JPH10271342A - Binary image encoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To insert a control code at an arbitrary position by defining the prescribed value of either '1' or '0' for discriminating a relevant code a real code as a leading bit value, when the code to be outputted is the same code as the control code which can be inserted. SOLUTION: When no control code is to be inserted, and when the code for one byte is not '0×00', such a code is outputted as it is and the code for one byte is outputted, while inserting the leading bit '0' showing that the code is the actual code. When the control code is to be inserted, it is judged whether or not the code for one byte is '0×00' and when it is not '0×00', the control code is outputted after '0×00' is outputted as an identification code. When the code is '0×00', that code for one byte is outputted as it is, and further more, the code for one byte is outputted while inserting the leading bit '0' showing that the code for one byte is the actual code. Moreover after '0×00' has been outputted as the identification code, the control byte is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a binary image encoding method.

[0002]

2. Description of the Related Art At present, there are three types of standard binary image coding systems used in G3 / G4 facsimile machines, and MH (Modified Huffman) and MR (M
modified Read), MMR (Modified
d MR) coding method.

While the MH coding method is a one-dimensional model coding method that does not require a reference line, MR, M
The MR coding method is a coding method using a two-dimensional model using a reference line. Generally, in a character image,
The coding efficiency increases in the order of the MMR, MR, and MH coding methods.

[0004] The MH and MR coding methods are standardized for G3 facsimile. In order to prevent the influence of coded data being lost during transmission from being propagated one after the next line, In the MH coding method, a line synchronization code is inserted for each line, and in the MR coding method, a line synchronization code is inserted for every predetermined plurality of lines.

On the other hand, the MMR coding system is standardized for G4 facsimile, and it is necessary to perform two-dimensional coding on all lines by omitting insertion of a line synchronization code on the premise of error-free transmission. This is an encoding method with improved encoding efficiency.

In a recent G3 facsimile machine,
Added as an optional function of G3 facsimile,
By adopting the ECM, an error retransmission scheme that realizes error-free transmission, most apparatuses can use the MMR coding scheme with the best coding efficiency.

[0007]

In a conventional facsimile coding method such as the MMR method, coded data output by coding is basically output in bit units, and these codes are output. Is a variable-length code, and therefore has the following major problem.

That is, it is difficult to insert an arbitrary code into the encoded data. Even if it can be inserted, it is difficult to search for the code instantly. Also, MMR
In the encoding method, it is difficult to instantaneously determine which position in the encoded data is a line break.

In the MH and MR coding methods, a certain degree of solution can be attained by using a line synchronous code, that is, an EOL (End of Line) code (“00000000001”). Since the EOL code is followed by 11 bits of "0", if the encoded data is divided into 8 bits, that is, one byte at a time, the EOL code portion always has 0x00 (0x is a prefix representing a hexadecimal number). ,
That is, if expressed in binary, "00000000"
0 "or 0x? 0, 0x0? (? Is a hexadecimal number from 0 to f), that is,"? " ? ? ? 0000 ”,“ 0000? ? ? ? "(?
Is a binary string of either 1 or 0), and it is possible to determine to a certain extent which position in the encoded data is a line break by the unique byte string.

On the other hand, in the MMR encoding method, since a line synchronization code such as an EOL code does not exist in the encoded data, the encoded data must be decoded and returned to the original image data after all. This means that it is not possible to determine a line break or the like, which is a very serious problem.

On the other hand, in the latest encoding schemes such as JPEG and JBIG encoding schemes, the above-mentioned problem does not occur because encoded data is output in byte units. In JPEG and JBIG, a control code called a marker code can be arbitrarily inserted into a code string, and is very effectively used. For example, it is used when it is desired to synchronize with an arbitrary number of lines, or when it is desired to change an encoding parameter on the way.

However, the JPEG and JBIG coding methods have a problem that the coding processing is very complicated and costly disadvantageous as compared with the MH, MR and MMR coding methods.

The present invention has been made in view of the above circumstances, and a binary image encoding method capable of inserting a control code at an arbitrary position even in encoded data encoded by the MMR encoding method. The purpose is to provide.

