JPH07143348A - Image coding method - Google Patents

Abstract

PURPOSE:To improve the reproduced image quality and also to reduce the data quantity by detecting the pixel error between the estimated pixel value calculated based on the peripheral pixel level and the actual pixel value and then calculating the average pixel error of all pixels. CONSTITUTION:The pixel data equivalent to a single block and to be processed are extracted at first, and a pixel to processed in the block is selected. In regard of each pixel included in the block, a pixel error is detected between the estimated pixel value calculated based on the peripheral pixel level of a relevant one and the actual pixel value. Then the average pixel error value is calculated for all pixels included in the block. If the average pixel error value is larger than a prescribed level, the block undergoes the multilevel coding through a multilevel coding/decoding part 7 and the prescribed multilevel coding processing is applied to the block. Meanwhile each pixel of the block undergoes the binary coding through a binary coding/decoding part 8 and the prescribed binary coding processing is applied if the average pixel error value is smaller than the prescribed level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image coding method for coding pixels of a predetermined gradation number, which are formed by raster decomposition at a predetermined resolution, in units of blocks consisting of a predetermined rectangular area.

[0002]

2. Description of the Related Art For example, a facsimile apparatus normally exchanges image information obtained by encoding and compressing a binary image, but in recent years, image data obtained by multilevel reading retains its gradation. Attempts have been made to improve the quality of a received image by exchanging the information as it is.

In this case, for example, it is conceivable that the image data of multi-gradation is coded and compressed by applying the image coding method of the JPEG system to the image data obtained by multi-value reading. Has been.

[0004]

By the way, in general,
Since the information amount of the multi-tone image data is significantly larger than that of the binarized image data, the data amount of the image information formed is considerably large even if the image data is encoded and compressed by the JPEG method. For this reason, when multi-gradation image data is encoded and compressed as it is to form image information, the communication cost at the time of image information transmission increases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image coding method in which the quality of a reproduced image is good and the amount of data can be reduced.

[0006]

SUMMARY OF THE INVENTION The present invention provides an image coding method in which pixels of a predetermined gradation number formed by raster decomposition at a predetermined resolution are coded in block units consisting of a predetermined rectangular area. For each included pixel, the pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels of that pixel and the pixel value of that pixel is detected, and the average of the pixel error for all pixels in the block A value is calculated, and when the average value is larger than a predetermined value, a predetermined multilevel encoding process is applied to the block, while when the average value is less than the predetermined value, each pixel of the block is binarized. A predetermined binary encoding process is applied to the binary pixel value obtained thereby.

Further, in an image coding method of coding a pixel of a predetermined gradation number formed by raster decomposition at a predetermined resolution in a block unit consisting of a predetermined rectangular area, for each pixel included in the block, the pixel The pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels and the pixel value of that pixel is detected, and the maximum value of that pixel error in that block is calculated. When the value is less than or equal to a predetermined value, a predetermined multi-value encoding process is applied to the block, while when the maximum value is larger than a predetermined value, each pixel of the block is binarized and the obtained binary value is obtained. A predetermined binary encoding process is applied to the encoded pixel value.

Further, in an image coding method of coding a pixel of a predetermined gradation number formed by raster decomposition at a predetermined resolution in a block unit consisting of a predetermined rectangular area, for each pixel included in the block, the pixel The pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels and the pixel value of the pixel is detected, and the average value of the pixel error for all the pixels in the block is calculated, and the block If the average value is greater than a predetermined value and the maximum value is less than or equal to a predetermined value, the predetermined multi-value encoding process is applied to the block while the average value is calculated. When the value is less than or equal to a predetermined value or when the maximum value is greater than the predetermined value, each pixel of the block is binarized, and the binarized pixel value obtained by the binarization is given a predetermined binary value. It is obtained so as to apply a No. process.

Further, as the multi-level encoding process, an encoding process for encoding pixel data in the block unit can be applied. Further, as the binary coding process, a coding process to which the MMR coding method is applied can be applied.

