JPH0837602A - Data compression device/method - Google Patents

Abstract

PURPOSE:To provide a data compression device/method which has high compressibility and can compress even the multi-bit data. CONSTITUTION:The received data are processed in steps by a storage means 11, in the 1st step of a changing point detection means 12, in the 2nd steps of the means 13, 14 and 15, and in the 3rd step of a means 16 respectively. In the 1st step, a changing point detection signal 19 is detected to show the changing point of the data set between a data row on a relevant line and that of the line preceding the relevant one. The signal 19 is turned into the changing point position information 20 on each prescribed bit in the 2nd step. Then a changing point position change signal 22 is detected to show the changing point between the information 20 on both lines. The signal 22 is turned into the changing point distribution information 23 on each prescribed bit in the 3rd step. These information 20 and 23 and the present line data 10 are selected and turned into the output data by a data control means 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data compressing apparatus and a data compressing method, and more particularly to a data compressing apparatus and a data compressing method for a data string having a large mutual correlation of data such as print data of a printer.

[0002]

2. Description of the Related Art Conventionally, a data compressing apparatus or a data compressing method using this kind of data change point is disclosed in Japanese Unexamined Patent Publication No. 62-274988, for example, as shown in FIG. It is used for the purpose of reduction.

FIG. 4 is a principle explanatory view showing an example of the conventional data compression method. In FIG. 4, “white / black” of the dot color of each line is set as a binary signal of “0/1” to be 2
Represents a color. In the illustrated case, the color information of the dot on the n-th line and the color information of the dot on the (n + 1) -th line are used as a set, and the data is compressed by the following procedure. 1) Until the color change appears on the (n + 1) th line or the nth line, only the color information of the dots on the (n + 1) th line is extracted. 2) At the time when the color change point appears, the (n + 1) th
Two pieces of a change point signal that inverts the color information of the dots up to that point on the line to instruct the generation of the change point and the color information of the dot on the n-th line at the change point are extracted.

In FIG. 4, the time of occurrence of the change point is the n-th time.
On the line, clocks T3, T6, T17, T19, and on the (n + 1) th line, T9, T12,
It is T15. If the information to be added at each clock time is expressed as “ab”, the first bit “a”
Indicates that a change point is generated by inverting the color information immediately before on the (n + 1) th line, and the color information at the change point on the nth line is displayed by "b" of the second bit. There is.

Therefore, in the information added at each clock time based on the above rule, at T3, "a" is the (n +) th.
1) "1" and "b" of the inverted signal of T2 on the line are the nth
It is "1" of the color information of the change point T3 on the line. Therefore, “ab” becomes “11”. Similarly, T6 is "10", T9 is "10", T12 is "00", T
The value is “10” at 15, the value is “01” at T17, and the value is “00” at T19.

FIG. 5 is a diagram showing a configuration example of a data compression circuit for executing the conventional data compression method shown in FIG.
The compression circuit of FIG. 5 includes a scanner 101 and an information extraction unit 10.
2, memory 103, encoding / decoding unit 104, control unit 10
5, a modem 106, a network control unit (NCU) 107 and a line 108. The information extraction unit 102 is further subdivided into line memory 111 for holding color information for n lines, change point detection unit 112, memory control unit 113, switching circuits 114 and 117, flip-flop 115, and inverting circuit. 116. Further, the printer 118 is connected to the data compression circuit.

The transmission operation in the conventional embodiment will be described below. In FIG. 5, the (n + 1) line data is
The data of the scanner 101 is selected by the switching circuit 117, and from the line memory 111, the timing delayed by one line with respect to the (n + 1) th line being scanned by the scanner 101, that is, the color information of the dot of the nth line is displayed. Is output. As a result, the following three types of color information are input to the switching circuit 114. 1) Dot color information of the (n + 1) th line 2) Inverted color information of the dot one dot before for the (n + 1) th line 3) Color information of the dot of the nth line

The change point detection unit 112 is supplied with the color information of the nth line and the color information of the (n + 1) th line, and when the change points on both lines are detected,
The change point signal of the detection result is output. This change point signal is input to the memory control unit 113. Memory control unit 1
Reference numeral 13 corresponds to the presence / absence of a change point signal output from the change point detection unit 112 and issues a read command to the line memory 111 and a select command to the switching circuit 114. That is, the memory control unit 113 instructs writing to the memory 103 by issuing a select command as follows.

