JP2001078042A - Picture expansion processing device and picture compression processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a picture expansion processing device which correctly expands two-dimensionally encoded compressed data and a picture compression processing device which correctly performs two-dimensional encoding processing. SOLUTION: In a two-dimensional encoding/decoding processing constitution where one-line data are stored in a line buffer 4 as reference data and data are encoded or decoded by comparison with stored data, reference data are stored in the line buffer in a run length data form if the side of run length data constituting reference data doesn't exceed that of the line buffer 4, but they are stored in a bit map data form if the size of run length data is larger than that of the line buffer. Since the selective constitution for data stored in the line buffer is adopted, accurate reference data are stored, and accurate two-dimensional encoding processing and decoding processing are possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image decompression processing device and an image compression processing device. More specifically, for example, an image decompression processing device used when decompressing data that has been two-dimensionally coded and compressed using MR compression or the like into bitmap data in real time and outputting it to a printer or the like, and two-dimensional coded compression And an image compression processing apparatus that executes the processing.

[0002]

2. Description of the Related Art In recent years, the quality of a printer has not been improved, and the amount of image data used for printing has been increasing. In order to process these enormous amounts of image data with limited computer resources, high-speed image data compression technology and image data expansion technology in real time are indispensable. Devices and image compression processing devices are being developed.

[0003] Among image data handled by a printer, particularly, bitmap data has a high correlation between adjacent pixels. Therefore, a modified read code (hereinafter referred to as MR code) and a modified modified read code (hereinafter referred to as MMR code) are used. In many cases, data is compressed using a dimensional encoding method. In this case, the data processing device is realized by, for example, a compression / decompression processor used in a facsimile machine.

[0004] However, facsimile machines are usually 3
With a resolution of only about 00 dots / inch (hereinafter abbreviated as dpi), the processing capacity of a facsimile compression / expansion processor is not sufficient for real-time expansion of 2D encoded compressed data in a high-speed, high-quality printer. It may be insufficient.

[0005] For this reason, Japanese Patent Application Laid-Open No. H05-205550 discloses an example of speeding up the compression / expansion processing of the two-dimensionally coded compressed data.
41809 is disclosed. This will be described below.
When compressing or decompressing two-dimensional encoded data, the data is decompressed into run-length data, which is a form of one-dimensional encoded compression, instead of being directly expanded into a bitmap. If necessary, the run-length data may be expanded to bitmap data thereafter. When decompressing two-dimensional encoded data, it is necessary to hold the previous scan line as a reference scan line, but the information required for decompression is position information of a pixel change point, and Length data list format (hereafter called run list)
It is possible to obtain the change point of the pixel at higher speed.
Further, if the reference scan line is realized using the run list format, the number of shifts can be reduced when the two-dimensional encoded compressed data is expanded, as compared with the case where the bit map data format is used. As a result, the processing speed of the decompression device can be increased and the configuration can be simplified.

[0006]

However, when the bitmap data to be encoded expresses a complicated image in which black and white are mixed, a large number of runs occur in one scan line. Generally, when a decompression device that requires real-time processing is implemented by hardware, a reference scan line is held in a register. Therefore, when the reference scan line is realized by the run list, depending on the bitmap data to be compressed, there is a possibility that all runs for one scan line cannot be included in the finite-scale run list. At this time, there is a problem that the image decompression processing device cannot decompress this bitmap data correctly.

The present invention has been made in consideration of the above points. When data of one scan line cannot be stored in a line buffer in a run list format, the data is stored in a bit map format instead of a run list format. Accordingly, it is an object of the present invention to provide an image decompression processing device that correctly decompresses two-dimensionally encoded and compressed data for image data of a certain size or less.

Further, when data of one scan line cannot be stored in the line buffer in the run list format,
It is an object of the present invention to provide an image compression processing device that realizes high-precision compression processing by storing data in a bitmap format instead of a runlist format.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an image decompression processing apparatus and an image compression processing apparatus made to achieve the above object.

An image decompression processing apparatus according to the present invention is adapted to decompress compressed data compressed by two-dimensional encoding into bitmap data.
Storage means for temporarily storing one-dimensionally encoded compressed data, first converting means for executing a process of converting two-dimensionally encoded compressed data stored in the storing means into run-length data, and the first converting means A conversion means for converting the run-length data generated in step 2 into bitmap data, a line buffer for holding data of one scan line as reference scan line data, and a line buffer generated in the first conversion means. Control for selecting one of the run-length data format consisting of the run-length data obtained and the bitmap data format generated by the second conversion means and writing the data for one scan line to the line buffer. And line buffer control means for performing the processing, wherein the first conversion means The conversion processing from the two-dimensional encoded compressed data to the run-length data is performed by referring to the data for one scan line stored in the buffer, and the reference scan line data stored in the line buffer is converted to bitmap data. It is characterized in that it has a configuration for executing a process of converting bitmap data into run-length data when the format is the format.

Further, in the image decompression processing device according to the present invention, the line buffer control means may determine a data size of one scan line in the run-length data format generated by the first conversion means and a line buffer size. Executing a comparison process, and as a result of the comparison process,
When the data size of one scan line in the run-length data format generated by the conversion unit exceeds the size of the line buffer, the bitmap data in the bitmap data format generated by the second conversion unit is If the data size of one scan line in the run-length data format generated by the first conversion means does not exceed the size of the line buffer as a result of the comparison processing, the first conversion means Wherein the process for writing the run-length data generated in step (1) to the line buffer is performed.

Further, in the image decompression processing apparatus according to the present invention, the line buffer control means measures the number of runs generated per scan line, thereby obtaining the run-length data generated by the first conversion means. The data amount for one scan line in the format is measured, and the data format to be stored in the line buffer is determined.

Further, in the image decompression processing device according to the present invention, the line buffer control means includes an identification flag indicating whether a data format stored in the line buffer is a run-length data format or a bitmap data format. It is characterized in that it is configured to be set at the time of storing data in the line buffer.

Further, in the image decompression processing device according to the present invention, when the first conversion means detects that the data stored in the line buffer is in a bitmap data format based on the identification flag, It is characterized in that it has a configuration for executing a process of converting bitmap data stored in the line buffer into run-length data.

Further, in the image decompression processing device of the present invention, the second conversion means has a bitmap data storage for temporarily holding the bitmap data generated by the second conversion means. And

Further, in the image decompression processing apparatus according to the present invention, the two-dimensional encoded compressed data is a modified read code.

Further, in the image decompression processing apparatus according to the present invention, the two-dimensional encoded compressed data is a modified modified read code.

