JP3142911B2 - Processing method of encoding / decoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method of an encoding / decoding apparatus for encoding and decoding image information.

[0002]

2. Description of the Related Art As an encoding method for compressing image information, MH (Modified Huffman) method,
MR (Modified Relative Elem)
The entAddress Design (MM) method or the Modified MR (MMR) method is well known. In each of these encoding methods, pixel data of image information is encoded in units of one line.

FIG. 7 shows a procedure of a decoding process for reproducing original pixel data from MMR coded data. That is, when the decoding process is started, the run length of the white pixel is defined at the head of each line.
First, a white run reproduction state is initialized (process 1). Then
The encoded data is input one bit at a time (process 2), and one code is extracted (process 3). This code is information indicating the run length and code mode of the white / black pixel. next,
The predetermined pixel data is restored from the code (process 4).

Thereafter, it is determined whether or not one line has been processed based on the number of bits of the restored pixel data (process 5).
If one line has not been processed yet (N in process 5), the next coded data is input and processed in the same way (to process 2). Then, when the processing for one line is completed (Y in processing 5), the processing is initialized to the white run reproduction state, and the same processing is performed for the next line (to processing 1). In this way, pixel data is sequentially reproduced from the encoded data.

Incidentally, as one method for speeding up such a decoding process, it is conceivable that the above-described code extracting operation and a restoring operation for restoring pixel data from the extracted code are performed simultaneously in parallel.

For example, such simultaneous processing is often performed in the MH system and the MR system. In the case of the MH system or the MR system, EOL indicating the end of one line is added to the encoded data.
Code is inserted. By detecting this EOL code, the end of one line is determined, and the white run reproduction state is initialized at the beginning of each line.

[0007]

However, in the case of the MMR system, an EOL code indicating the end of one line is not inserted in the encoded data. Therefore, the end of one line
As in the above processing, it cannot be determined unless the number of bits of the pixel data obtained by the restoration operation is counted. Therefore, the code extraction operation and the restoration operation cannot be performed at the same time, and there is a problem that the decoding process takes time.

An object of the present invention is to provide a processing method of an encoding / decoding apparatus capable of solving the above-mentioned problem and shortening the time required for decoding processing even for encoded data in which an EOL code is not inserted. Aim.

[0009]

For this purpose, the present invention relates to an operation of extracting run length and code mode information from input coded data and storing the information in a buffer memory during decoding processing. While the operation of reproducing pixel data based on the stored information is simultaneously executed, when the reproduction of one line is completed, the information of the next line stored in the buffer memory is temporarily restored. After performing predetermined initialization at the beginning of the line,
Each information is obtained again from the coded data restored.

[0010]

The predetermined initialization can be performed at the beginning of one line, and the code extraction operation and the restoration operation can be performed at the same time. Can be shortened.

[0011]

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

FIG. 1 is a block diagram showing an encoding / decoding apparatus according to an embodiment of the present invention. In the figure, a pixel data input / output circuit 101 inputs pixel data line by line from an external device or outputs line data line by line to the device. Change point detection circuit 10
Numeral 2 detects a white / black change point of the input pixel data and outputs predetermined run-length information and code mode information. The selector 103 selectively outputs one of the two input signals. The FIFO buffer 104 includes a FIFO (First In Firsts).
t Out) is a memory that has a function and temporarily stores data. The code conversion circuit 105 internally has a data table for code conversion, and converts the run-length information and the code mode information into a predetermined code word, and performs the reverse conversion. The P / S conversion circuit 106 outputs data input as a parallel signal as a serial signal.

The coded data input / output circuit 107 outputs coded data to an external device line by line or inputs coded data from the device line by line.
The selector 108 selects and outputs one of the three input signals. The S / P conversion circuit 109 outputs data input as a serial signal as a parallel signal. The save register 110 includes an S / P conversion circuit 109
Is temporarily saved. EOL detection circuit 11
Numeral 1 detects an EOL code in the encoded data. The FIFO buffer 112 is a memory for temporarily storing data similar to the above. Pixel data restoration circuit 11
Reference numeral 3 is for restoring pixel data from run length information and code mode information. The pixel number counting circuit 114 counts pixel data for one line. Control circuit 1
Reference numeral 15 is for monitoring and controlling the operation of each circuit.

