Implementing the PPM data compression scheme
نویسندگان
چکیده
منابع مشابه
Implementing the PPM data compression scheme
The “Prediction by Partial Matching” (PPM) data compression algorithm developed by Cleary and Witten is capable of very high compression rates, encoding English text in as little as 2.2 bits/character. Here it is shown that the estimates made by Cleary and Witten of the resources required to implement the scheme can be revised to allow for a tractable and useful implementation. In particular, a...
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A significant cost in PPM data compression (and often the major cost) is the provision and efficient coding of escapes while building contexts. This paper presents some recent work on eliminating escapes in PPM compression, using bit-wise compression with binary contexts. It shows that PPM without escapes can achieve averages of 2.5 bits per character on the Calgary Corpus and 2.2 bpc on the Ca...
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Over 45 years ago Claude E. Shannon estimated the entropy of English to be about 1 bit per character [16]. He did this by having human subjects guess samples of text, letter by letter. From the number of guesses made by each subject he estimated upper and lower bounds of 1.3 and 0.6 bits per character (bpc) for the entropy of English. Shannon’s methodology was not improved upon until 1978 when ...
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ژورنال
عنوان ژورنال: IEEE Transactions on Communications
سال: 1990
ISSN: 0090-6778
DOI: 10.1109/26.61469