Further, the image compression processing device of the present invention
In an image compression processing apparatus that performs compression of image data by two-dimensional encoding to generate two-dimensional encoded compressed data,
A line buffer for holding one scan line of data as reference scan line data, and selecting one of a run length data format consisting of run length data or a bit map data format to store the data of one scan line. A line buffer control unit that controls writing to the line buffer; and executes two-dimensional encoding processing with reference to data for one scan line stored in the line buffer; Encoding means for converting bitmap data into run-length data when the scan line data is in bitmap data format.

Further, in the image compression processing apparatus according to the present invention, the line buffer control means compares the data size of one scan line in the run-length data format to be stored in the line buffer with the size of the line buffer. If the data size of one scan line in the run-length data format to be stored in the line buffer exceeds the size of the line buffer as a result of the comparison processing, the run-length data to be stored in the line buffer is deleted. The bitmap data generated by conversion to the bitmap data format is written to the line buffer, and as a result of the comparison processing, the data size of one scan line in the run length data format to be stored in the line buffer is set to the line buffer. If it does not exceed the size of It characterized by having a configuration that executes a process of writing to the line buffer the run-length data stored scheduled Nbaffa.

Further, in the image compression processing apparatus according to the present invention, the line buffer control means measures the number of runs generated per one scan line, thereby obtaining one of the run-length data formats to be stored in the line buffer. It is characterized in that a data amount for a scan line is measured and a data format to be stored in the line buffer is determined.

Further, in the image compression processing apparatus according to the present invention, the line buffer control means includes an identification flag indicating whether a data format stored in the line buffer is a run-length data format or a bitmap data format. It is characterized in that it is configured to be set at the time of storing data in the line buffer.

Further, in the image compression processing apparatus according to the present invention, when the encoding processing means detects that the data stored in the line buffer is in a bitmap data format based on the identification flag, It is characterized by having a configuration for executing a process of converting bitmap data stored in a line buffer into run-length data.

Further, in the image compression processing apparatus according to the present invention, the two-dimensional encoded compressed data is a modified read code.

Further, in the image compression processing apparatus according to the present invention, the two-dimensional encoded compressed data is a modified modified read code.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an image decompression processing device and an image compression processing device according to the present invention will be described below with reference to the drawings.

[0026]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an image decompression processing apparatus according to the present invention. In FIG. 1, an image decompression processing device includes a storage unit 1, a first conversion unit 2, a second conversion unit 3,
It comprises a line buffer 4 and line buffer control means 5. The storage unit 1 is for temporarily storing compressed data that has been two-dimensionally coded and compressed and transmitted via a network I / F (not shown).

The first conversion means 2 takes out the compressed data from the storage means 1 and converts the two-dimensionally encoded compressed data into a run-length data format while referring to information in a line buffer 4 described later. It is.

The second conversion means 3 acquires run-length data from the first conversion means 2 and converts it into a bitmap.

The line buffer 4 holds reference scan line information required for the first conversion means 2 to convert the compressed data into the run-length data format.

FIG. 2 shows a format of the information of the reference scan line held in the line buffer 4. Line buffer 4
The reference scan line held in the table is, as shown in FIG. 2A, a run list format using a plurality of continuous black and white block lengths (referred to as run lengths). As shown in FIG. 2B, the data is stored in a bitmap data format represented as a white and black bitmap. W4 shown in the run list format line buffer of FIG.
Indicates that there are 4 white pixels, and B7 indicates that there are 7 continuous black pixels.
In the line buffer shown in FIG. 2B, 0 indicates a white pixel and 1 indicates a black pixel.

The line buffer control means 5 uses which data format in the line buffer 4, that is, either the run list system shown in FIG. 2A or the bit map system shown in FIG. It controls whether data is stored in the line buffer 4. The data format to be stored is determined based on the result of calculating the data size of the run length format, that is, the run list format in the first conversion means 2 and comparing the calculated data size with the size of the line buffer 4. In other words, if the data size in the run-length format does not exceed the size of the line buffer 4, the data is stored in the run list format shown in FIG. 2A, and if the data size in the run-length format exceeds the size of the line buffer 4, The bitmap data is stored in the line buffer 4 using the bitmap method.

Here, before describing the flow of data processing in the image decompression processing device of the first embodiment, the format of two-dimensional encoding will be described. Here, the outlines of the MH coding method, the MR coding method, and the MMR coding method will be particularly described.

1) MH coding method Although the MH coding method is not two-dimensional coding but one-dimensional coding, it is a coding method which is the basis of the MR coding method and the MMR coding method described later. Shown in In the MH encoding method, data of all scan lines is one-dimensionally encoded and compressed. As shown in FIG. 3, the compressed data of one scan line is added at the beginning of EOL (End Of).
Line) code and a data code following the code. After the last line of one page, an RTC code composed of six consecutive EOL codes is added.

Here, the EOL code is “00000000”.
0001 "is a 12-bit code. If the number of code bits in one scan line is shorter than a predetermined bit length T, a variable length “0” is added after the data code to satisfy the condition of the minimum code bit number.

FIG. 4 shows data codes in MH coding. The data code is a variable length code indicating a white or black run length, and white runs and black runs alternately occur. It should be noted that the head of the scan line starts from a white run, and when the head pixel is black, a code indicating a white 0 pixel is used. When the run length is 63 or less, one terminating code is used as the data code. When the run length is 64 or more, a makeup code representing a quotient obtained by dividing the run length by 64 and a terminating code representing a remainder of 64 of the run length are used. FIGS. 5 to 7 show the makeup code and the terminating code.

2) MR encoding method In the MR encoding method, one or three continuous scan lines are two-dimensionally encoded and compressed after one scan line is one-dimensionally encoded and compressed. In two-dimensional encoding,
With reference to the scan line immediately before the scan line currently being encoded, the positional relationship between the reference scan line and the changed pixel (the pixel that changes from black to white or from white to black) on the encoded scan line is encoded. In coding, the following changed pixels are defined.

A0: starting change pixel of the coded scan line a1: first change pixel on the coded scan line to the right of a0 a2: first change pixel on the coded scan line to the right of a1 b1: reference scan line Of the above change pixels, a0
A pixel to the right of the opposite color to a0 b2: The first changed pixel to the right of b1 on the reference scan line

Then, one of the following three encoding modes is selected according to the positional relationship between these changed pixels. This is shown in FIG.

(1) Pass mode When b2 is on the left side of a1, the pass mode is set. In this case, it is encoded into "0001" as shown in FIG.
After encoding, a new a0 is set immediately below b2.

