JP2000069294A - Data compression method and its device, data expansion method and its device, and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently compress repetitive data in 2 to 3 bytes appearing in image data expressing a half tone by using data in a prescribed positional relation to discriminate matching or not for directly preceding data or a prescribed-number preceding data with respect to processing object data. SOLUTION: Compression object data latched in a compression object data register 101 are given to a line buffer 102 via a data line. When the processing object data match with one previous data of the image object data, the number of repetition times of matching is obtained, and code data consisting of a data bit denoting the watching and bit data decided depending on the number of time are outputted. Furthermore, when the processing object data do not match with one data before the processing object data but match with two or a prescribed number of preceding data, the data and the number of repetition times of the coincidence are obtained and code data consisting of bit data denoting the matching and bit data decided depending on the number of times are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data compression method and apparatus and a data decompression method and apparatus. The invention also relates to a printer provided with a data decompression device.

[0002]

2. Description of the Related Art As a conventional typical data compression method, a run length method is known. The basic idea of the run-length method is to look at a certain data sequence (raster) in order from the left, and if the same data (numerical value) is continuous, express it as a set of two numerical values of the data and the number of consecutive times. , To compress the data. Therefore, according to the run-length method, the compression ratio increases as the same data continues.

In the case of image data composed of a plurality of data strings, it is known that certain data coincides with data located immediately above it with a relatively high probability. Therefore, when the data located immediately above the data of interest matches, there is also a method of compressing the data by expressing this in one bit.

[0004] These data compression methods are used for data handled by printers, copiers and the like.

[0005] In recent years, many printers and the like can express gradations (halftones) so that higher quality images can be output. For example, in the case of monochrome, a halftone is expressed as light and shade by combining some halftone cells composed of a plurality of dots. In the case of color, it is expressed by overlapping the combination of halftone cells of the screen of each color. In the image data expressing such a halftone, a specific halftone cell is repeated.

[0006]

Therefore, in the above-mentioned conventional data compression method, the data to be processed is compared with only the immediately preceding data or only with the immediately preceding data, and the data is compressed. Therefore, the image data expressing the halftone cannot be efficiently compressed.

That is, in the image data expressing the halftone, the data to be processed and the data immediately above it often do not match, and the compression ratio is rather reduced only by comparing with the data immediately above. There was a problem that it became lower.

In addition, image data representing halftones often have 2-byte or 3-byte data repeated, and cannot be efficiently compressed by a conventional data compression method that compares only the immediately preceding data. was there.

Accordingly, an object of the present invention is to provide a data compression method capable of efficiently compressing a few bytes of repeated data appearing in image data expressing a halftone.

[0010]

According to the present invention, data to be processed is specified one by one in the direction of one line from image data constituting an image, and the data to be processed matches data having a predetermined positional relationship. Is determined, and if it is determined that they match, the number of times the matching is repeated is obtained, and the bit data indicating the positional relationship of the matched data and bit data determined according to the number of times are determined. A data compression method for outputting encoded data,
The data compression method is characterized in that the data having the predetermined positional relationship is at least one data before the processing target data and two or more data before a predetermined number of data.

More specifically, the present invention relates to a data compression method for outputting code data while scanning data to be processed in image data constituting an image one by one in a line direction. When the data and the data to be processed coincide with the data one data before, the number of times the coincidence with the data one data before is repeated is obtained, and the bit data indicating the coincidence with the data one data before and Code data consisting of bit data determined according to the number of times is output, and the data to be processed does not match the data before one data, and the data to be processed and the data to be processed are two or more data preceding the predetermined number of data. Is found, the number of times of repetition of the match with the data before the predetermined number of data is obtained, and pit data indicating the match with the data before the predetermined number of data and A data compression method and outputs the code data composed of bit data determined according to 該回 number.

In the data compression method, when the data to be processed coincides with data located above the data to be processed, the number of times that the coincidence with the data located above is repeated is determined. Alternatively, code data composed of pit data indicating coincidence with data located above and bit data determined according to the number of times may be output.

