JP2005252531A - Device and program for compressing data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase compressibility for a data compressing device, or the like for performing data compression processing to data to be compressed, comprising a sequence of numerical values indicated by a prescribed number of unit bits. <P>SOLUTION: There are a run length coder 550 and a binary coder 530. At the run-length coder 550, a numeric value except one or a plurality of prescribed numerical values to be compressed in the data to be compressed is outputted, as it is, and coding is performed to a numerical value to be compressed and a numerical value for indicating the continuous number of the same numerical values to be compressed as the numerical value to be compressed for outputting for the numerical value to be compressed. At the binary coder 530, two kinds of numerical values are identified by 1 bit, for bringing together the sequence of 1 bit for each number of unit bits, when the data to be compressed are binary data expressed by the two kinds of numerical values only, thus generating new data to be compressed comprising the sequence of numerical values indicated by the number of unit bits for passing to the run-length coder 550. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a data compression apparatus that compresses data such as image data, and a data compression program that causes an information processing apparatus such as a computer to operate as a data compression apparatus.

  2. Description of the Related Art Conventionally, techniques for compressing data such as image data have been widely adopted in order to reduce storage capacity and communication volume.

  For example, in Patent Document 1, when a representative color is selected from an original image and a CLUT (color look-up table) is configured, color numbers are assigned so that continuous color numbers have color data of close values, When a bitmap corresponding to the CLUT is created to obtain the difference in color number between adjacent pixels, and the difference takes a large value, the color number of the bitmap is changed within a range that does not cause image quality degradation, and the difference is set to a small value. A technique is disclosed in which run length encoding is applied to biased and differential data.

  Further, Patent Document 2 encodes image data configured by irreversibly compressing a plurality of data assigned to each color and assigning one of the data to a transparent color, The transparent color is reversible, and the image data is composed of an immediate value (the first value at the time of differential encoding) and a plurality of differential values (the previous value at the time of differential encoding) following the immediate value. When encoding a value by irreversible compression, the immediate value representing the transparent color and the difference value are made reversible, and the immediate value representing the transparent color is set to an intermediate value between the data values of each color, or the transparent color is changed. A technique has been proposed in which the difference value to be expressed is set to “0”.

  Patent Document 3 proposes that the number is encoded by the difference between the predicted number (s' (j)) and the actual number (s (j)).

  Further, Patent Document 4 recognizes the distribution status of the same pixel data in the sub-scanning direction and the distribution status of the same pixel data in the main scanning direction with respect to the n-th pixel data column. Based on this recognition result, there has been proposed an image compression device that determines whether to compress the same pixel data continuous in the sub-scanning direction or to compress the same pixel data continuous in the main scanning direction.

  Here, one system to which the data compression technology is applied is introduced.

  FIG. 1 is a diagram illustrating an example of a print system to which a data compression technique is applied, and FIG. 2 is a diagram illustrating a flow of data processing in the print system.

  As shown in FIG. 1, the print system includes a host controller 100, an interface device 200, and a printer 300. A general-purpose interface cable 150 such as SCSI is used between the host controller 100 and the interface device 200. Further, the interface device 200 and the printer 300 are connected by a dedicated interface cable 250.

  In the host controller 100, as shown in FIG. 2, character and image data 11 described in various languages and formats such as PDF, PS, and TIFF are image (CT) data, characters and lines. Etc. (LW; Line Work) data, RIP (Raster Image Processing) is performed for each to generate bitmap data 12A and 13A, and further, data compression processing is performed for each, and CT is performed. Generates irreversible compressed data 14 and reversible compressed data 15 for LW. These compressed data 14 and 15 are transferred from the host controller 100 to the interface device 200 via the general-purpose interface cable 150 shown in FIG. In the interface device 200, the compressed data 14 and 15 transferred are subjected to data decompression processing, and the bitmap data 12B and 13B corresponding to the bitmap data 12A and 13A in a state before the host controller 100 performs the data compression processing. Is generated. Here, since the CT data is subjected to lossy compression processing at the time of data compression by the host controller 100, the CT data (bitmap data 12B) after data decompression is completely CT data before data compression ( Although it does not return to the bitmap data 12A), almost the same bitmap data is restored. Since the LW data is subjected to lossless compression processing at the time of data compression by the host controller 100, the LW data (bitmap data 13B) after data expansion is the LW data (bitmap data 13A) before data compression. Is restored to the same data.

  In the interface device 200, CT data (bitmap data 12B) after data expansion and LW data (bitmap data 13B) are combined, and halftone dot information and the like are added as tags and sent to the printer 300. In the printer 300, an image is printed out according to the bitmap data received from the interface device 200 and the tag information added thereto.

  For example, when the host controller 100 and the interface device 200 are separated from each other, or when the interface device 200 is a system that receives image data from a plurality of host controllers, the host controller 100 and the interface device 200 are separated from each other. 2, the host controller 100 compresses data, transfers the data to the interface device 200, and decompresses the data using the interface device, as shown in FIG. Data transfer time to the interface device 200 can be shortened, and print productivity is improved.

  Here, generally, a compression method such as JPEG which is irreversible but has a high compression rate is adopted for CT data, and a reversible compression method such as PackBits is adopted for LW data.

  Hereinafter, for comparison with an embodiment of the present invention described later, an encoding method using PackBits will be described.

  FIG. 3 is an explanatory diagram of the PackBits encoding method.

  The original data is “01 02 02 02 03 03 03 03 04 05” arranged in the upper row. In this case, it is assumed that all are expressed in hexadecimal notation, the first numerical value of the original data is “01”, the next is “02”, and the next is “02”, and “02” is the same. Since the numerical values of are consecutive, there is only one numerical value “01” that is not continuous.

  Therefore, here, a numerical value “00” obtained by subtracting 1 from the number of numerical values that are not continuous (here, 1) is set (the first numerical value “00” in the lower part of FIG. 3). Subsequently, the discontinuous numerical value itself (here, “01”) is placed (the second numerical value “01” in the lower row). That is, here, “01” of the original data is replaced with “00 01” by PackBits encoding.

  Next, since “02” of the original data is continuous, the number (−2) obtained by subtracting 1 (here 2) from the consecutive number (here 3) minus 1 is expressed in hexadecimal. Is placed (the third numerical value “FE” in the lower row), and the continuous numerical value itself (here, “02”) is placed behind it (the fourth numerical value “02” in the lower row). ). That is, here, “02 02 02” of the original data is replaced with “FE 02” by PackBits encoding.

  Next, since “03” is consecutive in the original data, the number (−3) in which the number 3 obtained by subtracting 1 from the number 4 is negative is expressed in hexadecimal as in the above. “FD” and the continuous numerical value “03” are placed. That is, here, “03 03 03 03” of the original data is replaced with “FD 03”.

