JP5855777B2 - Data compression apparatus, data decoding apparatus, data compression method, data decoding method, and data compression and decoding system - Google Patents

Description

  The present invention relates to a data compression device, a data decoding device, a data compression method, a data decoding method, and a data compression and decoding system.

  In the AC component processing of Huffman coding used in JPEG, the length of the “0” coefficient (zero run length) is obtained, and when the coefficient is other than “0” (effective coefficient), the group of zero run length and effective coefficient A method for assigning a Huffman code is known (for example, see Patent Document 1).

JP-A-6-139346

  However, in the above-described method, the maximum value of the AC coefficient increases as the bit length after quantization increases, so the number of groups for specifying the AC coefficient increases. Therefore, the code types for encoding groups also increase. As the code type increases, the data length fluctuates more and the range that the data amount can take is expanded. Further, in a system that transmits and receives fixed length data, it is necessary to convert the data compression to a fixed length and transmit it. Therefore, in a system that transmits and receives fixed-length data, when transmitting and receiving Huffman-encoded data using the above-described method, it is necessary to determine the maximum bit length of data after Huffman encoding as a fixed length. Even when the bit length is short, useless data must be transmitted, and communication efficiency cannot be improved.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a data compression device, a data decoding device, a data compression method, a data decoding method, and a data compression and decoding system capable of improving communication efficiency. And

According to one aspect of the present invention, an input unit that inputs encoding target data constituting a numerical sequence including a plurality of values, and zero run length encoding of the encoding target data are performed, and the numerical sequence is 0. A determination unit in which the number of consecutive values is runz data, the non-zero value is value data, and a numerical value indicating a minimum bit length that can represent the absolute value of the value data is group data; The runz data is Huffman encoded using a one-dimensional first Huffman table, the group data is Huffman encoded using a one-dimensional second Huffman table different from the first Huffman table, and an encoding unit for calculating additional bits for specifying the value data from the group data; and Encoding the runz data, the group data Huffman-encoded by the encoding unit, and the additional bits calculated by the encoding unit as encoded data of the encoding target data. A transmitting unit that transmits in a communication method for transmitting and receiving the data, and when the number of consecutive values that are 0 in the numerical sequence is 0, the determination unit does not use the number as the runz data. The determination unit is a data compression apparatus characterized in that the set of values that are not 0 is continuous as the value data .

  Further, in the data compression device according to another aspect of the present invention, the determination unit sets the value that is 0 to the value that is not 0 only when the number of consecutive values that are 0 in the numerical sequence is 1. The value is regarded as the value data.

  In another aspect of the present invention, the encoded data transmitted from the data compression apparatus is received using a communication unit that transmits and receives fixed-length data, and a Huffman encoding is performed using the first Huffman table. And decoding the runz data using the first Huffman table, decoding the group data encoded using the second Huffman table, using the second Huffman table, and a decoding unit for calculating the value data based on the group data and the additional bits, a calculation for calculating the encoding target data based on the decoded runz data, and the calculated value data And a data decoding device characterized by comprising:

According to another aspect of the present invention, an input step for inputting encoding target data constituting a numerical sequence including a plurality of values, and zero-run length encoding of the encoding target data are performed. Determination that the number of consecutive 0 values is runz data, the non-zero value is value data, and a numerical value indicating the minimum bit length that can represent the absolute value of the value data is group data And Huffman encoding the runz data using a one-dimensional first Huffman table, and encoding the group data using a one-dimensional second Huffman table different from the first Huffman table, Further, an encoding step for calculating additional bits for specifying the value data from the group data. , The runz data Huffman encoded in the encoding step, the group data Huffman encoded in the encoding step, and the additional bits calculated in the encoding step. A transmission step of transmitting in a communication scheme for transmitting and receiving fixed-length data as encoded data, and in the determination step, when the number of consecutive values that are 0 in the numerical sequence is 0, The data compression method is characterized in that the number is not the runz data, and in the determination step, the continuous non-zero set of values is the value data .

  According to another aspect of the present invention, there is provided a reception step of receiving the encoded data encoded by the data compression method by a communication method for transmitting and receiving fixed-length data, and a Huffman code using the first Huffman table. Decoding the runz data using the first Huffman table, decoding the group data encoded using the second Huffman table, using the second Huffman table, Decoding step of calculating the value data based on the group data and the additional bits, calculating the encoding target data based on the decoded runz data, and the calculated value data And a calculation step.

According to another aspect of the present invention, an input unit that inputs encoding target data constituting a numerical sequence including a plurality of values, and zero-run length encoding of the encoding target data are performed. Determination that the number of consecutive 0 values is runz data, the non-zero value is value data, and a numerical value indicating the minimum bit length that can represent the absolute value of the value data is group data And Huffman encoding the runz data using a one-dimensional first Huffman table, and encoding the group data using a one-dimensional second Huffman table different from the first Huffman table, A coding unit for calculating additional bits for identifying the value data from the group data; The runz data encoded by Huffman, the group data Huffman encoded by the encoding unit, and the additional bits calculated by the encoding unit are used as encoded data of the encoding target data, and are fixed length. A data compression apparatus having a transmission unit that transmits data in a communication scheme; a reception unit that receives the encoded data transmitted from the transmission unit in a communication scheme that transmits and receives fixed-length data; and The runz data encoded using the first Huffman table is decoded using the first Huffman table, and the group data encoded using the second Huffman table is converted into the second data. And the value data is calculated based on the group data and the additional bits. It includes a decoding unit that, said runz data decoded, the calculated on the basis of the value data, and a data decoding apparatus having: a calculation unit for calculating the encoding object data, the determination When the number of consecutive 0 values in the numerical sequence is 0, the number is not used as the runz data, and the determination unit determines the set of consecutive non-zero values as follows: The data compression and decoding system is characterized by using the value data .

  According to another aspect of the present invention, an input unit that inputs encoding target data constituting a numerical sequence including a plurality of values, and the value that is not 0 among the encoding target data are value encoding targets. A value storage unit that stores data, and a runz storage that stores, as runz encoding target data, the number of consecutive values that are 0 between the non-zero value and the other non-zero values. And the runz encoding target data are encoded using a first Huffman table, and the value encoding target data is encoded using a second Huffman table different from the first Huffman table. An encoding unit; and a transmission unit that transmits the encoded data encoded by the encoding unit by a communication method for transmitting and receiving fixed-length data. Is a data compression system, characterized in that the length based on the bit width of the elephants data.

  In the data compression apparatus according to another aspect of the present invention, the runz storage unit does not store the number as the runz encoding target data when the number of consecutive zero values is zero. The value storage unit stores consecutive sets of values other than 0 as the value encoding target data.

  Further, in the data compression apparatus according to another aspect of the present invention, the value storage unit and the runz storage unit may reduce the value of 0 to 0 only when the number of consecutive values of 0 is 1. It is considered that there is no value, and the value is stored as the value encoding target data.

  According to another aspect of the present invention, the encoded data transmitted from the data compression apparatus is encoded using a receiving unit that receives a communication method for transmitting and receiving fixed-length data and the first Huffman table. The runz encoding target data is decoded using the first Huffman table, and the value encoding target data encoded using the second Huffman table is used using the second Huffman table. And a decoding unit that calculates the encoding target data based on the decoded runz encoding target data and the decoded value encoding target data. A data decoding apparatus characterized by the above.

  According to another aspect of the present invention, the encoded data transmitted from the data compression apparatus is encoded using a receiving unit that receives a communication method for transmitting and receiving fixed-length data and the first Huffman table. The runz encoding target data is decoded using the first Huffman table, and the value encoding target data encoded using the second Huffman table is used using the second Huffman table. And a decoding unit that calculates the encoding target data based on the decoded runz encoding target data and the decoded value encoding target data. A data decoding apparatus characterized by the above.

