WO1999037085A2 - Arithmetic coding-based facsimile compression with error detection - Google Patents
Arithmetic coding-based facsimile compression with error detection Download PDFInfo
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- WO1999037085A2 WO1999037085A2 PCT/US1999/000865 US9900865W WO9937085A2 WO 1999037085 A2 WO1999037085 A2 WO 1999037085A2 US 9900865 W US9900865 W US 9900865W WO 9937085 A2 WO9937085 A2 WO 9937085A2
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/41—Bandwidth or redundancy reduction
- H04N1/411—Bandwidth or redundancy reduction for the transmission or storage or reproduction of two-tone pictures, e.g. black and white pictures
- H04N1/413—Systems or arrangements allowing the picture to be reproduced without loss or modification of picture-information
- H04N1/417—Systems or arrangements allowing the picture to be reproduced without loss or modification of picture-information using predictive or differential encoding
Definitions
- the present invention generally concerns the field of facsimile transmission of documents, and more particularly concerns an algorithm for compressing facsimile documents based on arithmetic coding.
- Arithmetic coding is a well known concept that has been applied in a number of information transmission environments, including facsimile.
- the basic idea behind arithmetic coding is the mapping of a sequence of symbols to be encoded to a real number in the interval [0.0,1.0), where a square bracket "[" indicates that equality is allowed and a curved bracket ")" indicates otherwise.
- the binary expansion of this real number is then transmitted to the arithmetic decoder, where the inverse mapping is performed to retrieve the encoded symbols.
- Fig. 1 An illustration of this principle is in Fig. 1, which can form the basis of an example of arithmetic coding.
- the illustration shows that the input symbol takes two possible values, B and W.
- B and W correspond to black and white picture elements (pel) respectively.
- Pb and P w be the probabilities of occurrences of B and W respectively.
- This coding interval is divided into two sub-intervals: [0.0, P w ) corresponding to W, and [P w 1.0) corresponding to B.
- This coding interval is further sub-divided into two sub-intervals: [P w , P w , + P b P w ) corresponding to W, and [Pw, + PbPw 1.0) corresponding to B.
- the new coding interval is [P w , P w , + P b P w )-
- the lower bound after the third symbol is P w , + P R b 2 and the coding interval [P w , +
- the corresponding upper bound U n can be obtained by adding L n and R n .
- the encoder encode only three input symbols and transmit a real number that lies in the coding interval after encoding the first three symbols.
- the decoder receives this number and lets it be a value, which lies in the interval [P w , + P w R b 2 > , + PwPb).
- the decoder divides the coding interval [0.0, 1.0) into two intervals: [0.0,P W ) corresponding to W and P w ,l-0) corresponding to B. Since, value lies in the interval corresponding to B, the decoder decodes the first symbol to be B.
- the new coding interval is [P w ,l .0), which in turn is sub-divided into two intervals, [P w , P w , + P b P w ) corresponding to W and [P w , + P b P w 1.0) corresponding to B. Since value lies in the interval corresponding to W, the decoder decodes the second symbol to be W and proceeds so on.
- a more efficient scheme is to initialize the probabilities to a suitable value at the start of encoding and adapt the values as the encoding proceeds. 37085
- N W + N ⁇ ⁇ W + N ⁇ initialization since the initial values for ⁇ b and N w are equal. It is also possible to use a biased initialization.
- the aforementioned method to update the counts N b and N w helps to adapt to the local distribution of white and black pels. However, this scheme fails to exploit the redundancy present in the document.
- the counts N and N w gives a measure of the probability of a pel being white or black. But, the probability of a pel being white or black can be better described if the "color" of some of the adjacent pels are known. This set of adjacent pels is defined to be the context.
- the pel marked 's' is being presently encoded and the shaded pels form the context for 's'.
- a further object is prevent the effect of a propagation of a transmission error to the whole document by using a combination of one-dimensional and two-dimensional arithmetic coding.
- Another object is to present appropriate contexts for the probabilistic models associated with arithmetic coding for one and two dimensional cases.
- Yet another object is to provide an error detection scheme to identify the presence of transmission errors.
- the present invention is a facsimile system embodying a signal processing method wherein a document is scanned and a sequence of symbols is generated for each of a plurality of scan lines.
- the sequence of symbols are arithmetic encoded by mapping the symbols to real numbers in a predetermined interval.
- the real numbers are subject to a binary expansion for transmission by a transmitter. After transmission and reception at a receiver, the received signal is inverse mapped to retrieve the encoded signals.