According to the present invention, there is provided a data compression apparatus which scans data to be processed one by one in a line direction from image data constituting an image and outputs coded data. First to determine whether the data matches the data one data before
Determining means for determining whether the data to be processed and the data to be processed are equal to or more than a predetermined number of data preceding the data to be processed by a predetermined number of data; and A number-of-coincidence acquiring means for acquiring the number of coincidences each time the coincidence of data having a predetermined positional relationship with the data to be processed is continuously repeated; Code output means for outputting code data composed of bit data determined in accordance therewith, and when the first determination means determines that there is a match, the match number acquisition means acquires the number of matches, Outputting bit data indicating the coincidence with the data preceding by one data and code data including bit data determined according to the number of coincidences; And the second determination means determines that the number of matches is equal, the number of matches is obtained by the number-of-matches obtaining means, and the bit data indicating the match with the data preceding the predetermined number of data and the matching A data compression device configured to output code data composed of pit data determined according to the number of times.

Further, the present invention includes a data decompression method and a data decompression device for decompressing decoded data compressed by the above data compression method or data compression device.

Specifically, according to the present invention, first command acquisition means for acquiring bit data indicating a positional relationship indicating coincidence with data one data before from input pit data, A second command acquisition means for acquiring bit data indicating a positional relationship indicating a match with data two or more data before a predetermined number of bits from the input bit data; A number-of-matches acquisition unit for acquiring bit data determined according to the number of coincidences associated with the bit data indicating the bit data indicating the positional relationship, when the first command acquisition unit acquires the bit data indicating the positional relationship, The decoded data is output as decoded data only for the number of matches determined according to the bit data indicating the number of matches obtained by the number of matches obtaining means, When the bit data indicating the positional relationship is acquired by the second command acquiring means, the data immediately before the last decoded data is indicated by the coincidence number acquired by the coincidence number acquiring means. And a decoding output means for outputting as decoded data the number of matches determined in accordance with the pit data.

Further, the present invention can be realized as a printing device such as a printer, a copying machine, a facsimile, etc., provided with a data decompression device for decoding compressed code data into original data.

The present invention can also be realized by causing a computer to execute a program having a predetermined function.

More specifically, the present invention provides a recording method for recording a program for realizing a function of scanning data to be processed one by one in a line direction from image data constituting image data and outputting code data. Medium, wherein the program comprises: first determination means for determining whether or not the data to be processed matches data one data before the data to be processed; Second determining means for determining whether or not the target data is equal to data two or more data preceding a predetermined number of data;
A coincidence number acquisition unit that acquires the number of coincidences each time the coincidence between the processing target data and the data having a predetermined positional relationship with respect to the processing target data is continuously repeated,
Code output means for outputting bit data indicating the positional relationship between the matched data and bit data determined in accordance with the number of matches, and a code output means for outputting the code data when the first determination means determines that they match; The number of coincidences is acquired by the number-of-times acquisition means, and bit data indicating the coincidence with the preceding data and code data including bit data determined according to the number of coincidences are output. When it is determined that they do not match, and the second determination means determines that they match, the number of matches is obtained by the number-of-matches obtaining means, and bit data indicating the match with the data preceding the predetermined number of data and the number of matches are obtained. And a code output means for outputting code data composed of bit data determined according to the program. It may be a recording medium.

In this case, the program is realized, for example, as a so-called printer driver, and causes a computer to realize predetermined functions under the control of an operating system.

Further, the present invention is a recording medium on which a program for causing a computer to perform a function of decoding compressed decoded data into original data is recorded. First command acquisition means for acquiring bit data indicating a positional relationship indicating coincidence with data before data, and a position indicating coincidence with data equal to or more than a predetermined number of data earlier than two data among input bit data A second command acquisition unit for acquiring bit data indicating a relationship; and
A case in which bit data indicating a positional relationship is obtained by the first command obtaining unit and a number-of-matches obtaining unit that obtains bit data determined in accordance with the number of matches associated with the bit data indicating the positional relationship; The decoded data that has been decoded last is output as decoded data for the number of matches determined according to the bit data indicating the number of matches obtained by the number-of-matches obtaining means, and the positional relationship is determined by the second command obtaining means. Is obtained, the bit data indicating the last decoded data is 1
And decoding output means for outputting the previous data as decoded data for the number of matches determined according to the bit data indicating the number of matches obtained by the number of matches obtaining means. It may be a recording medium.

Here, the recording medium is, for example, a hard disk (HD), a DVD-RAM, a flexible disk (FD), a CD-ROM, etc.
Includes memory such as OM. Also, the computer is
For example, a so-called central processing unit such as a CPU or an MPU that performs a predetermined process by interpreting a program includes a so-called microcomputer.