  According to another aspect of the present invention, the encoded data transmitted from the data compression apparatus is encoded using a receiving unit that receives a communication method for transmitting and receiving fixed-length data and the first Huffman table. The runz encoding target data is decoded using the first Huffman table, and the value encoding target data encoded using the second Huffman table is used using the second Huffman table. And a decoding unit that calculates the encoding target data based on the decoded runz encoding target data and the decoded value encoding target data. A data decoding apparatus characterized by the above.

  According to another aspect of the present invention, a step of inputting encoding target data constituting a numerical sequence including a plurality of values, and the value that is not 0 among the encoding target data are set to value encoding target data. Storing as a runz encoding target data the number of consecutive values that are 0 between the non-zero value and the other non-zero value, and the runz An encoding step of encoding the encoding target data using a first Huffman table and encoding the value encoding target data using a second Huffman table different from the first Huffman table; Transmitting the encoded data encoded in the encoding step by a communication method for transmitting and receiving fixed length data, wherein the fixed length is the code It is a data compression method which is a length based on the bit width of the target data.

  According to another aspect of the present invention, there is provided a step of receiving data encoded by a data compression method using a communication method for transmitting and receiving fixed-length data, and the runz encoded using the first Huffman table. The data to be encoded is decoded using the first Huffman table, and the value encoding target data encoded using the second Huffman table is decoded using the second Huffman table. And a step of calculating the encoding target data based on the decoded runz encoding target data and the decoded value encoding target data. Decoding method.

  According to another aspect of the present invention, an input unit that inputs encoding target data constituting a numerical sequence including a plurality of values, and the value that is not 0 among the encoding target data are value encoding targets. A value storage unit that stores data, and a runz storage that stores, as runz encoding target data, the number of consecutive values that are 0 between the non-zero value and the other non-zero values. And the runz encoding target data are encoded using a first Huffman table, and the value encoding target data is encoded using a second Huffman table different from the first Huffman table. A data compression apparatus comprising: an encoding unit; and a transmission unit that transmits the encoded data encoded by the encoding unit using a communication method for transmitting and receiving fixed-length data. A reception unit that receives the encoded data transmitted from a unit by a communication method that transmits and receives fixed-length data; and the runz encoding target data that is encoded using the first Huffman table. And a decoding unit that decodes the value encoding target data encoded using the second Huffman table using the second Huffman table and the second Huffman table. A data decoding device comprising: a calculation unit that calculates the encoding target data based on the runz encoding target data and the decoded value encoding target data; and the fixed length Is a data compression and decoding system characterized in that the length is based on the bit width of the data to be encoded.

  According to the data compression device or data compression method of the present invention, the input unit inputs data to be encoded that constitutes a numerical sequence including a plurality of values. In addition, the determination unit performs zero-run length encoding of the encoding target data, sets the number of consecutive zero values in the numerical sequence as runz data, sets non-zero values as value data, and further sets the value data. A numerical value indicating the minimum bit length that can express the absolute value of is defined as group data. The encoding unit also encodes the runz data using a one-dimensional first Huffman table and the group data using a one-dimensional second Huffman table different from the first Huffman table. Further, an additional bit for specifying value data is calculated from the group data. Further, the transmission unit uses the runz data encoded by the encoding unit as Huffman, the group data encoded by the encoding unit as Huffman, and the additional bits calculated by the encoding unit as encoded data of the encoding target data. , And transmit using a communication method for transmitting and receiving fixed-length data. The fixed length is the maximum length of data to be transmitted, and the fixed length can be shortened based on the maximum bit length after encoding of the encoding target data.

  In this way, since encoding is performed using a one-dimensional Huffman table, the number of code types is reduced. As the number of code types decreases, the maximum bit length after Huffman encoding also decreases. Therefore, when data is transmitted by a communication method for transmitting and receiving fixed-length data, the fixed length can be shortened and communication efficiency can be improved.

  Further, according to the data decoding device or the data decoding method of the present invention, the receiving unit receives the encoded data transmitted from the data compression device by a communication method for transmitting and receiving fixed length data. The decoding unit also decodes the runz data encoded using the first Huffman table using the first Huffman table and the group data encoded using the second Huffman table. Then, decoding is performed using the second Huffman table, and value data is calculated based on the group data and the additional bits. Further, the calculation unit calculates encoding target data based on the decoded runz data and the calculated value data.

  Thus, since decoding is performed using a one-dimensional Huffman table, the number of code types is reduced. As the number of code types decreases, the maximum bit length after Huffman encoding also decreases. Therefore, the fixed length can be shortened and the communication efficiency can be improved when data is received by a communication method for transmitting and receiving fixed length data.

  Further, according to the data compression and decoding system of the present invention, the input unit inputs the encoding target data constituting a numerical sequence including a plurality of values. In addition, the determination unit performs zero-run length encoding of the encoding target data, sets the number of consecutive zero values in the numerical sequence as runz data, sets non-zero values as value data, and further sets the value data. A numerical value indicating the minimum bit length that can express the absolute value of is defined as group data. The encoding unit also encodes the runz data using a one-dimensional first Huffman table and the group data using a one-dimensional second Huffman table different from the first Huffman table. Further, an additional bit for specifying value data is calculated from the group data. Further, the transmission unit uses the runz data encoded by the encoding unit as Huffman, the group data encoded by the encoding unit as Huffman, and the additional bits calculated by the encoding unit as encoded data of the encoding target data. , And transmit using a communication method for transmitting and receiving fixed-length data. The receiving unit receives the encoded data transmitted from the data compression apparatus by a communication method for transmitting and receiving fixed length data. The decoding unit also decodes the runz data encoded using the first Huffman table using the first Huffman table and the group data encoded using the second Huffman table. Then, decoding is performed using the second Huffman table, and value data is calculated based on the group data and the additional bits. Further, the calculation unit calculates encoding target data based on the decoded runz data and the calculated value data. The fixed length is the maximum length of data to be transmitted, and the fixed length can be shortened based on the maximum bit length after encoding of the encoding target data.

  Thus, since encoding and decoding are performed using a one-dimensional Huffman table, the number of code types is reduced. As the number of code types decreases, the maximum bit length after Huffman encoding also decreases. Therefore, when data is transmitted / received by a communication method for transmitting / receiving fixed length data, the fixed length can be shortened, and communication efficiency can be improved.

It is the block diagram which showed the structure of the data compression and decoding system in the 1st Embodiment of this invention. It is the block diagram which showed the structure of the compression part in the 1st Embodiment of this invention. It is the block diagram which showed the structure of the expansion | extension part in the 1st Embodiment of this invention. It is explanatory drawing which showed the specific example of the zero run length encoding in the 1st Embodiment of this invention. It is the schematic which showed the related table which specifies uniquely the relationship between the quantization scale which the memory | storage part in the 1st Embodiment of this invention memorize | stores, and the kind of Huffman table. It is the schematic which put together the value of runz in the 1st Embodiment of this invention, value, and group. It is the block diagram which showed the structure of the Huffman encoding part in the 1st Embodiment of this invention. It is the flowchart which showed the process sequence of the determination part in the 1st Embodiment of this invention. It is the flowchart which showed the process sequence of the encoding part in the 1st Embodiment of this invention. It is the block diagram which showed the structure of the Huffman expansion part in the 1st Embodiment of this invention. It is the flowchart which showed the process sequence of the decoding part in the 1st Embodiment of this invention. It is the flowchart which showed the process sequence of the output part in the 1st Embodiment of this invention. It is explanatory drawing which showed the specific example of the zero run length encoding in the 2nd Embodiment of this invention. It is explanatory drawing which showed the specific example of the value run length encoding in the 2nd Embodiment of this invention. It is the schematic which put together the value of runz, runv, value, and group in the 2nd Embodiment of this invention. It is the block diagram which showed the structure of the Huffman encoding part in the 2nd Embodiment of this invention. It is the flowchart which showed the process sequence of the determination part in the 2nd Embodiment of this invention. It is the flowchart which showed the process sequence of the encoding part in the 2nd Embodiment of this invention. It is the block diagram which showed the structure of the Huffman expansion part in the 2nd Embodiment of this invention. It is the flowchart which showed the process sequence of the decoding part in the 2nd Embodiment of this invention. It is the flowchart which showed the process sequence of the output part in the 2nd Embodiment of this invention. It is explanatory drawing which showed the specific example of the zero run length encoding in the 3rd Embodiment of this invention. It is explanatory drawing which showed the specific example of the value run length encoding in the 3rd Embodiment of this invention. It is the schematic which put together the value of runz, runv, value, and group in the 3rd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a data compression and decoding system 1 in the present embodiment. In the illustrated example, the data compression and decoding system 1 includes a data compression device 2 and a data decoding device 3. The data compression device 2 includes a compression unit 20 and a transmission unit 30. The data decoding device 3 includes a reception unit 40 and an expansion unit 50.

