EP0259588A2
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EP
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Method and apparatus for block coding vertical mode codes for enhanced compression of image data
Assignee: NETEXPRESS SYSTEMS Inc
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Filing: 1987-07-24
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Granted: —
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Expires: 2007-07-24
Abstract
Abstract A method and apparatus for improving the performance of data compression processes, such as relative address coding, CCITT standard facsimile processes, and similar two-dimensional image coding processes, by block coding one or more of the vertical mode codes produced by these processes. The performance of data compression processes is improved by representing one or more sequences of vertical mode code words with a single block code word. A reference scan line is preferably selected from among a plurality of previous scan lines, for example, the immediately preceding ten scan lines, for two-dimensional image coding. The previous scan line which is most similar to the current scan line to be coded is selected as the reference scan line. The selected reference scan line is then fed with the current scan line to be coded to a two-dimensional data compression coding process so as to yield a first tier of data compression. The image data are preferably checked during the two-dimensional data compression coding process for a predetermined run of a given vertical mode code, and a preselected block code is substituted if the predetermined run of the given vertical mode code appears so as to yield a second tier of data compression. Preferably, eleven consecutive vertical offset zero code words are represented by a single block code word. This provides enhanced data compression and reduces the amount of image data stored or transmitted and concomitantly lowers the cost for operation of the image data storage or transmission apparatus.
Inventors
- 👤 Larry Roberts
- 👤 Alex Henderson
- 👤 Frederick Drain
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 15:01
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/41; H04N1/4105; H04N1/411; H04N1/413; H04N1/417; H04N1/4175
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
117 words
A method for processing image data for data compression, said image data representing a two-dimensional image, said image data defining successive input scan lines, said method comprising the steps of: establishing one of said scan lines as a current scan line; establishing another of said scan lines as a reference scan line; using said current scan line and said reference scan line in connection with a two-dimensional image coding process to produce vertical mode codes; detecting a characteristic of image data produced during said image coding process determinative of a sequence of vertical mode codes within the output of said image coding process; and substituting a preselected block code for said sequence of said vertical mode codes.
Claim 2
Independent Claim
117 words
A method for processing image data for data compression, said image data representing a two-dimensional image, said image data defining successive input scan lines, said method comprising the steps of: establishing one of said scan lines as a current scan line; establishing another of said scan lines as a reference scan line; using said current scan line and said reference scan line in connection with a two-dimensional image coding process to produce vertical mode codes; detecting a characteristic of image data produced during said image coding process determinative of a sequence of vertical mode codes within the output of said image coding process; and substituting a preselected block code for said sequence of said vertical mode codes.
Claim 3
Dependent Claim
22 words
The method of Claim 1 wherein said sequence of vertical mode codes comprises a predetermined run of a given vertical mode code.
Claim 4
Dependent Claim
25 words
The method of Claim 2 wherein said predetermined run of said given vertical mode code is a predetermined run of vertical offset zero code words.
Claim 5
Dependent Claim
26 words
The method of Claim 2 wherein said predetermined run of said given vertical mode code is a run of eleven consecutive vertical offset zero code words.
Claim 6
Dependent Claim
115 words
The method of Claim 3 wherein said scan lines include a first scan line as said current scan line, a second scan line immediately preceding said first scan line, and a third scan line preceding said first scan line, and wherein said step of establishing said reference scan line comprises: selecting said reference scan line, said reference scan line being selected from among said preceding second scan line and said preceding third scan line, and said current scan line and said reference scan line being for use in connection with said two-dimensional image coding process wherein data compression is directly related to a pattern relationship between said current scan line and said reference scan line.
Claim 7
Dependent Claim
32 words
The method of Claim 5 wherein said selecting step comprises defining as said reference scan line said preceding third scan line at a fixed, preselected line separation from said current scan line.
Claim 8
Dependent Claim
76 words
The method of Claim 5 wherein said step of establishing said reference scan line comprises: comparing said current scan line with each one of at least two candidate scan lines of said input scan lines preceding said current scan line to obtain pattern relationship criteria; and choosing as said reference scan line said one of said candidate scan lines which yields a most desired one of said pattern relationship criteria relative to said current scan line.