[0022]

Next, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] The present embodiment relates to an apparatus and a method for performing data compression processing. The data compression process is a process of compressing (sometimes called encoding) image data and converting it into encoded data.

FIG. 1 is a diagram showing a configuration of a data compression unit according to the present embodiment. In the figure, a compression target data register 101 holds n-bit compression target data. In the present embodiment, it is assumed that 8-bit (1 byte) data to be compressed is held. The compression target data held in the compression target data register 101 is transmitted to the line buffer 102 via a data line by a control unit (not shown).
Sent to The line buffer 102 stores data for one line. The data to be compressed is sent to the line buffer 101 at a predetermined timing according to the pointer value held in the line buffer address pointer 103 and is held therein.

The upper data register 104a is data located immediately above the compression target data held in the compression target register 101 (hereinafter, also referred to as "upper data").
Hold. When the data to be compressed is on the first line, all data of the previous raster is set to “0”.
That is, the upper data becomes "0".

The first left data register 104b stores the data immediately before the data to be compressed in the second left data register 10b.
4c holds data two data before the data to be compressed, and the third left data register 104d holds data three data before the data to be compressed. The relationship between these data is shown in FIG.
It becomes as shown in. That is, in the figure, the data immediately above the data to be compressed (byte) indicated by diagonal lines, the data one byte before the left, the data two bytes before the left, and the data three bytes before the left are stored in the respective registers. Will be retained.

Returning to FIG. 1, the first comparing unit 105a compares the data to be compressed held in the data register to be compressed 101 with the upper data held in the upper data register 104a, and determines that they match. If it is determined, the counter value held in the coincidence counter 106 is changed. Similarly, the second comparison unit 105b to the fourth comparison unit 105d respectively compare the compression target data held in the compression target data register 101 with the data held in the first left register 104b to the third left register 104d. And
If it is determined that they match, the match counter 106
To change the counter value held in. The first comparing section 105a to the fourth comparing section 105d send the data to be compressed to the code output section 109 under predetermined conditions. The match counter 106 includes a first comparison unit 105 a to a fourth comparison unit 105.
The number of times that any one of d is determined to be the same is held as a counter value.

The fifth comparing section 105e compares the compression target data held in the compression target data register 101 with the data indicated by the mismatch buffer address pointer 108 held in the mismatch buffer 107. If the fifth comparing unit 105e determines that the data match, the fifth comparing unit 105e outputs the matched data to the code output unit 109. On the other hand, if it is determined that they do not match, the data that is determined not to match is sent to the mismatch buffer 107.

The mismatch buffer 107 holds the mismatch data according to the address indicated by the pointer value held in the mismatch buffer address pointer 108. The mismatch buffer 107 is a cylinder buffer that can hold, for example, 16 bytes of data. Image data expressing a halftone can usually be expressed by about 16 types of data (bytes). Therefore, a buffer amount of about 16 bytes is sufficient for the mismatch buffer 107, but the present invention is not particularly limited to this. The mismatch buffer address pointer 108 holds a pointer value indicating the latest address in the mismatch buffer 107.

The code output section 109 is provided with a first comparing section 105a.
To generate code data based on the data transmitted from any one of the fourth to fifth comparison units 105d and the counter value held in the coincidence counter 106, or based on the data transmitted from the fifth comparison unit 105e, Output.

The code data is, as shown in FIG.
It is expressed by a combination of a command and a matching repetition number NUM, a combination of a command and a pointer value of the mismatch buffer pointer 108, or a combination of a command and actual data. The command and the number of matching repetitions are represented by variable-length bit data, the pointer value is represented by 4-bit fixed-length pit data, and the actual data is represented by 8-bit fixed-length pit data.

The code data is output in order from the LSB. In the present embodiment, the code data is converted from LSB to MS
I will read in the direction of B.

FIG. 3B is a diagram showing the value of the number of coincidence repetitions NUM. When the number of repetitions is 8 or more, the NUM value is 0111 (binary) followed by a 7-bit number. However, it ends with a value other than 127 (decimal). If the coincidence continues to the end of the same raster, it is set to 000000 + 0111 as shown in FIG.

Next, the data compression processing by the operation of each block configured as described above will be described.