  The compression unit 20 compresses the image data and inputs the compressed data to the transmission unit. The configuration of the compression unit 20 and the compression method used by the compression unit 20 will be described later. The transmission unit 30 transmits the compressed data compressed by the compression unit 20 to the data decoding device 3 using a standard for transmitting and receiving fixed-length data. The receiving unit 40 receives the compressed data transmitted from the transmitting unit 30 and inputs the received compressed data to the decompressing unit 50. The decompressing unit 50 decompresses (decodes) the compressed data input from the receiving unit 40 and outputs the decompressed data.

  Next, the compression unit 20 will be described. FIG. 2 is a block diagram showing the configuration of the compression unit 20 in the present embodiment. In the example illustrated, the compression unit 20 includes a frequency conversion unit 21, a quantization unit 22, a storage unit 23 (compression device storage unit), and a Huffman encoding unit 24 (encoding unit).

  The frequency conversion unit 21 performs spatial frequency conversion (Fourier transform), and divides the image data input to the compression unit 20 into frequency components. The quantization unit 22 quantizes the frequency component converted by the frequency conversion unit 21 and changes the resolution of each frequency component. The storage unit 23 stores a one-dimensional Huffman table. The Huffman encoding unit 24 encodes the frequency component (encoding target data) quantized by the quantization unit 22 using the Huffman table stored in the storage unit 23, and outputs compressed data.

  Next, the extension unit 50 will be described. FIG. 3 is a block diagram showing the configuration of the decompression unit 50 in the present embodiment. In the illustrated example, the expansion unit 50 includes a storage unit 51 (decoding device storage unit), a Huffman expansion unit 52 (decoding unit), an inverse quantization unit 53, and an inverse frequency conversion unit 54.

  The storage unit 51 stores a one-dimensional Huffman table. The Huffman decompression unit 52 decompresses (decodes) the compressed data input from the reception unit 40 using the Huffman table stored in the storage unit 51, and restores the quantized frequency component. The inverse quantization unit 53 restores the frequency component of the image data from the quantized frequency component. The inverse frequency transform unit 54 performs inverse spatial frequency transform (inverse Fourier transform) to restore image data from the frequency components.

  Next, the encoding method in the Huffman encoder 24 of this embodiment will be described. Hereinafter, among the frequency components input to the Huffman encoding unit 24, the AC component (encoding target data) “5,0,0,0,3,0,0,1,2,0,0,4,0 , 6,... "Will be described using an example of encoding.

  First, the Huffman encoding unit 24 performs zero run length encoding. Specifically, the number of consecutive “0” s in the encoding target data is calculated, and the encoding target data is represented by the number of consecutive “0” s and a value other than “0”. Hereinafter, data indicating the number of consecutive “0” s is referred to as runz. Data indicating a value other than “0” is set to value.

  FIG. 4 is an explanatory diagram showing a specific example of zero-run length encoding. In the illustrated example, the data to be encoded is “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. Since the leading value of the encoding target data shown in the figure is “5”, the number of consecutive “0” s is “0”. Since the value after the encoding target data “5” is “0, 0, 0, 3”, the number of consecutive “0” s is “3”. Further, since the value after the encoding target data “3” is “0, 0, 1”, the number of consecutive “0” is “2”. Since the value after the encoding target data “1” is “2”, the number of consecutive “0” s is “0”. Since the value after the encoding target data “2” is “0, 0, 4”, the number of consecutive “0” s is “2”. Similarly, when the number of consecutive “0” s is calculated, runz becomes “0” “3” “2” “0” “2” “1”. Further, values (values) other than “0” are “5”, “3”, “1”, “2”, “4”, “6”,.

  Next, the Huffman encoding unit 24 calculates a group specifying the value and an additional bit. The group is the same value as the minimum bit length (length of additional bits) that can express the absolute value of Value. The value can be specified by the group and the additional bit. FIG. 5 is a schematic diagram showing the correspondence between groups, values, and additional bit lengths. In the illustrated example, the group corresponding to the value “−1, 1” is “1”, and the additional bit length is “1”. The group corresponding to the value “−3, −2, 2, 3” is “2”, and the additional bit length is “2”. Further, the group corresponding to the value “−7... -4, 4... 7” is “3”, and the additional bit length is “3”. The groups corresponding to other values and the additional bit length are as shown in the figure. With this correspondence, when the value is “5” “3” “1” “2” “4” “6”..., The group is “3” “2” “1” “2” “3” “ 3 "... Further, the additional bit length at this time is “3” “2” “1” “2” “3” “3”.

  FIG. 6 shows the runz, value, and group of the encoding target data “5,0,0,0,3,0,0,1,2,0,0,4,0,6,. It is the schematic which summarized the value of. In the illustrated example, values of runz, value, and group are described in order from the top of the line. For example, in row 101, runz “0”, value “5”, and group “3” are described. In line 102, runz “3”, value “3”, and group “2” are described. The other rows are as illustrated. Note that the data of each row is one code set.

  Next, the Huffman encoding unit 24 encodes runz, group, and value for each code set using a one-dimensional encoding table. It is assumed that the Huffman table (first Huffman table) used for the runz encoding is Hz. Also, the Huffman table (second Huffman table) used for group encoding is Hg. As a result, data obtained by Huffman encoding one code set is Hz [runz] + Hg [group] + value. enc. value. enc is an additional bit. In addition, it is suffixed to the encoded one. enc is added.

  Next, the configuration of the Huffman encoding unit 24 of this embodiment will be described. FIG. 7 is a block diagram showing the configuration of the Huffman encoder 24 of this embodiment. In the illustrated example, the Huffman encoding unit 24 includes an input unit 240, a determination unit 241, and an encoding unit 242. The determination unit 241 includes a storage unit 2410 (value storage unit, runz storage unit). The determination unit 241 determines input data to be encoded, and causes the storage unit 2410 to store trig, one set of runz, group, and value. Also, the determination unit 241 inputs the trig, one set of runz, group, and value stored in the storage unit 2410 to the encoding unit 242. When trig is input, the encoding unit 242 encodes a set of runz, group, and value input together with the trig using a one-dimensional Huffman table. The encoding unit 242 then encodes one set of encoded data, Hz [runz] + Hg [group] + value. output enc. The encoding unit 242 performs this process each time trig is input. By such a procedure, the Huffman encoder 24 encodes the encoding target data.

Next, a detailed processing procedure of the determination unit 241 will be described. FIG. 8 is a flowchart illustrating a processing procedure of the determination unit 241 in the present embodiment.
(Step S <b> 101) The determination unit 241 initializes the value of each variable to “0”. Thereafter, the process proceeds to step S102.

  (Step S102) If it is i <63, the determination part 241 will perform the process of step S103-step S111 after setting it as i ++. Further, the determination unit 241 ends the process unless i <63. Note that since there are 63 AC components that are data to be encoded, the determination unit 241 repeats the processing from step S103 to step S111 63 times. That is, if the number of executions of the processes in steps S103 to S111 is less than 63, the process proceeds to step S103, and otherwise the process ends.