  Further, “04 05” follows on the original data, but these “04” and “05” are each independent and the same numerical value is not continuous. Therefore, here, 1 is subtracted from the number (in this case, 2) of the non-consecutive numerical values (“04”, “05”) to place “01”, followed by the non-contiguous numerical value itself “04”. 05 ”. That is, here, “04 05” of the original data is replaced with “01 04 05” by PackBits encoding.

In PackBits, encoding is performed according to the above rules.
JP-A-5-328142 Japanese Patent Laid-Open No. 10-164620 Japanese translation of PCT publication No. 2001-5-20822 Japanese Patent Laid-Open No. 9-200540

  In the case of the PackBits encoding described above, values that can be taken as consecutive numbers of the same numerical value are −1 to −127. That is, up to 128 can be expressed as a continuous number. Since this is expressed by 2 bytes (8 bits × 2), the maximum compression rate that can be realized in principle is 2/128 = 1/64.

  However, in the case of LW data, for example, there are many cases where the same numerical value such as continuous blanks continues, and the efficiency is poor when the maximum compression ratio is 1/64.

  Further, as can be seen from FIG. 3, the original data “01” is encoded as “00 01”, the original data “04 05” is encoded as “01 04 05”, and the like. Sometimes it becomes redundant.

  In FIG. 3, multi-value data “01”, “02”, “03”, “04”, “05”,... Has been described, but in the case of LW data, for example, the same density on a white background. There are many cases of binary data such as LW data representing an image consisting only of characters.

  In view of the above circumstances, the present invention provides a data compression apparatus capable of performing data compression processing with an improved compression ratio, and an information compression apparatus for performing data compression processing with an improved compression ratio. An object of the present invention is to provide a data compression program that can be operated as:

A data compression apparatus of the present invention that achieves the above object is a data compression apparatus that performs data compression processing on data to be compressed consisting of a series of numerical values represented by a predetermined unit bit number.
In the data to be compressed, numerical values other than one or a plurality of predetermined compression target values are output as they are, and for the compression target numerical values, the compression target numerical value and the number of consecutive compression target numerical values that are the same as the compression target numerical value are displayed. A first data compression unit that encodes and outputs a numerical value to be represented;
When the data to be compressed is binary data represented by only two kinds of numerical values, the two kinds of numerical values are identified by one bit, and the continuation of the one bit is grouped by the number of unit bits. And a second data compression unit that generates new compressed data composed of a series of represented numerical values and passes the data to the first data compression unit.

  Here, in the data compression apparatus of the present invention, the first data compression unit performs encoding that expresses the continuous number with a different number of bits according to the continuous number of the same numerical value to be compressed. Is preferred. As an example, the first data compression unit expresses the continuous number by a unit bit number when the number of consecutive compression target numerical values is equal to or smaller than a predetermined number, and when the continuous number exceeds the predetermined number You may perform the encoding expressed by 2 unit bit number.

  In the data compression apparatus of the present invention, the difference between adjacent numerical values for a series of numerical values constituting the data to be compressed is obtained before the first data compression unit and the second data compression unit. It is preferable to include a third data compression unit that generates new compressed data including a series of numerical values representing the difference. In this case, the third data compression unit outputs the first numerical value for each delimiter when the sequence of numerical values constituting the compressed data is sequentially delimited, and adjoins other than the first numerical value. It is more preferable to output a numerical value represented by the lower unit bit number of the difference between the numerical values.

  In addition, when the compressed data is binary data, the third data compression unit identifies two types of numerical values constituting the binary data as 00 and 80 in hexadecimal notation. It is preferable that the difference is obtained for the continuous compressed data, and new compressed data including a series of numerical values representing the difference is generated.

  Further, in the data compression apparatus according to the present invention, entropy coding is performed on the data after being encoded by the first data compression unit, following the first data compression unit and the second data compression unit. It is also a preferable form to include a fourth data compression unit.

  It is also a preferred form that a data type determination unit is provided for determining whether the data to be compressed is binary data including only two types of numerical values or multi-value data including three or more types of numerical values.

The data compression program of the present invention that achieves the above object is executed in an information processing apparatus that executes the program, and converts the information processing apparatus into compressed data consisting of a series of numerical values represented by a predetermined number of unit bits. A data compression program that operates as a data compression device that performs data compression processing,
The information processing apparatus is
In the data to be compressed, numerical values other than one or a plurality of predetermined compression target values are output as they are, and for the compression target numerical values, the compression target numerical value and the number of consecutive compression target numerical values that are the same as the compression target numerical value are displayed. A first data compression unit that encodes and outputs a numerical value to be represented;
When the data to be compressed is binary data including only two kinds of numerical values, these two kinds of numerical values are identified by one bit, and the continuation of the one bit is grouped for each unit bit number, and expressed by the unit bit number. It is characterized by operating as a data compression apparatus comprising a second data compression unit that generates new compressed data consisting of a series of numerical values and passes it to the first data compression unit.

  Here, in the data compression program of the present invention, the first data compression unit performs encoding that expresses the continuous number with a different number of bits according to the continuous number of the same numerical value to be compressed. As an example, the first data compression unit expresses the continuous number by a unit bit number when the consecutive number of the same numerical value to be compressed is a predetermined number or less, and the continuous number indicates the predetermined number. When exceeding, encoding expressed by the number of 2 unit bits may be performed.

  In the data compression apparatus of the present invention, the difference between adjacent numerical values for a series of numerical values constituting the data to be compressed is obtained before the first data compression unit and the second data compression unit. It is preferable to include a third data compression unit that generates new compressed data including a series of numerical values representing the difference. In this case, the third data compression unit outputs the first numerical value for each delimiter when the sequence of numerical values constituting the compressed data is sequentially delimited, and adjoins other than the first numerical value. It is more preferable to output a numerical value represented by the lower unit bit number of the difference between the numerical values.

  In addition, when the compressed data is binary data, the third data compression unit identifies two types of numerical values constituting the binary data as 00 and 80 in hexadecimal notation. It is preferable that the difference is obtained for the continuous compressed data, and new compressed data including a series of numerical values representing the difference is generated.

  Furthermore, in the data compression program of the present invention, entropy coding is performed on the data after being encoded by the first data compression unit after the first data compression unit and the second data compression unit. It is also a preferable form to include a fourth data compression unit.

  Furthermore, it is preferable that a data type determination unit that determines whether the data to be compressed is binary data expressed by only two types of numerical values or multi-value data expressed by three or more types of numerical values is also preferable. It is.

  According to the data compression apparatus or data compression program of the present invention, only the numerical value to be compressed is encoded into the numerical value representing the numerical value to be compressed and the continuous number, and therefore as described with reference to FIG. Thus, a situation in which redundancy is increased as compared with the original data is avoided, and the compression rate is improved.