Next, the operation of the encoding / decoding apparatus according to the present embodiment having the above configuration will be described.

Now, assume that an encoding process is performed. In this case, the pixel data input / output circuit 101 inputs raw pixel data before encoding from an external device and converts the pixel data of the encoded line to be encoded and the pixel data of the reference line into the change point detection circuit 10.
2 sequentially. The change point detection circuit 102 detects a white / black change point of input pixel data. And M
According to a known procedure of the MR system, one of three coding modes, “pass”, “horizontal” and “vertical” is selected as shown in FIG. Here, when “horizontal” is selected, the run lengths of two sections of white and black are further counted. When “vertical” is selected, the mode is further classified into six types. Note that "P",
"H", "V (0)", "VR (n)" or "VL
(N) "is a conventional symbol representing each mode. The change point detection circuit 102 outputs the encoding mode information and the run length information selected in this way. The output information is sequentially stored in the FIFO buffer 104 via the selector 103.

The code conversion circuit 105 reads the coding mode information and the run length information from the FIFO buffer 104, and sequentially converts them into corresponding predetermined code words as shown in FIG. It should be noted that “M1” and “M2” in FIG.
Is an MH code indicating a run length. Each code word is variable-length data, as is apparent from FIG.

The P / S conversion circuit 106 receives the codeword of the variable-length data as a parallel signal and sequentially outputs a serial signal corresponding to the data length. The encoded data input / output circuit 107 outputs the encoded data to an external device.

In the above process, the operation of storing the information in the FIFO buffer 104 by the change point detection circuit 102 and the operation of reading and encoding the information from the FIFO buffer 104 are performed simultaneously in parallel. become.

Next, a decoding process is performed. FIG. 3 shows the operation of the decoding process. That is, in this case, the encoded data input / output circuit 107 inputs the encoded data from an external device as a serial signal, and sequentially outputs the serial data to the selector 108. At this time, the selector 108
Converts the input encoded data into an S / P conversion circuit 10
9 is output. S / P conversion circuit 109 converts the encoded data into a parallel signal and outputs the parallel signal. In this case, the code conversion circuit 105 performs the operation shown in FIG.
Each codeword shown in (b) is converted into encoding mode information and run-length information shown in FIG.
1). The converted information is temporarily stored in the FIFO buffer 112. The pixel data restoration circuit 113
Each piece of information is read from the O-buffer 112 to restore the original pixel data (process 1002).

The pixel number counting circuit 114 counts the number of bits of the restored pixel data. The control circuit 115
Based on the counted value, it is monitored whether or not one line is completed (process 1003). If the counted value is less than the number of bits of one line and the end of one line is not reached (processing 100
3N), the decoding operation is repeated (process 1001).
What).

As a result, as shown by the information path R1 in FIG. 4, the encoded data is sequentially decoded and restored, and the raw pixel data is reproduced. At this time, the code conversion circuit 10
5, the operation of storing the decoded information in the FIFO buffer 112 and the operation of the pixel data restoring circuit 113 reading out the information and reproducing the pixel data are performed simultaneously in parallel.

In this way, when the number of bits of the restored pixel data reaches one line and the restoration of one line is completed (Y in step 1003), it is determined whether or not one page is completed (step 1004). Here, if the end of one page has not yet been reached (N in process 1004), the S / P conversion circuit 10
9 is temporarily transferred to the save register 110 and saved (process 1005).