(Step S103) The determination unit 241 sets trig = 0. Thereafter, the process proceeds to step S104.
(Step S104) The determination unit 241 determines whether or not din (i) is “0”. If the determination unit 241 determines that din (i) is “0”, the process proceeds to step S105. Otherwise, the process proceeds to step S108.

(Step S105) The determination unit 241 sets runz_cnt ++. Thereafter, the process proceeds to step S106.
(Step S <b> 106) The determination unit 241 determines whether i is “62”. If the determination unit 241 determines that i is “62”, the process proceeds to step S107, and otherwise, the process proceeds to step S111.

  (Step S107) The determination unit 241 sets runz = EOB. The determination unit 241 sets runz_cnt = 0. The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S111.

(Step S108) The determination unit 241 sets runz = runz_cnt. Thereafter, the determination unit 241 sets runz_cnt = 0. Thereafter, the process proceeds to step S109.
(Step S109) The determination unit 241 sets the group to a group uniquely specified by din (i). Further, the determination unit 241 sets value = din (i). Thereafter, the process proceeds to step S110.

(Step S110) The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S111.
(Step S111) The determination unit 241 returns to the process of Step S102.

  Through the processing in steps S101 to S111 described above, the determination unit 241 inputs the runz, group, value, and trig to the encoding unit 242 for each code set.

Next, a detailed processing procedure of the encoding unit 242 will be described. FIG. 9 is a flowchart showing a processing procedure of the encoding unit 242 in the present embodiment. The encoding unit 242 performs the following processes of steps S201 to S204 every time a trigger is input from the determination unit 241.
(Step S201) The encoding unit 242 determines whether or not the input trig is “1”. If the encoding unit 242 determines that the input trig is “1”, the process proceeds to step S202. Otherwise, the process ends.

(Step S202) The encoding unit 242 performs Huffman encoding on the input runz using the one-dimensional Huffman table Hz stored in the storage unit 23, and outputs Hz [runz]. Thereafter, the process proceeds to step S203.
(Step S203) The encoding unit 242 determines whether or not the input runz is “EOB”. If the encoding unit 242 determines that the input runz is not “EOB”, the process proceeds to step S204. Otherwise, the process ends.

  (Step S204) The encoding unit 242 performs Huffman coding on the input group using the one-dimensional Huffman table Hg stored in the storage unit 23, and outputs Hg [group]. Also, the encoding unit 242 calculates additional bits corresponding to the input group and value, and sets value. output enc. Thereafter, the process ends.

  Through the processing in steps S201 to S204 described above, the encoding unit 242 encodes runz, group, and value using a one-dimensional Huffman table for each code set, and encodes runz. Hz [runz], Hg [group] encoding group, and additional bit value. enc is output.

  Next, the configuration of the Huffman decompression unit 52 in this embodiment will be described. FIG. 10 is a block diagram showing a configuration of the Huffman decompression unit 52 in the present embodiment. In the illustrated example, the Huffman decompression unit 52 includes a decoding unit 521 and an output unit 522 (calculation unit). The decoding unit 521 decodes the input encoded data, and obtains runz and value for each code set. Also, the encoding unit 521 inputs the acquired one set of runz and value to the output unit 522. The output unit 522 calculates and outputs one set of encoding target data based on the input set of runz and value. Also, the output unit 522 outputs trig to the decoding unit 521 after outputting the encoding target data for one set. When the trig is input, the decoding unit 521 acquires the runz and value of the next code set and inputs them to the output unit 522. When the decoding unit 521 and the output unit 522 repeat the above processing, the Huffman decompression unit 52 decodes the encoded data to be encoded.

  Next, a detailed processing procedure of the decoding unit 521 will be described. FIG. 11 is a flowchart showing a processing procedure of the decoding unit 521 in the present embodiment.

  (Step S301) If num <63, the decoding unit 521 executes the processing of steps S302 to S306, and otherwise ends the processing. Note that the initial value of num is 0. Further, the process of step S301 after the second time is executed when a trigger is input from the output unit 522.

(Step S302) The decoding unit 521 decodes Hz [runz] using the one-dimensional Huffman table Hz stored in the storage unit 51. Also, the decoding unit 521 sets runz as the decoded value of Hz [runz]. Then, the decoding unit 521 inputs runz to the output unit 522. Thereafter, the process proceeds to step S303.
(Step S303) The decryption unit 521 determines whether or not the runz is “EOB”. If the encoding unit 521 determines that the runz is not “EOB”, the process proceeds to step S304. Otherwise, the process proceeds to step S305.

  (Step S304) The decoding unit 521 sets num = runz + 1. Also, the decoding unit 521 decodes Hg [group] using the one-dimensional Huffman table Hg stored in the storage unit 51. Also, the decryption unit 521 sets the group to the decrypted value of Hg [group]. The decoding unit 521 also includes a group and an additional bit value. Based on enc, value is calculated. In addition, the decoding unit 521 sets value [j] as the calculated value value. Then, the decoding unit 521 inputs value [j] to the output unit 522. Thereafter, the process proceeds to step S306.

(Step S305) The decoding unit 521 sets num = 63. Thereafter, the process proceeds to step S306.
(Step S306) The decoding unit 521 returns to the process of Step S301.

  Through the processing in steps S301 to S306 described above, the decoding unit 521 performs Hz [runz], Hg [group], value. enc is decoded using a one-dimensional Huffman table, and runz and value [j] are input to the output unit 522.

Next, a detailed processing procedure of the output unit 522 will be described. FIG. 12 is a flowchart illustrating a processing procedure of the output unit 522 in the present embodiment.
(Step S401) The output unit 522 initializes the value of each variable to “0”. Thereafter, the process proceeds to step S402.
(Step S402) If i <63, the output unit 522 executes the processing of steps S403 to S411, and otherwise proceeds to the processing of step S412.

(Step S403) The output unit 522 sets z_num = runz [k]. Further, the output unit 522 is assumed to be k ++. Thereafter, the process proceeds to step S404.
(Step S <b> 404) The output unit 522 determines whether z_num is not “EOB”. If the output unit 522 determines that z_num is not “EOB”, the process proceeds to step S405. Otherwise, the process proceeds to step S406.

(Step S405) The output unit 522 sets j = 0. The output unit 522 sets n = z_num. Further, the output unit 522 sets i = i + n. Thereafter, the process proceeds to step S407.
(Step S406) The output unit 522 sets j = i. The output unit 522 sets n = 63. Further, the output unit 522 sets i = 63. Thereafter, the process proceeds to step S407.

(Step S407) If j <n, the output unit 522 outputs “0” and proceeds to the process of step S408, and otherwise proceeds to the process of step S409.
(Step S408) The output unit 522 returns to the process of step S407 after setting j ++.

(Step S409) The output unit 522 determines whether i <63. If the output unit 522 determines that i <63, the process proceeds to step S410; otherwise, the process proceeds to step S411.
(Step S410) The output unit 522 sets i ++. The output unit 522 outputs value [m]. The output unit 522 is m ++. Thereafter, the process proceeds to step S411.
(Step S411) The output unit 522 returns to the process of step S402.

  (Step S412) The output unit 522 sets trig = 1. As a result, the output unit 522 inputs trig to the decoding unit 521. Thereafter, the process ends.

  Through the processing in steps S401 to S409 described above, the output unit 522 outputs the encoding target data for each code set.