(2) Vertical mode When the distance between a1 and b1 is within 3 pixels, the mode is the vertical mode. According to the relative distance between a1 and b1, V0, VR1, V
R2, VR3, VL1, VL2, and VL3 are encoded into one of seven codes. Note that VRn means that a2 is to the right of n pixels of a1, and VLn is that a2 is n pixels of a1.
It means that it is to the left of the pixel. After encoding, a new a0 is set at the position of a1.

(3) Horizontal mode When the distance between a1 and b1 is larger than 3 pixels, the horizontal mode is set. In the case of the horizontal mode, the distance and the color between a0 and a1 and the distance and the color between a1 and a2 are represented by MH codes after "001". After the encoding, a new a0 is set at the position of a2.

In MR coding, one-dimensional coding and 2
Since the dimensional coding is mixed, a tag bit is provided after the EOL code so that it is possible to identify whether the subsequent scan line is coded by one-dimensional coding or two-dimensional coding. .

3) MMR encoding method In MMR encoding, all scan lines are two-dimensionally encoded and compressed. To encode the first scan line, a virtual all-white line is set as a reference scan line. After the last line of one page, two EOL codes are successively added as the RTC code, and then “0” is added so that the number of bits of the code data for one page becomes an 8-bit boundary.

Next, details of each module in the image decompression processing device of the first embodiment will be described.

First, the first conversion means 2 in the configuration shown in FIG. 1 will be described. FIG. 10 shows a detailed configuration of the first conversion means 2. As shown in FIG. 10, the first conversion unit 2 includes a Huffman decoding unit 21, a Huffman table 22, an edge cutting unit 23, and a two-dimensional decoding unit 24.
And a run length data storage unit 25.

The Huffman decoding section 21 extracts the MR compressed data stored in the storage means 1 and outputs the extracted MR data.
This is converted to an MR code based on the compressed data.
Here, the MR code is a white and black run length, or a horizontal mode, a vertical mode, and a pass mode (see FIG. 8).
Is constituted by a fixed-length code for indicating

When the MR code is converted from the MR compressed data, a matching code is cut out with reference to the Huffman table 22. Here, the Huffman table 22 stores the tables shown in FIGS. 5 to 7 and FIG. 9, and the Huffman decoding unit 21 extracts a matching code by performing reverse lookup of the table.

The edge cutting section 23 is used only when the data stored in the line buffer 4 is in a bitmap format. The edge cutting unit 23 scans the line buffer 4 from the left end, detects a pixel change point, and outputs a run length. That is, conversion processing from a bitmap format to a run-length data format is performed.

The two-dimensional decoding unit 24 includes the Huffman decoding unit 21
Based on the MR code output from the Huffman decoding unit 21 and the run length data obtained from the edge cutout unit 23 or the line buffer 4, the MR code output from the Huffman decoding unit 21 is converted into run length data. The result is stored in the run-length data storage unit 2 in scan line units.
5 is stored. The processing flow will be described below.

The two-dimensional decoding unit 24 reads the flag of the line buffer 4, that is, the flag indicating whether the data stored in the line buffer 4 is run-length data or bitmap data, and reads the flag stored in the line buffer 4. It is determined whether the scan line information is run-length data or bitmap data.

When the reference scan line information stored in the line buffer 4 is bitmap data, the two-dimensional decoding unit 24 converts the run length data from the bitmap format of the reference scanline executed in the edge cutout unit 23. The run-length data of the reference scan line obtained as a result of the format conversion processing is received via the edge cutout unit 23.

When the reference scan line information stored in the line buffer 4 is run-length data, the two-dimensional decoding unit 24 directly requests the line buffer 4 to extract the run-length data.

Next, the two-dimensional decoding unit 24 executes decoding of the MR code cut out by the Huffman decoding unit 21 with reference to the read reference run length data as the read reference scan line information, and executes the run length. Output data.

The output processing of run-length data for each MR code will be described below. In the following formula, run
Is the output run length, and p_run (n) is the n-th run length of the reference scan line.

(1) Pass mode, that is, output processing of run-length data when there is a correspondence between a reference scan line and an encoded scan line as shown in FIG.

[0056]

(Equation 1)

Expression (1) is a case where the color of the run to be output next is the same as the color of the first run of the reference scan line, and expression (2) is a case where the color is different.

2) Output processing of run-length data in the vertical mode, that is, when there is a correspondence between a reference scan line and an encoded scan line as shown in FIG.

[0059]

(Equation 2)

Expression (3) is the case where the color of the run to be output next and the color of the first run of the reference scan line are the same, and Expression (4) is the case where the color is different. Note that the dist uses the numerical values shown in [Table 1].

[0061]

[Table 1]

3) Horizontal Mode In the horizontal mode, the two MR codes following "001" are run-length data as shown in FIG. 9, and are expanded and output.

Finally, the two-dimensional decoding unit 24 updates the run list of the line buffer 4 or the edge cutting unit 23. Here, the update process will be described for each MR code.

1) Pass Mode If the output run color is the same as the first run color of the reference scan line, the first two runs are deleted from the reference scan line run list. If the color of the run is different,
Delete the first three runs from the run list.

2) Vertical Mode (VL) When the output run color is the same as the head run color of the reference scan line, the head run length of the reference scan line is changed to the absolute value of dist. If the colors of the runs are different, the first run of the reference scan line is deleted, and the run length of the second run is changed to the absolute value of dist.

3) Vertical mode (V0) When the output run color is the same as the head run color of the reference scan line, the head run of the reference scan line is deleted. If the colors of the runs are different, the first and second run lengths are changed to the absolute value of dist.

4) Vertical Mode (VR) When the output run color is the same as the first run color of the reference scan line, the first run of the reference scan line is deleted, and the run length of the second run is changed. Decrease by the absolute value of dist. If the colors of the runs are different, the head of the reference scan line and the second run are deleted, and the run length of the third run is reduced by the absolute value of dist.

5) Horizontal mode Run 2 output from the run list of the reference scan line
Delete or change one total length. That is, if the run length of the output run is 7, 3 and the run length of the run list of the reference scan line is 3, 4, 5 from the beginning, the run of run length 3, 4 is deleted, and the run of 5 is Change to 3.

The run length data storage unit 25 stores the run length data and notifies the line buffer control means 5 of the size of the run length data. In addition, according to the requests from the line buffer control means 5 and the second conversion means 3, it outputs run-length data to these modules.

Next, the line buffer control means 5 will be described. FIG. 11 shows the configuration of the line buffer control means 5. The line buffer control unit 5 includes a data format determination unit 51, a data acquisition unit 52, and a data writing unit 53.