By the way, as shown in FIG. 5A, when encoded data is sequentially transferred from the encoded data input / output circuit 107 to the S / P conversion circuit 109, at time t, one line Suppose the end is reached. At this point, the S / P conversion circuit 109 stores the encoded data D1 corresponding to the capacity. Also, FIFO buffer 1
12 stores a certain amount of information D2, as shown in FIG. Therefore, the information D3 before the information D2 corresponds to the pixel data D4 of one line just restored as shown in FIG. The information D2 is the encoded data D shown in FIG.
The information D3 corresponds to the coded data D5 before one and the coded data D6 before that.

In this case, the encoded data D5, D1 and information D2 are information of the next line. As described above, at the beginning of the line, initialization must be performed so as to reproduce a white run. However, in this case, the information D2
Is erroneous because the information such as the encoding mode is extracted without executing the initialization.

In the process 1005, the information route R shown in FIG.
As shown in FIG. 2, the encoded data D1 is saved in the save register 110.

Next, as shown in the information path R3, the FIF
The information D2 in the O-buffer 112 is transmitted to the selector 103 and the FI
The signal is input to the code conversion circuit 105 via the FO buffer 104. At this time, the code conversion circuit 105 returns the information D2 to the coded data D5 by a coding operation. Then, the coded data D5 is transmitted to the S / P conversion circuit 1 via the P / S conversion circuit 106 and the selector 108.
09 (process 1006).

Next, the code conversion circuit 105 initializes the white run so as to reproduce the white run, and then converts the coded data D5 into various information such as a predetermined coding mode again. The information is stored in the FIFO buffer 1 as shown in the information path R4.
The signal is input to the pixel data restoration circuit 113 via the line 12.
The pixel data restoring circuit 113 restores the information to pixel data (step 1007). As a result, FIG.
Is correctly reproduced.

Next, as shown in the information path R5, the encoded data D1 saved in the save register 110 is input to the code conversion circuit 105 via the selector 108 and the S / P conversion circuit 109. The code conversion circuit 105 converts the coded data D1 into predetermined information, and the pixel data restoration circuit 113 reproduces pixel data based on the information (process 1008). As a result, the encoded data D1 is correctly reproduced.

Thereafter, the process returns to the process shown in the information route R1 (to the process 1001). As a result, the same processing is sequentially performed line by line.

A known RTC code is set at the end of one page of the encoded data. This R
The TC code is a sequence of two consecutive EOL codes. At the end of the encoded data, the EOL detection circuit 111
The EOL code is detected. The control circuit 115 determines that one page has ended when the EOL code is continuously detected.

By thus determining the end of one page (Y in step 1004), the above-described decoding processing is completed.

The procedure for encoding pixel data of the MH system and the MR system is the same as that of the MMR system described above.

On the other hand, when decoding the encoded data of the MH system and the MR system, the processes 1001 and 1002 in FIG. 3 are executed in the same manner. In this case, the EOL detection circuit 111 detects the EOL code inserted in each line of the encoded data. When the EOL code is detected, the code conversion circuit 105 executes the initialization for reproducing the white run. Then, the decoding process for the next line is similarly started. This process is repeated until the RTC code is detected. Thereby, one page of pixel data is reproduced.

As described above, in the present embodiment, at the time of the encoding process, the change point detection circuit 102 extracts run-length and code mode information from the pixel data, and
Since the operation of storing the data in the IFO buffer 104 and the operation of reading the stored information and generating the encoded data by the code conversion circuit 105 are performed simultaneously,
The encoding process can be executed at high speed.

At the time of decoding, each information is extracted from the encoded data by the code conversion
Since the operation of storing the data in the O-buffer 112 and the operation of restoring the pixel data by the pixel data restoring circuit 113 from the respective stored information are performed simultaneously,
The decoding process can be executed at high speed.

In this case, when the restoration for one line is completed, the information of the next line stored in the FIFO buffer 112 is returned to the original coded data by the code conversion circuit 105 once, and the line After the initial initialization, each information is obtained again from the encoded data. Thereby, the encoded data of each line can be correctly restored.

FIG. 6 shows another embodiment of the present invention.