FIGS. 4 to 6 are diagrams for explaining the operation processing of the data compression device according to the present embodiment. As shown in FIG. 4, first, the compression target data register 101
And the other registers 104a to 104d, the line buffer 102, the mismatch buffer 107, and the address pointers 103 and 108 are initialized (S
TEP401). Next, the compression target data register 101
Is set in STEP 402 (STEP 402), and the first comparing unit 105a determines whether the data to be compressed matches the upper data (STEP 403). S
In TEP403, when it is determined that they match, the processing shifts to the processing of the terminals A1 and A2. The processing of the terminals A1 and A2 will be described later.

If it is determined in STEP 403 that they do not match, the second comparing unit 105b determines whether or not the data to be compressed matches the data one byte before (STEP 404). When it is determined that the terminal A1 and the terminal A2 have been determined, Similarly, if it is determined that they do not match, the third
The comparing unit 105c determines whether the data to be compressed matches the data two bytes before (STEP 40).
5) Next, the fourth comparing unit 105d determines whether the data to be compressed matches the data three bytes before (STEP 406).

If it is determined in STEP 406 that they do not match, the fifth comparing unit 105e determines whether or not the data to be compressed matches the data in the mismatch buffer 107 (STEP 407 in FIG. 5). ).

Here, terminals A1 to A shown in FIG.
The process 2 will be described. In the figure, first, the counter value of the coincidence counter 106 is counted up (ST
(EP601), the line buffer 102 and the registers 104a to 104d are updated (STEP602). Next, it is determined whether the data to be compressed is the last data of one line (raster) (STEP 603). If it is determined that the data is not the last data of one line, the next data to be compressed is set. (Step 604). next,
It is determined whether or not the data (shown as “X” in the figure) held in the register that has been determined to match the data to be compressed further matches (STEP 605). It returns to the process of STEP601. That is, if the process proceeds to STEP 601 assuming that the data matches the upper data in STEP 403 of FIG. 4, it is determined whether or not the data to be compressed matches the upper data. If the process proceeds to STEP 601 assuming that they match, it is determined whether or not the data to be compressed matches the data one byte before. STEP405, STEP4
The same applies to the case where the process has shifted from 06.

On the other hand, if it is determined in STEP 605 that they do not match, the code output unit 109 outputs the code data consisting of the NUM value and the command according to the number of repetitions indicated by the match counter 106 at that time. Output.

If it is determined in STEP 603 that the data is the last data of one line, the code output unit 109 outputs 00000000 + 0111 bit data indicating a match up to the end of one line (STEP 607).

Returning to FIG. 5, when it is determined in STEP 407 that the data matches the mismatch buffer 107, the line buffer 102 and the registers 104a to 104a are output.
104d is updated (STEP 408), and the code output unit 1
09 outputs code data consisting of the pointer value held in the mismatch buffer address pointer 108 and the command “00” (STEP 409). On the other hand, STEP4
If it is determined in step 07 that the codes do not match, the code output unit 10.9 outputs code data including the data to be compressed and the command “10” at the time when the codes do not match (STEP 410). The buffer 102, the left data registers 104b to 104d, and the mismatch buffer 107 are updated (STEP 411).

Next, it is determined whether or not the data to be compressed is the last data of one line (STEP 412).
When it is determined that the data is the last data of the line, each of the registers 104a to 104d is initialized (STEP 4).
13).

Finally, it is determined whether or not all the data to be compressed has been compressed (STEP 414). If there is data not yet to be compressed, the process returns to STEP 402 and repeats the above processing.

Although the data compression process is configured sequentially, the present invention is not limited to this.
That is, as long as there is no inconsistency in the operation of the processing, the order of the processing may be changed or the processing may be performed in parallel.

Next, an example of data compression by the data compression section according to the present embodiment will be described. Now, it is assumed that there is a data group as shown in FIG. That is, in FIG. 11A, the left corner of the first line is the leading data, and the compression process is sequentially performed in the rightward direction as a target of the compression process. When the compression process reaches the right end of the line, the next process is performed. Move to the beginning of the line.

"0" at the upper left corner is set in the compression target data register 101, and comparison with the upper data is performed. In this case, “0” is stored in the upper data register 104a.
Is held, the number of times of repetition that matches the upper data is counted. The fifth "A" from the left is set in the compression target data register 101 and compared with the upper data, it is determined that they do not match, and the NUM value "" corresponding to the number of repetitions "4" up to that time is determined. Code data consisting of a command "011" indicating the match between the data 1011 "and the upper data is output.