[0014]

According to a first aspect of the present invention, there is provided a binary image encoding method, wherein a control code which can be inserted into encoded data is determined in advance while MMR is used.
The encoded data encoded by the encoding method is sequentially output as a code in byte units, and when the output code is the same code as the control code that can be inserted into the encoded data, After the code, a real code discrimination code having a predetermined value of 1 or 0 as a leading bit value for discriminating that the code is an actual code is output.

According to a second aspect of the present invention, in the binary image encoding method, an identification code which can be inserted into encoded data is predetermined as a hexadecimal number "00", while the encoded data encoded by the MMR encoding method is defined. Are sequentially output as codes in byte units, and when the output code is the same code as the identification code that can be inserted into the encoded data, either 1 or 0 follows the code. By outputting a real code discriminating code having a predetermined value as a leading bit value, following the identification code, an arbitrary control code having a leading bit value different from the leading bit value of the real code discriminating code It is characterized in that insertion is possible.

According to a third aspect of the present invention, in the binary image encoding method, the identification code that can be inserted into the encoded data is predetermined as a hexadecimal number “00”, while the encoded data encoded by the MMR encoding method is set. Are sequentially output as codes in byte units, and when the output code is the same code as the identification code that can be inserted into the encoded data, the code is output following the same code as the identification code. The first bit is a predetermined value of either 1 or 0 and the remaining bits are codes composed of the following coded data, so that the same code as the identification code follows the identification code. , An arbitrary control code having a value different from the leading bit value of the code outputted after the leading bit value can be inserted.

According to a fourth aspect of the present invention, in the binary image encoding method according to any one of the first to third aspects, the control code or the identification code is inserted into the encoded data. At this time, if the code of the immediately preceding byte is not determined, the bits of the undetermined one in the byte are padded with 0, and the code of the byte is determined. A control code or an identification code is inserted.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a block configuration in a case where an image is transmitted via a transmission path between facsimile apparatuses to which a binary image encoding method according to an embodiment of the present invention is applied.

In the figure, first, on the transmitting side, an image reading section 1 reads a document using a CCD image sensor or the like, and a subsequent image processing section 2 performs processing for converting transmission data into appropriate data. The encoded data generated by performing the encoding in the encoding unit 3 is transmitted to the receiving side via the transmission path.

On the other hand, when an image is reproduced on the receiving side, the encoded data is decoded by the decoding unit 4, the image processing unit 5 performs image processing suitable for the output device, and the image output unit 6 such as a plotter is used. To get a hard copy. Note that examples of processing performed by the image processing unit 2 or 5 include resolution conversion and size conversion.

Examples of the encoding system used in the encoding unit 3 and the decoding unit 4 include a conventional MH, MR, MMR encoding system and the latest JBIG system. The present invention relates to the MMR coding method among them. However, since the MMR coding method itself is already well-known by the ITU-T standard recommendation and the like, the following description will be made. Detailed descriptions other than those related to the present invention will be omitted.

Next, a communication procedure in the G3 facsimile will be briefly described with reference to FIG. In the figure, when the transmitting side calls the receiving side, the receiving side returns to the transmitting side a signal (CED) indicating that the receiving state has been entered. Subsequently, the receiving side notifies the transmitting side of the manufacturer specifications (NSF) and the functions (CSI, DIS) of the receiving side. The transmitting side refers to the function of the receiving side received from the receiving side, determines the transmitting side mode (TSI, DCS), and notifies the receiving side.

Next, the modem on the receiving side is prepared (TRAI
NING) to perform a communication speed test (TCF). Upon successful completion of the communication test, the receiving side informs the transmitting side that the communication test has been completed (CFR). The sender prepares the receiving modem again for transmission of image information (RE
TRAIN) and transmission of image information (MESSAG
Start E). What is transmitted at this time is the encoding unit 3
Is the data encoded with.

When the transmission of the image information is completed, the transmitting side sends a signal (EOP) notifying the receiving side of the end of the transmission.
After confirming that the image has been successfully received, the receiving side informs the transmitting side that the transmission of the image information has been completed normally (MCF). When the above procedure is completed, the transmitting side informs the receiving side of disconnecting the line (DCN) and disconnects the line. In this way, image information as encoded data is transmitted between the transmitting and receiving apparatuses.

