公开(公告)号：DE2340250A1

公开(公告)日：1974-02-28

申请号：DE2340250

申请日：1973-08-09

Applicant: IBM

Inventor： BAHL LALIT R ,  BARNEA DANIEL I ,  KOBAYASHI HISASHI

IPC: H03M7/30 ,  G06T9/00 ,  H03M7/32 ,  H04B14/06 ,  H04N1/417 ,  H03K13/00

Abstract: A data compaction system wherein segmented binary data that has redundancy between segments is compacted by means of differential run-length encoding. For compaction of document digitized data, the segments represent lines on the document. Black image points on the document which are represented by a "1" are coded relative to the position of a 1 appearing in the line above the one being coded. The differential distance between binary 1 bit positions on successive lines are coded in accordance with a compaction code. Codewords having a small number of bits are used for small differentials.

公开(公告)号：DE2340230A1

公开(公告)日：1974-02-28

申请号：DE2340230

申请日：1973-08-09

Applicant: IBM

Inventor： BAHL LALIT R ,  BARNEA DANIEL I ,  GROSSMAN DAVID D ,  KOBAYASHI HISASHI

IPC: H04B1/66 ,  H03M7/46 ,  H04L25/48 ,  H04N1/40 ,  H04N1/417 ,  H04L3/00

Abstract: A system for compacting digital data by means of prediction error coding. Prediction for each unknown bit is a function of previous detected levels in the data stream. A plurality of n-bit up-down counters, each associated with one of the possible states of prediction for an unknown bit, is utilized to arrive at a prediction of the level of the unknown bit. If the value found in the up-down counter is above a pre-specified level, a prediction will be made that the unknown bit is a one, otherwise, the prediction is zero.

公开(公告)号：GB1277158A

公开(公告)日：1972-06-07

申请号：GB5401570

申请日：1970-11-13

Applicant: IBM

Inventor： TANG DONALD TAO-NAN ,  KOBAYASHI HISASHI

IPC: H04L1/00 ,  H04L25/48 ,  H04L25/497

Abstract: 1277158 Data transmission INTERNATIONAL BUSINESS MACHINES CORP 13 Nov 1970 [30 Dec 1969] 54015/70 Heading H4P A data transmission system uses correlation encoding with resulting increase in the number of signal value levels. In Fig. 2, an input signal train A(D)= a 0 + a 1 + D + a 2 D 2 + ... (where D is a time delay operator) where each signal can have any of m levels, is preceded at 10 (to prevent propagation of a chain of errors from a single error in the received transmission) by dividing by G(D)= g 0 + g 1 D + g 2 D 5 + ... and taking the resulting levels mod m, to give a train B(D)=b 0 + b 1 D + b 2 D 2 + .... This is correlatively encoded, 12, by multiplying by G(D) to give C(D)=c 0 + c 1 D + c 2 D 2 + ... in which each level can have any of M (greater than m) levels. C(D) is transmitted over a channel 14 and the received signal C 1 (D) decoded, 18, by dividing by G(D) to give B 1 (D) which in the absence of error equals B(D) and so has only m levels. If there are more than m levels, a level detector 22 (two thresholders feeding an OR gate) produces an error signal to give a warning or cause retransmission and inhibition of a decoder 20 which otherwise multiplies B 1 (D) by G(D) and takes the resulting levels mod m to give A 1 (D), which is equal to A(D) in the absence of errors. A modified system combines 10 and 12 into a unitary encoder, combines 18, 20, 22 into a unitary decoder and precedes the latter with a level splitter which standardizes the received levels to their nominal values after detecting them with thresholders. Fig. 4 shows the unitary encoder, assuming G(D)=g 0 + g 1 D + g 2 D 2 + ... 5 + g N D N , and is self-explanatory, the notation being as before. The unitary decoder is like Fig. 4 except that the mod m detector 34 follows the adder 46, the result from multiplier 36 is not taken mod m, and the output from this multiplier is also fed to a level detector to produce the error signal. If G(D) is 1 - D 2 , then b k =a k + b k-2 , mod m, and c k = b k - b k-2 . A(D) may have m = 3 and result from a preliminary 2-to-3 level transformation (no details).