The data format judging section 51 obtains the size of the run-length data from the first conversion means 2 (see FIGS. 1 and 10), compares it with the size of the line buffer, and stores it in the line buffer 4. Determine the data format to use when doing Here, the data format used is a run-length format or a bitmap format as shown in FIG. The data format determined by the data format determination unit 51 is notified to the data acquisition unit 52, the data writing unit 53, and the second conversion unit 3.

The data size datasize of the run-length data required for comparing the data size of the run-length data in the line buffer control means 5 with the size of the line buffer 4 is calculated by the following equation.

[0073]

(Equation 3)

Here, runbit is the number of bits required to represent the run length. When the maximum width of the image is W, it is an integer not less than 1 + log2 (W). The first bit is a bit necessary to indicate white or black. That is, W is 25
In the case of 6, runbit has 9 bits. Therefore, when 256 bits equal to the maximum width W of the image are adopted as the size of the line buffer 4, runcu
When nt is 28 or less, the run length data size is smaller than the line buffer size, and can be accommodated in the line buffer.

If the run-length data is smaller than the line buffer 4, the run-length format is adopted as the storage format of the line buffer, and the line buffer control means 5 stores the run-length data in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored as run-length data in the line buffer.

If the run-length data is larger than the line buffer 4, the run-length data cannot be stored in the line buffer. Therefore, a bitmap format is adopted as the storage format of the line buffer.

At this time, the bitmap data stored in the line buffer 4 is the bitmap data generated by the second conversion means 3. That is, as a result of receiving the run-length data generated by the first conversion means 2 by the second conversion means 3 and performing a conversion process from the received run-length data to bitmap data by the second conversion means 3 The obtained bitmap data is acquired by the line buffer control means 5 and stored in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored in the bitmap data format in the line buffer 4.

The data acquisition section 52 is provided with a data format determination section 5
According to the data format notified from 1, data of one scan line to be stored in the line buffer 4 is selected and acquired. That is, when the data format to be stored is the run-length format as described above, the run-length data is acquired from the first conversion unit 2, more specifically, from the run-length data storage unit 25 of the first conversion unit 2, and stored. I do. When the data format to be stored is the bitmap format, the bitmap data is acquired from the second conversion unit 3 (see FIG. 1).

The data writing unit 53 includes the data acquisition unit 5
Write the data obtained in step 2 to the line buffer. Further, flag information indicating the data format is written to the line buffer. As described above, this flag information is read by the first conversion means 2, more specifically, the two-dimensional decoding unit 24.

The configuration of each module has been described above. Next, the flow of processing in the first embodiment will be described with reference to the flowchart in FIG.

First, in S101, the data compressed by MR in the compression means (not shown) is
The data is stored in the storage unit 1 via / F or the like. Here, the image to be compressed is a binary image, and the maximum value of the horizontal width of the image size is W. Here W is 25
Assume 6 pixels. In the case of font data, if the output resolution of the printer is 600 dpi, it corresponds to characters up to 30 points.

Next, in S102, the first conversion means 2 reads out the compressed data stored in the storage means 1 using the MR compression. Then, the MR compressed data is cut out by reverse lookup of the Huffman table shown in FIGS. This is performed until EOL is detected. Then, the information is converted into run-length data by the information of the reference scan line read from the line buffer or the edge cutout unit and this MR code.

When the MR compressed data for one scan line is converted into run-length data, in S103,
The line buffer control unit 5 determines the storage format of the line buffer as reference line data based on a comparison between the data size of the run-length data and the size of the line buffer 4. In order to compare the data size of the run length data with the size of the line buffer 4,
First, the data size of the run length data: datas
The size is calculated by the following equation.

[0084]

(Equation 4)

In the above equation, runbit is the number of bits required to represent the run length. When the maximum width of the image is W, it is an integer not less than 1 + log2 (W) (the first 1). Bits are needed to indicate white or black). That is, when W is 256, runb
It has 9 bits. Therefore, line buffer 4
When 256 bits equal to the maximum width W of the image are adopted as the size of the image, when the runcount is 28 or less, the run length data size is smaller than the line buffer size and can be accommodated in the line buffer.

If the run length data is smaller than the line buffer 4, the run length format is adopted as the storage format of the line buffer. In S104, the line buffer control means 5 stores the run length data in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored as run-length data in the line buffer. And
The first conversion means 2 outputs the run-length data to the second conversion means 3, and in S105, the second conversion means 3 converts the run-length data into bitmap data.

If the run-length data is larger than the line buffer 4, the run-length data cannot be stored in the line buffer. Therefore, the bit buffer format is adopted as the storage format of the line buffer. At this time, the first conversion means 2 outputs the run-length data to the second conversion means 3, and in S106, the second conversion means 3 converts the run-length data into bitmap data. In step S <b> 107, the line buffer control unit 5 acquires the scan line information that has been converted into the bitmap data by the second conversion unit 3, and stores the information in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored in the bitmap data in the line buffer.

In S108, it is checked whether the decoded scan line is the last line. If it is not the last line, the process returns to S102, and the same sequence is repeated.
If the last line, end.

As described above, when the run-length data size is smaller than the line buffer size, the data is stored in the line buffer in the run-length data format. When the run-length data size is larger than the line buffer size, the bit length is stored. By storing data in the map data format, scan lines that cannot be stored in the line buffer in the run-length data format can be stored in the line buffer. Make it possible.

Embodiment 2 (Expansion Processing Apparatus) Next, a second embodiment of the image expansion processing apparatus of the present invention will be described. The block diagram showing the basic configuration of the second embodiment is the same as that of FIG.

Next, details of each module in the second embodiment will be described. Only different points from the first embodiment will be described. Here, the second conversion unit 3 'will be described.

FIG. 13 shows the structure of the second conversion means 3 '. The second conversion unit 3 ′ includes a run-length extending unit 31.
And a bitmap storage unit 32.

The run-length decompression unit 31 converts the run-length data received from the first conversion unit 2 (see FIGS. 1 and 10) into a bit map, and has a function of the second conversion unit 3 of the first embodiment. Function is the same as The bitmap storage unit 32 has a function of storing bitmap data for one scan line before outputting the bitmap data to an output unit (not shown).

Next, the flow of processing in the second embodiment will be described with reference to the flowchart of FIG. First, S
At 201, data compressed by MR in a compression unit (not shown) is stored in the storage unit 1 (see FIG. 1) via a network I / F or the like. Here, the image to be compressed is a binary image, and the maximum value of the horizontal width of the image size is W. Here, W is 256 pixels. In the case of font data, if the output resolution of the printer is 600 dpi, it corresponds to characters up to 30 points.