Next, the binary image encoding method according to the present invention performed in the encoding unit 3 will be described with reference to FIG. The processing procedure shown in FIG.
The encoding unit 3 internally encodes the image data from the image processing unit 2 using the same MMR encoding scheme as the conventional one, thereby internally outputting the encoded data in bit units. The output bit-unit encoded data is shown in FIG.
The processing is performed according to the procedure shown in FIG.

On the premise of the above, in FIG.
Determines whether the encoding of the image data from the image processing unit 2 by the MMR encoding method has been completed (decision 101), and if the encoding has been completed (Yes in decision 101), the terminal code, that is, the ITU-T Recommendation Facsimile block end (EOFB) code (in binary, "000000"
0000001000000000001 ”, in hexadecimal notation in byte units,“ 0x00 ”“ 0x10 ”“ 0x0 ”
1 "is output, and the process is terminated.

If not completed (No in decision 101)
Continues the MMR encoding (process 102) and repeats the MMR encoding until the code becomes 1 byte (decision 10).
3 (No loop of No. 3), when the code becomes one byte (decision 1)
03 (Yes), it is determined whether a control code is to be inserted for the purpose of synchronizing lines or the like (decision 104).

If the control code is not inserted (No in decision 104), it is determined whether the code for one byte is "0x00" (decision 105), and if it is not "0x00" (decision 105).
No) outputs the 1-byte code as it is (process 108). If “0x00” (judgment 10
5 (Yes), the code for one byte, that is, “0x00” is output as it is (process 106), and further, the code “0x00” for one byte is an actual code. A one-byte code with the leading bit '0' inserted is output (process 107). The one-byte code with the leading bit '0' inserted is a code composed of only the leading bit '0' and the remaining seven bits composed of the following MMR encoded data.

When inserting a control code (Y in decision 104)
es) determines whether the code for one byte is “0x00” (decision 109), and if it is not “0x00” (decision 109)
No) outputs “0x00” as an identification code (process 110), and then outputs a control byte, that is, a control code (process 111). The control byte is
Only the first bit is '1' and the remaining 7 bits are used as a net control code.

If the code for one byte is "0x00" (Yes in decision 109), the code for one byte, that is, "0x00" is output as it is (step 11).
2) Further, the code “0x00” for one byte is
A one-byte code with the leading bit '0' inserted, indicating that it is an actual code, is output (process 113), and “0x00” as an identification code is output (process 11).
4) Output a control byte, that is, a control code (process 115). In the control byte, only the first bit is “1”, and the remaining 7 bits are used as a net control code.

Process 107, 108, 111 or 115
After that, the process returns to the determination 101.

As described above, the encoding method according to the present embodiment of the procedure shown in FIG. 3 is basically the same as the conventional MMR encoding method. Point to determine whether or not
3) and a process (process 107, process 113) for distinguishing the actual code from the identification code (“0x00”) when inserting the control code in consideration of the case where the control code is inserted. The feature is the point.

In the procedure shown in FIG. 3, the identification code is set to "0x00", and if the actual code and the identification code are the same, the first bit added after the actual code same as the identification code is added. By setting the first bit of the control byte to “1” while setting it to “0”, the code “0x00” becomes
Whether the code is an actual code or an identification code is distinguished. The first bit added after the actual code same as the identification code is set to “1”, while the first bit of the control byte is set to “0”. This also makes it possible to distinguish whether the code “0x00” is an actual code or an identification code. Also, “0x00” is, according to the confirmation of the inventor, I
When the TU-T standard chart # 1 (A4, 200 dpi) is encoded, since only 4 bytes appear in encoded data divided into bytes, it is used as an identification code for inserting a control code. In other words, when the actual code is the same as the identification code, the code byte following the actual code that is the same as the identification code is used as the actual byte. Eliminating the opportunity of adding the first bit “0” for code determination makes it possible to reduce the redundancy and achieve efficient coding. Also, the 7 bits other than the first bit “0” of the code byte after the actual code same as the identification code are
Since the data is R-encoded data, encoding without waste is possible.

FIG. 4 shows an example of a code string generated by the coding method according to the present embodiment in comparison with a conventional MMR coding method.

