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1、中国科学技术大学硕士学位论文分布式编码的关键技术研究姓名：张威申请学位级别：硕士专业：信号与信息处理指导教师：李厚强2011-05摘 要 I摘摘 要要 无线传感器网络、多视角视频监控系统、高光谱遥感等新型应用由于其编码终端资源受限所以要求编码非常简单；而现有的图像/视频编码方法通常编码算法比较复杂，不能满足这种需求。 分布式编码是一种全新的编码框架， 其基本思想是多个相关信源独立编码、联合解码时可以达到与联合编解码方法相同的压缩效率。这种编码方法具有许多独有的优势，尤其可将编码端的计算复杂度转移到解码端，目前已经成为了信源编码领域的一个研究热点，具有重要的理论价值和广泛的应用价值。 本论文通过
2、大量实验分析了理想信源进行分布式编码的效率，并在此基础上研究实际信源（如高光谱图像、视频图像）分布式编码方案中的一些关键技术。论文的主要工作及创新之处在于： 1. 分析了理想信源的分布式编码效率 论文对不同信源（包括二进制信源、高斯信源、拉普拉斯信源）分别进行无损的 Slepian-Wolf 编码和有损的 Wyner-Ziv 编码，并定量分析了分布式编码的性能、熵编码的性能以及理想性能之间的差距。同时论文也分析了基于分布式编码的联合信源信道编码的优势。论文通过大量的实验结果对分布式编码的压缩性能进行了定量的研究分析。 2. 提出了一种高光谱图像的无损分布式编码方案 本方案能够将探索数据相关性的
3、操作转移至解码端，以实现简单编码。在编码端，各个波段图像分为多个子图像，分别进行编码传输。解码端则利用已解码波段图像和当前波段图像的已解码子图像，采用自适应预测波段选择、滑动窗预测、K 近邻预测等技术来生成边信息。该方案编码简单、压缩效率高，非常适合于星上压缩应用。 3. 提出了一种基于渐进编解码的分布式视频编码方案 本方案采用基于块的下采样方法将 Wyner-Ziv 帧分为多个子图像依次进行编码传输，后面的子图像还需要进行自适应帧内预测但不需传输帧内模式的信息。在解码端，每个 Wyner-Ziv 帧渐进地进行解码，解码端运动估计的精度随之不断提高。该方案能够在编码端不传任何额外信息的情况下使
4、得解码Wyner-Ziv 帧时能够得到当前帧的部分信息， 从而提高边信息质量以获得更高的压缩性能。 本论文对提出的两个实际分布式编码方案进行了大量实验。实验结果证明文中提出的实际分布式编码方案在降低编码复杂度的同时能够获得较高的编码效率。 摘 要 II关键词：关键词：分布式编码 分布式信源编码 视频编码 高光谱图像 LDPC 码 LDPCA 码 低编码复杂度 高压缩效率 Abstract IIIABSTRACT Some emerging applications, e.g. sensor network, multiview video surveillance system and hyp
5、erspectral remote sensing, require low complexity encoding because the computational power and the memory are limited at the encoder. The conventional image and video coding methods can not meet such demand. The distributed source coding technique is a fire-new coding paradigm with promising perform
6、ance. The theoretical basis is Slepian-Wolf theory and Wyner-Ziv theory, which state that with two correlated sources encoded separately but decoded jointly one can achieve the same performance as with the two sources encoded and decoded jointly. This technique has many advantages, including the abi
7、lity to move the computational burden from the encoder to the decoder, and becomes a very hot research area. Therefore, research on practical distributed source coding schemes is of both theoretical significance and practical value. This thesis experimentally analyzes the efficiency of the distribut
8、ed source coding of ideal sources. And on this basis, the thesis investigates a number of key techniques of the distributed source coding of some pratical sources such as images and videos. The main contributions of this thesis are as follows: 1. This thesis analyzes the efficiency of the distribute
9、d source coding of ideal sources. In this thesis, Slepian-Wolf coding and Wyner-Ziv coding are performed to compress the ideal sources including the binary source, the Gaussian source and the Laplacian source. Moreover, the compression performance of the distributed source coding and the entropy cod
10、ing is compared to the theoretical bound. Also the thesis studies the joint source-channel coding scheme based on distributed source coding. Via lots of experiment results, the efficiency of the distributed source coding of ideal sources is studied in quantity. 2. This thesis proposes a new lossless
11、 distributed hyperspectral image coding scheme. The proposed scheme moves the correlation exploitation operations to the decoder in order to design a lightweight encoder. At the encoder, sub-sampled images/bands are successively encoded and transmitted. At the decoder, side information is generated
12、with the knowledge of decoded sub-sampled images and other previously decoded bands. Reference bands are adaptively selected, and sliding Abstract IVwindow prediction or K nearest neighbor prediction is performed to exploit the spatial and spectral correlation. With the characteristics of low-comple
13、xity encoding and high compression efficiency, the proposed scheme is very suitable for onboard applications. 3. This thesis proposes a distributed video coding scheme based on progressive encoding and decoding. At the encoder, each Wyner-Ziv frame is sub-sampled using a block-based sub-sampling alg
14、orithm, and resulting sub-samples are successively encoded and transmitted. For the latter samples, adaptive intra prediction is employed with no intra mode bits transmitted. At the decoder, the current Wyner-Ziv frame is progressively decoded, and thus the motion estimation accuracy is iteratively
15、improved. The decoder has partial access to the current Wyner-Ziv frame without receiving any extra information from the encoder, and thus the quality of the side information is improved to achieve better compression performance. A number of simulations have been carried out to demonstrate that the
16、proposed two practical distributed source coding schemes are able to achieve high compression efficiency while providing a very low-complexity encoder. Key Words: distributed coding, distributed source coding, video coding, hyperspectral image, LDPC code, LDPCA code, low-complexity encoding, high compression efficiency 缩略语和关键术语定义 IX缩略语和关键术语定义 DC Distributed Coding 分布式编码 DSC Distributed Source Coding 分布式信源编码 DVC Distributed Video Coding 分布式视频编码 DMVC D