Next, in S202, the first conversion means 2 reads out the compressed data stored in the storage means 1 using the MR compression, and performs reverse lookup of the Huffman table shown in FIGS. 5 to 7 and FIG. , One MR code is extracted. Then, by referring to the information of the reference scan line read from the line buffer or the edge cutout unit, the data is converted into run-length data corresponding to the MR code 1 code. This run length data is stored in the run length storage unit 25 in S203.
(See FIG. 10) and output to the second conversion means 3 '(see FIG. 13).

Upon receiving the run-length data, the second conversion means 3 'executes a process of converting the run-length data into bitmap data in S204. Then, in S205, the generated bitmap data is stored by the bitmap storage unit 32. This S
The steps from 202 to S205 are repeated for one scan line until EOL is detected.

When the MR compressed data for one scan line is converted into bitmap data, in S207,
The line buffer control unit 5 determines the storage format of the line buffer as reference line data based on a comparison between the data size of the run-length data and the size of the line buffer 4. In order to compare the data size of the run length data with the size of the line buffer 4,
First, the data size of the run length data: datas
The size is calculated by the following equation.

[0098]

(Equation 5)

Here, runbit is the number of bits required to represent the run length, and when the maximum width of the image is W, it is an integer not less than 1 + log2 (W) (the first one bit). Is needed to indicate white or black). That is, when W is 256, runbi
t has 9 bits. Therefore, when 256 bits equal to the maximum horizontal width W of the image are adopted as the size of the line buffer 4, when the runcount is 28 or less, the run length data size becomes smaller than the line buffer size and can be accommodated in the line buffer.

If the run length data is smaller than the line buffer 4, the run length format is adopted as the storage format of the line buffer. In S208, the line buffer control unit 5 retrieves the run length data for one scan line from the run length storage unit 25,
The data is stored in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored as run-length data in the line buffer.

If the run-length data is larger than the line buffer 4, the run-length data cannot be stored in the line buffer, and the bit buffer format is adopted as the storage format of the line buffer. S209
In step (2), the line buffer control means 5 takes out the bit map data for one scan line from the bit map storage unit 32 and stores it in the line buffer 4. At the time of this storage, the line buffer control means 5 sets a flag indicating that the data is stored in the bitmap data in the line buffer.

Next, the second conversion means 3 'outputs bit map data for one scan line to an output unit (not shown). Then, in S210, it is checked whether the currently decoded scan line is the last line. If it is not the last line, the process returns to S202, and the same sequence is repeated. If the last line, end.

As described above, when the MR compressed data is converted into the bitmap, the run length data and the bitmap data for one scan line are temporarily stored, and the run length data size is smaller than the line buffer size. When the run-length data format is larger than the line buffer size, the scan is performed using the bitmap data format and stored in the line buffer, so that the run-length data format cannot be stored in the line buffer. The line can be stored in the line buffer, and the two-dimensionally encoded and compressed data can be expanded.

As described above, in the description of the first embodiment and the second embodiment,
The case where the MR coding method was used for the dimensional coding compression was used. In addition, as two-dimensional encoding compression in the compression means,
For example, it is also possible to use the MMR coding method. M
In the MR encoding method, only the two-dimensional compression part in the MR encoding process is performed. Therefore, a detailed description thereof will be omitted.

Note that the decompression processing configuration of the present invention described above
For example, a personal computer, a printer, or a network-connected printer as a printer having communication means, a CAD, a scanner, or a facsimile machine, etc. This makes it possible to decompress the two-dimensionally encoded data in real time, thereby realizing high-speed, high-quality print processing.

[Third Embodiment (Compression Processing Apparatus)] Next, as a third embodiment of the present invention, an image compression processing apparatus, that is, an apparatus for executing an encoding process will be described.

FIG. 15 shows the configuration of an image compression processing apparatus according to the present invention. The image compression processing device includes a storage unit 61, an encoding processing unit 62, a line buffer 63, and a line buffer control unit 64.

The storage means 61 is for temporarily storing data transmitted via a storage device such as a hard disk or a network I / F (not shown).

The encoding processing means 62 fetches data from the storage means 61 and executes two-dimensional encoding processing as data compression processing while referring to information in a line buffer 63 described later.

The line buffer 63 is provided for the encoding processing means 6.
2 holds information on reference scan lines required for two-dimensionally encoding data.

The format of the reference scan line information stored and held in the line buffer 63 is the format shown in FIG. 2 described above. In other words, as shown in FIG. 2A, the reference scan line held in the line buffer 63 is a run using a plurality of continuous white and black lump lengths (this is called a run length). List or
As shown in FIG. 2B, the data is stored in a bitmap data format represented as a black and white bitmap.

The line buffer control means 64 uses any data format in the line buffer 63, that is, either the run list system shown in FIG. 2A or the bit map system shown in FIG. 2B. Controls whether data is stored. The storage data format is determined by comparing the size of the run-length data generated by the encoding processing means 62 with the size of the line buffer. That is, if the data size of the run-length format does not exceed the size of the line buffer 63, FIG.
When the data size in the run length format exceeds the size of the line buffer 63, the bitmap data is stored in the line buffer 63 using the bitmap method.

The data encoding process according to the third embodiment is based on the MH encoding method described in the first embodiment and the MR encoding method.
It can be realized by using an encoding method and an MMR encoding method.

Next, details of the encoding processing means 62 in the image compression processing apparatus of the third embodiment will be described.

FIG. 16 shows the structure of the encoding processing means 62. As shown in FIG. 16, the encoding processing means 62 includes a Huffman encoding unit 71, a table storage unit 72, a run-length data storage unit 73, a two-dimensional encoding unit 74, an edge cutout unit 75, It comprises a data conversion unit 76.

The Huffman encoding unit 71 extracts data stored in the storage unit 61 and performs compression by Huffman encoding based on the extracted data. EOL added to the beginning of compressed data of one scan line
(End Of Line) code and a data code following the code. After the last line of one page, an RTC code composed of six consecutive EOL codes is added. The EOL code is a 12-bit code represented by “0000000000001”. If the number of code bits in one scan line is shorter than a predetermined bit length T, a variable length “0” is added after the data code to satisfy the condition of the minimum code bit number. FIG. 4 shows data codes in MH coding. The data code is a variable length code indicating a white or black run length, and white runs and black runs alternately occur. It should be noted that the head of the scan line starts from a white run, and when the head pixel is black, a code indicating a white 0 pixel is used. When the run length is 63 or less, one terminating code shown in FIG. 5 is used as the data code. When the run length is 64 or more, a makeup code representing a quotient obtained by dividing the run length by 64 shown in FIGS. 6 and 7 and a terminating code representing a remainder of 64 of the run length are used.