FIG. 3 shows a case where a code is just separated at a byte boundary, a case where a code is not exactly separated at a byte boundary, and a case where "0x00" appears with a normal code. Note that, in the same figure, the code string indicated by P is a code for the Pass mode in the MMR coding system, and is V (0), VR (1), VR (2).
Alternatively, the code string indicated by VL (1) indicates a code for each vertical mode.

As shown when the codes are just separated by byte boundaries, in the MMR coding of the present invention, the control code (in this case, “0x8f”) is replaced by the identification code (“0x0f”).
0 ”) and 8 bits (“ 1000 ”) constituting the byte of the control code“ 0x8f ”.
1111 "), the leading bit" 1 "indicates that the byte is a control byte, and the remaining bits (" 0 "
001111 ") means the net control code.

Also, as shown when the code is not just separated by a byte boundary, in the MMR coding of the present invention, the control code (in this case, “0x8f”) is used together with the identification code (“0x00”). Prior to being inserted into the code sequence, the procedure shown in FIG. 3 was not described,
In order to determine the code of one byte, in this case, by adding six consecutive “0” as insertion bits,
The 3-bit code string VL (1) (“0
10 "), the last two bits (" 10 ") are determined as eight bits, that is, a one-byte code.
Even if "0" is added, no problem occurs as a code.

When “0x00” appears in a normal code, in the MMR coding of the present invention, after the actual code “0x00”, the “0x00” is not an identification code. A leading bit '0' is inserted to indicate that it is an actual code. Therefore, "0x0
8 bits (“01010000”) from the beginning of 9 bits (“010100001”) in which a bit “0” is inserted at the beginning of the 8 bits (“10100001”) constituting the byte of code “0xa1” after “0” , That is, "0
x50 ”follows the actual code“ 0x00 ”, and the last bit“ 1 ”of the 9 bits
Will be pushed to the beginning of the next code byte. Accordingly, when a code byte of “0x00” appears in the encoded data string, whether the “0x00” is an identification code or an actual code is immediately determined by the leading bit of the subsequent byte. Since it can be determined, if it is an identification code, the subsequent 7-bit net control code can be extracted from the encoded data string, and if it is an actual code, the first bit of the code byte following the actual code is excluded. By doing so, a correct encoded data string can be obtained.

As described above, in the encoding method according to the embodiment of the present invention, an additional process is performed on the code output of the MMR encoding system, so that an arbitrary It is possible to solve problems such as difficulty in inserting a code, difficulty in searching for the code instantly even if it is inserted, and difficulty in finding a line break instantly. Further, since an arbitrary control code can be inserted and the code can be searched instantaneously, there is a possibility that a wide range of applications can be realized.

In the above-described embodiment, an example in which the binary image encoding method according to the present invention is applied to a facsimile apparatus has been described. However, the present invention is not limited to this, and may be applied to an image filing apparatus and other devices. The same can be applied to a device that handles images of the above type.

[0042]

According to the first aspect of the present invention, JPEG
And a marker code that can be used in the JBIG encoding method, and outputs a code in byte units so that a control code can be arbitrarily inserted into encoded data encoded in the MMR encoding method. When the control code and the actual code are the same, either 1 or 0 for discriminating that the code is the actual code to distinguish it from the actual code. Since the real code discriminating code having the predetermined value as the leading bit value is continuously output, an effect is obtained that a reproduced image without error at the time of decoding can be obtained. Whether or not the real code discrimination code is the real code discrimination code can be easily discriminated by its leading bit value. Further, since a control code can be inserted at an arbitrary position in the encoded data, it is possible to realize encoding that is easy to handle and has a wide application range.

According to the second aspect of the present invention, when encoded data obtained by encoding a character image or the like by the MMR encoding method is divided into codes in byte units, the code of one byte is a hexadecimal number. Paying attention to the fact that the chance of becoming "00" is extremely small, by using a byte which hardly appears in actual encoded data as an identification code for inserting a control code, When the code is the same as the code, there is almost no chance of adding the real code discrimination code, the redundancy is reduced, and efficient binary image coding can be realized. Actually, ITU-T standard chart # 1
The inventor has confirmed that when (A4, 200 dpi) is encoded, only four bytes of hexadecimal “00” appear in the encoded data divided into bytes. Also, since any control code is inserted into the encoded data can be determined by the identification code placed before it, any control code can be inserted at any position in the encoded data. , Easy to handle,
In addition, encoding with a wide range of applications can be realized. Whether the actual code happens to be the same as the identification code or whether the identification code is inserted along with the control code is determined by the first bit value of the real code determination code and the control code. Since the first bit values are different from each other, the identification code or the first bit value of the code following the same actual code as the identification code can be easily distinguished, and the processing can be speeded up. .