[0010]

Therefore, when the image of the block in the rectangular area is a binary image, the multi-gradation pixel of the block is binarized after being binarized, and the image of the block is not a binary image. In this case, since the multi-gradation pixel of the block is subjected to the multi-value encoding process as it is, it is encoded and compressed in a block unit by the encoding method suitable for the content of the image of the block. The image quality of the image is improved, and the data amount of the encoded image information can be significantly reduced. Further, as the multi-level encoding process, a standard JPEG encoding process can be applied,
Further, since the MMR encoding process which is the encoding method of the group 4 facsimile apparatus can be applied as the binary encoding process, the existing technique can be used as the encoding method and the cost can be reduced.

[0011]

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

FIG. 1 shows a group 3 facsimile apparatus according to an embodiment of the present invention.

In FIG. 1, the system control unit 1 performs control processing of each unit of the facsimile apparatus and facsimile transmission control procedure processing. The system memory 2 is a control processing program executed by the system control unit 1. , And various data necessary for executing the processing program, and constitutes a work area of the system control unit 1. The parameter memory 3 stores various information unique to the group 3 facsimile machine. Is for storing.

The scanner 4 is for reading an original image with a predetermined resolution and a predetermined gradation number (for example, 16 gradations), and the plotter 5 has a predetermined resolution and a predetermined gradation number (for example, 16 gradations). , 16 gradations) for recording and outputting an image, and the operation display unit 6 is for operating this facsimile apparatus and is composed of various operation keys and various display devices.

The multi-level encoding / decoding unit 7 is for encoding and compressing a multi-gradation image signal and for decoding the encoded and compressed image information into the original image signal. As the encoding method, for example, a well-known JPEG encoding method is applied.

The binary encoding / decoding unit 8 is for encoding and compressing the binary image signal and for decoding the encoded and compressed image information into the original image signal. As the encoding method, for example, a well-known MMR encoding method is applied.

The image storage device 9 is for storing a large number of coded and compressed image information, and the group 3
The facsimile modem 10 is for realizing the modem function of the group 3 facsimile, and has a low-speed modem function (V.21 modem) for exchanging transmission procedure signals and a high-speed modem mainly for exchanging image information. Functions (V.33 modem, V.29 modem, V.2
7ter modem etc.).

The network control device 11 is for connecting this facsimile device to a public telephone line network and has an automatic call originating / receiving function.

These system control unit 1, system memory 2, parameter memory 3, scanner 4, plotter 5, operation display unit 6, multi-level encoding / decoding unit 7, binary encoding / decoding unit 8, image storage. The device 9, the group 3 facsimile modem 10 and the network control device 11 are connected to the system bus 12, and data is exchanged between these respective elements mainly via the system bus 12. .

Data is exchanged directly between the network control device 11 and the group 3 facsimile modem 10.

Next, the encoding method of this embodiment will be described.

In the present embodiment, first, as shown in FIG. 2A, an image is divided into blocks BLK each consisting of a rectangular area having a size of 8 × 8 pixels, and a multi-value coding process or The coding process to be applied is selected from the binary coding processes.

Here, as the size of the block BLK,
The reason why the 8 × 8 pixel size is applied is that the JPEG encoding method used in the multi-level encoding / decoding unit 7 performs an encoding process in block units, and 8 × 8 pixels are used as a block in this processing unit. This is because the size is used. In this way, by matching the selection unit of the encoding process with the processing unit of the multi-level encoding / decoding unit 7, it is possible to perform consistent image encoding process.

Then, the pixel matrix of 3 × 3 pixel size shown in FIG. 9B is applied to each pixel of the block BLK formed by dividing in this way. At this time, the application position of the pixel matrix is arranged such that the target pixel to be processed is located at the pixel X at the center of the pixel matrix.

Here, in this pixel matrix, as shown in FIG. 3C, the pixel of interest X has a coefficient of "1", and the surrounding pixels A, B, C, which are adjacent to the pixel of interest X.
A coefficient of “− (1/8)” is set for each of D, E, F, G, and H, and the predicted value Xe of the pixel of interest X is calculated based on the following equation (I).

Xe = X− (A + B + C + D + E + F + G + H) / 8 (I)

Here, the terms A, B, C, and
D, E, F, G, and H are surrounding pixels A, B, C, and
It represents the pixel values of D, E, F, G, and H.