  Further, according to the present invention, in the case of binary data, the binary value is identified by 1 bit, and a new multi-value data is generated by collecting the continuation of the 1 bit for each unit bit number. For binary data, the compression ratio is further improved.

  Here, the first data compression unit is configured to perform encoding that expresses the continuous number with different bit numbers in accordance with the continuous number of the same compression target numerical value, for example, the continuous number of the same compression target numerical value is When the encoding is performed such that when the number is less than the predetermined number, the continuous number is expressed by 1 unit bit number, and when the continuous number exceeds the predetermined number, the encoding is expressed by 2 unit bit number. When the number is a large number, the compression is performed at a high compression rate, and the compression rate is further improved.

  Further, when the third data compression unit is provided, if the same numerical value continues, the difference becomes a numerical value zero, the appearance probability of the numerical value zero increases, and the combination with the first and second data compression units The compression rate can be further improved.

  Here, when the numerical difference is obtained, for example, when the numerical value is expressed by 1 byte (8 bits), the difference is expressed by 9 bits including the sign. As shown in the embodiment described later, by storing the first numerical value as it is, by omitting 1 bit of the MSB as a numerical value representing the difference and storing the lower 8 bits (1 byte), The numerical value can be restored.

  Therefore, the third data compression unit outputs the first numerical value for each delimiter when the series of numerical values constituting the compressed data are sequentially delimited, and the adjacent numerical values other than the first numerical value. By adopting a configuration that outputs a numerical value represented by the number of lower unit bits among the differences, it is possible to prevent one difference from increasing by one bit due to the difference, which helps to further improve the compression rate.

  Here, in the case of a numerical string composed of 00 and 80 in hexadecimal, the result of the difference calculation is also expressed as 00 and 80 excluding the sign bit. Therefore, when the compressed data is binary data, if the two types of numerical values constituting the binary data are identified as 00 and 80 in hexadecimal, 2 which consists of 00 and 80 even after the difference calculation is performed. In addition to being expressed as value data, the difference probability increases the appearance probability of the numerical value zero (00), which contributes to further improvement of the compression rate.

  Furthermore, when the fourth data compression unit is provided, further improvement of the compression rate by entropy coding is expected.

  The present invention is intended for the case where the data to be compressed is binary data, or the case where the data to be compressed includes binary data. Whether the data to be compressed is binary data or multi-value data. Can be obtained separately, or the data type discriminating section may be provided to determine whether the data is binary data or multi-value data by examining the data to be compressed. Good.

  Hereinafter, embodiments of the present invention will be described.

  The embodiment described below is a data compression apparatus incorporated in the host controller 100 in the overall system shown in FIG. 1. More specifically, the LW bitmap data 13A in the host controller shown in FIG. Is related to the data compression processing. Therefore, it is understood here that the data compression processing and data decompression processing for the LW data described with reference to FIGS. 1 and 2 replaces the processing according to the embodiment of the present invention described below. Duplicate illustrations and duplicate descriptions of the overall system shown and the processing flow shown in FIG. 2 are omitted.

  FIG. 4 is a block diagram showing an embodiment of the data compression apparatus of the present invention.

  The data compression apparatus 500 shown in FIG. 4 includes a data type determination unit 510, a differential encoding unit 520, a binary encoding unit 530, a specific numerical value detection unit 540, a run length encoding unit 550, and a data scanning. Part 560 and a Huffman encoding part 570. Although details of the respective units 510 to 570 will be described later, the flow of image data in the data compression apparatus 500 is as follows.

  An input image file (in this embodiment, a file storing LW data 13A expanded in a bitmap as shown in FIG. 2) is different from the data type determination unit 510 of the data compression apparatus 500 shown in FIG. The data is input to the encoding unit 520. The data type determination unit 510 determines whether the image data in the input image file input this time is binary data or multi-value data of three or more values. In determining the data type, the data type determination unit 510 sequentially checks each numerical value constituting the image data in the input image file input this time, and detects the third type numerical value in the middle of the image data. In some cases, it is determined that the data is multi-value data, and it is determined that the data is binary data with the fact that only two types of numerical values have appeared until the end of the image data.

  The determination result is transmitted to the differential encoding unit 520. When the determination result is binary data, the output data of the differential encoding unit 520 is input to the binary encoding unit 530 and 2 In order to perform value encoding (this content will be described later), and in the case of multi-value data, the output data of the differential encoding unit 520 is binary encoded by the binary data encoding unit 530 The destination of the output data of the differential encoding unit 520 is switched so that it is input to the specific numerical value detection unit 540 and the run length encoding unit 550 without receiving the signal.

  In the differential encoding unit 520, for the input image file that has been input, a differential encoding process, that is, a numerical value representing the difference by obtaining a difference between adjacent numerical values for a series of numerical values constituting the input data. A process for generating data consisting of a series of is performed. The differential encoding unit 520 corresponds to an example of a third data compression unit referred to in the present invention. More specifically, the differential encoding unit 520 outputs the first numerical value for each segment when the sequence of the numerical values constituting the input data is sequentially segmented, and also outputs other than the first numeric value. Is processed to output a numerical value represented by the number of lower unit bits of the difference between adjacent numerical values. For binary data, the differential encoding unit 520 identifies binary values constituting the binary data as hexadecimal numbers 00 and 80, and regards it as compressed data consisting of a series of 00 and 80. Difference calculation is performed. Details will be described later.

  The data encoded by the differential encoding unit 520 is subjected to binary encoding processing by the binary encoding unit 530 for binary data, and then the specific numerical value detection unit 540, the run length encoding unit 550, and the like. Are input to both. The specific numerical value detection unit 540 detects the presence of one or a plurality of compression target numerical values and the continuous number of the same compression target numerical values from the input data. The run-length encoding unit 550 receives the detection result from the specific numerical value detection unit 540 and outputs the numerical values excluding the numerical values to be compressed in the input data as they are, and the numerical values to be compressed with respect to the numerical values to be compressed. Then, an encoding process is performed in which the compressed numerical value is encoded into a numerical value representing the continuous number of the numerical values to be compressed and output. In the run-length encoding unit 550, in the encoding process, encoding is performed in which the continuous number is expressed by a different number of bits according to the continuous number of the same numerical value to be compressed. More specifically, when the number of consecutive compression target numerical values is less than or equal to a predetermined number, the number of consecutive numbers is expressed by one unit bit number, and when the number of consecutive values exceeds the predetermined number, it is expressed by two unit bit numbers. Encoding to represent is performed. In the present embodiment, the combination of the specific numerical value detection unit 540 and the run length encoding unit 550 corresponds to the first data compression unit referred to in the present invention.

