JPH02126773A - Mr encoder - Google Patents

Abstract

PURPOSE:To realize LSI of a part other than a code memory by supervising whether or not the encoding line by one line read from an image memory all consists of the picture elements having the same value, and outputting information to indicate it. CONSTITUTION:The title device consists of an image memory 101, an encoding line change point detector 103, a reference line change point detector 104, an MR encoder 105, an encoding line supervising device 106, and data buses 110 to 116 to connect respective blocks. Whether or not the encoding line by one line read from the image memory 110 by the encoding line change point detector 103 all consists of the picture elements having the same value is supervised, and the information to indicate whether or not the encoding line all consists of the picture elements having the same value is outputted. Thus, since a control is easy, a part other than the memory can be easily made into a large scale integrated circuit(LSI).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a binary image encoding device, and particularly to an MR encoding device.

[Conventional technology]

In recent years, the importance of information has been increasing due to the advanced informationization of society. Along with this, the need to communicate more information faster is increasing. Under these circumstances, in the field of image transmission factors <'), C
The CITT (International Telegraph and Telephone Intercommunication Commission) is working to standardize image encoding methods for more efficient image communication, and currently the MH method and the MR method have been established as standards.

The MH method (one-dimensional encoding method) focuses on the horizontal statistical properties of an image and encodes the white or black run length of each line. At this time, Huffman encoding is used to assign short codes to frequently occurring runs and long codes to infrequently occurring runs. As a result, C:
CITT test chart (A4 size, 1728x237
6 dots) is reduced by approximately 1/
The amount of information can be compressed to 8.

The MR method (two-dimensional encoding method) also focuses on the statistical properties of the image in the vertical direction, and changes the pixels on the line to be encoded (encoding line) from white to black or from black to white. The relative positional relationship between a changing point (change point) and a change point on the line immediately above it (reference line) is encoded. As a result, in the MR method, the previous CCI T'
i'' test chart can be compressed to about 1714 pieces of information.

By the way, in the MH method, encoding processing can be realized by simply reading out the image information stored on the image memory once.

On the other hand, in the Ml (1 method), each line must be read twice in order to read the encoded line and the reference line. Therefore, the MR method requires twice as many memory accesses as the MH method.

The fact that the number of memory accesses is twice as many as in the Ml method has the drawback that the encoding processing time itself cannot be faster than this memory access time.

Furthermore, the fact that there are many accesses to the image memory means that if this image memory is shared by several devices, there is a high probability that the encoder will access the memory and leave other memory locations in the queue. However, it has the disadvantage of reducing the performance of the entire system.

For such situations, M with built-in line buffer
There is an R encoding device.

An example of this is shown in FIG. The M RF3 encoding device shown in FIG. 4 includes an image memory 401. 402° Encoding line change point detector 403. Reference line change point detector 404. MR encoder 405. Line buffer 406.

The operation of this M-base encoding device is as follows.

The encoded line change point detector 403 is connected to the image memory 40.
The encoded line data is read from 1 to 1, the position where the pixel value changes (change point) is detected, and the change point address is output to the MR encoder 405. Further, the read data is output to the line buffer 406 as is.

The line buffer 406 has a capacity to store at least two lines of image data, and stores the image data of the encoded line sent from the encoded line change point detector 403 line by line.

Further, the line buffer 406 sequentially outputs one line of image data stored during encoding of the previous line to the reference line change point detector 404 in accordance with a request from the reference line change point detector 404 .

Reference line change point detector 404 is line buffer 406
Request image data from the liner.

The data output from the filter 406 is regarded as a reference line, the change point of the line is detected, and the change point address is output to the MR encoder 405.

MR encoder 405 is encoded line change point detector 403
An MR code is generated from the change point address output from the reference line change point detector 404 and the data is written into the code memory 402.

Therefore, in such an MR encoding device, the number of data accesses to the image memory required for encoding can be made the same as in the MH method.

[Problem to be solved by the invention]

However, the above-mentioned conventional encoding device incorporating a line buffer has the drawback that a large capacity memory must be prepared in order to completely store one line of data. For example, when scanning 1++s+ with a resolution of 16 lines, an A4 size image requires a line buffer of 3456 bits per line.
This becomes a major obstacle when converting parts other than the image memory and code memory of such an encoding device into an LSI.