However, for example, as shown in FIG. 3D, the adjacent pixels A, B, C, D, E, F, and
If the adjacent pixels A, B, C, D, and F of G and H are not included in the block BLK to which the target pixel X belongs, the pixel values of these adjacent pixels A, B, C, D, and F are , The median of possible values is virtually used. In this case, the pixel value can take a value of 0 to 16, so that the terms A, B, and
As the values of C, D, and F, for example, "8" can be used.

Next, the difference ε between the calculated predicted value Xe and the pixel value of the target pixel X is calculated based on the following equation (II).

Ε = | X−Xe | (II)

Here, the term X in the equation (II) represents the pixel value of the target pixel X.

For example, when a pixel matrix is applied to a solid white portion or a solid black portion of the original image, the pixel values of the pixels in this pixel matrix are substantially equal. That is, in this case, the pixel value of the target pixel X is substantially equal to the pixel values of the adjacent pixels A, B, C, D, E, F, G, and H, so that the value of the difference ε is almost “0”. become.

On the other hand, when a pixel matrix is applied to a portion of an image having a halftone such as a photograph, the pixel values of the pixels in this pixel matrix have some variation. Therefore, in this case, the pixel value of the target pixel X is not equal to the pixel values of the adjacent pixels A, B, C, D, E, F, G, and H, and therefore the value of the difference ε is to some extent. It has a size.

Therefore, the average value of the differences ε in one block BLK is calculated, and if the calculated average value is less than or equal to a predetermined value, it can be determined that the block BLK belongs to the character portion. If the average value exceeds the predetermined value, it can be determined that the block BLK belongs to the halftone image portion.

When it is determined that one block BLK belongs to the character portion, each pixel of the block BLK is binarized, and the MMR coding process is applied to the binarized pixel value after the binarization. , The image data of the block BLK is converted into binary image information. At this time, assuming that one line consists of 8 pixels and one page consists of 8 lines,
Encode.

When it is determined that one block BLK belongs to the halftone image portion, the JPEG encoding process is applied to the block BLK to convert the image data of the block BLK into multi-valued image information. .

In the present embodiment, the image information of the block BLK of the multivalued image information is shown in FIG. 3 so that it can be identified whether the image information of each block consists of binary image information or multivalued image information.
As shown in (a), an attribute bit of data "1" is added to the beginning of the image information of the block BLK of the binary image information, as shown in FIG. An attribute bit of data "0" is added.

Further, since the multivalued image information is added with the code EOB indicating the end of the block on a block-by-block basis,
The end of one block can be determined by detecting this code EOB at the time of decoding. In contrast, MMR
Since there is no concept of block in the encoding system, MMR
When the code is used directly, it is necessary to determine the end of one block when the decoded data for one block (64 pixels in this case) is obtained in order to determine the end of the block at the time of decoding.

Further, if the data of the next block is continuous, the overhead of the process for extracting the attribute bits of the next block increases, and the efficiency of the decoding process may deteriorate. .

Therefore, in the present embodiment, when the data length of the code data is not in byte units (1 byte = 8 bits), so-called zero padding processing is applied to set the data "0" in the remaining bits of the final byte. However, the coded data of the binary image information is shaped in byte units so that the efficiency of the decoding process can be improved.

If the binary encoding / decoding unit 8 can efficiently realize data access in bit units, the coded data of binary image information need not be shaped in byte units.

FIG. 4 shows an example of processing when encoding one page of image data. In this case, the scanner 4
The image data obtained by reading in 1. is stored in a page buffer formed in a predetermined area of the system memory 2.

First, image data of pixels for one block to be processed is extracted (process 101), and pixels to be processed in the block are selected (process 102). Then, the above-mentioned pixel matrix is applied to the pixel and the above equation (I) is calculated to calculate the predicted value Xe (Processing 1
03), and then the above equation (II) is calculated to calculate the prediction error ε (process 104).

In this way, when the prediction error ε is calculated for one pixel, it is checked whether or not the processing has been completed for all the pixels of the block to be processed at that time (decision 105), and the result of the judgment 105 is When the answer is NO, the process returns to step 102 and the process for the next pixel is executed.