  Further, the data encoded by the run-length encoding unit 550 is then input to both the data scanning unit 560 and the Huffman encoding unit 570. The data scanning unit 560 scans all the data after being encoded by the run length encoding unit 550, and obtains the appearance frequency (histogram) of all the numerical values appearing in the data. Here, in this embodiment, the data for obtaining the appearance frequency is the data after each input image file is encoded by the run-length encoding unit 550 in units of one input image file shown in FIG. Appearance frequency of the numerical value inside is calculated. The data histogram (numerical frequency appearance frequency) obtained by the data scanning unit 560 is input to the Huffman coding unit 570. In the Huffman coding unit 570, in accordance with the rules of Huffman coding, a coding process that replaces the numerical value constituting the data input to the Huffman coding unit 570 with a value represented by a shorter bit length as a numerical value having a higher appearance frequency. Is done.

  This Huffman coding is a kind of entropy coding. In this embodiment, the combination of the data scanning unit 560 and the Huffman coding unit 570 corresponds to the fourth data compression unit referred to in the present invention.

  The data after Huffman coding by the Huffman coding unit 570 is set according to the data histogram obtained by the data scanning unit 560, the value of the input data to the Huffman coding unit 570, and the value after Huffman coding. Interface table and other information necessary for data decompression are attached to the interface device via a general-purpose interface 150 such as SCSI shown in FIG. 1 as a compressed image file storing the LW lossless compressed data 15 shown in FIG. 200. In the interface device 200, the received LW lossless compression data 15 is subjected to data expansion processing. In this data expansion processing, first, decoding for the encoding processing performed in the Huffman encoding unit 570 of FIG. Next, a decoding process is performed on the encoding process performed by the run-length encoding unit 550 shown in FIG. 4, and the binary data is further processed by the binary encoding unit 530 shown in FIG. 4, the decoding process for the encoding process performed by the differential encoding unit 520 in FIG. 4 is performed, and the same image data as the original input image file is obtained. Restored to image data.

  FIG. 5 is a hardware configuration diagram of the host controller shown in FIG.

  The host controller 100 shown in FIG. 1 is configured by a computer system having the configuration shown in FIG.

  5 includes a CPU 111, a RAM 112, a communication interface 113, a hard disk controller 114, an FD drive 115, a CDROM drive 116, a mouse controller 117, a keyboard controller 118, a display controller 119, And a communication board 120 are connected to each other via a bus 110.

  The hard disk controller 114 controls access to the hard disk 104 built in the host controller 100, and the FD drive 115 and the CDROM drive 116 are flexible disks (FD) loaded in the host controller 100 so as to be removable. 130, controls access to the CDROM 140. The mouse controller 117 and the keyboard controller 118 play a role of detecting operations of the mouse 107 and keyboard 108 provided in the host controller 100 and transmitting them to the CPU 111. Further, the display controller 119 plays a role of displaying an image on the display screen of the image display 109 provided in the host controller 100 based on the instruction of the CPU 111.

  The communication board 120 is responsible for communication conforming to a general-purpose interface protocol such as SCSI, and is responsible for transferring the compressed image data to the interface device 200 (see FIG. 1) via the interface cable 150.

  Furthermore, the communication interface 113 is responsible for general-purpose communication such as the Internet, and the host controller 100 can also capture image data via the communication interface 113.

  A program stored in the hard disk 104 is read into the RAM 112 and expanded for execution by the CPU 111, and the program expanded in the RAM 112 is read out and executed by the CPU 111.

  FIG. 6 is a schematic configuration diagram of the data compression processing program of the present invention.

  Here, the data compression program 600 is stored in the CDROM 140.

  The data compression program includes a data type determination unit 610, a differential encoding unit 620, a binary encoding unit 630, a specific numerical value detection unit 640, a run length encoding unit 650, a data scanning unit 660, and a Huffman encoding unit 670. It is configured. In addition to the data compression program 600 shown here, the CDROM 140 stores various programs for executing the series of processing shown in FIG. 2 in the host controller 100 shown in FIG. Therefore, illustration and description are omitted.

  The CDROM 140 shown in FIG. 6 is loaded into the host controller 100 shown in FIG. 5 and accessed by the CDROM drive 116, and the program stored in the CDROM 140 is uploaded to the host controller 100 and stored in the hard disk 104. When the program stored in the hard disk 104 is read from the hard disk 104, loaded into the RAM 112, and executed by the CPU 111, the host controller 100 includes the data shown in FIG. 2 operates as a device that executes various processes as the host controller shown in FIG.

  Here, the data compression program 600 shown in FIG. 6 is installed in the host controller 100 and executed by the CPU 111, thereby realizing the data compression apparatus 500 shown in FIG. Type determination unit 610, differential encoding unit 620, binary encoding unit 630, specific numerical value detection unit 640, run length encoding unit 650, data scanning unit 660, and Huffman encoding unit 670 are executed by CPU 111. Thus, the host controller 100 is configured by the data type determination unit 510, the differential encoding unit 520, the binary encoding unit 530, the specific numerical value detection unit 540, and the run length code, respectively, constituting the data compression apparatus 500 shown in FIG. 550, data scanning unit 560, and Huffman code A program component that operates as a part 570. The operations of the units 620 to 670 constituting the data compression program 600 of FIG. 6 when executed by the CPU 111 are the operations themselves of the units 510 to 570 constituting the data compression apparatus 500 of FIG. Therefore, the description so far regarding each of the units 510 to 570 of the data compression apparatus 500 of FIG. 4 and the detailed description described below also serve as the description of the units 620 to 670 constituting the data compression program 600 of FIG. And

  FIG. 7 is a diagram illustrating the data structure of image data in the input image file input to the data compression apparatus 500 of FIG. 4 and the concept of differential encoding.

As shown in FIG. 7, the image data input to the data compression apparatus 500 shown in FIG. 4 has M pixels arranged in a predetermined main scanning direction. For the Nth line when taught in the sub-scanning direction perpendicular to the main scanning direction, the pixel values of the pixels arranged in the main scanning direction are as follows:
Dn _{, 1} , Dn _{, 2} ,..., Dn _{, m-2} , Dn _{, m-1} , Dn _{, m}
It is expressed.

Similarly, for the (N + 1) th line in the sub-scanning direction, the pixel values of the pixels arranged in the main scanning direction are as follows:
Dn _{+ 1,1} , Dn _{+ 1,2} ,..., Dn _{+ 1, m-2} , Dn _{+ 1, m-1} , Dn _{+ 1, m}
It is expressed.

