Process for compressing and expanding structurally associated mu

Details Process for compressing and expanding structurally associated mu Process for compressing and expanding structurally associated mu

1987-05-18

1990-02-20

Shoop Jr., William M.

Coded data generation or conversion

Digital code to digital code converters

Adaptive coding

341 90, 382 56, 3582611, H03M 738

Patent

active

049030183

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION



Technical Field

The invention relates to a process for compressing and expanding structurally associated multiple data sequences, particularly data sets (records) in which data sequences to be compressed are stored in parallel in a storage matrix on the basis of their structural association, performed for obtaining a characteristic connecting a number of data elements of the data sequences for multiple data sequences as structural analysis of data elements of conforming ordinal numbers, a code is used instead of these data elements and, during expansion, the data elements obtained by decoding the code are arranged in data sequences on the basis of the corresponding data element ordinal number. The invention relates further to data processing systems for implementing the process.


BACKGROUND ART

Data sequences are often redundant to a high extent, i.e. they contain a basically higher number of data elements or signs than are necessary for representing the information they contain at the time. An example for this is the regularly constructed data sets (records) for files pertaining to the economy and to the administration. A further example of this is the transmission of TV pictures in which the subsequently taken and then as data sequences stored or transmitted partial images, relative to individual areas of a scene, are identical, since they were not exposed to any change relative to their position, light intensity or color of picture points (elements). This is the case for the majority of picture points without changing the scene. In order to be able to carry out the transmission of data sequences economically, it is necessary to compress them and to expand them again at the end of the transmission path (route).
Processes are already known in which the compression of data sequences is made by means of a coding of variable length. The coding diagram of this type effects that the bit strings of a fixed predetermined length are coded in bit strings of variable length, and bit strings of the often occurring code words are represented shorter than code words of a fixed predetermined length. This conversion of code words of a fixed length into code words of variable length is known as Huffman-coding. In case of a meaningful allocation of code words of variable length with the given data, a considerably slighter length of such code words will then result in comparison with the respective code words of a predetermined fixed length, though many code words of variable length are considerably longer than the corresponding code words of a fixed length.
Furthermore, processes for compressing and expanding data sequences are known in which a structural analysis is applied, in order to recognize in a predetermined number of data elements of data sequences a characteristic that connects them. Such a characteristic can be, for example, in a repeated occurrence of the same sign or can be given also in an increasing numerical character string of the type 1, 2 . . . . The given number of data elements is converted then into a code. Such a code in a string of signs equal to n should contain at least a separating sign, the respective sign and the number of its occurrence, in order to be able to produce again the original string during expansion.
Further known is a process for compressing and expanding data sequences in which two logically associated data sequences are interlinked by an EXCLUSIVE-OR before the compression proper of the usual type. This logical interlinkage (combination) effects that zeros are produced on the points on which equal signs are present. Since the data sequences are presumably logically associated by EXCLUSIVE-OR association, a data sequence is produced which often contains zeroes as data elements. The data sequence strongly interspersed with zeroes is then compressed in the usual manner.
The structural association, especially the logic association of at least two data sequences for the purpose of compressing, is used in this process in order to improve the result of compressing. Ho

REFERENCES:
patent: 3521241 (1970-07-01), Rumble
patent: 4077034 (1978-02-01), Dell
patent: 4319225 (1982-03-01), Klose

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