The tables shown in FIGS. 5 to 7 and 9 are stored in the table storage section 72, and the Huffman decoding section 21 cuts out codes by referring to the tables.

The run-length data storage 73 temporarily stores the run-length data generated by the Huffman encoder 71.

After the two-dimensional encoding unit 74 performs one-dimensional encoding on the scan line in the Huffman encoding unit 71,
Alternatively, three consecutive scan lines are two-dimensionally encoded. In the two-dimensional encoding process in the two-dimensional encoding unit 74, the scan line immediately before the scan line currently being encoded is taken out from the line buffer 63 and referred to, and the reference scan line and the changed pixel of the encoded scan line ( The positional relationship between pixels that change from black to white or from white to black) is encoded. In coding, the following changed pixels are defined.

A0: Start-point change pixel of the coded scan line a1: First change pixel to the right of a0 on the coded scan line a2: First change pixel to the right of a1 on the coded scan line b1: Reference scan line Of the above change pixels, a0
A pixel to the right of the opposite color to a0 b2: The first changed pixel to the right of b1 on the reference scan line

Then, one of the following three encoding modes is selected according to the positional relationship between these changed pixels. This is shown in FIG.

(A) Pass mode When b2 is on the left side of a1, the pass mode is set. In this case, it is encoded into "0001" as shown in FIG.
After encoding, a new a0 is set immediately below b2.

(B) Vertical mode When the distance between a1 and b1 is within 3 pixels, the mode is the vertical mode. According to the relative distance between a1 and b1, V0, VR1, VR
2, VR3, VL1, VL2, and VL3. Note that VRn is n in which a2 is a1.
VLn means that a2 is n pixels to the left of a1. After encoding, a
Set to position 1.

(C) Horizontal mode When the distance between a1 and b1 is larger than 3 pixels, the horizontal mode is set. In the case of the horizontal mode, the distance and the color between a0 and a1 and the distance and the color between a1 and a2 are represented by MH codes after "001". After the encoding, a new a0 is set at the position of a2.

In MR encoding, one-dimensional encoding and 2
Since the dimensional coding is mixed, a tag bit is provided after the EOL code so that it is possible to identify whether the subsequent scan line is coded by one-dimensional coding or two-dimensional coding. .

In the MMR encoding, all scan lines are two-dimensionally encoded and compressed. To encode the first scan line, a virtual all-white line is set as a reference scan line. After the last line of one page, two EOL codes are successively added as the RTC code, and then “0” is added so that the number of bits of the code data for one page becomes an 8-bit boundary.

The edge extracting section 75 is used only when the reference data stored in the line buffer 63 is in the bitmap format. The edge cutout unit 75 scans the line buffer 63 from the left end, detects a pixel change point, and outputs a run length. That is, conversion processing from a bitmap format to a run-length data format is performed.

The two-dimensional encoding unit 74 includes the line buffer 6
By reading the flag of No. 3, that is, the flag indicating whether the data stored in the line buffer 63 is the run-length data or the bitmap data, the reference scan line information stored in the line buffer 63 is changed to the run-length data or the bitmap data. Determine which one.

When the reference scan line information stored in the line buffer 63 is bitmap data, the two-dimensional encoding unit 74 changes the run length from the bitmap format of the reference scanline executed in the edge extracting unit 75. The run-length data of the reference scan line obtained as a result of the data format conversion processing is received via the edge cutout unit 75.

When the reference scan line information stored in the line buffer 63 is run-length data, the two-dimensional encoding unit 74 directly requests the line buffer 63 to extract the run-length data.

The two-dimensional encoding unit 74 includes run-length data of data to be encoded, which is output from the Huffman encoding unit 71 via the run-length data storage unit 73, and the edge extraction unit 75 or the line buffer 63.
Performs two-dimensional encoding of run-length data of data to be encoded, based on the run-length data as reference scan line information acquired from.

The run-length data storage 73 stores run-length data of data to be encoded. Also,
In accordance with a request from the line buffer control unit 64 and the two-dimensional encoding unit 74, run-length data is output to these modules.

The data conversion section 76 converts the run-length data into a bitmap when the run-length data stored in the run-length data storage section 73 is larger than the size of the line buffer 63. The bitmap data generated by the data converter 76 is stored in the line buffer 63.

Next, the line buffer control means 64 will be described. FIG. 17 shows the configuration of the line buffer control means 64. The line buffer control unit 64 includes a data format determination unit 81, a data acquisition unit 82, and a data writing unit 83.

The data format judging section 81 obtains the size of the run-length data from the Huffman coding section 71 (see FIG. 16), compares it with the size of the line buffer, and stores it in the line buffer 63. Decide which data format to use. Here, the data format used is a run-length format or a bitmap format as shown in FIG. The data format determined by the data format determination unit 81 is notified to the data acquisition unit 82 and the data writing unit 83.

The data size datasize of the run-length data required to compare the data size of the run-length data in the line buffer control means 64 with the size of the line buffer 63 is calculated by the following equation.

[0137]

(Equation 6)

Here, runbit is the number of bits required to represent the run length, and when the maximum width of the image is W, it is an integer not less than 1 + log2 (W) (the first one bit). Is needed to indicate white or black). That is, when W is 256, runbi
t has 9 bits. Therefore, the line buffer 63
When 256 bits equal to the maximum width W of the image are adopted as the size of the image, when the runcount is 28 or less, the run length data size is smaller than the line buffer size and can be accommodated in the line buffer.

If the run-length data is smaller than the line buffer 63, the run-length format is adopted as the storage format of the line buffer, and the line buffer controller 64 stores the run-length data in the line buffer 63.
To be stored. At the time of this storage, the line buffer control means 6
No. 4 sets a flag indicating that the data is stored as run-length data in the line buffer.

If the run-length data is larger than the line buffer 63, the run-length data cannot be stored in the line buffer. Therefore, a bitmap format is adopted as the storage format of the line buffer.

At this time, the bitmap data stored in the line buffer 63 is the bitmap data generated by the data conversion unit 76. That is, the run-length data generated by the Huffman encoding unit 71 is stored in the run-length data storage unit 73, and the data is converted in the data conversion unit 76 from the run-length data to bitmap data. The line buffer control means 64 acquires the bitmap data to be obtained and stores it in the line buffer 63. At the time of this storage, the line buffer control means 64 sets a flag indicating that the data is stored in the bitmap data format in the line buffer 63.