Here, the difference encoding unit 520 constituting the data compression apparatus 500 shown in FIG. 4 inputs the image data as described above, and obtains a difference between pixels adjacent in the sub-scanning direction. That is, if the difference between the Nth line and the (N + 1) th line and the jth pixel lined up in the main scanning direction is Sn _{, j} , the difference _{Sn, j} is
S _{n, j} = D _{n + 1, j} −D _{n, j} (j = _{1 to m} )
It is expressed.

  This difference calculation will be specifically described.

  FIG. 8 is a diagram illustrating a differential encoding process in the differential encoding unit 520 constituting the data compression apparatus 500 of FIG.

Here, the pixel values in one vertical line arranged in the sub-scanning direction shown in FIG. 7 are “image data” in FIG.
As shown in the column
"12 01 02 FF 64 ... 40 40 3F ..."
Suppose that Here, each pixel value is represented by two hexadecimal digits (1 byte = 8 bits). Here, “line” indicates pixels arranged in the main scanning direction.

  First, the pixel value “12” on the first line is output as it is.

  Next, the pixel value “12” of the first line is subtracted from the pixel value “01” of the second line, and the result is output. Here, the result of subtracting “12” from “01” is a negative number and is expressed as “1EF” by 9 bits, but “1” that is 1 bit of the MSB is omitted and “8” is the lower 8 bits. Only “EF” is output.

  Next, the pixel value “01” of the second line is subtracted from the pixel value “02” of the third line, and the resultant value “01” is output.

  Next, the pixel value “02” of the third line is subtracted from the pixel value “FF” of the fourth line, and the resultant value “FD” is output.

  Next, the pixel value “FF” of the fourth line is subtracted from the pixel value “64” of the fifth line, and “1” that is 1 bit of the MSB is omitted from the resulting value, and the lower 8 bits. “65” is output.

  Hereinafter, by repeating the same operation, it is represented in the column of “differential encoding (lower 8 bits)” in FIG.

"(12) EF 01 FD 65 ... L0 00 FF ..."
Is output.

  In decoding the differentially encoded data, the interface device 200 shown in FIG. 1 performs the operation shown on the right side of FIG.

  First, the pixel value of the first line remains “12”.

  The pixel value of the second line is “01” represented by the lower 8 bits of the result of adding the pixel value “12” of the first line to the difference value “EF”.

  The pixel value of the third line is “02” obtained by adding the pixel value “01” of the second line obtained above to the difference value “01”.

  The pixel value of the fourth line is “FF” obtained by adding the pixel value “02” of the third line obtained above to the difference value “FD”.

  The pixel value of the fifth line is “64” represented by the lower 8 bits of the result obtained by adding the pixel value “FF” of the fourth line obtained above to the difference value “65”.

  Thereafter, the same calculation is repeated, whereby the same data as the data before differential encoding is decoded.

  Here, the calculation illustrated in FIG. 8 is performed with the pixel value of each pixel arranged in the first line in the main scanning direction as the first numerical value in the calculation. In other words, in the example shown here, one column in the sub-scanning direction is treated as “each delimiter when the sequence of numerical values constituting the input data is sequentially delimited” according to the present invention. The pixel value is handled as “the first numerical value for each segment”.

  Here, one column in the sub-scanning direction is defined as one segment, but the unit of segmentation is arbitrary. For example, one column in the sub-scanning direction may be segmented into a plurality of columns, and a plurality of columns in the sub-scanning direction are grouped together. It is good also as one division.

  FIG. 9 is a diagram for explaining the operation by differential encoding.

  FIG. 9A shows the concept of an image. Here, the vertical direction in the figure is the main scanning direction, the horizontal direction is the sub scanning direction, and each of the arrows A drawn in the sub scanning direction (horizontal direction) is shown in FIG. Focus is on the pixel value of the pixel.

  On this image, a straight line L1 having a density of pixel value “63” extending in the main scanning direction and a straight line L2 having a density of pixel value “FF” are drawn. There is a CT image area to be fitted. A region to which a CT image is fitted is represented by a pixel value “00”.

  As shown in FIG. 9B, the pixel values of the pixels arranged on the arrow A in FIG. 9A are, in order from the left, first “01”, followed by “63” on the straight line L1, and again “01 ”Continues to“ FF ”on the straight line L2, returns to“ 01 ”again,“ 00 ”continues in the area where the CT image is fitted, and“ 01 ”continues again when the CT image area ends. Here, the pixel value “01” represents an area in which nothing is drawn (paper area).

  When the difference calculation is performed on the original data shown in FIG. 9B, the difference data shown in FIG. 9C is obtained, and the appearance probability of “00” is greatly increased. In the differential encoding unit 520 of FIG. 4 described with reference to FIG. 8, one bit (code bit) of the MSB is omitted, so that the data output from the differential encoding unit 520 is as shown in FIG. become that way. Even in this case, as described with reference to FIG. 8, the original data is sequentially restored by transmitting the first pixel value (the pixel value “12” of the first line in the case of FIG. 8) as it is. be able to.

  Next, processing in the differential encoding unit 520 when the data type determination unit 510 determines that the data is binary data will be described.

  When the differential encoding unit 520 receives a determination result indicating that the image data in the input image file input this time is binary data from the data type determination unit 510, the binary constituting the image data is changed. Whatever value (for example, “01” and “FF” in hexadecimal), one of the two values is “00” in hexadecimal and the other is “80” in hexadecimal. Thereafter, the differential encoding unit 520 performs the differential encoding process shown in FIG.

  FIG. 10 is a diagram showing a differential encoding process for binary data consisting of 00 and 80.

Here, as shown in the “binary image data” column of FIG.
"00 80 80 00 00 80 00 00 80 ..."
Suppose that As in the case of FIG. 8, here, each image value is expressed by two hexadecimal digits (1 byte = 8 bits). First, the pixel value “00” on the first line is output as it is.

  Next, the pixel value “00” of the first line is subtracted from the pixel value “80” of the second line, and the resultant value “80” is output.

  Next, the pixel value “80” of the second line is subtracted from the pixel value “80” of the third line, and the resulting value “00” is output.

  Next, the pixel value “80” of the third line is subtracted from the pixel value “00” of the fourth line, and the resultant value is output. Here, the result of subtracting “80” from “00” is a negative number and is expressed as “180” with 9 bits, but “1”, which is 1 bit of the MSB, is omitted, and the lower bit 8 is “ Only 80 "is output.

  Next, the pixel value “00” of the fourth line is subtracted from the pixel value “00” of the fifth line, and the result “00” is output.

  Hereinafter, by repeating the same calculation, it is represented in the “difference encoding” column of FIG.

"(00) 80 00 80 00 80 80 00 80 ..."
Is output.

  In decoding the differentially encoded data, the interface device 200 shown in FIG. 1 performs the operation shown on the right side of FIG.

  This decoding operation is the same as the decoding operation described with reference to FIG. 8 except that the numerical values to be handled are binary values of “00” and “80”, and redundant description is omitted here.