When the prediction error ε is calculated for all the pixels of one block and the result of the determination 105 is YES, the average value of the prediction errors ε of the pixels for one block calculated at that time, that is, , Average prediction error ε
m is calculated (process 106), and it is checked whether the value of the prediction error average value εm is larger than the predetermined value Km (decision 107).

When the result of the judgment 107 is YES, the block to be processed is the part of the halftone image, so the image data of the block is multi-value coded by the multi-value coding / decoding section 7 (processing 108), the attribute bit of data "1" is added to the head of the code data obtained thereby (process 109), and multi-valued image information for one block is formed. Then, the multi-valued image information for one block is
The data is stored in block order in the buffer area (code data page buffer) set in a predetermined area of the system memory 2 (process 110).

In this way, when the processing for one block is completed, it is checked whether or not the encoding processing of the image data for one page is completed (decision 111). If the result of the judgment 111 is NO, the processing is performed. Returning to 101, the encoding process of the next block is executed.

When the result of the determination 107 is NO, the block to be processed is the portion of the character image, so that the multi-valued data is converted into binary data for each pixel of the block (process 112). ).

Then, 1 after conversion into the binary data
The image data for a block is binary-coded by the binary coding / decoding unit 8 (process 113), and the data length of the code data obtained thereby is shaped into a byte unit (process 114).

Next, the attribute bit of data "0" is added to the head of the coded data that has been shaped in bytes (Processing 1
15) Binary image information for one block is formed. Then, the binary image information for one block is stored in the buffer area set in the predetermined area of the system memory 2 in the block order (process 116), and the process proceeds to the determination 111 to determine the end of the process for one page. To do.

The predetermined value Km may be set experimentally. This value also changes in relation to the characteristics of the calculation for calculating the predicted value of the formula (I).

FIG. 5 shows an example of processing when decoding one page of image information. In this case, the image information is received from the transmission terminal and stored in the image storage device 9.

First, the attribute bit located at the beginning of the image information for one block is extracted (process 201). For example, the attribute bit of the first block of the image information for one page is arranged at the first bit of the image information for one page. The attribute bits of the other blocks are arranged in the bit next to the end position of the image information for the immediately preceding one block.

Then, it is checked whether the attribute bit is data "1" (decision 202). When the result of determination 202 is YES, the image information for one block to be processed is multi-valued image information, so 1 bit of code data (multi-valued image information) is input (process 203) and the input 1 The multi-level encoding / decoding unit 7 decodes the bit code data (process 204).

When the decoded data is output as a result, the decoded data is stored in the block buffer (multi-valued data) formed in a predetermined area of the system memory 2 in the pixel order (process 205), and the code is stored at that time. It is checked whether EOB is detected (decision 206). When the result of determination 206 is NO, the process returns to step 203 and the next code data is input.

When the result of the judgment 206 is YES, the decoding processing for one block has been completed, so that the contents of the block buffer (multi-valued data) at that time are formed in a predetermined area of the system memory 2. In a page buffer to be stored in block order (process 208), it is checked whether or not the decoding process for one page is completed (decision 20).
8).

When the result of judgment 208 is NO,
Returning to the process 201, the decoding process of the next block is executed. When the result of the determination 208 is YES, the image information decoding process for one page is completed.

When the result of the determination 202 is NO, since the image information for one block to be processed is binary image information, first, the code data (binary image information) for one byte is input (process. 209).

Then, 1 bit is input from the input 1-byte data (process 210), and the input 1-bit code data is decoded by the binary encoding / decoding unit 7, whereby the decoded data is obtained. Is output, the decoded data is stored in a block buffer (binary data) formed in a predetermined area of the system memory 2 in pixel order (process 211).

Then, it is checked whether or not the decoded data for 64 pixels has been obtained at that time (decision 212). When the result of the decision 212 is NO, the process returns to the process 209 and the next 1-byte coded data is obtained. input.

When the result of the judgment 212 is YES, the decoding processing for one block has been completed, so the contents of each bit of the block buffer (binary data) at that time are converted into multivalued data. Then, the converted multi-valued data is stored in a page buffer formed in a predetermined area of the system memory 2 in a block order (process 213), and the process proceeds to the determination 208 to end the decoding process for one page. Find out if you did.

