JPH01194672A - Picture information decoder - Google Patents

Abstract

PURPOSE:To improve a whole decoding processing speed by using a memory for a referring line equipped to supply the picture information of a referring line to a decoder at a high speed for a buffer between a decoder and a data bus. CONSTITUTION:When the change of the color of a picture element obtained by a referring line buffer A102 is not present, a decoder 101 writes at a high speed the picture information of a single color to a referring line buffer B103. For this reason, the processing of the decoder 101 is not stopped. When the change of the color of the picture element is many at a referring line, the decoder 101 decodes many code data obtained from an input bus interface 104 and the picture information with many changes of the color is written to the referring line buffer B103. In this case, the writing from an output bus interface 105 to a memory 107 is not stopped.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device for decoding encoded image information into image information again, and relates to a relative relationship between colors of pixels of multiple lines at 0%. The present invention relates to an image information decoding device suitable for a device having a line buffer for decoding based on .

[Conventional technology]

In the transmission and filing of image information, the number of images transmitted per unit time and the number of images stored per one storage medium are important performance factors. For this reason, it is common practice to compress the amount of image information before transmission or filing. Typical examples are HTG (Modified Hoffman) encoding and MR (Modified Hoffman) encoding used in facsimile.
MH encoding is a one-dimensional compression method that processes each line of the image to be compressed, and processes the point at which the color of one pixel changes from black to white or from white to black (change point). , and encodes the number of pixels between two changing points. MR encoding is a two-dimensional compression method and generally has a higher compression rate than ME encoding. This method encodes the relative relationship between change points in two vertically adjacent lines. FIG. 4 shows an example of image information, in which the object of encoding is called a coding line, and the line on which the relative relationship is determined on the coding line is called a reference line. In this figure, the change point A401 is assigned the same position as the change point on the reference line, and the change point B4O2 is assigned a position shifted by 1 to the right from the change point on the reference line.

In decoding an MR code, as is clear from the simple explanation of the encoding method above, a coded line is generated from a reference line, and this coded line becomes the next reference line. To achieve this, the decoded image information is written once in memory,
It is read out and used as image information of the reference line. FIG. 2 is an example of a conventional image information decoding device. Decoding device 101
The image information output from the image output FIFO 202,
Output bus interface 105 and data bus 106
is written into the memory 107 through. Once the image information of the reference line is written, it is read out from the memory 1o7 and transferred to the data bus 106. Decoding device 101 through input bus interface 104 and image input FIFO 201
is input to. In this configuration, in order to obtain the image information of the reference line, the data bus 106 is accessed which is slower than the data transfer rate of the internal circuit of the decoding device 101, and waiting time is required before gaining access to the bus, resulting in a decrease in processing speed. there's a possibility that.

On the other hand, as described in Japanese Unexamined Patent Publication No. 55-79564, the decoding device itself is provided with a reference line memory.

There are also some that eliminate bus access to improve processing speed.

On the other hand, in decoding an MR code, encoding is performed using the relative positions of the change points of the reference line and the change points of the encoded line. As shown in the figure, there is almost no processing required in areas where there are no changing points, so high-speed processing is possible; however, in areas where there are changing points, the processing speed decreases, resulting in uneven processing speed. On the other hand, when a bus access is required to write image information to a memory, the waiting time until the bus access right is obtained is not constant. Therefore, the decoding process ends quickly and image information can be output, but the bus usage rate is high and the bus access is forced to wait, or the decoding process takes a long time and the bus becomes empty. 101 and data bus 1
06, and the overall processing speed decreases.

To solve this problem, use memory or FIFO (first-in first-out buffer) as a bus buffer as described in Japanese Patent Application Laid-Open No. 57-61379.
The above inconsistency has been resolved. FIG. 2 is a block diagram of a conventional image information decoding device used in a FIFO pass buffer.

[Problem to be solved by the invention]

Among the above-mentioned conventional technologies, using FIFO as a path buffer can be realized with a smaller circuit configuration than using memory, but FIFO has a small capacity and there is a large gap between the decoding device and the data bus. If there is matching, there is a problem that the difference cannot be absorbed and the overall processing speed decreases.

The object of the present invention is to provide a buffer for absorbing a large mismatch between the decoding device and the data bus by adding a simple circuit, thereby improving the overall decoding processing speed.

[Means to solve the problem]

The above object is achieved by using a reference line memory provided for supplying reference line image information to a decoding device at high speed as a buffer between the decoding device and a data bus.

[Effect]

The decoding device writes the image information of the encoded line being decoded into the reference line memory in order to use it as the next reference line. The image information written in this reference line memory is read out and output to the data bus to operate as a buffer.