  As described above, in the differential encoding unit 520, in the case of binary data, any value (for example, “01” and “FF”) constituting the binary data is “00”. ”And“ 80 ”. In the compression information transmitted from the host controller 100 shown in FIG. 1 to the interface device 200, which values (for example,“ 01 ”and“ FF ”) are“ 00 ”and“ 80 ”, respectively. In the interface device, the “decoding result” field in FIG. 10 is included. For example, the “decoding result” field in FIG. 10 includes the information that “80” is assigned (eg, “01” is assigned to “00” and “FF” is assigned to “80”). After being decoded into binary data consisting of “00” and “80”, these “00” and “80” are restored to the original values assigned to “00” and “80” ( For example, “00” is “0” Returned to "," 80 "is returned to" FF ").

  FIG. 11 is an explanatory diagram of the binary encoding process in the binary encoding unit 530 of FIG.

  In the binary encoding unit 530, binary encoding is performed on binary image data composed of “00” and “80” after the differential encoding process is performed by the differential encoding unit 520 shown in FIG. Processing is performed.

As shown in the column of “differential encoded image data” in FIG. 11, the image data differentially encoded by the differential encoding unit 520 of FIG.
"00 00 00 00 00 80 80 80 ..."
Suppose that

Here, these two types of numerical values “00” and “80” are identified by one bit. Here, “00” is identified by 1 bit “0”, “80” is identified by 1 bit “1”, and is shown in the column of “differential encoded image data” in FIG.
"00 00 00 00 00 80 80 80 ..."
As shown in the column of “binary encoded bitstream” in FIG.
"0 0 0 0 0 1 1 1 ..."
In addition, as shown in the “byte-packeted byte stream” column, the bit stream is further grouped by 8 bits.
"07 C0 03 81 ..."
Converted to a numeric column. The converted numerical sequence is input to the specific numerical value detection unit 540 and the run length encoding unit 550 of FIG.

  In decoding in the interface device 200 shown in FIG. 1, processing is performed in the reverse order to the above description.

  In the case of binary data, the amount of data can be greatly reduced by performing the binary encoding process shown in FIG.

  The data after the above-described differential encoding process is performed by the differential encoding unit 520 shown in FIG. 4 is the same as that in the case of multilevel data. After the conversion processing is performed, this is input to both the specific numerical value detection unit 540 and the run length encoding unit 550 shown in FIG.

  The run-length encoding unit 550 performs encoding processing only on specific numerical values among a plurality of numerical values constituting the data received from the differential encoding unit 520, while the specific numerical value detection unit 540 performs differential encoding unit 520. Alternatively, a numerical value (in this case, this numerical value is referred to as a “compression target numerical value”) in which the run-length encoding unit 550 performs encoding processing from the data received from the binary encoding unit 530 and a series of compression target numerical values. A number is detected.

  In the specific numerical value detection unit 540 of FIG. 4 in this embodiment, as an example, three numerical values “01”, “FF”, and “00” are used as compression target numerical values.

  Since it is considered that the background of the LW image has a lot of “01” representing the color of the background of the paper, “01” is one of the numerical values to be compressed here.

  “FF” is a value representing the maximum density. The character portion of the LW image does not always have a pixel value of “FF”, but “FF” appears relatively frequently, so “FF” is also one of the numerical values to be compressed here.

  Further, “00” in the LW image is a value for instructing to select CT data instead of LW data in the synthesis / tag addition processing in the interface device internal processing shown in FIG. In the case where the LW image and the CT image are mixed in one image finally printed by the printer 300, “00” in the LW data is also a pixel value having a high appearance frequency. For this reason, here, “00” is also one of the numerical values to be compressed.

  Here, as described above, the three numerical values “01”, “FF”, and “00” are the compression target numerical values, but “FD” and “02” may also be specified as the compression target numerical values for the following reason. .

In the embodiment shown in FIG. 4, a differential encoding unit 520 is placed in the preceding stage of the run length encoding unit 550 of FIG. 4. Therefore, when the difference between the above three frequently occurring numerical values “00”, “FF”, “01” is obtained, the sign bit is excluded,
FF-00 = FF
00-FF = 01
01-00 = 01
01-01 = FF
FF-01 = FE
02-FF = 0
Of these six difference values, “FF” and “01” have already been cited as compression target values for the above reasons, and the remaining “FE” and “02” are used as compression target values. In addition, five values “01”, “FF”, “00”, “FE”, and “02” may be set as the compression target numerical values.

  However, here, the description will be continued on the assumption that three of “01”, “FF”, and “00” are designated as compression target numerical values.

  FIG. 12 is an explanatory diagram of encoding in the run-length encoding unit 550 shown in FIG. The upper line in FIG. 12 is data received from the differential encoding unit 520 or the binary encoding unit 530, and the lower line is data after the encoding process in the run length encoding unit 550 is performed.

Here, as shown in the upper line of FIG. 12, from the differential encoding unit 520 or the binary encoding unit 530,
"06 02 02 02 01 01 01 01 01 04 05 00 ..."
It is assumed that the following data is input. At this time, in the specific numerical value detection unit 540 of FIG. 4, the leading “06” is not the compression target numerical value, and the subsequent “02 02 02” is not the compression target numerical value. ”Is consecutive, and next, it is detected that 32767 consecutive“ 00 ”numerical values to be compressed with“ 04 ”and“ 05 ”that are not numerical values to be compressed in between. The information is transmitted to the run-length encoding unit 550 of FIG.

  FIG. 13 is a diagram illustrating an encoding algorithm for a numerical value to be compressed in the run-length encoding unit.

  In FIG. 13, Z is a continuous number of the same numerical values to be compressed, for example, Z = 4 for “01” in the upper line of FIG. 12, and Z = 32767 for “00”.

  In FIG. 13, “YY” represents the numerical value to be compressed itself represented by two hexadecimal digits. “0” or “1” following “YY” is “0” or “1” expressed by 1 bit, and “XX...” That follows “XY” represents one bit. This “XX...” Represents the value of Z.

  That is, in FIG. 13, when the compression target numerical value “YY” continues for Z <128, the compression target numerical value “YY” is expressed by the first byte, the first bit is “0”, and the subsequent byte is the subsequent one. Express the value of Z with 7 bits, and when the compression target numerical value “YY” continues Z ≧ 128, express the compression target numerical value “YY” with the first byte, followed by 2 bytes (16 bits) The first 1 bit of “1” is expressed as “1” to express that it is expressed over 2 bytes, and the subsequent 15 bits indicate that the value of Z is expressed.

  An example of encoding shown in FIG. 12 will be described in accordance with the rules shown in FIG.