- the present invention further comprises arithmetic coding the scan lines using a combination of one-dimensional and two-dimensional arithmetic coding.
- the arithmetic encoding step further comprises 2-D coding a first plurality of adjacent scan lines, followed by 1-D coding at least one scan line subsequent to the plurality of scan lines. This sequence of 2-D and 1 -D coding can be repeated for a plurality of scan lines generated from scanning a document.
- Yet another feature of the invention is the application of an end of line
- EOL EOL code
- a further feature of the invention is to conduct the scanning with a reduced horizontal resolution through minimum difference compression.
- Yet another feature of the invention is to apply, at the end of an encoding of a scan line, M bits to represent the "quarter" in which the arithmetic coding interval lies.
- Figure 1 is a basic illustration of arithmetic coding as applied to the transmission of black and white symbols.
- Figure 2 is an illustration of a context for arithmetic coding using one dimensional (1-D) and two dimensional (2-D) approaches.
- Figure 3 is a flow chart for error detection at the decoder, in accordance with the present invention.
- Figure 4 is a flow chart of an arithmetic encoding algorithm used in the present invention.
- Figure 5 is a flow chart of an arithmetic decoding algorithm used in the present invention.
- the present invention concerns a method and apparatus for compressing facsimile documents based on arithmetic coding.
- Underlying the invention is the use of a combination of one-dimensional and two-dimensional arithmetic coding, in order to ensure that the effect of a transmission error is not propagated to the whole document, together with an error detection scheme to identify the presence of transmission errors.
- Fundamental to the present invention is the task of identifying an appropriate context for one and two dimensional arithmetic coding.
- Figure 2 shows the contexts used for one and two dimensional coding. The appropriate contexts were arrived at after thorough experimentation with over 25 facsimile documents in standard resolution, as reflected in ITU recommendations.
- the Standardization of Group 3 Facsimile Apparatus for Document Transmission defines standard resolution to be 3.85 line/mm and 1728 pels along the scan line.
- the horizontal resolution is reduced by half through a maximum-differences compression, which is designed to preserve the black- to-white or white-to-black transitions.
- the resulting document is then coded with arithmetic coding.
- a line is said to be 1-D coded, if the context used in coding the pels in that line does not contain any pels from the previous line.
- a line is said to be 2-D coded, if the context used in coding the pels in that line contains pels from the previous lines.
- every fourth line is 1-D coded with the three intermediate lines coded by 2-D coding.
- Two dimensional coding exploits the vertical redundancy in the document, but allows decoding errors in a line to be propagated to the following lines. To prevent this, every fourth line is 1-D coded. This ensures that any error in the bitstream caused by the channel does not propagate to more than four lines.
- Table 1 Prior Initialization of the probabilities for 2-d ⁇ mens ⁇ onal Mode of Coding (the pels a, b, c, and d are as designated in Figure 1).
- Table 1 shows the initial values of the counts used for the two dimensional coding. These initial counts have been arrived at through testing over a varied set of facsimile documents. Every fourth scan line is coded using one dimensional coding. When the following line is coded using two dimensional coding, the N w and N are initialized according to Table 1. As the encoding process continues these counts are updated. For 1-D coding, if the context pel is a B, then N b and N w are initialized to be 9 and 1 respectively, and vice versa if the context pel is a W. The compression efficiency achieved is different for different documents, but is in the range of 1.6 to 2.0, when compared to the standard T4 one dimensional compression.
- EOL End Of Line
- the encoder At the end of an encoding of a scan line, the encoder outputs two bits to represent the "quarter" in which the arithmetic coding interval lies. These two bits can be either '01 ' or '10' and will be followed by the EOL to denote the end of the scan line. However, if the last two bits happen to be '10', this trailing '0' can be confused with the zeros in EOL. To circumvent this, a ' 1 ' bit is introduced between the two bits representing the "quarter" and the EOL.
- the decoder first reads the 16 bits of the compressed data and then exactly mimics the operation of the encoder, i.e., decoder maintains the changes in the values of the probabilities, coding interval and takes in input bits at the same time when the encoder outputs bits, etc. Owing to this nature of the implementation, the decoder "leads" the encoder by 16 bits, i.e., the decoder will require 16 bits more than the compressed data output by the encoder to generate a scan line. Since the encoder generates 15 extra bits (2 bits to represent the quarter, a ' 1 ' bit and 12 bits in EOL), the decoder would require one more bit after EOL is reached to completely decode a scan line.