As described above, according to the present embodiment, since encoding and decoding are performed using a one-dimensional Huffman table, there are fewer types of codes than when encoding and decoding are performed using a two-dimensional Huffman table. . For example, since the Huffman tree depends on the appearance probability of data, the maximum bit length cannot be calculated. However, in a JPEG image, it is considered that the probability distribution is such that the appearance probability of data falls within 16 bits. Assuming this, the code type (number of tables) when the data after quantization of the JPEG image is 12 bits is as follows.
JPEG image: 16 × 12 = 196
This embodiment: 64 + 12 = 76
(Runz: 64 group: 12)
Thus, in JPEG, a short code cannot be assigned even if the appearance probability is high due to an increase in the bit width of input data. However, in this embodiment, the result of encoding using a one-dimensional table is connected, so the number of each code type affects the maximum bit.
Thus, when the code type decreases, the maximum bit length after Huffman encoding also decreases. In addition, since the data compression and decoding system 1 according to the present embodiment transmits and receives data using a communication method for transmitting and receiving fixed-length data, the maximum length of data to be transmitted is determined as a fixed length, and even if the data length to be transmitted is long Send and receive fixed-length data every time, even if it is short. However, in this embodiment, since the maximum bit length after Huffman coding is shortened, the fixed length can be shortened, and communication efficiency can be improved.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. The difference between this embodiment and the first embodiment is that not only zero run length but also value run length is used in this embodiment. Note that the configuration of the data compression and decoding system 1 in the present embodiment is the same as each configuration in the first embodiment.

  Next, the encoding method in the Huffman encoder 24 of this embodiment will be described. Hereinafter, among the frequency components input to the Huffman encoding unit 24, the AC component (encoding target data) “5,0,0,0,3,0,0,1,2,0,0,4,0 , 6,... "Will be described using an example of encoding.

  First, the Huffman encoding unit 24 performs zero run length encoding. Specifically, the number of consecutive “0” s in the encoding target data is calculated, and the encoding target data is represented by the number of consecutive “0” s and a value other than “0”. Hereinafter, data indicating the number of consecutive “0” s is referred to as runz. Data indicating a value other than “0” is set to value. In this embodiment, unlike the first embodiment, when values other than “0” are consecutive, the number of consecutive “0” s is not considered.

  FIG. 13 is an explanatory diagram showing a specific example of zero-run length encoding. In the illustrated example, the data to be encoded is “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. Since the leading value of the encoding target data shown in the figure is “5”, the number of consecutive “0” s is “0”. Since the value after the encoding target data “5” is “0, 0, 0, 3”, the number of consecutive “0” s is “3”. Further, since the value after the encoding target data “3” is “0, 0, 1”, the number of consecutive “0” is “2”. Further, the value after the encoding target data “1” is “2”. However, in this embodiment, when values other than “0” continue, the number of consecutive “0” s between them is not considered. Since the value after the encoding target data “2” is “0, 0, 4”, the number of consecutive “0” s is “2”. Hereinafter, similarly, when the number of consecutive “0” s is calculated, runz becomes “0” “3” “2” “2” “1”. Further, values (values) other than “0” are “5”, “3”, “1, 2”, “4”, “6”,.

  Next, the Huffman encoder 24 performs value run length encoding. Specifically, the number of consecutive values other than “0” in the encoding target data is calculated. Hereinafter, data indicating the number of consecutive values other than “0” is referred to as runv.

  FIG. 14 is an explanatory diagram showing a specific example of value run length encoding. In the illustrated example, the data to be encoded is “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. Since the leading value of the encoding target data shown in the figure is “5” and the subsequent value is “0”, the number of consecutive values other than “0” is “1”. Further, since the value after the encoding target data “5” is “0, 0, 0, 3, 0”, the number of consecutive values other than “0” is “1”. Further, since the value after the encoding target data “3” is “0, 0, 1, 2, 0”, the number of consecutive values other than “0” is “2”. Also, since the value after the encoding target data “2” is “0, 0, 4, 0”, the number of consecutive values other than “0” is “1”. Since the value after the encoding target data “4” is “0, 6,...”, The number of consecutive values other than “0” is “1”. Similarly, when the number of consecutive numbers other than “0” is calculated similarly, runv becomes “1” “1” “2” “1” “1”.

  Next, the Huffman encoding unit 24 calculates a group specifying the value and an additional bit. When the value is “5” “3” “1, 2” “4” “6”..., the group becomes “3” “2” “1, 2” “3” “3”. . Further, the additional bit length at this time is “3” “2” “1, 2” “3” “3”.

  FIG. 15 shows the runz, runv, and value of the encoding target data “5,0,0,0,3,0,0,1,2,0,0,4,0,6,. It is the schematic which summarized the value with, group. In the illustrated example, values of runz, runv, value, and group are described in order from the top of the line. For example, in the row 201, runz “0”, runv “1”, value “5”, and group “3” are described. In line 202, runz “3”, runv “1”, value “3”, and group “2” are described. In line 203, runz “2”, runv “2”, value “1,2”, and group “1,2” are described. The other rows are as illustrated. Note that the data of each row is one code set.

  Next, the Huffman encoder 24 encodes runz, runv, group, and value for each code set using a one-dimensional encoding table. It is assumed that the Huffman table (first Huffman table) used for the runz encoding is Hz. Also, a Huffman table used for coding the runv (the third Huffman table is Hv. Also, a Huffman table used for the group coding (the second Huffman table is Hg. This makes one code set. The Huffman encoded data is Hz [runz] + Hv [runv] + Hg [group] + value.enc, where value.enc is an additional bit, where .enc is the suffix for the encoded data. It is added.

  Next, the configuration of the Huffman encoding unit 24 of this embodiment will be described. FIG. 16 is a block diagram showing a configuration of the Huffman encoder 24 of the present embodiment. In the illustrated example, the Huffman encoding unit 24 includes an input unit 240, a determination unit 241, and an encoding unit 242. The determination unit 241 includes a storage unit 2410 (value storage unit, runz storage unit, runv storage unit). The determination unit 241 determines the input encoding target data, and causes the storage unit 2410 to store trig, one set of runz, runv, group, and value. Also, the determination unit 241 inputs the trig stored in the storage unit 2410, one set of runz, runv, group, and value to the encoding unit 242. When trig is input, the encoding unit 242 encodes a set of runz, runv, group, and value input together with the trig using a one-dimensional Huffman table. Then, the encoding unit 242 outputs one set of encoded data. The encoding unit 242 performs this process each time trig is input. By such a procedure, the Huffman encoder 24 encodes the encoding target data.

Next, a detailed processing procedure of the determination unit 241 will be described. FIG. 17 is a flowchart illustrating a processing procedure of the determination unit 241 in the present embodiment.
(Step S501) The determination unit 241 initializes the values of variables other than trig_tmp to “0”. Thereafter, the process proceeds to step S502.

  (Step S502) If it is i <63, the determination part 241 will perform the process of step S503-step S520 after setting it as i ++. Further, the determination unit 241 ends the process unless i <63. Since there are 63 AC components that are data to be encoded, the determination unit 241 repeats the processing from step S503 to step S520 63 times. That is, if the number of executions of steps S503 to S520 is less than 63, the process proceeds to step S503, and otherwise the process ends.

(Step S503) The determination unit 241 sets trig = 0. Thereafter, the process proceeds to step S504.
(Step S504) The determination unit 241 determines whether or not trig_tmp is “1”. If the determination unit 241 determines that trig_tmp is “1”, the process proceeds to step S505; otherwise, the process proceeds to step S506.

(Step S505) The determination unit 241 sets runz = EOB. The determination unit 241 sets runz_cnt = 0. The determination unit 241 sets trig_tmp = 0. The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, runv, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S506.
(Step S506) The determination unit 241 determines whether or not din (i) is “0”. If the determining unit 241 determines that din (i) is “0”, the process proceeds to step S507. Otherwise, the process proceeds to step S514.

(Step S507) The determination unit 241 determines whether i is not “0” and the runv_cnt is not “0”. If i is not “0” and the determination unit 241 determines that runv_cnt is not “0”, the process proceeds to step S508. Otherwise, the process proceeds to step S509.
(Step S508) The determination unit 241 sets runv = runv_cnt. The determination unit 241 sets runv_cnt = 0. The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, runv, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S509.