  Since the first numerical value “06” constituting the data (upper line) input from the differential encoding unit 520 or the binary encoding unit 530 in FIG. 4 is not a compression target numerical value, the “06” is output as it is. Is done. In addition, “02 02 02” that follows, “02” is not a numerical value to be compressed, and these three “02” are output as they are. Next, since “01”, which is a numerical value to be compressed, continues, it is encoded into “01 04”. Since the next “04” and “05” are not compression target numerical values, “04 05” is output as it is.

  Next, since there are 32767 consecutive “00s”, “00” is placed, the first 1 bit of the next 1 byte is set to “1”, and then 32767-128 is expressed by 15 bits. It represents that 32767 “00” s are consecutive in 3 bytes of “00 FF 7F”. That is, the consecutive number 128 is expressed as “00 00” except for the first bit “1”.

FIG. 14 is a diagram illustrating an example of an encoding process according to the number of consecutive steps in the run-length encoding unit 550 of FIG.
When “00” is 127 consecutive, it is encoded to “00 7E” using 2 bytes,
When “00” is 32767 consecutive, it is encoded into “00 FF 7E” using 3 bytes,
When “00” is 32895 consecutive, it is encoded into “00 FF FF” using 3 bytes,
When “00” is 128 consecutive, it is encoded to “00 80 00” using 3 bytes,
-When 4096 "FFs" are contiguous, they are encoded into "FF 8F 80" using 3 bytes.

  The run-length encoding unit 550 shown in FIG. 4 performs the encoding process as described above.

  In this case, since the numerical values other than the compression target numerical values are output as they are, the situation of becoming redundant rather than the PackBits encoding described with reference to FIG. 3 is avoided. 3, the maximum compression rate is 1/64, but according to the run-length encoding unit 550 according to the present embodiment, the maximum compression rate is 3/32895 = 1/10, It improves to 965.

  The data after the above-described encoding process is performed by the run-length encoding unit 550 in FIG. 4 is then input to the data scanning unit 560 and the Huffman encoding unit 570 in FIG.

  The data scanning unit 560 obtains the appearance frequency of pixel values for the pixels constituting the entire LW image, and informs the Huffman coding unit 570 of the order of the appearance frequencies.

  Here, the appearance frequency of “A1” is the strongest, and it is assumed that “A2”, “A3”, “A4”,. These “A1”, “A2” and the like do not directly represent numerical values, but are symbols representing numerical values. That is, “A1” is, for example, a numerical value “00”, “A2” is a numerical value “FF”, and the like. Here, for simplicity, the data sent from the run-length encoding unit 550 of FIG. 4 is expressed by any one of the 16 numerical values “A1” to “A16” for all pixels. Shall be.

  FIG. 15 is a diagram illustrating an encoding process in the Huffman encoder 570 illustrated in FIG. 4.

  Here, “A1” having the highest appearance frequency is replaced with “00” represented by 2 bits, and the next “A2” is replaced with “01” also represented by 2 bits. "A3" and further "A4" are replaced by "100" and "101", respectively, and the following "A5" to "A8" are numerical values expressed by 5 bits. In the same manner, a numerical value with a lower appearance frequency is replaced with a numerical value represented by a larger number of bits.

  FIG. 16 is a diagram illustrating an example of the Huffman table.

  This Huffman table is consistent with FIG. 15 and is arranged so that the higher the appearance frequency is, the shorter the number of bits is, and the number before encoding (before replacement) and after encoding ( It is a correspondence table with numerical values after replacement.

  The interface device 200 shown in FIG. 1 performs decoding for Huffman coding by referring to the Huffman table.

  FIG. 17 is a diagram illustrating an example of a data format of image data output from the data compression apparatus 500 illustrated in FIG.

  First, a code indicating SOI (Start Of Image) indicating the beginning of the image data file is arranged, followed by a header in which information such as the size of the image is recorded, followed by FIG. The compression information related to the data compression processing performed by the data compression apparatus 500 is arranged. The compressed information includes information indicating the distinction between binary data and multi-value data determined by the data type determination unit 510 in FIG. 4. In the case of binary data, “00” in the binary encoding unit 530. 1 and information representing each numerical value assigned to “80”, the Huffman table used in the Huffman encoder 570 (see FIG. 16), etc., all information necessary for decoding by the interface device 200 in FIG. ing.

  This compressed information is followed by actual image data after Huffman coding, and finally concluded with a code of EOI (End Of Image).

  From the data compression apparatus 500 shown in FIG. 4, the image data file whose format is arranged as shown in FIG. 17 is transferred to the interface device 200 shown in FIG. 1, and the interface device 200 performs the encoding described above. The data is decompressed by decoding in the reverse order, and restored to the same image data as the image data in the input image file before being input to the data compression apparatus 500 shown in FIG.

  Note that the data compression apparatus 500 shown in FIG. 4 includes the differential encoding unit 520, and it is preferable to include the differential encoding unit 520 because the appearance frequency of the numerical value “00” increases as described above. In the present invention, it is not always necessary to include the differential encoding unit 520. Binary data is directly input to the binary encoding unit 530 without performing differential encoding processing on the input data. Alternatively, the multi-value data may be directly input to the specific numerical value detection unit 540 and the run length encoding unit 550. Alternatively, instead of the above-described differential encoding unit 520 that performs differential encoding, an encoding unit that performs other data compression processing may be arranged there.

  Also, in the data compression apparatus 500 shown in FIG. 4, a Huffman encoding unit 570 is placed after the run length encoding unit 550, and the Huffman code is further added to the data encoded by the run length encoding unit 550. However, it is not always necessary to perform the Huffman encoding process on the data encoded by the run-length encoding unit 550, and other Huffman encoding processes may be used instead of the Huffman encoding process. Entropy encoding processing may be performed, and the data encoded by the run length encoding unit 550 may be output from the data compression apparatus 500 as it is.

  Further, the data compression apparatus 500 of FIG. 4 includes a data type determination unit 510 that determines whether the image data in the input image file is binary data or multi-value data. When information representing the distinction between value data and multi-value data can be obtained, this data type determination unit 510 is not necessarily required.

  The above-described embodiment is an example in which the present invention is applied to LW data. However, the present invention is not limited to data compression only for LW data. Depending on the properties of an image, CT data and LW Even when applied to image data in which CT and CT are mixed, sufficient data compression can be performed.

