【作者】 张如亮；

【导师】 高勇； 余宁梅；

【作者基本信息】 西安理工大学 ， 微电子学与固体电子学， 2004， 硕士

【摘要】 矢量量化(VQ)是近年来图像压缩研究中的重要技术，广泛应用于语音编码、音视频压缩和远程会议等系统中。在该技术中，减少运算复杂度、降低平均编码比特率、提高恢复图像的质量和便于硬件实现等方面是当前研究的主要方向。 本文首先利用图像内部的空间相关性，提出一种旨在降低平均编码时间的超前预测相关矢量量化快速算法，并对其进行测试。测试结果表明该算法在减少平均编码时间的同时，也降低了平均编码比特率。其次，为减少每个矢量的编码时间，提出一种基于均值排序码书的快速搜索算法，测试结果显示，该算法编码速度是穷尽搜索算法的二十多倍，但是恢复图像的质量大大地降低了。为了弥补这个缺陷，在保持该算法编码速度快这个优点的基础上，从结构并行性和码书排序结构两方面对其改进，得到一种既提高了恢复图像质量，又适合VLSI硬件实西安理工大学硕士学位论文现的编码算法。最后结合各个算法的优点，综合考虑各方面性能，给出一个折衷的快速搜索算法，并且设计出与算法对应的编码电路系统。该编码电路的FPGA实现及FPGA验证结果表明，本文提出的快速算法大大地减少了编码时间、有效地提高了恢复图像质量，同时也降低了硬件实现的难度。更多还原

【Abstract】 Vector Quantization (VQ) is an important technology in the field of image compression, which is widely used in various applications such as speech coding, audio and video compression, and teleconferencing systems. The current researches include how to cut down the computation complexity, how to reduce the average coding bit rate, how to improve the quality of reconstructed image, and which algorithm to be suitable to VLSI implementation.In this paper, firstly, based on image spatial correlation, a fast algorithm named advance predictive correlation VQ ( APCVQ) is presented, which aims at reducing the average coding time. The simulation results show that the algorithm have not only cut down the average coding time, but also reduced the average coding bit rate. Then, in order to reduce the coding time of each image vector, a fast algorithm based onMean-Order-Search is proposed. The simulation results of this algorithm show that its coding speed is twenty times faster than that of Full Search algorithm (FS), but its reconstructed image is badly ruined. For overcoming this disadvantage and keeping its advantage of short coding time, we improve the algorithm on the two aspects of structure parallelism and codebook order structure, to gain a better coding algorithm, which meets the requirement of reconstructed image and VLSI implementation. Finally, considering the advantages and disadvantages of these algorithms, a trade-off algorithm is proposed. A corresponding VLSI coding circuit system is designed and verified with FPGA. The FPGA post simulation results prove that the trade-off algorithm is an effective fast search algorithm of VQ coding on the three aspects of reducing the coding time, improving the reconstructed image quality, and lowering the difficulty of VLSI implementation.更多还原