The method for reading image information from the reference line memory is 2.
There are different types. When writing the image information of the encoded line to the reference line memory, there is a method of reading only the already written image information and outputting it to the data bus, and when reading the image information from the reference line memory as the reference line. ,1
There is a method of sequentially reading image information for lines and outputting it to a data bus.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 is a block diagram of an image information decoding device used in this embodiment.

The memory 107 stores coded data that is input to the decoding device 101 and image data that is output from the decoding device 101. Before starting processing, only code data is stored.

The data bus 106 serves as a data transfer medium between the memory 107 and the decoding device 101. Although omitted in FIG. 1, code data is stored in the memory 107 before starting processing.
It can also be used to transfer image data to a printer, display, etc. after processing is completed.

The input bus interface 104 is an interface between the decoding device 101 and the data bus 106, and is an interface between the data bus 1
The code data is stored in the memory 10 according to the bus timing of 06.
7, and sends the encoded data to the decoding device 101 according to the processing timing of the decoding device 101.

The decoding device 101 decodes the encoded data obtained from the input bus interface 104, receives the image information of the reference line from the reference line buffer AlO2 or the reference line buffer yB105, calculates the relative position of the reference line from the pixel, and calculates the relative position of the reference line from the pixel. The image information is output to the encoded line data selector 108.

Reference line buffer AlO2 and reference line buffer B1
03 stores image information for each reference line for one line. The two line buffers are a selector 10B for encoded line data and a selector 10 for reference line data.
9, the image information of the reference line is output alternately. That is, when the encoded line data selector 108 selects the reference line buffer B 103 and the reference line data selector 109 selects the reference line buffer AlO2, the decoding device 101 from the reference line buffer AlO2
At the same time, the image information of the reference line is output to the decoding device ICN, and the image information of the encoded line that becomes the next reference line is output to the decoding device ICN.
input to the reference line buffer E 103. Next 1
The selection direction of the encoded line data selector 108 and the reference line data selector 109 is switched for each line process, and the encoded line data selector 108 selects the reference line buffer, (102), and the reference line data selector 109 selects the reference line buffer. When the line buffer B103 is selected, the reference line buffer E i03 outputs the image information of the encoded line input during the previous line processing as a reference line, and the reference line buffer AlO2 inputs the image information of the encoded line.

The bus output selector 110 selects the same line buffer as the encoded line data selector 108, and selects the reference line buffer A 102 f or the reference line buffer B 10.
3, the image information output from the decoding device 101 is sent to the output bus interface 105.

When the image information is set, the output bus interface 105 writes the image data to the memory 107 according to the bus timing of the data bus 106.

With the above configuration, the image information output from the decoding device 101 is always written to the reference line buffer AlO2 or reference line buffer B103, and the image data written to the buffer is transferred to the data bus 106 via the output bus interface 105. Output to.

Hereinafter, it is assumed that the encoded line data selector 108 and the bus output selector 110 select the reference line buffer B103, and the reference line data selector 109 selects the reference line buffer AlO2, and the image information decoding apparatus shown in FIG. Explain the operation.

If there is no change in pixel color in the reference line obtained from the reference line buffer AlO2, the decoding device 101 writes monochrome image information to the reference line buffer B103 at high speed. Although the decoding device 101 outputs image information at a higher speed than the data transfer rate of the data bus 1o6, that is, the reading speed of the reference line buffer B103 of the output bus interface 105, the amount of unread image information in the reference line buffer B103 only increases. The processing of the decoding device 101 does not stop due to failure to output one image information.

On the other hand, if the reference line obtained from the reference line buffer AlO2 has many changes in pixel color, the decoding device 101 decodes a lot of code data obtained from the input bus interface 104 and uses the image information with many changes in one color as the reference line. Write to buffer B103. Since there is a lot of processing, the decoding device 10
1 outputs image information at a lower speed than the data transfer speed of the data bus 1o6, but only the unread image information in the reference line buffer B 103 decreases, and there is no more image information to be output, and the output bus interface 105 Writing to memory 107 never stops.

FIG. 3 shows the reference line buffer A 102 shown in FIG.

Reference line buffer J103. Selector 108 for encoded data. 2 is a detailed block diagram of a reference line data selector 109 and a bus output selector 110. FIG.

The reference line buffer A layer memory 601 stores encoded line data using the signal from the buffer A address selector 606 as an address when the signal from the memory write pulse selector 303 is "1°."

The signal from the pulse selector 303 including memo 178 is @0
', the reference line data selector 10 uses the signal from the buffer A address selector 306 as an address.
9 and outputs the stored data to the bus output selector 110.