1 is a diagram illustrating an example of a print system to which a data compression technique is applied. FIG. 6 is a diagram illustrating a flow of data processing in the print system. It is explanatory drawing of a PackBits encoding system. It is a block block diagram which shows one Embodiment of the data compression apparatus of this invention. It is a hardware block diagram of the host controller shown in FIG. It is a schematic block diagram of the data compression processing program of this invention. FIG. 5 is a diagram illustrating a data structure of image data in an input image file input to the data compression apparatus in FIG. 4 and a concept of differential encoding. It is a figure which illustrates and illustrates the differential encoding process in the differential encoding part which comprises the data compression apparatus of FIG. It is operation | movement explanatory drawing by difference encoding. It is a figure which shows the difference encoding process in the case of the binary data which consists of 00 and 80. It is explanatory drawing of the binary encoding process in the binary encoding part of FIG. It is explanatory drawing of the encoding in the run length encoding part shown in FIG. It is a figure which shows the algorithm of the encoding for the numerical value for compression in a run length encoding part. FIG. 5 is a diagram illustrating an example of an encoding process according to a continuous number in the run length encoding unit of FIG. 4. It is the figure which illustrated the encoding process in the Huffman encoding part shown in FIG. It is a figure which shows an example of a Huffman table. FIG. 5 is a diagram illustrating an example of a data format of image data output from the data compression apparatus illustrated in FIG. 4.

Explanation of symbols

11 data 12A, 12B, 13A, 13B, bitmap data 14 compressed data 15 LW lossless compressed data 100 host controller 140 CDROM
DESCRIPTION OF SYMBOLS 150 General-purpose interface 200 Interface apparatus 250 Dedicated interface 300 Printer 500 Data compression apparatus 510 Data type discrimination | determination part 520 Differential encoding part 530 Binary encoding part 540 Specific numerical value detection part 550 Run length encoding part 560 Data scanning part 570 Huffman encoding Unit 600 data compression program 610 data type determination unit 620 differential encoding unit 630 binary encoding unit 640 specific numerical value detection unit 650 run length encoding unit 660 data scanning unit 670 Huffman encoding unit

Claims (16)

In a data compression apparatus that performs data compression processing on data to be compressed consisting of a series of numerical values represented by a predetermined number of unit bits,
Among the data to be compressed, numerical values other than one or a plurality of predetermined compression target numerical values are output as they are, and for the compression target numerical values, the compression target numerical value and the number of consecutive compression target numerical values that are the same as the compression target numerical value A first data compression unit that encodes and outputs a numerical value representing
When the data to be compressed is binary data represented by only two kinds of numerical values, the two kinds of numerical values are identified by one bit, and the continuation of the one bit is collected for each unit bit number. A data compression apparatus comprising: a second data compression unit that generates new compressed data composed of a series of expressed numerical values and passes the data to the first data compression unit.   2. The data compression apparatus according to claim 1, wherein the first data compression unit performs encoding to express the continuous number with a different number of bits according to the continuous number of the same numerical value to be compressed. .   The first data compression unit expresses the continuous number by one unit bit number when the number of consecutive identical numerical values to be compressed is equal to or smaller than a predetermined number, and two unit bits when the continuous number exceeds the predetermined number 3. The data compression apparatus according to claim 2, wherein encoding is performed by a number.   The first stage of the first data compression unit and the second data compression unit is a new stage consisting of a series of numerical values representing the difference by obtaining a difference between adjacent numerical values for a series of numerical values constituting the compressed data. The data compression apparatus according to claim 1, further comprising a third data compression unit that generates data to be compressed.   The third data compression unit outputs the first numerical value for each delimiter when the sequence of the numerical values constituting the compressed data is sequentially delimited, and the other numerical values other than the first numerical value are adjacent to each other. 5. The data compression apparatus according to claim 4, wherein a numerical value represented by a lower unit bit number of the difference is output.   When the data to be compressed is the binary data, the third data compression unit identifies the two types of numerical values constituting the binary data as 00 and 80 in hexadecimal numbers, and continues the 00 and 80. 5. The data compression apparatus according to claim 4, wherein the difference is obtained for data to be compressed, and new data to be compressed consisting of a series of numerical values representing the difference is generated.   A fourth data compression unit that performs entropy coding on the data that has been encoded by the first data compression unit is provided at a stage subsequent to the first data compression unit and the second data compression unit. The data compression apparatus according to claim 1.   2. A data type determination unit for determining whether the data to be compressed is binary data including only two types of numerical values or multi-value data including three or more types of numerical values. Data compression device. A data compression program that is executed in an information processing apparatus that executes a program, and causes the information processing apparatus to operate as a data compression apparatus that performs data compression processing on data to be compressed consisting of a series of numerical values represented by a predetermined number of unit bits. There,
The information processing apparatus;
Among the data to be compressed, numerical values other than one or a plurality of predetermined compression target numerical values are output as they are, and for the compression target numerical values, the compression target numerical value and the continuous number of the compression target numerical values that are the same as the compression target numerical value A first data compression unit that encodes and outputs a numerical value representing
When the data to be compressed is binary data including only two kinds of numerical values, the two kinds of numerical values are identified by one bit, and the continuation of the one bit is grouped by the unit bit number to be expressed by the unit bit number. A data compression program that operates as a data compression apparatus including a second data compression unit that generates new compressed data composed of a series of numerical values and passes the data to the first data compression unit.   10. The data compression program according to claim 9, wherein the first data compression unit performs encoding to express the continuous number with a different number of bits according to the continuous number of the same numerical value to be compressed. .   The first data compression unit expresses the continuous number by one unit bit number when the number of consecutive identical numerical values to be compressed is equal to or smaller than a predetermined number, and two unit bits when the continuous number exceeds the predetermined number 11. The data compression program according to claim 10, wherein the data compression program performs encoding expressed by a number.   The first stage of the first data compression unit and the second data compression unit is a new stage consisting of a series of numerical values representing the difference by obtaining a difference between adjacent numerical values for a series of numerical values constituting the compressed data. The data compression program according to claim 9, wherein the data compression program is operated as a data compression apparatus including a third data compression unit that generates data to be compressed.   The third data compression unit outputs the first numerical value for each delimiter when the sequence of the numerical values constituting the compressed data is sequentially delimited, and the other numerical values other than the first numerical value are adjacent to each other. 13. The data compression program according to claim 12, wherein a numerical value represented by a lower unit bit number of the difference is output.   When the data to be compressed is the binary data, the third data compression unit identifies the two types of numerical values constituting the binary data as 00 and 80 in hexadecimal numbers, and continues the 00 and 80. 13. The data compression program according to claim 12, wherein the difference is obtained for data to be compressed and new data to be compressed consisting of a series of numerical values representing the difference is generated.   Data provided with a fourth data compression unit that performs entropy coding on the data that has been encoded by the first data compression unit after the first data compression unit and the second data compression unit The data compression program according to claim 9, wherein the data compression program is operated as a compression device.   Operates as a data compression device having a data type determination unit that determines whether the data to be compressed is binary data represented by only two types of numeric values or multi-value data represented by three or more types of numeric values The data compression program according to claim 9, wherein the data compression program is executed.

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