Here, the conversion of binary data into multivalued data is performed, for example, when the value of the binary data is "0", the value of the multivalued data is changed to "0 (minimum value)". In the case of binary data or data "1", the value of multi-valued data is changed to "1".
6 (maximum value) ”.

As described above, in the present embodiment, when the image of the block in the rectangular area is a binary image, the multi-gradation pixels of the block are binarized and then binarized. When the image of the block is not a binary image, the multi-gradation pixel of the block is subjected to the multi-valued encoding processing as it is, so that the encoding method suitable for the content of the image of the block is used for each block. It is encoded and compressed, and therefore, the quality of the reproduced image is improved, and the data amount of encoded image information can be significantly reduced.

Further, the standard JPEG encoding process is used as the multi-level encoding process, and the MMR encoding process which is the encoding method of the group 4 facsimile machine is applied as the binary encoding process. Therefore, existing ones can be used as the multi-level encoding / decoding unit 7 and the binary encoding / decoding unit 8, and the device cost can be reduced.

By the way, in the above-described embodiment, the average value of the differences ε in one block BLK is calculated, and if the calculated average value is less than the predetermined value, the block BL is calculated.
While it is determined that K belongs to the character portion, and when the average value thereof exceeds a predetermined value, it is determined that the block BLK belongs to the halftone image portion. With such a determination method, when the block BLK is located on the black-and-white boundary of the character portion, the determination is erroneous.

To prevent such an erroneous determination, for example, the maximum value εx of the difference ε is calculated, and when the maximum value εx is large, the block BLK is located at the black and white boundary of the character portion. It is determined that the block belongs to the character portion even in such a case.

FIG. 6 shows an example of processing when encoding one page of image data in such a case. In this case, the image data read by the scanner 4 is stored in the page buffer formed in the predetermined area of the system memory 2.

First, image data of pixels for one block to be processed is extracted (process 301), and pixels to be processed in the block are selected (process 302). Then, the pixel matrix described above is applied to the pixel, and the above equation (I) is calculated to calculate the predicted value Xe (Processing 3
03), and then the above equation (II) is calculated to calculate the prediction error ε (process 304).

In this way, when the prediction error ε is calculated for one pixel, it is checked whether or not the processing has been completed for all pixels in the block to be processed at that time (judgment 305), and the result of judgment 305 is If NO, the process returns to step 302 and the process for the next pixel is executed.

When the prediction error ε is calculated for all the pixels of one block and the result of determination 305 is YES, the average value of the prediction errors ε of the pixels for one block calculated at that time, that is, , Average prediction error ε
m is calculated (process 306), and it is checked whether or not the value of the prediction error average value εm is larger than the predetermined value Km (decision 307).

When the result of the judgment 307 is YES, the maximum value ε of the prediction error ε in the block to be processed is
x is calculated (process 308), and it is checked whether or not the maximum value εx is larger than the predetermined value Kx (decision 309).

When the result of the determination 309 is NO, the block to be processed is the part of the halftone image.
The image data of the block is multi-value encoded by the multi-value encoding / decoding unit 7 (process 310), the attribute bit of data “1” is added to the head of the code data obtained thereby (process 311), and 1 Multi-valued image information for blocks is formed. Then, the multi-valued image information for one block is stored in block order in the buffer area (code data page buffer) set in a predetermined area of the system memory 2 (process 312).

When the processing for one block is completed in this way, it is checked whether or not the encoding processing of the image data for one page has been completed (decision 313). When the result of the judgment 313 is NO, the processing is performed. Returning to 301, the encoding process of the next block is executed.

When the result of the judgment 307 is NO and when the result of the judgment 309 is YES,
Since the block to be processed is a part of the character image, multivalued data is converted into binary data for each pixel of the block (process 314).

Then, 1 after conversion into the binary data
The image data for a block is binary-coded by the binary coding / decoding unit 8 (process 315), and the data length of the code data obtained thereby is shaped into a byte unit (process 316).

Next, the attribute bit of data "0" is added to the head of the coded data that has been shaped in bytes (process 3
17) Binary image information for one block is formed. Then, the binary image information for one block is stored in the buffer area set in the predetermined area of the system memory 2 in the block order (process 318), and the process proceeds to the determination 313 to determine the end of the processing for one page. To do.

