Methods and means for image and voice compression
First Claim
1. A method for lossy compression of source data for transmission to a remote location or to a storage medium, the source data being made up of data units ui from a first alphabet U, a string of the source data units ui to uj being denoted uij, the source data units being mappable on to code data units vi of a second alphabet V, there being defined a distortion measure d(ui,vi) indicative of the distortion caused by encoding source data unit ui as code data unit vj, the method comprising the steps of:
- (a) inputting a string of l source data units, u0l-1 ;
(b) searching within a database, v-n-1, starting from v-l-1, for a database substring, v-p-p+l-I, corresponding within a given non-zero average distortion tolerance level per data unit to said string, u0l-1 ;
(c) in a case that such a said database substring is found;
(i) transmitting a compressed data signal indicative of;
(A) the finding of said database substring, and(B) the position of said database substring within said database, and(ii) appending said database substring to said database as v0l-1, and re-indexing said database; and
(d) in a case that no such said database substring is found;
(i) transmitting a compressed data signal indicative of;
(A) the non-finding of a said database substring, and(B) a new database substring, v0l-1, corresponding within said average distortion tolerance level per data unit to said string, u0l-1, and(ii) appending said new database substring, v0l-1, to said database and re-indexing said database,wherein said new database substring is selected by use of a block-coding algorithm subject to a fidelity criterion, said block-coding algorithm being based on information about a frequency distribution of the source data, said information being built up empirically from the source data.
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Accused Products
Abstract
A system for lossy compression of digital data for transmission to a remote location or to a storage medium and subsequently reconstructing the digital data includes an encoder which compares sequences of characters with an encoder database of data records to generate a compressed code. The compressed code includes pointer information relating to locations within the encoder database of data records corresponding within a given average distortion tolerance level per character to the sequences, and update information for the addition to the encoder database of new data records corresponding within the average distortion tolerance level per character to the sequences. The system also includes a decoder for receiving the compressed code, the receiver processing the compressed code to substantially reconstruct the digital data.
115 Citations
4 Claims
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1. A method for lossy compression of source data for transmission to a remote location or to a storage medium, the source data being made up of data units ui from a first alphabet U, a string of the source data units ui to uj being denoted uij, the source data units being mappable on to code data units vi of a second alphabet V, there being defined a distortion measure d(ui,vi) indicative of the distortion caused by encoding source data unit ui as code data unit vj, the method comprising the steps of:
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(a) inputting a string of l source data units, u0l-1 ; (b) searching within a database, v-n-1, starting from v-l-1, for a database substring, v-p-p+l-I, corresponding within a given non-zero average distortion tolerance level per data unit to said string, u0l-1 ; (c) in a case that such a said database substring is found; (i) transmitting a compressed data signal indicative of; (A) the finding of said database substring, and (B) the position of said database substring within said database, and (ii) appending said database substring to said database as v0l-1, and re-indexing said database; and (d) in a case that no such said database substring is found; (i) transmitting a compressed data signal indicative of; (A) the non-finding of a said database substring, and (B) a new database substring, v0l-1, corresponding within said average distortion tolerance level per data unit to said string, u0l-1, and (ii) appending said new database substring, v0l-1, to said database and re-indexing said database, wherein said new database substring is selected by use of a block-coding algorithm subject to a fidelity criterion, said block-coding algorithm being based on information about a frequency distribution of the source data, said information being built up empirically from the source data. - View Dependent Claims (2, 3, 4)
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Specification