The reference line buffer B memory 302 operates similarly to the reference line buffer A layer memory 301.

The memory write pulse selector 303 selects either the reference line buffer A layer memory 301 or the reference line buffer B memory 3.
02 to which the encoded line data will be written. Normal memory devices do not store input data when applied to it.

This memory write pulse selector 3 is used to store when a write pulse is applied while input data is not applied.
03 functions as the encoded line data selector 108 in FIG.

The reference line counter 304 outputs the same address to both the reference line buffer A layer memory 301 and the reference line buffer B memory 302 for writing encoded line data and reading reference line data. In order to calculate the relative position of reference line data and encoded line data, pixels at the same position are read and written, so the same address is given.

The bus output counter 305 outputs an address to either the reference line buffer A layer memory 301 or the reference line buffer B memory 302 in order to read the image output data. □ The comparator 308 is for monitoring the magnitude relationship between the two addresses so that the address of the bus output counter 305 does not precede the address of the reference line counter 504. If the address of the bus output counter 305 is smaller than the address of the reference line counter 504, there remains image data to be output, so
However, if both addresses are equal, there is no image data to be output, so output to the data bus 106 is stopped.

The buffer A address selector 306 selects whether the address of the reference line buffer A layer memory 301 is the reference line counter 504 or the bus output counter 305. When reading reference line data from the reference line buffer A layer memory 301, the reference line counter 604 is always selected. - On the other hand, when writing encoded line data, select the reference line counter 304 only while the memory write pulse is "1", and select the bus output counter 305 while the memory write pulse is "0°". .

Address selector 507 for buffer B operates in the same manner as address selector 306 for buffer A.

The operation of the configuration shown in FIG. 3 will be explained below. Please refer.

When reading reference line data from the in-buffer A memory 301, the memory write pulse selector 303
The bus output selector 110 selects the reference line buffer B memory 302, and the reference line data selector 1 selects the reference line buffer B memory 302.
09 selects the in-buffer A memory 301 to be examined. Further, the buffer A address selector 306 selects the reference line counter 304, and the buffer B address selector 307 selects the reference line counter 304 and the bus output counter 305 according to the signal from the memory write pulse selector 303.

Reference line buffer B memory 302 serves as a buffer for outputting encoded line data as image output data. Memory write pulse selector 3030 input is °1
When the temperature reaches .degree., the memory write pulse of the reference line buffer B memory 302 becomes "1".

As a result, the value of the reference line counter 304 passes through the buffer B address selector 607 and is given to the reference line buffer B memory 302, and using this as an address, the value of the encoded line data is transferred to the reference line buffer B memory 302. written. Then, at the timing when this memory write pulse reaches “1°,” the reference line buffer A
Since the reference line data is read from the address given by the reference line counter 304 of the layer memory 301, the reference line counter 304 is then counted up.

When the input of the memory write pulse selector 303 becomes 0"K, the memory write pulse of the reference line buffer B memory '502 also becomes "0". As a result, the value of the output counter 305 changes to
7 and is applied to the reference line buffer B memory 602, and the contents of the reference line buffer B memory 302 are read out using this as an address. This read value passes through the path output selector 110 and becomes image output data. here.

A comparator 608 compares the value of the reference line counter 304 and the value of the path output counter 605, and if the value of the bus output counter is small, an unoutput pixel residual signal is output.

When this signal is output, it is taken into the image output booter output bus interface 105.

The data bus 106 is accessed and the bus output counter 605 is counted up. Conversely, if no signal is output, no processing is performed.

As explained above, according to this embodiment, the reference line buffer can be made into an output buffer with a data amount of one line by adding simple circuits such as a nine-sided counter, a comparator, a selector, etc. Can absorb speed differences.

〔Effect of the invention〕

According to the present invention, it is possible to provide an image output buffer for one line without adding a large amount of new circuitry or memory, which has the effect of improving the speed of the entire decoding process.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image information decoding device used in an embodiment of the present invention, FIG. 2 is a block diagram of a conventional image information decoding device, and FIG. 3 is a buffer section used in an embodiment of the present invention. FIG. 4 is a block diagram showing an example of image information. 101......Decoding device 102...
・・・・・・Reference line buffer AlO3...
......Reference line buffer B108...
......Selector 10 for encoded line data
9...Reference line data selector 110...Buse output selector Agent Patent attorney Katsutoshi Ogawa 1st Zuto? Figure IQ Wa

Claims (1)

[Claims] 1. An image information decoding device equipped with a reference line buffer, characterized in that the reference line buffer is also used as an image output buffer.