(Step S509) The determination unit 241 sets Runz_cnt ++. Thereafter, the process proceeds to step S510.
(Step S <b> 510) The determination unit 241 determines whether i is “62”. If the determination unit 241 determines that i is “62”, the process proceeds to step S511. Otherwise, the process proceeds to step S520. That is, the determination unit 241 determines whether or not din (i) is the final data. If it is determined that din (i) is the final data, the process proceeds to step S511. Advances to the process of step S520.

(Step S511) The determination unit 241 determines whether or not trig is “0”. If the determination unit 241 determines that trig is “0”, the process proceeds to step S512. Otherwise, the process proceeds to step S513.
(Step S512) The determination unit 241 sets runz = EOB. The determination unit 241 sets runz_cnt = 0. The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, runv, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S520.
(Step S513) The determination unit 241 sets runz_cnt = 0. The determination unit 241 sets trig_tmp = 1. Thereafter, the process proceeds to step S520.

(Step S514) The determination unit 241 determines whether or not runv_cnt is “0”. If the determination unit 241 determines that runv_cnt is “0”, the process proceeds to step S515; otherwise, the process proceeds to step S516.
(Step S515) The determination unit 241 sets runz = runz_cnt. The determination unit 241 sets runz_cnt = 0. Thereafter, the process proceeds to step S516.

(Step S516) The determination unit 241 sets group [runv_cnt] as a group uniquely specified by din (i). Further, the determination unit 241 sets value [runv_cnt] = din (i). Thereafter, the process proceeds to step S517.
(Step S517) The determination unit 241 sets runv_cnt ++. Thereafter, the process proceeds to step S518.
(Step S518) The determination unit 241 determines whether i is “62”. If the determination unit 241 determines that i is “62”, the process proceeds to step S519. Otherwise, the process proceeds to step S520. That is, the determination unit 241 determines whether or not din (i) is final data. If it is determined that din (i) is final data, the process proceeds to step S519; Advances to the process of step S520.

(Step S519) The determination unit 241 sets runv = runv_cnt. The determination unit 241 sets runv_cnt = 0. The determination unit 241 sets trig = 1. As a result, trig becomes “1”, so the determination unit 241 outputs runz, runv, group, value, and trig to the encoding unit 242. Thereafter, the process proceeds to step S520.
(Step S520) The determination unit 241 returns to the process of Step S502.

  Through the processing in steps S501 to S520 described above, the determination unit 241 inputs runz, runv, group, value, and trig to the encoding unit 242 for each code set.

Next, a detailed processing procedure of the encoding unit 242 will be described. FIG. 18 is a flowchart illustrating a processing procedure of the encoding unit 242 in the present embodiment. The encoding unit 242 executes the processes of the following steps S601 to 607 each time a trigger is input from the determination unit 241.
(Step S601) The encoding unit 242 determines whether or not the input trig is “1”. If the encoding unit 242 determines that the input trig is “1”, the process proceeds to step S602; otherwise, the process ends.

(Step S602) The encoding unit 242 performs Huffman coding on the input runz using the one-dimensional Huffman table Hz stored in the storage unit 23, and outputs Hz [runz]. Thereafter, the process proceeds to step S603.
(Step S603) The encoding unit 242 determines whether or not the input runz is not “EOB”. If the encoding unit 242 determines that the input runz is not “EOB”, the process proceeds to step S604; otherwise, the process ends.
(Step S604) The encoding unit 242 performs Huffman coding on the input runv using the one-dimensional Huffman table Hv stored in the storage unit 23, and outputs Hv [runv]. Thereafter, the process proceeds to step S605.

  (Step S605) If j <runv, the encoding unit 242 executes the process of step S606 after setting j ++. In addition, the encoding unit 242 ends the process unless i <runv. The initial value of j is 0.

  (Step S606) The encoding unit 242 performs Huffman coding on the input group [j] using the one-dimensional Huffman table Hg stored in the storage unit 23, and outputs Hg [group [j]]. Also, the encoding unit 242 calculates additional bits corresponding to the input group [j] and value [j], and sets value [j]. output enc. Thereafter, the process returns to step S605.

  Through the processing in steps S601 to S606 described above, the encoding unit 242 encodes runz, group [j], and value [j] using a one-dimensional Huffman table for each code set. Hz [runz] in which runz is encoded, Hg [group [j]] in which group is encoded, and additional bits value [j]. enc is output.

  Next, the configuration of the Huffman decompression unit 52 in this embodiment will be described. FIG. 19 is a block diagram showing a configuration of the Huffman decompression unit 52 in the present embodiment. In the illustrated example, the Huffman decompression unit 52 includes a decoding unit 521 and an output unit 522 (calculation unit). The decoding unit 521 decodes the input encoded data, and obtains runz, runv, and value for each code set. Also, the encoding unit 521 inputs the acquired set of runz, runv, and value to the output unit 522. The output unit 522 calculates and outputs one set of encoding target data based on the input set of runz, runv, and value. Also, the output unit 522 outputs trig to the decoding unit 521 after outputting the encoding target data for one set. When trig is input, the decoding unit 521 acquires runz, runv, and value of the next code set and inputs them to the output unit 522. When the decoding unit 521 and the output unit 522 repeat the above processing, the Huffman decompression unit 52 decodes the encoded data to be encoded.

  Next, a detailed processing procedure of the decoding unit 521 will be described. FIG. 20 is a flowchart showing a processing procedure of the decoding unit 521 in the present embodiment.

  (Step S701) If num <63, the decoding unit 521 executes the processes of steps S702 to S708, and otherwise ends the process. Note that the initial value of num is 0. Further, the process of step S701 after the second time is executed when a trigger is input from the output unit 522.

(Step S <b> 702) The decoding unit 521 decodes Hz [runz] using the one-dimensional Huffman table Hz stored in the storage unit 51. Also, the decoding unit 521 sets runz as the decoded value of Hz [runz]. Then, the decoding unit 521 inputs runz to the output unit 522. Thereafter, the process proceeds to step S703.
(Step S703) The decryption unit 521 determines whether or not the runz is “EOB”. If the encoding unit 521 determines that the runz is not “EOB”, the process proceeds to step S704. Otherwise, the process proceeds to step S707.

  (Step S704) The decoding unit 521 decodes Hv [runv] using the one-dimensional Huffman table Hv stored in the storage unit 51. Also, the decoding unit 521 sets the runv as the value of the decoded Hv [runv]. Then, the decoding unit 521 inputs runv to the output unit 522. The decoding unit 521 sets num = runz + runv. Thereafter, the process proceeds to step S705.

  (Step S705) If j <runv, the decoding unit 521 performs the process of step S706 after setting j ++. If i <runv is not the case, the decoding unit 521 proceeds to the process of step S708. The initial value of j is 0.

(Step S706) The decoding unit 521 decodes Hg [group [j]] using the one-dimensional Huffman table Hg stored in the storage unit 51. Also, the decoding unit 521 sets group [j] as the value of the decoded Hg [group [j]]. In addition, the decoding unit 521 uses group [j] and additional bits value [j]. Based on enc, value [j] is calculated. Then, the decoding unit 521 inputs value [j] to the output unit 522. Thereafter, the process returns to step S705.
(Step S707) The decoding unit 521 sets num = 63. Thereafter, the process proceeds to step S708.
(Step S708) The decoding unit 521 returns to the process of Step S701.

  Through the processing in steps S701 to S708 described above, the decoding unit 521 performs Hz [runz], Hg [group [j]], value [j]. enc is decoded using a one-dimensional Huffman table, and runz and value [j] are input to the output unit 522.