Claim 9
Dependent Claim
76 words
The method of Claim 7 wherein said comparing step comprises: applying a vertical mode coding technique with each said candidate scan line, each said candidate scan line being used as a coding reference for said current scan line; and determining numbers of output bits yielded by each one of said applying steps; and wherein said choosing step comprises: selecting as said reference scan line said candidate scan line which yields the least number of output bits.
Claim 10
Dependent Claim
53 words
The method of Claim 7 wherein said comparing step comprises: summing differences between image data of said current scan line and corresponding image data for each said candidate scan line; and wherein said choosing step comprises: selecting as said reference scan line said candidate scan line yielding the least number of said differences.
Claim 11
Dependent Claim
43 words
The method of Claim 9 wherein said comparing step further comprises: exclusive-OR combining image data for each said candidate scan line with corresponding image data of said current scan line to obtain combination bits of a predetermined logic state representative of said differences.
Claim 12
Independent Claim
103 words
An apparatus for processing image data for data compression, said image data representing a two-dimensional image, said image data defining successive input scan lines, said apparatus comprising: means for establishing one of said scan lines as a current scan line; means for establishing another of said scan lines as a reference scan line; means for using said current scan line and said reference scan line in connection with a two-dimensional image coding process to produce vertical mode codes; and block coding means for substituting a preselected block code for a sequence of vertical mode codes within the output of said image coding process.
Claim 13
Independent Claim
103 words
An apparatus for processing image data for data compression, said image data representing a two-dimensional image, said image data defining successive input scan lines, said apparatus comprising: means for establishing one of said scan lines as a current scan line; means for establishing another of said scan lines as a reference scan line; means for using said current scan line and said reference scan line in connection with a two-dimensional image coding process to produce vertical mode codes; and block coding means for substituting a preselected block code for a sequence of vertical mode codes within the output of said image coding process.
Claim 14
Dependent Claim
22 words
The apparatus of Claim 11 wherein said sequence of vertical mode codes comprises a predetermined run of a given vertical mode code.
Claim 15
Dependent Claim
25 words
The apparatus of Claim 12 wherein said predetermined run of said given vertical mode code is a predetermined run of vertical offset zero code words.
Claim 16
Dependent Claim
26 words
The apparatus of Claim 12 wherein said predetermined run of said given vertical mode code is a run of eleven consecutive vertical offset zero code words.
Claim 17
Dependent Claim
117 words
The apparatus of Claim 13 wherein said scan lines include a first scan line as said current scan line, a second scan line immediately preceding said first scan line, and a third scan line preceding said first scan line, and wherein said means for establishing said reference scan line comprises: means for selecting said reference scan line, said reference scan line being selected from among said preceding second scan line and said preceding third scan line, and said current scan line and said reference scan line being for use in connection with said two-dimensional image coding process wherein data compression is directly related to a pattern relationship between said current scan line and said reference scan line.
Claim 18
Dependent Claim
34 words
The apparatus of Claim 15 wherein said selecting means comprises means for defining as said reference scan line said preceding third scan line at a fixed, preselected line separation from said current scan line.
Claim 19
Dependent Claim
80 words
The apparatus of Claim 15 wherein said means for establishing said reference scan line comprises: means for comparing said current scan line with each one of at least two candidate scan lines of said input scan lines preceding said current scan line to obtain pattern relationship criteria; and means for choosing as said reference scan line said one of said candidate scan lines which yields a most desired one of said pattern relationship criteria relative to said current scan line.
Claim 20
Dependent Claim
82 words
The apparatus of Claim 17 wherein said comparing means comprises: means for applying a vertical mode coding technique with each said candidate scan line, each said candidate scan line being used as a coding reference for said current scan line; and means for determining numbers of output bits yielded by each one of said applying steps; and wherein said choosing means comprises: means for selecting as said reference scan line said candidate scan line which yields the least number of output bits.
Claim 21
Dependent Claim
57 words
The apparatus of Claim 17 wherein said comparing means comprises: means for summing differences between image data of said current scan line and corresponding image data for each said candidate scan line; and wherein said choosing means comprises: means for selecting as said reference scan line said candidate scan line yielding the least number of said differences.
Claim 22
Dependent Claim
46 words
The apparatus of Claim 19 wherein said comparing means further comprises: exclusive-OR means operative to combine image data for each said candidate scan line with corresponding image data of said current scan line to obtain combination bits of a predetermined logic state representative of said differences.
References Cited (Backward Citations)
No citation records indexed.
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