[Means to solve the problem]

The MR encoding device of the present invention comprises: an image memory for storing binary image information; a code memory for storing codes encoded by a modified read (hereinafter abbreviated as MR) encoding method; an encoded line change point detector that reads an encoded line from the image memory, detects a change point, and outputs an address of the detected change point; and an encoded line change point detector that reads a reference line from the image memory, detects a change point, and detects the change point. a reference line change point detector that outputs the address of the change point of the encoded line; a change point address of the encoded line output from the encoded line change point detector; and a reference line change point address output from the reference line change point detector; In an MR encoding device including an MR encoder that generates an MR code of a coded line from a change point address and writes it into the code memory, the coded line change point detector reads out an MR code from the image memory. A coding line monitor that monitors whether or not all coding lines are composed of pixels with the same value, and outputs information indicating whether the coding line is composed of pixels with the same value. It has the following.

[Example 1] The present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of the present invention. The present invention provides image memory 101. Code memory 102° Encoding line change point detector 103. Reference line change point detector 104
．． MB, encoder 105. It is composed of an encoded line monitor 106 and data buses 110 to 116 connecting each block.

Further, the internal configuration of the encoded line monitor 106 in the first embodiment is shown in FIG. The encoded line monitor 106 of the first embodiment is an OR circuit 202 and a 1-bit register 203.
Consisted of.

The encoding process by the MR encoding device of this embodiment will be explained between stations.

The encoded line change point detector 103 is connected to the image memory 1
The image data of the encoded line is sequentially read from 01 and the change point is detected. The position of the detected change point is then output to the MR encoder 105 as a change point address. The change point address indicates the position of a pixel that has changed, and the first pixel of the line is the address l, and the address of the last pixel of the line is the number of pixels in one line. Furthermore, when reading image data from the image memory 101, it is divided into fixed length data. In this embodiment, it is assumed that reading is performed in units of 8 bits.

Similarly to the encoded line change point detector 103, the reference line change point detector 104 also reads the image information of the reference line from the image memory 101, detects the change point, and outputs the change point address to the MR encoder 105. do. The data length read from the image memory 101 is 8 bits, similar to the encoded line change point detector 103.

The MR encoder 105 has two change point detectors 103゜10.
An MR code is generated from the change point address of the encoded line and the reference line outputted from 4, and is sequentially written into the code memory 102.

The above is the conventional MR encoding process.

Next, a case in which the encoded line monitor 106 is included will be explained.

The encoded line change point detector 103 reads the encoded line 8 bits at a time from the image memory 101 as described above, and also outputs the read data as is to the encoded line monitor 106.

The output data is input to the zero filter circuit 202 in the encoded line monitor via the data bus 116 of FIG. O
The R1 circuit 202 outputs OR logic of 9-pit data. The output signal is latched into a 1-bit register 203. The data held in this 1-bit register 203 also serves as an input to the 0-ordin circuit 202.

In other words, the encoded line monitor 106 performs OR logic on all pixels of the encoded line, and when reading of data for one line is completed, the register 203 output on the signal line 117 If the line is O, it means that the line was composed of all values of "0".In other words, the encoded line was a white line.

The reference line change point detector 104 receives the signal output on the signal line 117 from the encoded line monitor 106 as soon as the encoding process of the l line is started. After this operation is completed, each change point detector 103, 104 reads data from the image memory 101. Here, if the signal 117 received by the reference line change point detector 104 is 0, the reference line change point detector 104 determines that the reference line to be read from now is a white line, and the 1 line code Reading from the image memory 101 is not performed during the conversion process. Then, a value corresponding to the number of pixels in the l line is outputted to the MR encoder 105 as a change point address, and the process is terminated.

Therefore, in this embodiment, it is monitored whether the encoded line is a white line, and if it is a white line, it is determined that the reference line is a white line and the reference line is changed when encoding the next line. The number of pixels in the l line is output as a change point address, and encoding processing is performed without reading the reference line from the image memory. If the line is not a white line, the normal MR encoding process described above is performed.

[Example 2] Next, Example 2 will be described with reference to the drawings.

The basic configuration of this embodiment is the same as that of the first embodiment, as shown in FIG. 1, but the difference from the first embodiment is the encoded line monitor 106. FIG. 3 shows the internal configuration of the encoded line monitor 106 in the second embodiment. The encoded line monitor 106 of the second embodiment includes an OB circuit 302. AND circuit 3
03, 2, and 304.

Encoding processing by the MR encoding device of this embodiment will be described.

In this embodiment as well, the normal Ml encoding process is the same as that of the MR encoding apparatus of the first embodiment described above, and a description thereof will be omitted.

A case in which the encoded line monitor 106 is included will be explained.