Next, a detailed processing procedure of the output unit 522 will be described. FIG. 21 is a flowchart showing the processing procedure of the output unit 522 in the present embodiment.
(Step S801) The output unit 522 initializes the value of each variable to “0”. Thereafter, the process proceeds to step S802.
(Step S802) If i <63, the output unit 522 executes the processing of step S803 to step S813, and otherwise proceeds to the processing of step S815.

(Step S803) The output unit 522 sets z_num = runz [k]. Further, the output unit 522 is assumed to be k ++. Thereafter, the process proceeds to step S804.
(Step S804) The output unit 522 determines whether z_num is not “EOB”. If the output unit 522 determines that z_num is not “EOB”, the process proceeds to step S805; otherwise, the process proceeds to step S806.

(Step S805) The output unit 522 sets j = 0. The output unit 522 sets n = z_num. Further, the output unit 522 sets i = i + n. Thereafter, the process proceeds to step S807.
(Step S806) The output unit 522 sets j = i. The output unit 522 sets n = 63. Further, the output unit 522 sets i = 63. Thereafter, the process proceeds to step S807.

(Step S807) If j <n, the output unit 522 outputs “0” and proceeds to the process of step S808, and otherwise proceeds to the process of step S809.
(Step S808) After setting j ++, the output part 522 returns to the process of step S807.

(Step S809) The output unit 522 determines whether i <63. If the output unit 522 determines that i <63, the process proceeds to step S810; otherwise, the process proceeds to step S814.
(Step S810) The output unit 522 sets v_num = runv [l]. The output unit 522 is assumed to be l ++. The output unit 522 sets i = i + v_num. Thereafter, the process proceeds to step S811.

  (Step S811) If j <v_num, the output unit 522 executes step S812 after setting j ++. Further, if j <v_num is not satisfied, the output unit 522 proceeds to the process of step S814. The initial value of j is 0.

(Step S812) The output unit 522 outputs value [m]. The output unit 522 is m ++. Thereafter, the process returns to step S811.
(Step S813) The output unit 522 returns to the process of step S802.
(Step S814) The output unit 522 sets trig = 1. As a result, the output unit 522 inputs trig to the decoding unit 521. Thereafter, the process ends.

  Through the processing in steps S801 to S814 described above, the output unit 522 outputs the encoding target data for each code set.

  As described above, according to the present embodiment, since encoding and decoding are performed using a one-dimensional Huffman table, there are fewer types of codes than when encoding and decoding are performed using a two-dimensional Huffman table. . Therefore, the maximum bit length after Huffman coding is also shortened. In addition, since the data compression and decoding system 1 according to the present embodiment transmits and receives data using a communication method for transmitting and receiving fixed-length data, the maximum length of data to be transmitted is determined as a fixed length, and even if the data length to be transmitted is long Send and receive fixed-length data every time, even if it is short. However, in this embodiment, since the maximum bit length after Huffman coding is shortened, the fixed length can be shortened, and communication efficiency can be improved. In this embodiment, encoding is performed using not only the zero run length but also the value run length. As a result, the data to be encoded can be encoded more efficiently.

In the present embodiment, the code type (number of tables) when the data after quantization of the JPEG image is 12 bits is as follows.
JPEG image: 16 × 12 = 196
This embodiment: 64 + 64 + 12 = 140
(Runz: 64 runv: 64 group: 12)

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. The difference between this embodiment and the second embodiment is that in this embodiment, “0” that is not continuous is treated as “a number other than 0 (value)”. Note that the configuration of the data compression and decoding system 1 in the present embodiment is the same as each configuration in the second embodiment.

  Next, the encoding method in the Huffman encoder 24 of this embodiment will be described. Hereinafter, among the frequency components input to the Huffman encoding unit 24, the AC component (encoding target data) “5,0,0,0,3,0,0,1,2,0,0,4,0 , 6,... "Will be described using an example of encoding.

  First, the Huffman encoding unit 24 performs zero run length encoding. Specifically, the number of consecutive “0” s in the encoding target data is calculated, and the encoding target data is represented by the number of consecutive “0” s and a value other than “0”. Hereinafter, data indicating the number of consecutive “0” s is referred to as runz. Data indicating a value other than “0” is set to value. In this embodiment, unlike the second embodiment, non-sequential “0” is treated as “a number other than 0”.

  FIG. 22 is an explanatory diagram showing a specific example of zero-run length encoding. In the illustrated example, the data to be encoded is “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. Since the leading value of the encoding target data shown in the figure is “5”, the number of consecutive “0” s is “0”. Since the value after the encoding target data “5” is “0, 0, 0, 3”, the number of consecutive “0” s is “3”. Further, since the value after the encoding target data “3” is “0, 0, 1”, the number of consecutive “0” is “2”. Further, the value after the encoding target data “1” is “2”. However, in this embodiment, when values other than “0” continue, the number of consecutive “0” s between them is not considered. Since the value after the encoding target data “2” is “0, 0, 4”, the number of consecutive “0” s is “2”. The value after the encoding target data “4” is “0, 6”. However, since “0” is “0” which is not continuous, it is treated as “a number other than 0”. Therefore, runz is “0” “3” “2” “2”. Further, values (values) other than “0” are “5”, “3”, “1, 2”, “4, 0, 6”,.

  Next, the Huffman encoder 24 performs value run length encoding. Specifically, the number of consecutive values other than “0” in the encoding target data is calculated. Hereinafter, data indicating the number of consecutive values other than “0” is referred to as runv.

  FIG. 23 is an explanatory diagram showing a specific example of value run length encoding. In the illustrated example, the data to be encoded is “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. Since the leading value of the encoding target data shown in the figure is “5” and the subsequent value is “0”, the number of consecutive values other than “0” is “1”. Further, since the value after the encoding target data “5” is “0, 0, 0, 3, 0”, the number of consecutive values other than “0” is “1”. Further, since the value after the encoding target data “3” is “0, 0, 1, 2, 0”, the number of consecutive values other than “0” is “2”. The value after the encoding target data “2” is “0, 0, 4, 0, 6”, and there is a non-continuous “0” between “4” and “6”. , The number of consecutive values other than “0” is “3”. Therefore, runv is “1” “1” “2” “3”.

  Next, the Huffman encoding unit 24 calculates a group specifying the value and an additional bit. When the value is “5” “3” “1, 2” “4, 0, 6”..., the group is “3” “2” “1, 2” “3, 1, 1”. It becomes. Further, the additional bit length at this time is “3”, “2”, “1, 2”, “3, 1, 1”,.

  FIG. 24 shows the runz, runv, and value of the encoding target data “5, 0, 0, 0, 3, 0, 0, 1, 2, 0, 0, 4, 0, 6,. It is the schematic which summarized the value with, group. In the illustrated example, values of runz, runv, value, and group are described in order from the top of the line. For example, the row 301 describes runz “0”, runv “1”, value “5”, and group “3”. In line 302, runz “3”, runv “1”, value “3”, and group “2” are described. In line 303, runz “2”, runv “2”, value “1,2”, and group “1,2” are described. In line 304, runz “2”, runv “3”, value “4, 0, 6”, and group “3, 1, 1” are described. Note that the data of each row is one code set.

  Next, the Huffman encoder 24 encodes runz, runv, group, and value for each code set using a one-dimensional encoding table. It is assumed that the Huffman table (first Huffman table) used for the runz encoding is Hz. Also, a Huffman table (third Huffman table) used for runv encoding is Hv. Also, the Huffman table (second Huffman table) used for group encoding is Hg. As a result, Huffman-encoded data of one code set is Hz [runz] + Hv [runv] + (Hg [group] + value.enc +...). value. enc is an additional bit. In addition, it is suffixed to the encoded one. enc is added.

  Next, the configuration of the Huffman encoding unit 24 of this embodiment will be described. The configuration of the Huffman encoding unit 24 of the present embodiment is the same as the configuration of the Huffman encoding unit 24 of the second embodiment.