When the above processing is completed, “A” set in the compression target data register 101 is
Since there is no match for any of the registers 104a to 104d and no match for the data in the mismatch buffer 107, "A" and the command "1" indicating the mismatch
"0" is output as the code data, and in this case, "A" is held in the non-coincidence buffer 107 (FIG. 3 (c)).

When the compression target data register 101 is updated and the sixth “A” is set, it is determined that the “A” matches the immediately preceding data, and Are counted. Therefore,
NUM value “101” corresponding to the number of matching repetitions “4”
Command “01” indicating the match between “1” and the immediately preceding data
1 "is output.

And: compression target data register 10
When 1 is updated and “B” and “C” are set,
An encoding process is performed as in the above case.

Assume that the compression target data register 101 is further updated and "A" located to the right of "C" is set. Since this “A” is determined to be coincident with the data three before, the number of times of repetition of the coincidence with the data three before is counted. Therefore, the number of times of repetition of matching with the data three data before is “5”, and the corresponding NUM
Code data including the value “01111” and the command “1111” is output.

When the rightmost “D” is set,
An encoding process is performed in the same manner as described above.

Assume that the compression target data register 101 is updated and "B" is set. This “B” matches only with the data indicated by the pointer value “1:” of the mismatch buffer 107. Therefore, the pointer value "1:"
And encoded data including the command “00”.

: Same as above.

(10): Same as above.

(11): Same as above.

(12): At the time when the encoding process of (11) is completed, “A” is set in the compression target data register 101. Since “A” is determined to match the immediately preceding data, the number of repetitions of matching with the immediately preceding data is counted. In this case, since this repetition continues to the end of the line, code data “00000000 + 0111” indicating that the data matches the end of the line is output.

Note that the data compression processing according to the present invention can be constituted by a program that causes a computer to realize a predetermined function. Further, it can be realized by combining a general-purpose gate, a flip-flop circuit, a RAM, and the like.

As described above, according to the present embodiment, it is possible to efficiently compress data expressing a halftone in which data is repeated every two bytes or more.

In particular, in the present embodiment, it is determined whether the data matches the upper data, and code data is output in accordance with the determination.
Various types of data can be efficiently compressed.

Further, in the present embodiment, when the data to be compressed does not match the data having a predetermined positional relationship with the data to be compressed, it is determined whether or not the data matches the mismatch buffer holding the mismatched data. Since it outputs sign data,
It becomes possible to more efficiently compress halftones in which limited types of data tend to be repeated.

[Second Embodiment] The present embodiment relates to an apparatus and a method for performing data decompression processing. The data decompression process according to the present embodiment is a process of decompressing (sometimes called decoding and decompression) code data that has already been compressed by the above-described data compression process and converting it into decoded data (original image data). It is. The data decompression process processes variable-length bit data in order from the first bit.

FIG. 8 is a diagram showing the configuration of the data decompression device according to this embodiment. In the figure, a decompression target data register 801 is a shift register that holds n-bit decompression target data transmitted from the outside. In the present embodiment, 16-bit expansion target data is held.

The command acquisition unit 802 interprets the data to be decompressed held in the data register for decompression 801 to obtain a command represented by variable-length pits, and sends this command to the decoding output unit 809. The control unit (not shown) determines the bit length and transmission destination of the next bit data in accordance with the command acquired by the command acquisition unit 802, and transmits the bit data to the determined transmission destination.

The matching repetition number obtaining section 803 interprets the transmitted bit data to obtain the number of matching repetitions, and sends it to the decoding output section 809.

The line buffer 804 includes the decoding output unit 80
9 (original image data)
Are held for one line in accordance with the address indicated by the pointer value held in the line buffer address pointer 805.

The upper data register 806a holds the upper data for the data to be decoded which is located next to the latest decoded data stored in the line buffer 804. If the data to be decoded belongs to the first line, the upper data is set to “0”.

The first left data register 806b stores the data immediately before the data to be decoded, that is, the latest decoded data, in the second left data register 806b.
c is the third data before the data to be decoded.
The left data register 806d holds data three data before the data to be decoded.

When the command acquisition unit 802 acquires a command indicating a mismatch, the mismatch buffer 807 stores the mismatch buffer address pointer 80.
In accordance with the address indicated by the pointer value held in 8, 8-bit data sent from the decompression target data register 801 is held.

