Low bit-rate subband coding of image and video signals using vector quantization
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| Опубліковано в:: | ProQuest Dissertations and Theses (1992) |
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ProQuest Dissertations & Theses
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| Онлайн доступ: | Citation/Abstract Full Text - PDF |
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| Короткий огляд: | This thesis contains two major parts: subband coding of monochrome and color still images, and subband coding of monochrome video signals. Several image coding techniques including vector quantization and subband coding are reviewed. The alternate color plane representation of color images and the advantages of color plane conversion are investigated. Finite-state vector quantization is applied to subband coding. The application of the subband coding and vector quantization to still color image coding has been accomplished successfully. The proposed two-stage multirate coding scheme demonstrated fine improvement and achieved good quality at 0.3 bits/pixel for (512 x 512) color images. Some problems of the extension of this approach to video signals at 64 kbits/sec have been solved. Motion compensation methods were examined and compared. The three-step search algorithm was judged the best candidate for the fast motion vector search for our system. A two-stage scheme for vector quantization was developed and was shown to improve the quality of output frames. The use of loop filtering was investigated and found to alleviate blocking effects, as well as reduce noise accumulation. To reduce the memory needed in vector quantization a two-stage residual vector quantization system is simulated and compared with the ordinary conventional vector quantization system and the two-stage vector quantization systems. The robustness of the coding system is tested. The designed codebooks were tested on sequences outside the training set as well as on those inside the training sequences. The complexity of the coding system was examined. Particularly, the performances of the system with FIR QMF filters and the subband systems with IIR filter were very close. Simulation results suggest that the video coding system proposed in this thesis is capable of achieving good quality. |
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| ISBN: | 9798208054079 |
| Джерело: | ProQuest Dissertations & Theses Global |