In the figure, the same reference numerals as those in FIG. 1 denote the same circuits or the same portions, and the difference is that the FIFO buffer 112 provided in FIG.
6 is newly provided.

With this configuration, when performing the encoding process, each information output from the change point detection circuit 102 is stored in the FIFO buffer 104 via the selector 103. Then, the stored information is input to the code conversion circuit 105 via the selector 116. On the other hand, when performing the decoding process, the code conversion circuit 105 stores each piece of information extracted from the encoded data in the FIFO buffer 104 via the selector 103. Then, the stored information is transmitted to the normal pixel data restoration circuit 113 via the selector 116.
Is input to the code conversion circuit 105 only when the end of the line is detected.

As described above, in this embodiment, one FIFO buffer 104 is shared between the encoding process and the decoding process. As a result, the number of FIFO buffers provided can be reduced, and the apparatus cost can be reduced.

In the above-described embodiment, the MMR method has been described as an example of a coding method in which an EOL code is not inserted. However, the present invention is similarly applied to other coding methods in which an EOL code is not inserted. be able to.

Although a general example of encoding and decoding pixel data has been described, it goes without saying that not only image information but also various types of data can be similarly processed.

[0043]

As described above, according to the present invention, the operation of extracting code information from input coded data and storing it in the buffer memory, and the operation of extracting pixel data based on the stored code information While performing the operation to play at the same time,
When the reproduction of one line is completed, the information of the next line stored in the buffer memory is once returned to the original coded data, and the predetermined initialization of the head of the line is performed.
Since each piece of information is obtained again from the coded data that has been restored, the time required for decoding processing can be reduced even for coded data in which an EOL code is not inserted.

[Brief description of the drawings]

FIG. 1 is a block diagram of an encoding / decoding device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of codes in the MMR system.

FIG. 3 is an operation flowchart of a decoding process.

FIG. 4 is an explanatory diagram of an information path at each time point.

FIG. 5 is an explanatory diagram of each data when the restoration processing is completed for one line.

FIG. 6 is a block diagram of an encoding / decoding device according to another embodiment of the present invention.

FIG. 7 is a flowchart of a conventional processing procedure for decoding MMR coded data.

[Explanation of symbols]

 Reference Signs List 101 pixel data input / output circuit 102 change point detection circuit 103, 108, 116 selector 104, 112 FIFO buffer 105 code conversion circuit 106 P / S conversion circuit 107 coded data input / output circuit 109 S / P conversion circuit 110 shunt register 111 EOL Detection circuit 113 Pixel data restoration circuit 114 Pixel count circuit 115 Control circuit

Claims (3)

(57) [Claims] 1. A change point detecting means for detecting a change point of pixel data inputted one line at a time and outputting each information indicating the change pattern, and converting each piece of information into each code word to each line. Encoding means for generating encoded data of
Decoding means for extracting each codeword from the encoded data input line by line and converting it into corresponding information; and pixel data restoring means for reproducing pixel data of each line based on the converted information. In the processing method of the encoding / decoding device that selectively executes the encoding process and the decoding process while performing a certain initialization at the beginning of each line during the decoding process, A buffer memory for storage; and line end determination means for detecting the end of reproduction of one line by counting the number of pixels of reproduced pixel data. The operation of storing the information obtained from the decoded data by the decoding means in the buffer memory and the operation of reproducing the pixel data by the restoration means based on the stored information are simultaneously performed. On the other hand, when the reproduction of one line is completed, the above information of the next line stored in the buffer memory is once returned to the original coded data by the coding means, and And the decoding unit obtains the information again from the coded data that has been restored. 2. The processing method according to claim 1, wherein the encoded data is generated by an MMR method and has no line end code. 3. A detecting means for detecting a line end code in the encoded data, wherein when the encoded data is generated by the MH method or the MR method, the detection means terminates reproduction of one line. The processing method of the encoding / decoding device according to claim 1, wherein the detection is performed.