- this extra bit is immaterial. If the decoder requires more than one extra bit after EOL to generate a scan line, then this is an indication of an error. On the other hand, if the decoder does not require an extra bit or if the scan line is decoded before the EOL is reached, this again is an indication of an error.
- Fig 3 shows a flow chart for error detection at the decoder.
- a series of compressed bits for a single scan line illustrated as individual blocks with a 1 or a 0, is followed by an EOC comprising eleven 0's and a single 1.
- the bits are input to a process 101 for starting decoding and outputting a scan line of picture elements. That series of picture elements is provided to a decision 102 as to whether the number of picture elements equals M, where M is a desired number. If so, the processing proceeds along the Y path to a decision 103 as to whether the number of extra input bits used equals 1. If so, the Y path is followed and there is "no error”. If not, the N path is followed and there is an "error detected".
- the N path is followed and another decision 104 is used to determine whether EOL has been detected and an extra bit used. If EOL has been detected and an extra bit has been used, the Y path is followed and an "error detected" indication is given. If EOL has not been detected and extra bit used, the N path takes the program back to the start decoding and output scan line box 101 for further processing.
- the arithmetic coding algorithm presented in the "Background" section is not amenable to implementation with finite precision arithmetic, because of precision problems. It can be observed that the range and the lower bound are floating point numbers between 0.0 and 1.0. The value of range decreases every time an input symbol is encoded. Therefore, as the encoding process proceeds, more and more bits are required to represent the range and the lower bound. Eventually, the precision requirement will not be met by the hardware platform on which the algorithm is implemented.
- the initial coding interval of [0.0,1.0) is replaced by an integer interval of 0 to 216 — 1.
- N w and N b can be interpreted as the counts of number of occurrences of the B and W symbols.
- L( n .i ) , U (n -i ) and R ⁇ n . i ) are the values of lower bound, upper bound and range before the n th symbol is encoded.
- a flow chart for encoder operation is illustrated and at step 200, symbol to be encoded, as well as the counts N w and N b , the bounds L( n -i), U( himself-i) and the range R ⁇ n -i), are input. The following steps are then taken to update these values. First, in a decision 201 , a check is made as to whether the nth symbol is B (or alternatively W). Then in steps 203 and 202, respectively: symbol is B:
- n' h symbol is W:
- Condition 1 at decision 205 If U n ⁇ HALF, then follow the Y path and output(O) at step 206; go to HERE at step 207; Condition 2 at decision 208: If L n ⁇ HALF, then follow the Y path and output(l) at step 209;
- bits corresponding to the 5 quarter in which the coding interval lies are sent. If the lower bound is less than QUAR, then the upper bound is greater than HALF, and the coding interval spans the interval QUAR to HALF. To represent this, bits 01 are sent. If the lower bound is greater than or equal to QUAR, then the upper bound is greater than 3* QUAR, and the coding interval spans the interval HALF to 10 3* QUAR. To represent this, bits 10 are sent.
- arithmetic decoder its functions may be understood with regard to Fig. 5 as follows.
- 16 bits received from the encoder are stored in a register value, with the first received bit placed at the MSB position and the 16 th bit placed at the LSB.
- L 0 , U 0 , Ro, 15 N b , N w , QUAR and HALF are initialized to be exactly the same as at the encoder.
- the decoder performs the same operations performed at the encoder by updating the lower, upper bound and range. Since the update rules are different for symbols B and W, the decoder has to first decode the symbol.
