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Method and apparatus for data compression and restoration

  • US 4,872,009 A
  • Filed: 12/07/1987
  • Issued: 10/03/1989
  • Est. Priority Date: 12/12/1986
  • Status: Expired due to Fees
First Claim
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1. A method of transforming an input data string comprising a plurality of data bytes, said plurality including portions of a plurality of consecutive data bytes identical to one another, wherein said data bytes may be of a plurality of types, each type representing different information, said method comprising the steps of:

  • selecting, in advance, a first subset of the plurality of types of data bytes which may occur, said subset including those data byte types which more frequently appear repetitively and consecutively than those data byte types not included in the first subset;

    detecting a compressible portion of the data string when one of said data bytes types of said first subset appears consecutively in the string a certain minimum number of times up to a certain maximum number of times,compressing the compressible portion according to a first compression method, said compression method including encoding the data byte of the compressible portion and counting the number of data bytes of the portion to produce a compressed portion representative of the number and kind of data bytes in the compressible portion;

    appending a compression mark byte, which indicates that compression has been affected, either at the front or rear of said compressed portion to generate a first compression information data;

    when said input data string contains a third portion consisting of one or more consecutive data bytes the same as a first compression mark byte, said compression step further includes encoding and counting data bytes contained in said third portion to obtain a compressed third portion; and

    connecting data bytes of said input data string that are not included in said first compressed information data and said compressed third portion, with said first compressed information data and said compressed third portion to produce a compressed output data string.

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