| 改进的PPM数据压缩算法及性能分析和比较 |
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| 引用本文： | 周小四,杨杰,王淑华.改进的PPM数据压缩算法及性能分析和比较[J].上海交通大学学报,2002,36(12):1841-1845. |
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| 作者姓名： | 周小四 杨杰 王淑华 |
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| 作者单位： | 上海交通大学,图像处理及模式识别研究所,上海,200030 |
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| 基金项目： | 国家高技术研究发展计划 (863 )项目(863 -3 0 6-ZD13 -0 5 -6) |
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| 摘 要： | PPM算法在文本无损压缩方面具有比LZ算法更高的压缩率。PPM算法分建模和编码两步，在建模时有两种方法选择上下文模型，一种是固定最大长度上下文，即PPM；另一种是不固定最大长度上下文，即PPM^*．在VC 环境下利用PPM^* D算法编制的压缩软件，通过对文本、图像、声音文件以及可执行文件进行实验，效果令人满意，其压缩率都比Winzip要高．
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| 关 键 词： | 数据压缩 信息处理 无损压缩 PPM PPM^＊ |
| 文章编号： | 1006-2467(2002)12-1841-05 |
| 修稿时间： | 2001年12月6日 |
Analysis of Data Compression Algorithm Based PPM and Its Comparison |
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| ZHOU Xiao-si,YANG Jie,WANG Shu-hua.Analysis of Data Compression Algorithm Based PPM and Its Comparison[J].Journal of Shanghai Jiaotong University,2002,36(12):1841-1845. |
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| Authors: | ZHOU Xiao-si YANG Jie WANG Shu-hua |
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| Abstract: | The state of the art in lossless text compression is the PPM data compression scheme. Two approaches to the problem of selecting the context models used in the scheme were described. One uses an a priori upper bound on the lengths of the contexts,while the other is unbounded,called PPM *. The scheme achieves greater compression ratio than that of Ziv-Lempel (LZ) dictionary based methods. The software based on PPM * D algorithm was realized on PC by VC++ programming. The ratios of various types of files compressed by this software are surprisingly satisfied and much better than Winzip software. |
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| Keywords: | data compression information processing lossless text compression prediction by partial matching (PPM) PPM * |
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