| With the fast development of PSTN and mobile telephone, a demand for image communication increases rapidly. Meanwhile, the wide use of Internet promotes the use of video mail, remote medical treatment, remote education and shopping through the net. A low-bit rate video communication is urgently needed in these applications. ITU-T (International Telecommunication Union) has been working on this project for a long time and recommended H.261, H.263 and H.263 + standards. With the outcome of these recommendations, video communication has been developed rapidly.After a careful study of the standards of ITU-T H.26X series, I developed some new algorithms for motion estimation and intra-frame / inter-frame model selection in H.263+ image compression encoding, by combination of some up-to-date methods published. In motion estimation, I proposed an algorithm of adaptive selection of 3-step and 4-step search. This algorithm increases the speed and accuracy of the motion vector search In intra-frame / inter-frame model selection, I proposed an adaptive selection method of intra-frame / inter-frame prediction model, based on TMN Recommendation.In this paper, Chapter one introduces the needs for low bit-rate video compression and relevant standards. Chapter two first introduces briefly some common image compression methods, then emphases on the algorithms used in H263+ encoding and decoding. Chapter three describes in detail the standards ofH.26X series. Chapter four, the core of this paper, presents my new method and algorithm for H.263+ encoding and decoding. Chapter five presents an application using H.263+ codec(COder/DECoder).In addition, a structure matching algorithm is proposed at the end of this paper. It is used for the solution of object tracing problems in water oil-driving project, where the water oil-driving micro images do not satisfy a block motion estimation criterion.
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