In this case, the predetermined values Km and Kx may be set experimentally. This value also changes in relation to the characteristics of the calculation for calculating the predicted value of the formula (I).

By the way, in the above-mentioned embodiment, the MMR coding method is applied as the method of the binary coding processing, but other than this, the coding processing of the MR method or the MH method can also be used. . However, in the case of the MH system, it is advisable to arrange the pixels in a block in a line and apply it as image data for one line. Similarly, as the multi-level encoding method, an appropriate method other than the JPEG method described above can be used.

Further, in the above-mentioned embodiment, one block is composed of 8 × 8 pixel blocks, but other block sizes can be used.

Further, although the present invention is applied to the group 3 facsimile apparatus in the above-described embodiments, the present invention can be applied to other image processing apparatuses in the same manner.

[0081]

As described above, according to the present invention,
If the image of the block in the rectangular area is a binary image,
The multi-gradation pixels of the block are binarized and then binary-encoded. If the image of the block is not a binary image, the multi-gradation pixels of the block are multi-valued encoded as they are. Therefore, each block is coded and compressed by a coding method suitable for the content of the image of the block. Therefore, the quality of the reproduced image is improved and the data amount of the image information after coding is significantly increased. The effect is that it can be reduced. Further, as the multi-level encoding process, a standard JPEG encoding process can be applied,
Further, since the MMR encoding process which is the encoding method of the group 4 facsimile apparatus can be applied as the binary encoding process, the existing technique can be used as the encoding method and the cost can be reduced. obtain.

[Brief description of drawings]

FIG. 1 is a block diagram showing a group 3 facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a block and a pixel matrix to be processed.

FIG. 3 is a schematic diagram showing an example of a format of code data.

FIG. 4 is a flowchart showing an example of encoding processing for one page.

FIG. 5 is a flowchart showing an example of a decoding process for one page.

FIG. 6 is a flowchart showing another example of the encoding process for one page.

Claims (5)

[Claims] 1. An image coding method for coding a pixel of a predetermined gradation number formed by raster decomposition at a predetermined resolution in a block unit made up of a predetermined rectangular area, and for each pixel included in the block, the pixel The pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels and the pixel value of that pixel is detected, and the average value of the pixel errors for all the pixels in the block is calculated, and the average value is calculated. Is greater than a predetermined value, a predetermined multi-level encoding process is applied to the block, while when the average value is less than or equal to a predetermined value, each pixel of the block is binarized and the obtained binary value is obtained. An image coding method characterized by applying a predetermined binary coding process to a binarized pixel value. 2. An image coding method for coding a pixel of a predetermined gradation number formed by raster decomposition at a predetermined resolution in a block unit consisting of a predetermined rectangular area, for each pixel included in the block, the pixel The pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels and the pixel value of that pixel is detected, and the maximum value of that pixel error in that block is calculated. When the value is less than or equal to a predetermined value, a predetermined multi-level encoding process is applied to the block, while when the maximum value is larger than a predetermined value, each pixel of the block is binarized.
An image coding method characterized in that a predetermined binary coding process is applied to the binarized pixel value obtained thereby. 3. An image coding method for coding a pixel of a predetermined gradation number formed by raster decomposition at a predetermined resolution in a block unit made up of a predetermined rectangular area, in each pixel included in the block, the pixel The pixel error between the pixel prediction value obtained by calculating based on the pixel level of the surrounding pixels and the pixel value of the pixel is detected, and the average value of the pixel error for all the pixels in the block is calculated, and the block If the average value is greater than a predetermined value and the maximum value is less than or equal to a predetermined value, the predetermined multi-value encoding process is applied to the block while the average value is calculated. When the value is less than or equal to a predetermined value or when the maximum value is larger than the predetermined value, each pixel of the block is binarized, and the binarized pixel value obtained by the binarization is given a predetermined binary code. Image encoding method characterized by applying the process. 4. The image coding method according to claim 1, wherein the multi-level coding process is a coding process for coding pixel data in the block unit. . 5. The image coding method according to claim 1, wherein the binary coding process is a coding method to which an MMR coding method is applied.