  Next, a detailed processing procedure of the determination unit 241 will be described. The processing procedure of the determination unit 241 of this embodiment is the same processing procedure as that of the determination unit 241 of the second embodiment. However, in the present embodiment, non-continuous “0” is treated as value (number other than 0) for the AC component (data to be encoded). Therefore, the determination unit 241 according to the present embodiment encodes the runz, runv, group, value, and trig for each code set, similarly to the determination unit 241 according to the second embodiment. To enter.

  Next, a detailed processing procedure of the encoding unit 242 will be described. The processing procedure of the encoding unit 242 of the present embodiment is the same processing procedure as that of the encoding unit 242 of the second embodiment. Therefore, the encoding unit 242 according to the present embodiment, like the encoding unit 242 according to the second embodiment, performs runz, group [j], and value [j] for each code set, respectively. Encoded using a one-dimensional Huffman table, Hz [runz] in which runz is encoded, Hg [group [j]] in which group is encoded, and additional bits value [j]. enc is output.

  Next, the configuration of the Huffman decompression unit 52 in this embodiment will be described. The configuration of the Huffman decompression unit 52 of the present embodiment is the same as the configuration of the Huffman decompression unit 52 of the second embodiment.

  Next, a detailed processing procedure of the decoding unit 521 will be described. The processing procedure of the decoding unit 521 of the present embodiment is the same processing procedure as that of the decoding unit 521 of the second embodiment. Therefore, the decoding unit 521 of the present embodiment, like the decoding unit 521 of the second embodiment, for each code set, Hz [runz], Hg [group [j]], and value [ j]. enc is decoded using a one-dimensional Huffman table, and runz and value [j] are input to the output unit 522.

  Next, a detailed processing procedure of the output unit 522 will be described. The processing procedure of the output unit 522 of the present embodiment is the same processing procedure as that of the output unit 522 of the second embodiment. Therefore, the output unit 522 of the present embodiment outputs data to be encoded for each code set, similarly to the output unit 522 of the second embodiment.

  As described above, according to the present embodiment, since encoding and decoding are performed using a one-dimensional Huffman table, there are fewer types of codes than when encoding and decoding are performed using a two-dimensional Huffman table. . Therefore, the maximum bit length after Huffman coding is also shortened. In addition, since the data compression and decoding system 1 according to the present embodiment transmits and receives data using a communication method for transmitting and receiving fixed-length data, the maximum length of data to be transmitted is determined as a fixed length, and even if the data length to be transmitted is long Send and receive fixed-length data every time, even if it is short. However, in this embodiment, since the maximum bit length after Huffman coding is shortened, the fixed length can be shortened, and communication efficiency can be improved. In this embodiment, encoding is performed using not only the zero run length but also the value run length. In the present embodiment, non-continuous “0” is treated as “a number other than 0 (value)”. As a result, the data to be encoded can be encoded more efficiently.

  The first to third embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design does not depart from the gist of the present invention. Etc. are also included.

  DESCRIPTION OF SYMBOLS 1 ... Data compression and decoding system, 2 ... Data compression apparatus, 3 ... Data decoding apparatus, 20 ... Compression part, 21 ... Frequency conversion part, 22 ... Quantization part, 23 51, 210... Storage unit, 24... Huffman encoding unit, 30... Transmitting unit, 40... Receiving unit, 50. ... Inverse quantization unit, 54 ... Inverse frequency conversion unit, 240 ... Input unit, 241 ... Determining unit, 242 ... Encoding unit, 521 ... Decoding unit, 522 ...・ Output section

Claims (6)

An input unit for inputting encoding target data constituting a numeric string including a plurality of values;
The encoding target data is subjected to zero-run length encoding, the number of consecutive values that are 0 in the numerical sequence is runz data, the non-zero value is value data, and the value data A determination unit that uses a numerical value indicating the minimum bit length capable of expressing an absolute value as group data;
The runz data is Huffman encoded using a one-dimensional first Huffman table, the group data is Huffman encoded using a one-dimensional second Huffman table different from the first Huffman table, and an encoding unit for calculating additional bits for specifying the value data from the group data;
The encoded data of the encoding target data includes the runz data encoded by the encoding unit, the group data encoded by the encoding unit, and the additional bits calculated by the encoding unit. As a transmission unit that transmits by a communication method for transmitting and receiving fixed-length data,
Have
When the number of consecutive 0 values in the numerical sequence is 0, the determination unit does not use the number as the runz data.
The determination unit uses the value data as a set of consecutive non-zero values . The determination unit regards the value that is 0 as the value that is not 0 only when the number of consecutive values that are 0 in the numerical sequence is 1, and sets the value as the value data. The data compression apparatus according to claim 1 . A receiving unit that receives the encoded data transmitted from the data compression device according to claim 1 in a communication scheme for transmitting and receiving fixed-length data;
The runz data encoded using the first Huffman table is decoded using the first Huffman table, and the group data encoded using the second Huffman table is Decoding using a second Huffman table and calculating the value data based on the group data and the additional bits;
A calculation unit that calculates the encoding target data based on the decoded runz data and the calculated value data;
A data decoding apparatus comprising: An input step for inputting data to be encoded that constitutes a numeric string including a plurality of values;
The encoding target data is subjected to zero-run length encoding, the number of consecutive values that are 0 in the numerical sequence is runz data, the non-zero value is value data, and the value data A determination step in which a numerical value indicating the minimum bit length capable of expressing an absolute value is set as group data;
The runz data is Huffman encoded using a one-dimensional first Huffman table, the group data is Huffman encoded using a one-dimensional second Huffman table different from the first Huffman table, and an encoding step for calculating additional bits for identifying the value data from the group data;
The runz data encoded in the encoding step, the group data encoded in the Huffman encoding in the encoding step, and the additional bits calculated in the encoding step are encoded data of the encoding target data. As a transmission step for transmitting in a communication method for transmitting and receiving fixed-length data,
Including
In the determination step, when the number of consecutive values that are 0 in the numerical sequence is 0, the number is not used as the runz data,
In the determination step, a set of values that are consecutive and not 0 is used as the value data . A reception step of receiving the encoded data encoded by the data compression method according to claim 4 in a communication method for transmitting and receiving fixed-length data;
The runz data encoded using the first Huffman table is decoded using the first Huffman table, and the group data encoded using the second Huffman table is Decoding using a second Huffman table and calculating the value data based on the group data and the additional bits;
A calculation step of calculating the encoding target data based on the decoded runz data and the calculated value data;
A data decoding method comprising: An input unit for inputting encoding target data constituting a numeric string including a plurality of values;
The encoding target data is subjected to zero-run length encoding, the number of consecutive values that are 0 in the numerical sequence is runz data, the non-zero value is value data, and the value data A determination unit that uses a numerical value indicating the minimum bit length capable of expressing an absolute value as group data;
The runz data is Huffman encoded using a one-dimensional first Huffman table, the group data is Huffman encoded using a one-dimensional second Huffman table different from the first Huffman table, and an encoding unit for calculating additional bits for specifying the value data from the group data;
The encoded data of the encoding target data includes the runz data encoded by the encoding unit, the group data encoded by the encoding unit, and the additional bits calculated by the encoding unit. As a transmission unit that transmits by a communication method for transmitting and receiving fixed-length data,
A data compression device comprising:
A receiver that receives the encoded data transmitted from the transmitter by a communication method for transmitting and receiving fixed-length data;
The runz data encoded using the first Huffman table is decoded using the first Huffman table, and the group data encoded using the second Huffman table is Decoding using a second Huffman table and calculating the value data based on the group data and the additional bits;
A calculation unit that calculates the encoding target data based on the decoded runz data and the calculated value data;
A data decoding device comprising:
Including
When the number of consecutive 0 values in the numerical sequence is 0, the determination unit does not use the number as the runz data.
The data decision and decoding system is characterized in that the determination unit uses the value data as a set of consecutive non-zero values .

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