That is, the memory control section 113 outputs a select command for controlling the switching circuit 114 as follows based on the presence / absence of the change point signal. When there is no change point signal input from the change point detection unit 112, the color information of the (n + 1) line data is selected. Further, when there is a change point signal, the color information from the inverting circuit 116 is selected. Next, the memory control unit 113 gives a read command to the line memory 111, and causes the switching circuit 114 to select color information.

The switching circuit 114 is a memory control circuit 113.
By the select command from, the above color information,
Any of the above is selected and the output data is supplied to the memory 103. The memory 103 receives the above-mentioned output data supplied from the switching circuit 114, and writes and stores it in the memory.

The encoding / decoding unit 104 reads out the data recorded in the memory 103 and encodes the read data.
The data is supplied to the decoding unit 104 and is encoded with data compression for transmission. Then, the control unit 105 performs transmission control, and transmits the compressed color information to the line 108 via the modem 106 and the network control unit (NCU) 107.

In the above case, the case of data transmission is explained, but when data is received, "line 108 → N"
CU107 → modem 106 → control unit 105 → encoding / decoding unit 104 → information extraction unit 102 → memory 103 → printer 108 ”, and by going through this procedure,
Data restoration on the receiving side is completed.

[0013]

However, in the above-mentioned conventional data compression method, data of two lines are compared, and a change point signal indicating the existence of the change point at the change point of the data and change data at the change point. Since the data is compressed by adding, the maximum compression rate becomes 50% even when the data of two lines completely match, and the compression rate does not increase even when the same data continues.

Further, since the generation of the change point is instructed by reversing the immediately preceding color information, the change point instruction cannot be expressed when the color information of one dot is multi-bit. Therefore, there is a problem that the above conventional example cannot be used.

It is an object of the present invention to provide a data compression device and a data compression method which have a high compression rate and can also compress multi-bit data.

[0016]

In order to achieve such an object, the data compression apparatus of the present invention compares the correlation of the data strings of the input data and outputs the position information of the changed data and this data. It is a data compression device, and compares the storage means for temporarily storing the data string with the data string of the line and the data string one line before stored in the storage means, and the data content between the two data strings is different. Change point detecting means for outputting a change point detection signal indicating the position of the change point of the change data of the line, and the change point detection signal as change point position information in units of predetermined bits, before temporarily storing this change point position information. A change indicating the position of the change point between the two change point position information by comparing the change point position information of the preceding line temporarily stored with the line change point position generation means and the change point position information of the line. A change point position comparison means for outputting a position change signal, a change point distribution generation means for using the change point position change signal as change point distribution information in a predetermined bit unit, a data string of the line, and a change point position of this data string And a data control means for selecting and outputting information and change point distribution information.

Further, regarding the relationship between the line number from the initial 0th line of the input data string and the output data output by the data control means, the 0th line is the total data of the input data, The line is the change point position information and the change data related to this change point position information, and the second and subsequent lines are the change point position distribution information, the change point position information related to this change point position distribution information, and the change point position. The change data of the information change point position may be used.