The data acquisition section 82 is provided with a data format determination section 8
In accordance with the data format notified from 1, data of one scan line stored in the line buffer 63 is selected and obtained. That is, when the data format to be stored is the run-length format as described above, the run-length data is acquired from the run-length storage unit 73 and stored. Also,
If the data format to be stored is the bitmap format, the bitmap data is obtained from the data conversion unit 76.

The data writing unit 83 is provided with the data acquisition unit 8
Write the data obtained in step 2 to the line buffer. Further, flag information indicating the data format is written to the line buffer. This flag information is stored in the two-dimensional encoding unit 7
4 is read.

The configuration of each module has been described above. Next, the flow of processing in the third embodiment will be described with reference to the flowcharts in FIGS.

First, data storage processing in the line buffer 63 will be described with reference to the flowchart of FIG.

First, in S301, the data received via the network I / F, for example, is stored in the storage unit 6.
1 is stored. Here, the image to be compressed is a binary image, and the maximum value of the horizontal width of the image size is W. Here, W is 256 pixels. In the case of font data, if the output resolution of the printer is 600 dpi, it corresponds to characters up to 30 points.

Next, in S302, the Huffman encoding unit 71 in the encoding processing means 62 performs a data position dimension encoding process. It is converted to run-length data with reference to the Huffman tables of FIGS.

When the data for one scan line is converted into run-length data, in step S303, the line buffer control unit 64 compares the data size of the run-length data with the size of the line buffer 63, and based on the comparison. The storage format as reference line data in the line buffer 63 is determined. In order to compare the data size of the run length data with the size of the line buffer 63, first, the data size of the run length data: datasize is calculated by the following equation.

[0149]

(Equation 7)

In the above equation, runbit is the number of bits required for expressing the run length. When the maximum width of the image is W, it is an integer not less than 1 + log2 (W). The first bit is a bit necessary to indicate white or black.

If the run length data is smaller than the line buffer 63, the run length format is adopted as the storage format of the line buffer. In S304,
The line buffer control means 64 stores the run length data in the line buffer 63. At the time of this storage, the line buffer control means 64 sets a flag indicating that the data is stored as run-length data in the line buffer.

If the run-length data is larger than the line buffer 63, the run-length data cannot be stored in the line buffer. Therefore, a bitmap format is adopted as the storage format of the line buffer. At this time, the run length data is stored in the run length data storage unit 7.
3 to the data conversion unit 76, and in S305, the data conversion unit 76 converts the run-length data into bitmap data. In step S <b> 306, the line buffer control unit 64 acquires the information of the scan line that has become the bitmap data by the data conversion unit 76 and stores the information in the line buffer 63. At the time of this storage, the line buffer control means 64 sets a flag indicating that bitmap data has been stored in the line buffer.

At S307, the current line buffer 63
It is checked whether the scan line stored in is the last line. If it is not the last line, the process returns to S301, and the same sequence is repeated. If the last line, end.

As described above, when the run-length data size is smaller than the line buffer size, the data is stored in the line buffer in the run-length data format. When the run-length data size is larger than the line buffer size, the bit is stored. By storing data in the map data format, scan lines that cannot be stored in the line buffer in the run-length data format can be stored in the line buffer, and two-dimensional encoding can be performed efficiently. And

Next, a flow for reading reference line data from the line buffer 63 and executing a two-dimensional encoding process will be described with reference to the flowchart of FIG.

First, in step S401, the data received via the storage means or the network I / F (not shown) is subjected to the EOL code processing in the Huffman coding section 71. Subsequently, step S40
In 2, data serving as a reference line in the two-dimensional encoding process is read from the line buffer 63.

Next, in step S403, it is determined whether the reference line data read from the line buffer 63 is in a run-length list format or a bitmap format. If it is the bitmap format, in step S404, a conversion process from the bitmap format to the run-length data format is performed. When the data stored in the line buffer 63 is in the bitmap format, the edge cutout unit 75 scans the line buffer 63 from the left end, detects a pixel change point, and outputs a run length. That is, a conversion process from the bitmap format to the run-length data format is performed.

Subsequently, in step S405, the run-length data of the data to be encoded is read from the run-length data storage unit 73 to the two-dimensional encoding unit 74, and in step S406, the reference line data is referred to. , Two-dimensional encoding of the data read from the run-length data storage 73 is performed.

In S407, it is checked whether the scan line just encoded is the last line. If it is not the last line, the process returns to S401, and the same sequence is repeated. If the last line, end.

As described above, in the image compression processing apparatus of the present invention, when the run-length data size is smaller than the line buffer size, the run-length data size is stored in the line buffer in the run-length data format. When the data exceeds the size of the buffer, the data is stored in a bitmap data format, and a two-dimensional encoding process using these data as reference data is executed. Even more accurate data can be stored in the line buffer, and higher-precision encoding is realized in the encoding process.

The above-described data compression processing configuration of the present invention can be implemented in, for example, a personal computer, a printer, a network-connected printer as a printer having communication means, a CAD, a scanner, a facsimile machine, or the like.

[0162]

As described above, according to the image decompression processing apparatus and the image compression processing apparatus of the present invention, in the two-dimensional encoding processing using the reference line data or the decoding processing thereof, one reference line is used. When the scan line data cannot be stored in the line buffer in the run-length format, by storing it in the bitmap format, the reference line data can be reliably stored in the line buffer. Two-dimensional encoding / compression processing or decoding processing can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an image decompression processing device according to the present invention.

FIG. 2 is a diagram illustrating a data storage format in a line buffer in the device of the present invention.

FIG. 3 is a diagram illustrating a configuration of compressed data of one scan line according to the MH encoding method.

FIG. 4 is a diagram showing a data code in the MH coding method.

FIG. 5 is a diagram showing a terminating code in the MH encoding method.

FIG. 6 is a diagram illustrating a make-up code (part 1) in the MH coding method.

FIG. 7 is a diagram illustrating a make-up code (2) in the MH coding method.

FIG. 8 is a diagram illustrating three modes in the MR encoding method.

FIG. 9 is a diagram showing conversion codes in three modes in the MR encoding method.

FIG. 10 is a block diagram showing a detailed configuration of a first conversion unit of the image decompression processing device of the present invention.

FIG. 11 is a block diagram showing a detailed configuration of a line buffer control unit of the image decompression processing device of the present invention.

FIG. 12 is a diagram showing a processing flow of the image decompression processing device of the present invention.

FIG. 13 is a block diagram illustrating a detailed configuration of a second conversion unit in Embodiment 2 of the image decompression processing device of the present invention.

FIG. 14 is a diagram showing a processing flow in Embodiment 2 of the image decompression processing device of the present invention.

