slots before multiplexing and transmission. Therefore, the synchronization of the start of each bitstream can be automatically obtained at the receiver. Finally, to alleviate the devastating image degradation resulted from errors in the beginning of the bitstreams, we propose an error concealment technique to both constrain the EREC/MDC decoding and post-process the decoded wavelet coefficients. With analysis and experimental results, we have demonstrated how each of these components has contributed to the overall robustness of the proposed transmission of compressed images over wireless channels. (c) 2008 Published by Elsevier Inc.

关键词： error resilience MDSQ wavelet tree coding EREC robust multiple description image coding wireless networks error concealment SPIHT

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Error resilient wavelet tree coding for robust image transmission

Error resilient wavelet tree coding for robust image transmi...

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Conference on Image and Video Communications and Processing

作者： Cao, L Chen, CW Univ Mississippi Dept Elect Engn University MS 38677 USA

ISBN: (纸本)0819448222

In this paper, a scheme for robust image coding and transmission over noisy channels is presented. First, the spatial-orientation trees in the wavelet domain are independently encoded using the algorithm of set partitioning in hierarchical trees (SPIHT). We generate multiple bitstreams in order to limit the error propagation. Because the self-similarity across subbands is preserved in each wavelet tree, a high coding efficiency is also obtained. However, when these bitstreams with variable length are transmitted sequentially, error impact may still be propagated across the boundaries between two consecutive bitstreams and may cause catastrophic decoding. Therefore, we apply error resilient entropy coding (EREC) to reorganize these bitstreams into fixed length slots so that synchronization of the start of each bitstream is automatically achieved at the receiver. This is particular useful for the progressive data where bits located in the beginning of bitstream are always more important than those at the end. Finally, to further alleviate the impact of errors in the beginning of the bitstreams, parity bits are added and exploited by an error concealment technique conducted only in the lowest frequency subband. Experimental results demonstrate an excellent error resilient performance of the proposed scheme.

关键词： wavelet tree coding SPIHT EREC error concealment robust image coding and transmission

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Multiple wavelet-tree-based image coding and robust transmission

Multiple wavelet-tree-based image coding and robust transmis...

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Conference on Multimedia Systems and Applications VII

作者： Cao, L Chen, CW Univ Mississippi Dept EE University MS 38677 USA

ISBN: (纸本)0819455539

In this paper, we present techniques based on multiple wavelet-tree coding for robust image transmission. The algorithm of set partitioning in hierarchical trees (SPIHT) is a state-of-the-art technique for image compression. This variable length coding (VLC) technique, however, is extremely sensitive to channel errors. To improve the error resilience capability and in the meantime to keep the high source coding efficiency through VLC, we propose to encode each wavelet tree or a group of wavelet trees using SPIHT algorithm independently. Instead of encoding the entire image as one bitstream, multiple bitstreams are generated. Therefore, error propagation is limited within individual bitstream. Two methods based on subsampling and human visual sensitivity are proposed to group the wavelet trees. The multiple bitstreams are further protected by the rate compatible puncture convolutional (RCPC) codes. Unequal error protection are provided for both different bitstreams and different bit segments inside each bitstream. We also investigate the improvement of error resilience through error resilient entropy coding (EREC) and wavelet tree coding when channels are slightly corruptive. A simple post-processing technique is also proposed to alleviate the effect of residual errors. We demonstrate through simulations that systems with these techniques can achieve much better performance than systems transmitting a single bitstream in noisy environments.

关键词： wavelet tree coding SPIHT multiple bitstreams robust image coding and transmission

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Robust image transmission over MIMO space-time coded wireless systems*

Robust image transmission over MIMO space-time coded wireles...

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Conference on Mobile Multimedia/Image Processing for Military and Security Applications

作者： Song, Daewon Chen, Chang Wen Florida Inst Technol Dep ECE Melbourne FL 32901 USA

ISBN: (纸本)081946306X

We present in this paper an integrated robust image transmission scheme using space-time block codes (STBC) over multi-input multi-output (MIMO) wireless systems. First, in order to achieve an excellent error resilient capability, multiple bitstreams are generated based on wavelet trees along the spatial orientations. The spatial-orientation trees in the wavelet domain are individually encoded using SPIHT. Error propagation is thus limited within each bitstreams. Then, Reed-Solomon (R-S) codes as forward error correction (FEC) are adopted to combat transmission errors over error-prone wireless channels and to detect residual errors so as to avoid error propagation in each bitstream. FEC can reduce the bit error rates at the expenses of increased data rate. However, it is often difficult to design an optimal FEC scheme for a time-varying multi-path fading channel that may fluctuate beyond the capacity of the adopted FEC scheme. Therefore, in order to overcome such difficulty, we propose an approach to alleviate the effect of multi-path fading by employing the STBC for spatial diversity with assumption that channel state information (CSI) is perfectly estimated at the receiver. Experimental results demonstrate that the proposed scheme can achieve much improved performance in terms of PSNR over Rayleigh flat fading channel as compared with a wireless system without spatial diversity.

关键词： MIMO space-time codes wavelet tree coding SPIHT robust image transmission multi-path fading

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Error resilient image transmission based on virtual SPIHT

Error resilient image transmission based on virtual SPIHT

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Conference on Multimedia on Mobile Devices 2007

作者： Liu, Rongke He, Jie Zhang, Xiaolin Beijing Univ Aeronaut & Astronaut Dept EE Beijing 100083 Peoples R China

ISBN: (纸本)9780819466204

SPIHT is one of the most efficient image compression algorithms. It had been successfully applied to a wide variety of images, such as medical and remote sensing images. However, it is highly susceptible to channel errors. A single bit error could potentially lead to decoder derailment. In this paper, we integrate new error resilient tools into wavelet coding algorithm and present an error-resilient image transmission scheme based on virtual set partitioning in hierarchical trees (SPIHT), EREC and self truncation mechanism. After wavelet decomposition, the virtual spatial-orientation trees in the wavelet domain are individually encoded using virtual SPIHT. Since the self-similarity across sub bands is preserved, a high source coding efficiency can be achieved. The scheme is essentially a tree-based coding, thus error propagation is limited within each virtual tree. The number of virtual trees may be adjusted according to the channel conditions. When the channel is excellent, we may decrease the number of trees to further improve the compression efficiency, otherwise increase the number of trees to guarantee the error resilience to channel. EREC is also adopted to enhance the error resilience capability of the compressed bit streams. At the receiving side, the self-truncation mechanism based on self constraint of set partition trees is introduced. The decoding of any sub-tree halts in case the violation of self-constraint relationship occurs in the tree. So the bits impacted by the error propagation are limited and more likely located in the low bit-layers. In additional, inter-trees interpolation method is applied, thus some errors are compensated. Preliminary experimental results demonstrate that the proposed scheme can achieve much more benefits on error resilience.

关键词： wavelet tree coding virtual SPIHT EREC error resilience self-truncation mechanism

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