In the data compression method of the present invention, in the data compression method of comparing the correlation of the data strings of the input data and outputting the position information of the changed data and this data, a storage step of temporarily storing the data string. And the data sequence of the line and the data sequence one line before stored in the storage process are compared to detect a change point indicating the position of the change point of the change data of the line having different data contents between the two data sequences. A changing point detecting step of outputting a signal, a changing point position generating step of temporarily storing this changing point position information by using the changing point detection signal as changing point position information of a predetermined bit unit, and a temporarily stored one line previous A change point position comparison step of comparing the change point position information with the change point position information of the line and outputting a change point position change signal representing the position of the change point between the two change point position information; A change point distribution generation process in which a change point position change signal is used as change point distribution information in predetermined bits, a data string of the line, and data for selecting and outputting change point position information and change point distribution information of this data string It is characterized by having a control process.

Further, regarding the relationship between the line number from the 0th line in which the data string is initially input and the output data output from the data control step, the 0th line is the total data of the input data, The first line indicates the change point position information and the change data related to the change point position information, the second and subsequent lines indicate the change point position distribution information, and the change point position information related to the change point position distribution information. Change in point position information Change data of the point position may be used.

[0020]

Therefore, according to the main part of the data compressing apparatus and the data compressing method of the present invention, the data string is temporarily stored, the data string of the line is compared with the data string of the preceding line, and the data string between two data strings is compared. And outputs a change point detection signal representing the position of the change point of the change data of the line having different data contents. This change point detection signal is temporarily stored as change point position information in units of a predetermined bit, the change point position information of the immediately preceding line is compared with the change point position information of the line, and the change point between the two change point position information is compared. A change point position change signal indicating the position of is output. The change point position change signal is used as change point distribution information in units of predetermined bits, and the data string of the line and the change point position information and change point distribution information of this data string are selected and output. The data is compressed by outputting the change point position information and the change point distribution information together with the change data.

[0021]

Embodiments of the data compression apparatus and data compression method according to the present invention will now be described in detail with reference to the accompanying drawings. 1-3, there is shown an embodiment of the apparatus and method of the present invention. FIG. 1 is a block diagram showing a data compression circuit to which this embodiment is applied. 2 and 3 are operation explanatory diagrams of the present embodiment.

The data compression circuit shown in FIG. 1 executes desired data processing by inputting data in a cascaded processing unit and selectively outputting predetermined data in the process by the data control means 17. I'm getting the data. This cascade is composed of a storage unit 11, a changing point detecting unit 12, a changing point position generating unit 13, a preceding line changing point position generating unit 14, a changing point position comparing unit 15 and a changing point distribution generating unit 16.

In each of the above components, the storage means 11
Is a line buffer memory for temporarily storing the input current data string 10.

The change point detecting means 12 stores the data string of the current line, which is the input current line data string, and the storing means 1.
This is a comparator for comparing with the preceding line data sequence 18 output from 1 and outputs a change point detection signal 19 indicating a data change for each dot.

The changing point position generating means 13 is a line buffer memory for temporarily storing the changing point detection signal 19 output from the changing point detecting means 12 as changing point position information.

The preceding line change point position generation means 14 has change point position information 20 output from the change point position generation means 13.
Is a line buffer memory for storing again.

The changing point position comparing means 15 has changing point position information 20 of the line output from the changing point position generating means 13 and the changing point position information of the previous line output from the preceding line changing point position generating means 14. 21 is a comparator that outputs a change point position change signal 22 indicating the data change.

The changing point distribution generating means 16 is a line buffer memory for temporarily storing the changing point position change signal 22 output from the changing point position comparing means 15 as changing point distribution information 23.

The data control means 17 is a 3-input / 1-output data selector. The three input signals are connected to the A, B, and C input terminals. As for the contents of the 3 input signals, the current line data 10 input from the outside is output to the C input terminal, the change position information 20 output from the change position generating means 13 is output to the B input terminal, and the change point distribution generating means 16 is output. The changing point distribution information 23 is input to the A input terminal. The select control signal for selecting this is the change point detection signal 1
9 and change point position change signal 22.