According to the third aspect of the invention, when encoded data obtained by encoding a character image or the like by the MMR encoding method is divided into codes in byte units, the code of one byte is a hexadecimal number. Paying attention to the fact that the chance of becoming "00" is extremely small, by using a byte which hardly appears in actual encoded data as an identification code for inserting a control code, When the code is the same as the code, there is almost no chance that a leading bit for discriminating that the actual code identical to the identification code is the actual code is added to the code output subsequently, and the redundancy is reduced. , And efficient binary image encoding can be realized. Also, since any control code is inserted into the encoded data can be determined by the identification code placed before it, any control code can be inserted at any position in the encoded data. In addition, encoding that is easy to handle and has a wide range of applications can be realized. Whether the actual code happened to be the same as the identification code or whether the identification code was inserted along with the control code is the same as the identification code or the same actual code as the identification code. It can be easily distinguished by the leading bit value of the code following the code, and the processing can be speeded up. Also, since the bits other than the first bit of the code following the actual code identical to the identification code are composed of the following coded data, coding without waste is possible.

According to the fourth aspect of the present invention, when the control code or the identification code is inserted at the end of a line or the like, the code may not be determined as a byte yet. By determining the remaining bits and outputting the code, a control code and an identification code can be inserted. Regarding whether to fill the remaining bits with “1” or “0”, “1” is already reserved as a code, so “0” must be used inevitably.
Even if padding is used, no problem occurs as a code. in this way,
Even if the code has not yet been determined for one byte, the control code and the identification code can be inserted without any problem by filling the remaining bits with "0" and determining the code, thereby enabling a wide range of applications. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration in a case where an image is transmitted via a transmission path between facsimile apparatuses to which a binary image encoding method according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a communication procedure in a G3 facsimile.

FIG. 3 is a flowchart illustrating a procedure of a binary image encoding method according to the present invention performed in an encoding unit.

FIG. 4 is a diagram showing an example of a code string generated by a binary image coding method according to an embodiment of the present invention, in comparison with a conventional MMR coding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading part 2 Image processing part 3 Encoding part 4 Decoding part 5 Image processing part 6 Image output part

Claims (4)

[Claims] 1. A control code that can be inserted into encoded data is determined in advance, and encoded data encoded by the MMR encoding method is sequentially output as a code in byte units. If the code is the same as the control code that can be inserted into the encoded data, a predetermined value of 1 or 0 following the code is used to determine that the code is an actual code. And outputting a real code discrimination code having the first bit value as a first bit value. 2. An identification code that can be inserted into encoded data is 1
The hexadecimal number “00” is predetermined, while the encoded data encoded by the MMR encoding method is sequentially output as a byte unit code, and the output code can be inserted into the encoded data. If the code is the same as the identification code, by outputting a real code identification code having a predetermined value of 1 or 0 as the first bit value following the code, A binary image encoding method, wherein an arbitrary control code having a value different from the head bit value of the real code discrimination code as a head bit value can be inserted. 3. An identification code that can be inserted into encoded data is 1
The hexadecimal number “00” is predetermined, while the encoded data encoded by the MMR encoding method is sequentially output as a byte unit code, and the output code can be inserted into the encoded data. If the code is the same as the identification code, the code output following the same code as the identification code is a coded data in which only the first bit is a predetermined value of 1 or 0 and the remaining bits are the following coded data. By following the identification code, an arbitrary control code having a value different from the first bit value of the code output following the same code as the first code following the identification code may be used. A binary image encoding method characterized in that insertion is possible. 4. When inserting the control code or the identification code into the encoded data, if the code of the immediately preceding one byte is not determined, the bits of the undetermined one byte are replaced by the undetermined bits. 4. The binary image encoding method according to claim 1, wherein the control code or the identification code is inserted after padding with 0 to determine the code for the one byte. .