The decoding output unit 809 sends the generated decoded data to the outside and also sends it to the line buffer 804. That is, the decoding output unit 809 determines whether the command is one of a match with the upper data, a match with the previous data, a match with the previous data, and a match with the previous data. , Data is read from the corresponding register among the registers 806a to 806d, and the data is output by the number of times of matching repetition. If the command indicates a match up to the end of one line, the decoding output unit 809 reads the data from the register read out immediately before and decodes the data by the number of matching repetitions up to the end of the line. Output. Further, when the command indicates a match with the mismatch buffer, the decoding output unit 809 outputs the data read from the mismatch buffer 807 in accordance with the address indicated by the 4-bit pointer value following the command. Output. If the command indicates that they do not match, the decryption output unit 809 outputs the data to the decompression target data register 8.
From 01, 8-bit data read following the command is output.

Next, a data decompression process by the operation of each block configured as described above will be described.

FIG. 9 to FIG. 11 are diagrams for explaining the operation processing of the data decompression device according to the present embodiment. FIG. 9
First, as shown in FIG.
01 and other registers 806a to 806d, line buffer 804, mismatch buffer 807, and address pointers 804 and 808 are initialized (STEP 901). Next, the decompression target data register 8
01 is set to the data to be decompressed (STEP 90).
2) In order to acquire a variable-length bit command, the command acquisition unit 802 interprets bit values in order from the LSB (STEPs 903 to 906). These STEP903-
When the command is obtained in 906, the terminal B1
The processing shifts to the subsequent processing (STEPs 913 to 917 in FIG. 11).

That is, when any of the commands is acquired in STEPs 903 to 906, the matching repetition number acquiring unit 803 determines whether or not the matching continues to the end of one line (STEP 913). If it is determined that the match does not reach the end, the bit data following the command is interpreted in order to obtain the number of matching repetitions (STEP 914). On the other hand, if it is determined that the match has reached the end of one line, the number of matching repetitions until the end of one line is obtained from the current pointer value of the line buffer address pointer 805 (STEP 91).
5). After the number of matching repetitions is obtained, the decoding output unit 809 sets the registers 806a to 806 corresponding to the matching location.
d, the data is read from the register corresponding to the matching location, and output for the number of matching repetitions (STEP 91).
6) Update the line buffer 804 and the registers 806a to 806d according to the output result <STEP>
917).

On the other hand, if none of the commands is obtained in STEPs 903 to 906, the command obtaining unit 802 determines whether or not the command indicates a match with the mismatch buffer (STEP 907). When a command indicating a match with the mismatch buffer is obtained, a pointer value represented by the following 4-bit data is obtained (STEP 908). The decoding output unit 809 outputs the mismatch buffer 80 according to the address indicated by the pointer value.
7 is read out and outputted (STEP 9).
09), the line buffer 804, the line buffer address pointer 805, and the registers 806a to 806.
06d is updated (STEP 910).

If it is determined in STEP 907 that the command is not a command indicating a match with the mismatched buffer, that is, if a command indicating mismatched data is obtained, the decoding output unit 809 sets the following 8
The bit data is output (STEP 911). Thereafter, the line buffer 804, the line buffer address pointer 805, and the registers 806a to 806d are updated. The 8-bit data at this time is sent to the mismatch buffer 807, and the mismatch buffer 807 and the mismatch buffer address pointer 808 are updated (STEP 910).

The above processing is repeated until all data is decompressed (STEP 918).

Although the data decompression process is configured sequentially, the present invention is not limited to this.
That is, as long as there is no inconsistency in the operation of the processing, the order of the processing may be changed or the processing may be performed in parallel.

The data decompression process according to the present invention can be constituted by a program that causes a computer to realize a predetermined function. Further, it can be realized by combining a general-purpose gate, a flip-flop circuit, a RAM, and the like.

[Third Embodiment] Next, another embodiment of the data decompression process will be described.

FIG. 12 is a block diagram of a data decompression device according to this embodiment. The input FIFO 1201 has 16
Bit × 4 Word data is held. The fetch unit 1202 receives the input FIFO 120 at a predetermined timing based on the bit shift control of the shift control unit 1203.
The 32-bit expansion target data held in 1 is transmitted to the next block.

The command decode 1204 decodes (extracts) a command of variable length bits included in the data to be decompressed. The command decode 1204 sends the extracted command to a control unit (not shown), and sends the number of bits of the command to the shift control unit 1203. N
The UM decoder 1205 extracts the NUM value of the variable-length bit and sends it to the control unit (not shown), and sends the number of bits to the shift control unit 1203. NUM8 decoding 1206 is decoding when the number of repetitions is 8 or more.