Next, the operation of FIG. 1 will be described with reference to FIGS.
Will be explained. If the data string input to the data input terminal of FIG. 1 is a data string in which one line of data is m continuous data and each data has a data width of 8 bits, the data of the nth line is D ( 0, n) ... D (m,
n).

Here, as shown in FIG. 2, the input data sequence is as follows: (a) The 0th line data sequence is D (m, 0) = (FF, EE, DD, CC, BB, AA, 99,88, AB, ..., F0) The data line of the first line of (B) is D (m, 1) = (F0, E0, DD, CC, BB, AA, 99,87, AB, ..., F0 ) It is assumed that the data line of the second line in (c) is D (m, 2) = (F0,07,01, CC, BB, A0, F1,87, AB, ..., F0). It is assumed that the data of the mark “...” Not shown in the above does not change line by line.

First, in the output data string of the 0th line of (a), since there is no data of the previous line in the storage means 11, all the data do not match. When the data match is "0" and the data mismatch is "1", all the change point detection signals 19 output from the change point detecting means 12 are "1". Therefore, the data control means 17 controls all the data strings of the 0th line,
In other words, the current line data 10 of m bytes is selected and used as output data.

Next, at the time of transferring the data line of the first line in (b), the previous line data 18 stored in the storage means 11 is transferred.
And the input current line data 10 to the change point detection means 1
2 is compared at any time, and the change point detection signal 19 is set to "1" only for the dot whose data has changed. In the case of FIG.
D (0,1), D (1,) in the data line of the first line in (b)
Since the data of 1) and D (7,1) are changing, the flag string P indicating the changing point is P flag (m, 1) = (1,1,0,0,0,0,0, 1,0, ..., 0), and the selector 17 indicates that the select signal 19 is "1".
Is output, that is, only the change data of the change point is output. This change data string consists of 3-byte data (F0), (E0), (87) of addresses D (0,1), D (1,1), D (7,1) of the first line data string. Yes, the following D data is available. D data = (F0, E0,87)

At this time, the changing point position generating means 13 generates changing point position information 20 in which the changing point detection signals 19 are collected in byte units. In the case of the change point detection signal 19 of the first line in FIG. 2D, only 1 byte from the beginning of the data string is change data. This change data is (e) 1
The line change point position information 20 becomes, and the change point position information sequence Q becomes the following Q data. Q data = (83,00, ..., 00) That is, the Q data is obtained by converting the P flag into byte unit data. This data is 1/8 of the number of data on the first line, that is, m / 8 bytes of data.

The data control means 17 outputs the change point data, and then outputs the change point position information 20 stored in the change point position generating means 13. Therefore, in the output data of the first line, the number of pieces of change point position information is 1/8 of the number of input data, as shown in FIG. Further, the change point position information 20 at this time is stored again in the previous line change point position generation means 14.

Next, at the time of transferring the data sequence of the second line in FIG. 2C, the previous line data stored in the storage means 11, that is, the first line in FIG. The change point detection means 12 compares the data string of (1) with the data string of the line, that is, the second line. In this comparison, the change point detection signal 19 is set to "1" only for the dot whose data has changed.

2nd line change point detection signal 1 of FIG.
In the case of 9, the change point detection signal sequence P is as follows. P flag (m, 2) = (0,1,1,0,0,1,1,0,0, ..., 0) Data corresponding to this change point detection signal sequence P, that is, the change of the first line Similar to the point detection signal, the data control means 17 uses only the change data of the change point where the change point detection signal 19 becomes "1" as the output data. The data corresponding to this output is the address D (1,2), D in FIG.
The data are (2,2), D (5,2), and D (6,2). The data string D data of this change data is the following 4 bytes. D data = (07,01, A0, F1) At this time, the changing point position information 20 of FIG. 2 (g) generated by the changing point position generating means 13 is the same as the first line described above. Q data = (66,00, ..., 00)

Next, the change point position information 20 of FIG. 2 (g) is output in the same manner as described above.
The changing point position information 20 of (e) is stored in the preceding line changing point position generating means 14, and the changing point position comparing means 15 executes the following processing. This process is the same as the above-mentioned input data comparison. Front line change position generation means 1
4 of the preceding line change point position information 21 (that is, the first line change point position information sequence of FIG. 2E), and the change point position information 20 of the line output from the change point position generation means 13. (That is, the change point position information sequence on the second line in FIG. 2G) is compared, and only when there is a change in the change point position information, as shown in FIG. The signal 22 is set to "1".