In this embodiment, as in the first embodiment, the encoded line change point detector 103 reads nine data from the image memory 101 and outputs the data as is to the encoded line monitor 106. The output data is input to an OR circuit 302 and an AND circuit 303 in the encoded line monitor via the data bus 116 shown in FIG. OR circuit 302 and AND circuit 3
03 outputs OR logic and AND logic of 9-bit data to signal lines 311 and 312, respectively. The two signals output on the signal lines 311 and 312 are 2-bit, register 3.
It is latched to 04. Also, this 2-bit register 304
The data held by each is also input to the corresponding logic circuit.

In other words, the encoded line monitor 106 outputs the results of OR logic and AND logic for all the pixels of the encoded line, and when the reading of data for one line is completed, the signal line 117A is output. The signal output to
If so, it indicates that the encoded line was a white line,
Further, if the signal output on the signal line 117B is 1, it indicates that the encoded line is a black line. The signal line 117 in FIG. 1 is composed of 2 bits, and if the value is OO, it is a white line, and if the value is 11, it is a black line.

The reference line change point detector 104 receives the 2-bit signal output on the signal line 117 from the encoded line monitor 106 as soon as the encoding process for one line is started. After this operation is completed, each change point detector 103, 10
4 reads data from the image memory 101.

Here, if the signal received by the reference line change point detector 104 is 00, the reference line change point detector 104
determines that the reference line to be read from now is a white line, and does not read from the image memo IJ 101 in the one-line encoding process. Then, a value corresponding to the number of pixels in one line is outputted to the MR encoder 105 as a change point address, and the process ends.

Further, if the reference line change point detector 104 receives a good signal of 11, the reference line change point detector 104 determines that the reference line to be read from now is a black line, and in the one line encoding process. image memory 10
Do not read from 1. Then, the MR encoder 1 uses values corresponding to the number of pixels of 0 and 1 line as change point addresses.
05 and ends the process.

Therefore, in this embodiment, it is monitored whether the encoded line is a white line or a black line, and if it is a white line, it is determined that the reference line is a white line when encoding the next line. The number of pixels in one line is output as a change point address of the reference line, and encoding processing is performed without reading out the reference line from the image memory. If it is a dead center line, when encoding the next line, it is determined that the reference line is a black line, and the two change point addresses of the number of pixels of 0 and 1 line are used as the change point address of the reference line. is output and the encoding process is performed without reading the reference line from the image memory. If the line is not a white line or a black line, the normal MR encoding process described above is performed.

In the above two embodiments, only MR type encoding has been described, but it is clear that the present invention is also applicable to MR type decoding.

〔Effect of the invention〕

As explained above, the present invention monitors whether an encoded line is a white line or a black line, and if the monitoring result shows that it is a white line or a black line, a reference line is used when encoding the next line. There is no need to read from image memory. Furthermore, in such a case, the change point address of the reference line can be easily generated.

This effect does not occur if there is even one change point on the line, but as mentioned above, in binary images such as document images, the proportion of white lines is large (in images with inverted pixel values, black lines occupy a large proportion). (The line occupies a large proportion.)

Therefore, when encoding the entire image, the number of memory accesses can be sufficiently reduced without providing a line buffer.

Furthermore, as is clear from the two embodiments of the present invention, compared to line buffers, hardware can be significantly reduced and control is easier, making it easier to incorporate parts other than memory into LSI. , the entire device can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of the present invention, FIG. 2 is an internal configuration diagram of the encoded line monitor in Embodiment 1 of the present invention, and FIG.
FIG. 4 is a diagram showing the internal configuration of a coding line monitor according to a second embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of a conventional example. 101--°-Image memory, 102...Code memory, 103...Encoding line change point detector, 104...Reference line change point detector, 1
05...MR encoder, 106... Encoding line monitor, 110-117... Data bus. Agent: Patent Attorney Susumu Uchihara

Claims (1)

[Claims] An image memory for storing binary image information, and an MR
a code memory for storing a code encoded by the encoding method; and a coded line change point detector that reads the coded line from the image memory, detects a change point, and outputs the address of the detected change point. a reference line change point detector that reads a reference line from the image memory, detects a change point, and outputs an address of the detected change point; and a coded line change point detector output from the encoded line change point detector. An MR encoding device comprising an MR encoder that generates an MR code of an encoded line from a change point address and a reference line change point address output from the reference line change point detector and writes it into the code memory, The encoded line change point detector monitors whether one encoded line read from the image memory is composed of pixels having the same value, and determines whether the encoded line is composed of pixels having the same value. 1. An MR encoding device characterized by having an encoding line monitor that outputs information indicating whether or not the MR encoding device has been configured.