The mismatch buffer pointer 1207 holds the address pointer of the mismatch buffer 1208, and the mismatch buffer 1208 sends data to the data restoration unit 1210 according to the address pointer. The completely mismatched data 1209 sends raw data composed of 8 bits of the data to be decompressed to the data restoration unit 1210.

The output FIFO holds the restored data, and is read at a predetermined timing for each 8-bit data. The data written in the output FIFO is also output to the line buffer 1212.

The line buffer 1212 restores (decompresses)
The obtained data is held at least one line. The line buffer read unit 1213 reads data from the address of the line buffer 1212 specified by the control unit (not shown) and sends the data to the data restoration unit 1210.

The address counter 1214 is a counter for indicating which address is expanded, and the total counter 1215 is a counter for indicating the expanded data amount. These are counted up by a control unit (not shown) every time the expansion target data is expanded.

FIG. 13 is a state transition diagram for explaining the operation of each block shown in FIG. Each of the above blocks operates under the control of a control unit (not shown) according to the state transition diagram. Hereinafter, each state will be described.

STATE1 (IDLE): Waiting.

STATE 2 (command decode): The command at the head of the compressed code is being analyzed.

STATE3 (NUM17): NUM field is being extracted.

STATE 4 (NUM 80): NUM field is being extracted. Processing of the first field in processing when NUM is 8.

STATE 5 (NUM 81): NUM field is being extracted. Processing of the second and subsequent fields in the processing when NUM is 8. In the processing of the first field, there is a code that repeats until the end of the raster, so the state is divided into two. The NUM 81 ignores a code that repeats until the end of the raster.

STATE 6 (mismatch buffer pointer): The pointer of the mismatch buffer is being extracted.

STATE 7 (completely mismatched): Data is being extracted for complete mismatch.

STATE 8 (unmatched buffer read):
Read data from mismatched buffer.

STATE 9 (mismatch buffer write):
Write data to the mismatch buffer.

STATE10 (Restore 0): Data is being restored. After this state, the process returns to STATE2.

STATE 11 (Restore 1): Data is being restored. When NUM is 127 or more, data is restored to this state. That is, since there is still data, after this state, the subsequent repetition number is extracted in STATE5.

STATE12 (Restore 2): Data is being restored. After this state, the process returns to STATE2.

As described above, according to this embodiment, compressed data (data to be decompressed) can be restored under predetermined control.

[0099]

As described above, according to the present invention, it is possible to efficiently compress data expressing a halftone in which data is repeated every two bytes or more.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a data compression device according to the present invention.

FIG. 2 is a diagram for explaining a positional relationship of data;

FIG. 3 is a diagram showing an example of bit data constituting code data.

FIG. 4 is a diagram for explaining an operation process of the data compression device according to the present invention.

FIG. 5 is a diagram for explaining an operation process of the data compression device according to the present invention.

FIG. 6 is a diagram for explaining an operation process of the data compression device according to the present invention.

FIG. 7 is a diagram for explaining an example of data compression by the data compression device according to the present invention.

FIG. 8 is a diagram showing a configuration of a data decompression device according to the present invention.

FIG. 9 is a diagram for explaining an operation process of the data decompression device according to the present invention.

FIG. 10 is a diagram for explaining an operation process of the data decompression device according to the present invention.

FIG. 11 is a diagram for explaining an operation process of the data decompression device according to the present invention.

FIG. 12 is a diagram showing another configuration of the data decompression device according to the present invention.

13 is a diagram showing a state transition of the data decompression device shown in FIG.

[Explanation of symbols]

 101: Data register to be compressed 102: Line buffers 103, 108: Address pointers 104a to 104d: Registers 105a to 105e: Comparison unit 106: Match counter 107: Non-match buffer 109: Code output unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Michio Maruyama 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (reference) 5C059 KK00 MA00 MA45 ME01 PP01 UA02 UA05 5C078 AA04 BA21 CA01 DA01 DA02

Claims (7)