The data control means 17 outputs only when the change point position change signal 22 becomes "1", that is, only the information that the change point position of the data has changed. If it is assumed that the data not shown in FIG. 2 does not change in FIG.
First data of the second line change point position information 20 of (g),
That is, only Q (0,2) becomes change data, and the flag row R indicating the change point position on the second line becomes the following R flag as shown in FIG. R flag = (1,0, ..., 0) The position change signal 22 of the change point of the second line in FIG. 2C is used as a select signal, and the data control means 17 uses the input terminal B
Q data = (66), which is the head data of the change point position information 20 input to

At this time, the changing point distribution generating means 16 collects the changing point position change signals 22 in byte units, and
It is stored as the change point distribution information 23 in (i). The data control means 17 outputs the change point position information 20 and then outputs the change point distribution information 23 of FIG. 2 (i) stored in the change point distribution generation means 16 to transfer the previously transferred FIG. 2 (g). The corresponding position of the change point position information 20 is displayed, and the transfer of all data is completed. The change point distribution information 23 of FIG. 2 (i), the change point position information 20 of FIG. 2 (g), and the data string D data of change data are one set of the second line output data of FIG. 3 (c). Becomes

In FIG. 2 (i), since only the R (0,2) of the change point position change signal 22 is changing, the change point distribution information 23 is the following S data. S data = (01,00, ..., 00) This data amount is expressed by 1/8 of the change point position information, that is, m / 64 bytes, as shown in FIG.

As described above, if the change in the input data string is viewed in byte units, a flag indicating the change is set, and the flags are further collected in byte units to see the change, if the change points are small, the data amount is changed. Is compressed to 1/8 unit. As a result, the data sequence of the second and subsequent lines is subjected to two-step data compression, so that the transfer data amount is composed of change point distribution information of the data sequence, change point position information, and change data. In other words, if there is no data change, 1/64 of the original data can be compressed.

The data compression results in this embodiment described above are summarized in FIGS. 3 (a), 3 (b) and 3 (c). In FIG. 3A, the 0th line initially input to the data compression apparatus has no data on the line preceding the line.
Therefore, since there is no comparison data, the original data of the current line of the relevant line is output. In FIG. 3B, since there is no change point position information in the data string of the 0th line data, the change point distribution information is not included in the 1st line output data string.
In FIG. 3C, the second and subsequent output data strings are
It is composed of change data, change point position information, and change point distribution information.

As described above, the data compressing apparatus and the data compressing method of the present invention detect the change point of the data string and transfer the position information and the change data to perform the data compression. It is applicable even when is composed of a multi-bit representation. Further, the change point position information indicating the change point of the data is compared with the change point position information of the previous line in the same manner as the input data, and the change point distribution information is created to compress the data and the change point position information. Since it can be realized with the same configuration, multi-stage data compression becomes possible, and in the case of simple data such as standard format data in the printer and logo data with little change in data, highly efficient data compression becomes possible.

Although the above-described embodiment is a preferred embodiment of the present invention, the present invention is not limited to this and various modifications can be made without departing from the gist of the present invention. For example, although the bit width of each data is 8 bits in the present embodiment, the invention is not limited to this.
The bit width of the change point position information and the change point distribution information is not limited to 8 bits. Further, in this embodiment, the data compression is performed in two steps and the change point position and the change point distribution of the data are obtained, but it is possible to further compress the data in multiple steps with the same configuration. Further, although the data compression has been described in the present embodiment, the data expansion is the reverse operation of the data compression. That is, by obtaining the change point position information from the change point distribution information and updating the data transferred only to the change points of the change point position information, the original data string can be restored.

