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Research On Error Resilience Technologies Of Image And Video

Posted on:2012-04-13Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z H DingFull Text:PDF
GTID:1118330371962498Subject:Military Intelligence
Abstract/Summary:PDF Full Text Request
With the development of data compression and communication technology, multimedia applications are growing rapidly. On the one hand, data compression technologies make less data that needs to be transmitted, on the other hand, as the correlation between the compression data is reduced, the effect of error to image and video quality increases. During the actual signal transmission, many reasons such as entironment and equipment make the transmission error and packet loss unavoidable. And the errors are prone to spread, resulting in a serious decline in the quality of image and video, even the failure of recovery The existing error resilience technologies such as error-correcting codes and retransmission mechanism, have their own advantages and disadvantages. Each is suitable for different environment. Among these technologies, error resilience technologys in source decoder does not increase the code word redundancy, and is standard compliant, and independent on transmission channel. Especially in some special applications, the error resilience technology in source decoder is the only choice.According to the characteristics of image and video compressed data, error correction and error concealment technologies of image and video are researched in this thesis. A new mechanism based on the analysis of the error resilient technologies in source decoder is researched. The main contribution of the thesis includes six aspects as follows:(1) A new mechanism for error resilience in source decoder is researched. It is the integrated application of the error resilience technologies in source decoder, and combines intelligent processing technologies with decoding technologies. In error detection, error correction and error concealment, intelligent technologies such as pattern recognition are used. The mechanism can give full play to error correction technology, early resynchronization technology and error concealment technology to their own advantages and effectively solve many difficult problems such as error localization.(2) Error correction decoding technologies to the still image are researched. Fax MMR error correction decoding algorithm based on probability statistics and JPEG2000 error correction decoding algorithm against the high weighted bits are proposed respectively. Using a large number of MMR code samples, the former algorithm gets the number of error line's bits and the probability of the same length of different sequences. The probability model is updated dynamically by maximum posteriori estimation based on Bayes theory before error correction. The results are used to guide the error correction decoding. As a result, the speed of the propsed algorithm is faster than the past one. Because different bits of the JPEG2000 have different influence to image restoration quality, once some bit errors are detected, a sliding window is used to search errors in the high weighted bits region. The experiment shows its good performance.(3) Video stream error detection technologies are researched. A hierarchical video error detection algorithm is proposed based on mutifeatures of macroblock. The existing video streams error detection technologies are studied firstly. Secondly according to the pattern recognition theory, a series of error detection features which are commonly used are summrized and some new characteristics are introduced. And finally the hierarchical error detection algorithm based on the syntax-based method, threshold method and support vector machine method is used to detect errors. Experiments show that the algorithm can detect errors in blocks which visual expression is not obvious and improve detection performance for error block.(4) Video spatial error concealment algorithms are researched. A new spatial error concealment method based on match of boundary subsection is proposed. According to computer vision theory, it first estimates edge of each block boundary. Then according to distribution and direction of the edge points, the boundaries are partitioned into several subsections. Pixels of each subsection are recovered by the best match pixels in the vicinity of the subsection. Concealment is accomplished by reconstructing each boundary repeatedly according to a suitable strategy. Experimental results show that the new algorithm can improve the subjective and objective quality of recovering image as it can effectively retain the edge information.(5) Video temporal error concealment algorithms are researched. For the case of consecutive macroblocks loss, a new temporal error concealment method for H.264 based on motion object is proposed to reconstruct the missing blocks. According to the visual attention mechanism, the method analyses the distribution of the motion vectors and the gray for adjacent macroblocks of the missing macroblocks firstly. Secondly, according to it, the smooth region and the motion region with similar gray values are concealed first. Finaly, the missing pixels which still exist are concealed. Experimental results shows that the new algorithm can keep the shape of motion object better and decreases the block effect. For the case of the whole frame loss, an error concealment algorithm based on residual distribution is proposed for whole frame packet lost in H.264. According to the visual attention mechanism, residual information of reference frame is analyzed. According to the result, motion vector copy algorithm is used for the region where the image is smooth or the image object's motion is rigid. To the other region, the motion vectors of each pixel are revaluation, and then optical flow algorithm is introduced. Experimental results show that the algorithm has better performance than traditional algorithms on both visual effect and PSNR.(6) According to the framework of the new mechanism for error resilience, fusion technologies of MH code and MPEG-2 code are proposed. For MH code, the distribution of the wrong scan lines is analysed after decoding. If the error scan line scan is isolate, a new error compensation technology is used to deal with the current scan line. Otherwise a error correction technology is used to recover the errors in the cunrrent scan line. If error correction fails, the compensation technology is used finally. For MPEG-2, after some error MBs are detected, whether the lost MB is flat or not is judged firstly. If it is a flat MB, error concealment techonoligies are used. Otherwise, error correction technology is used. If error correction fails and then some early resynchronization technologies and error concealment technologies are used in order finally. Experiment results show that the new mechanism can mitigate the conflict between the speed of calculation and the high performance of error resilience in a certain extent.At present, this research-based system has already been used in the relevant units and plays an important role in practical.
Keywords/Search Tags:image, MMR code, JPEG2000, video, error resilience, error correction decoding, error detection, error concealment
PDF Full Text Request
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