[Claims] An image processing method comprising: identifying data to be processed one by one in a line direction from image data constituting an image; determining whether the data to be processed matches data having a predetermined positional relationship; If it is determined that they match, a data compression method for obtaining the number of times the matching is repeated and outputting code data composed of bit data indicating the positional relationship of the matching data and bit data determined according to the number of times The data compression method, wherein the data having the predetermined positional relationship is at least one data before the processing target data and two or more data before a predetermined number of data. 2. A data compression method for outputting code data while scanning data to be processed in image data constituting an image one line at a time in one line direction, wherein the data to be processed and the data to be processed are When the data coincides with the immediately preceding data, the number of times the coincidence with the immediately preceding data is repeated is determined, and bit data indicating the coincidence with the immediately preceding data and a bit determined according to the number of times are determined. If the code data consisting of data is output and the data to be processed does not match the data before one data, and the data to be processed and the data to be processed match the data two or more data before the predetermined number of data, The number of times the match with the data before the predetermined number of data is repeated is obtained, and the bit data indicating the match with the data before the predetermined number of data and the number of times determined according to the number of times are determined. A data compression method characterized by outputting code data composed of bit data. 3. The data compression method according to claim 1, wherein when the data to be processed coincides with data positioned above the data to be processed, a number of times of repetition of matching with the data positioned above is determined. 3. The data compression method according to claim 2, wherein code data including bit data indicating a match with the data located above and bit data determined according to the number of times is output. 4. A data compression apparatus for scanning data to be processed one by one in a line direction from image data constituting an image and outputting code data, wherein the data to be processed and the data to be processed are First determining means for determining whether or not the data before one data matches, and whether or not the data to be processed and the data to be processed match a predetermined number of data two or more data before the data to be processed Second determining means for determining whether the data to be processed and the data having a predetermined positional relationship with the data to be processed are repeatedly obtained each time the number of matches is obtained. Means, and code output means for outputting code data consisting of bit data indicating the positional relationship of the matched data and bit data determined according to the number of matches, When it is determined by the first determination unit that the number of matches is determined, the number of matches is obtained by the number-of-matches obtaining unit, and the number of matches is determined according to the bit data indicating the match with the preceding data and the number of matches. When the first means determines that they do not match and the second determining means determines that they match, the matching number obtaining means obtains the number of matches. A data compression device configured to output code data including bit data indicating a match with the data preceding the predetermined number of data and bit data determined according to the number of matches. 5. The data compression apparatus further comprises: third determination means for determining whether or not the data to be processed matches data located above the data to be processed, and When it is determined that the number of matches is equal, the number of matches is obtained by the number-of-matches obtaining means, and the bit data indicating the match with the data located thereon and the bit data determined according to the number of matches. 5. The data compression apparatus according to claim 4, wherein code data consisting of the following is output. 6. A first command acquisition means for acquiring bit data indicating a positional relationship indicating a match with data one data before from input bit data, and: A second command acquisition unit for acquiring bit data indicating a positional relationship indicating coincidence with two or more predetermined number of data before, and associating the input bit data with the bit data indicating the positional relationship. A number-of-matches acquisition unit for acquiring bit data determined in accordance with the determined number of matches, and when the first command acquisition unit acquires bit data indicating a positional relationship, the decoded data decoded last is The number of matches determined in accordance with the bit data indicating the number of matches acquired by the number of matches acquisition unit is output as decoded data, and the second command acquisition is performed. When the bit data indicating a positional relationship between the means is acquired,
Decoding output means for outputting the data immediately preceding the last decoded data as decoded data by the number of matches determined according to the pit data indicating the number of matches obtained by the number of matches obtaining means. A data decompression device, comprising: 7. A printing apparatus provided with a data decompression device for decoding compressed code data into original data, wherein the data decompression device is configured to determine whether the input bit data is one data before. First command acquiring means for acquiring bit data indicating a positional relationship indicating a match; and, among input bit data, bit data indicating a positional relationship indicating a match with data equal to or more than a predetermined number of data earlier than two data. A second command acquisition unit for acquiring, and a coincidence number acquisition unit for acquiring, from input bit data, bit data determined according to the number of coincidences associated with the bit data indicating the positional relationship, When bit data indicating a positional relationship is obtained by the first command obtaining means, the last decoded data is obtained by the matching number obtaining means. When only match count determined in accordance with the bit data indicating the number of matches is output as decoded data, pit data showing the positional relationship by the second command acquisition means is acquired,
Decoding output means for outputting, as decoded data, the data immediately preceding the last decoded data by the number of matches determined according to the bit data indicating the number of matches obtained by the number-of-matches obtaining means. A printing device, comprising: