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    2.
    发明专利
    未知

    公开(公告)号：DE68926270T2

    公开(公告)日：1996-10-10

    申请号：DE68926270

    申请日：1989-06-08

    Applicant: IBM

    Inventor： CHEVION DAN SHMUEL ,  KARNIN EHUD DOV ,  WALACH EUGENIUSZ

    IPC: H03M7/40

    Abstract: An improved method is disclosed for generating a compressed representation of a source data string each symbol of which is taken from a finite set of m + 1 symbols, a0 to am . 'The method is based on an arithmetic coding procedure wherein the compressed representation is recursively generated as successive sub-intervals within a predetermined interval. The width of each sub-interval is theoretically equal to the width of the previous sub-interval multiplied by the probability of the current symbol. The improvement is achieved by approximating the width of the previous sub-interval so that the approximation can be obtained by a single shift and add operation using a suitable shift register.

    5.
    发明专利
    未知

    公开(公告)号：DE68926270D1

    公开(公告)日：1996-05-23

    申请号：DE68926270

    申请日：1989-06-08

    Applicant: IBM

    Inventor： CHEVION DAN SHMUEL ,  KARNIN EHUD DOV ,  WALACH EUGENIUSZ

    IPC: H03M7/40

    Abstract: An improved method is disclosed for generating a compressed representation of a source data string each symbol of which is taken from a finite set of m + 1 symbols, a0 to am . 'The method is based on an arithmetic coding procedure wherein the compressed representation is recursively generated as successive sub-intervals within a predetermined interval. The width of each sub-interval is theoretically equal to the width of the previous sub-interval multiplied by the probability of the current symbol. The improvement is achieved by approximating the width of the previous sub-interval so that the approximation can be obtained by a single shift and add operation using a suitable shift register.

    METHOD FOR COMPRESSING AND DECOMPRESSING FORMS BY MEANS OF VERY LARGE SYMBOL MATCHING
    6.
    发明专利
    METHOD FOR COMPRESSING AND DECOMPRESSING FORMS BY MEANS OF VERY LARGE SYMBOL MATCHING 未知

    公开(公告)号：CA2019134C

    公开(公告)日：1996-04-09

    申请号：CA2019134

    申请日：1990-06-15

    Applicant: IBM

    Inventor： CHEVION DAN SHMUEL ,  KARNIN EHUD DOV ,  WALACH EUGENIUSZ

    IPC: G06T9/00 ,  H04N1/411 ,  G06K9/36

    Abstract: This method relates to the compression of information contained in filled-in forms (O) by separate handling of the corresponding empty forms (CP) and of the information written into them (VP). Samples of the empty forms are prescanned, the data obtained digitized and stored in a computer memory to create a forms library. The original, filled-in form (O) to be compressed is then scanned, the data obtained digitized and the retrieved representation of the empty form (CP) is then subtracted, the difference being the digital representation of the filled-in information (VP), which may now be compressed by conventional methods or, preferably, by an adaptive compression scheme using at least two compression ratios depending on the relative content of black pixels in the data to be compressed.

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