FIG. 15 is a block diagram showing an embodiment of the image compression processing device of the present invention.

FIG. 16 is a block diagram showing a detailed configuration of an encoding processing unit of the image compression processing device of the present invention.

FIG. 17 is a block diagram showing a detailed configuration of a line buffer control unit of the image compression processing device of the present invention.

FIG. 18 is a flowchart illustrating data storage processing to a line buffer of the image compression processing device of the present invention.

FIG. 19 is a flowchart illustrating an encoding process of the image compression processing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage means 2 1st conversion means 3 2nd conversion means 4 Line buffer 5 Line buffer control means 21 Huffman decoding part 22 Huffman table 23 Edge extraction part 24 Two-dimensional decoding part 25 Run length data storage part 31 Run length extension part 32 Bitmap storage unit 51 Data format determination unit 52 Data acquisition unit 53 Data writing unit 61 Storage unit 62 Encoding processing unit 63 Line buffer 64 Line buffer control unit 71 Huffman encoding unit 72 Table storage unit 73 Run-length data storage unit 74 Two-dimensional encoding unit 75 Edge extraction unit 76 Data conversion unit 81 Data format determination unit 82 Data acquisition unit 83 Data writing unit

Continued on the front page F term (reference) 5B057 CA02 CA06 CA12 CB02 CB06 CB12 CC01 CG04 CG10 DB02 DB05 DB08 5C059 KK35 MA00 ME05 SS11 UA02 UA05 UA32 5C078 AA01 BA26 BA27 CA12 CA27 CA31 DA00 DA02 DA05 DA06

Claims (15)

[Claims] 1. An image decompression processing apparatus for decompressing compressed data compressed by two-dimensional encoding into bitmap data, comprising: storage means for temporarily storing two-dimensional encoded compressed data to be decompressed; First converting means for performing a process of converting the obtained two-dimensional encoded compressed data into run-length data; and a second performing of converting the run-length data generated by the first converting means into bitmap data. Conversion means, a line buffer for holding one scan line of data as reference scan line data, and a run-length data format comprising the run-length data generated by the first conversion means;
Line buffer control means for selecting one of the bit map data formats generated by the conversion means and writing data for one scan line into the line buffer. Means for performing a conversion process from the two-dimensional encoded compressed data to the run-length data with reference to the data for one scan line stored in the line buffer, and a reference scan line stored in the line buffer; An image decompression processing apparatus having a configuration for executing processing for converting bitmap data into run-length data when the data is in a bitmap data format. 2. The method according to claim 1, wherein said line buffer control means includes:
Performing a comparison process between the data size of one scan line in the run-length data format generated by the conversion unit and the size of the line buffer, and as a result of the comparison process, the run-length generated by the first conversion unit. When the data size of one scan line in the data format exceeds the size of the line buffer, the bitmap data in the bitmap data format generated by the second conversion means is written to the line buffer. As a result, if the data size of one scan line in the run-length data format generated by the first conversion means does not exceed the size of the line buffer, the run-length data generated by the first conversion means is converted to the run-length data. It has a configuration to execute the process of writing to the line buffer Image decompression apparatus according to claim 1, wherein the door. 3. The data amount for one scan line in the run length data format generated by the first conversion means by measuring the number of runs generated per scan line. The image decompression processing device according to claim 1, further comprising: a configuration for measuring a data format and determining a data format to be stored in the line buffer. 4. The line buffer control means according to claim 1, further comprising: an identification flag indicating whether a data format stored in said line buffer is a run-length data format or a bitmap data format when data is stored in said line buffer. 2. The apparatus according to claim 1, further comprising:
4. The image decompression processing device according to any one of claims 1 to 3. 5. The apparatus according to claim 1, wherein said first converting means detects the data stored in said line buffer in a bitmap data format based on said identification flag. The image decompression processing apparatus according to claim 4, further comprising a configuration for executing processing for converting data into run-length data. 6. The apparatus according to claim 1, wherein said second conversion means has a bitmap data storage for temporarily storing the bitmap data generated by said second conversion means. 5. The image decompression processing device according to 1. 7. The method according to claim 1, wherein the two-dimensional encoded compressed data is a modified read code.
The image decompression processing device according to any one of the above. 8. An image decompression processing apparatus according to claim 1, wherein said two-dimensional encoded compressed data is a modified modified read code. 9. An image compression processing apparatus for compressing image data by two-dimensional encoding to generate two-dimensional encoded compressed data, comprising: a line buffer for holding data of one scan line as reference scan line data; Run-length data format consisting of run-length data,
A line buffer control means for selecting one of the bitmap data formats and writing data for one scan line to the line buffer; and for controlling the data for one scan line stored in the line buffer. Referring to FIG. 1, a configuration for executing a two-dimensional encoding process and executing a process of converting bitmap data into run-length data when the reference scan line data stored in the line buffer is in a bitmap data format. An image compression processing apparatus comprising: 10. The line buffer control means according to claim 1, wherein said line buffer control means is a run-length data format to be stored in said line buffer.
A comparison process is performed between the data size of the scan line and the size of the line buffer. As a result of the comparison process, the data size of one scan line in the run-length data format to be stored in the line buffer is the size of the line buffer. Is exceeded,
The bitmap data generated by converting the run length data to be stored in the line buffer into a bitmap data format is written to the line buffer. As a result of the comparison processing, the run length data format to be stored in the line buffer is written. 10. The method according to claim 9, wherein when the data size of one scan line does not exceed the size of the line buffer, a process of writing run-length data to be stored in the line buffer to the line buffer is performed. The image compression processing apparatus according to any one of the preceding claims. 11. The line buffer control means measures a data amount for one scan line in a run length data format to be stored in the line buffer by measuring the number of runs generated per scan line. The image compression processing apparatus according to claim 9, further comprising a configuration for determining a data format to be stored in the line buffer. 12. The line buffer control means according to claim 1, further comprising: an identification flag indicating whether a data format stored in said line buffer is a run-length data format or a bitmap data format, when data is stored in said line buffer. The image compression processing apparatus according to claim 9, wherein the image compression processing apparatus has a configuration in which the image compression processing is set. 13. When the encoding processing means detects that the data stored in the line buffer is in a bitmap data format based on the identification flag, the encoding processing means stores the bitmap data stored in the line buffer. 13. The image compression processing apparatus according to claim 12, wherein the apparatus has a configuration for executing a process of converting the image data into run-length data. 14. The image compression processing apparatus according to claim 9, wherein said two-dimensional encoded compressed data is a modified read code. 15. The image compression processing apparatus according to claim 9, wherein said two-dimensional encoded compressed data is a modified modified read code.