[0046]

As is apparent from the above description, the main part of the data compression apparatus and the data compression method of the present invention compares the data sequence of the line with the data sequence of one line before,
A change point detection signal representing the change point position of the data content between the two data strings is output. This change point detection signal is temporarily stored as change point position information in a predetermined bit unit, the change point position information of the immediately preceding line and the change point position information of the line are compared, and the change points of the two change point position information are compared. Is output as a change point position change signal. Since the change point position change signal is used as change point distribution information for each predetermined number of bits and the data string, change point position information and change point distribution information are selected and output, the output data is compressed.

By outputting the changing point position information, the changing point distribution information and the changed data, the data compression rate is improved. Also, by setting the length of the original data string in advance,
Since the data amounts of the change point position information and the change point distribution information are determined, it is possible to handle even if the original data string is multi-bit data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a data compression apparatus of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 4 is a diagram illustrating the principle of a conventional technique.

FIG. 5 is a diagram showing a configuration example based on a conventional technique.

[Explanation of symbols]

 10 Current line data 11 Storage means 12 Change point detection means 13 Change point position generation means 14 Previous line change point position generation means 15 Change point position comparison means 16 Change point distribution generation means 17 Data control means 18 Previous line data 19 Change point detection Signal 20 Change point position information 21 Previous line change point position information 22 Change point position change signal 23 Change point distribution information

Claims (4)

[Claims] 1. A data compression apparatus for comparing the correlation of data strings of input data and outputting position information of changed data and the data, a storage unit for temporarily storing the data string, and The data string and the data string one line before stored in the storage means are compared, and a change point detection signal indicating the position of the change point of the change data of the line having different data contents between the two data strings is obtained. Change point detecting means for outputting, change point position information in a predetermined bit unit for the change point detection signal, previous line change point position generating means for temporarily storing the change point position information, and the temporarily stored one line previous line Change point position comparison means for comparing the change point position information with the change point position information of the line and outputting a change point position change signal representing the position of the change point between the two change point position information. , A change point distribution generation unit that uses the change point position change signal as change point distribution information in a predetermined bit unit, a data string of the line, and the change point position information and the change point distribution information of the data string And a data control means for outputting the data. 2. The relationship between the line number from the 0th line from which the data string is initially input and the output data output by the data control means is that the 0th line is all data of the input data. , The first line is the change point position information and the change data related to the change point position information, and the second and subsequent lines are the change point position distribution information and the change point related to the change point position distribution information. 2. The data compression device according to claim 1, wherein the data is the position information and the change data of the change point position of the conversion point position information. 3. A data compression method for comparing the correlation of data strings of input data and outputting position information of changed data and the data, a storage step of temporarily storing the data string, and The data string is compared with the data string stored one line before stored in the storing step, and a change point detection signal indicating the position of the change point of the change data of the line having different data contents between the two data strings is output. Change point detection step of: changing the change point detection signal to change point position information in units of a predetermined bit, and a previous line change point position generating step of temporarily storing the change point position information; A change point position comparison step of comparing the point position information with the change point position information of the line and outputting a change point position change signal representing the position of the change point between the two change point position information; A change point distribution generation step of using the change point position change signal as change point distribution information in a predetermined bit unit, a data string of the line, the change point position information and the change point distribution information of the data string are selected. And a data control step of outputting the data. 4. The relationship between the line number from the 0th line from which the data string is initially input and the output data output from the data control step is that the 0th line is all data of the input data. , The first line is the change point position information and the change data related to the change point position information, and the second and subsequent lines are the change point position distribution information and the change point related to the change point position distribution information. The data compression method according to claim 3, wherein the data is the position information and the change data of the change point position of the conversion point position information.