- the following rule in step 301 is used to decode the symbol:
- the input() function performs the following: input() ⁇
Abstract
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US09/600,291 US6760129B1 (en) | 1998-01-16 | 1999-01-15 | Arithmetic coding-based facsimile compression with error detection |
AU22296/99A AU2229699A (en) | 1998-01-16 | 1999-01-15 | Arithmetic coding-based facsimile compression with error detection |
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US7168098P | 1998-01-16 | 1998-01-16 | |
US60/071,680 | 1998-01-16 |
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WO1999037085A2 true WO1999037085A2 (en) | 1999-07-22 |
WO1999037085A3 WO1999037085A3 (en) | 1999-10-14 |
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PCT/US1999/000865 WO1999037085A2 (en) | 1998-01-16 | 1999-01-15 | Arithmetic coding-based facsimile compression with error detection |
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Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
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US6683173B2 (en) | 1998-04-03 | 2004-01-27 | Epoch Biosciences, Inc. | Tm leveling methods |
US6949367B1 (en) | 1998-04-03 | 2005-09-27 | Epoch Pharmaceuticals, Inc. | Modified oligonucleotides for mismatch discrimination |
US7045610B2 (en) | 1998-04-03 | 2006-05-16 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
EP1944310A2 (en) | 2000-03-01 | 2008-07-16 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
EP1975256A1 (en) | 2000-03-01 | 2008-10-01 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
US7715989B2 (en) | 1998-04-03 | 2010-05-11 | Elitech Holding B.V. | Systems and methods for predicting oligonucleotide melting temperature (TmS) |
WO2012129547A1 (en) | 2011-03-23 | 2012-09-27 | Elitech Holding B.V. | Functionalized 3-alkynyl pyrazolopyrimidine analogues as universal bases and methods of use |
WO2013048583A2 (en) | 2011-05-24 | 2013-04-04 | Elitech Holding B.V. | Detection of methicillin-resistant staphylococcus aureus |
WO2014159063A1 (en) | 2013-03-14 | 2014-10-02 | Elitech Holding B.V. | Functionalized 3-alkynyl pyrazolopyrimidine analogues as universal bases and methods of use |
WO2014186147A2 (en) | 2013-05-13 | 2014-11-20 | Elitech Holding B.V. | Droplet digital pcr with short minor groove probes |
WO2016094607A2 (en) | 2014-12-12 | 2016-06-16 | Elitechgroup B.V. | Methods and compositions for detecting antibiotic resistant bacteria |
WO2016094162A1 (en) | 2014-12-12 | 2016-06-16 | Elitechgroup B.V. | Methods and compositions for detecting antibiotic resistant bacteria |
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Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7715989B2 (en) | 1998-04-03 | 2010-05-11 | Elitech Holding B.V. | Systems and methods for predicting oligonucleotide melting temperature (TmS) |
US6949367B1 (en) | 1998-04-03 | 2005-09-27 | Epoch Pharmaceuticals, Inc. | Modified oligonucleotides for mismatch discrimination |
US7045610B2 (en) | 1998-04-03 | 2006-05-16 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
US7368549B2 (en) | 1998-04-03 | 2008-05-06 | Epoch Biosciences, Inc. | Tm leveling compositions |
US6683173B2 (en) | 1998-04-03 | 2004-01-27 | Epoch Biosciences, Inc. | Tm leveling methods |
US7751982B2 (en) | 1998-04-03 | 2010-07-06 | Elitech Holding B.V. | TM leveling methods |
EP1944310A2 (en) | 2000-03-01 | 2008-07-16 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
EP1995330A1 (en) | 2000-03-01 | 2008-11-26 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
EP1975256A1 (en) | 2000-03-01 | 2008-10-01 | Epoch Biosciences, Inc. | Modified oligonucleotides for mismatch discrimination |
WO2012129547A1 (en) | 2011-03-23 | 2012-09-27 | Elitech Holding B.V. | Functionalized 3-alkynyl pyrazolopyrimidine analogues as universal bases and methods of use |
WO2013048583A2 (en) | 2011-05-24 | 2013-04-04 | Elitech Holding B.V. | Detection of methicillin-resistant staphylococcus aureus |
EP2801626A1 (en) | 2011-05-24 | 2014-11-12 | Elitech Holding B.V. | Detection of methicillin-resistant staphylococcus aureus |
WO2014159063A1 (en) | 2013-03-14 | 2014-10-02 | Elitech Holding B.V. | Functionalized 3-alkynyl pyrazolopyrimidine analogues as universal bases and methods of use |
WO2014186147A2 (en) | 2013-05-13 | 2014-11-20 | Elitech Holding B.V. | Droplet digital pcr with short minor groove probes |
WO2016094607A2 (en) | 2014-12-12 | 2016-06-16 | Elitechgroup B.V. | Methods and compositions for detecting antibiotic resistant bacteria |
WO2016094162A1 (en) | 2014-12-12 | 2016-06-16 | Elitechgroup B.V. | Methods and compositions for detecting antibiotic resistant bacteria |
US9988670B2 (en) | 2014-12-12 | 2018-06-05 | Elitechgroup B.V. | Methods and compositions for detecting antibiotic resistant bacteria |
Also Published As
Publication number | Publication date |
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WO1999037085A3 (en) | 1999-10-14 |
AU2229699A (en) | 1999-08-02 |
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