JP5202919B2 - Characteristic data compression apparatus, characteristic data compression method, characteristic data compression program, characteristic data expansion apparatus, characteristic data expansion method, characteristic data expansion program, information processing apparatus, and image processing apparatus - Google Patents

Description

  The present invention relates to a compressed data structure, a characteristic data compression apparatus, a characteristic data compression method, a characteristic data compression program, a characteristic data expansion apparatus, a characteristic data expansion method, a characteristic data expansion program, and an information processing apparatus.

  An image processing apparatus such as a printing apparatus may have one or more gamma correction tables to perform color correction. For example, in an ink processing system such as CMYK, one gamma correction table is used for each color.

  Characteristic data such as a gamma correction table is usually stored in a rewritable nonvolatile memory or the like so that it can be updated. The storage areas of the nonvolatile memory built in various devices are allocated for each area necessary for various purposes. Since the nonvolatile memory is relatively expensive, characteristic data such as a gamma correction table is stored in a compressed state in order to save a storage area (see, for example, Patent Document 1). The compressed and stored characteristic data is used after being decompressed.

  Further, in the storage area of the nonvolatile memory incorporated in various devices, such characteristic data is stored in a fixed-length area allocated in advance. Therefore, since characteristic data exceeding the fixed length cannot be stored, when updating characteristic data in the apparatus, the updated characteristic data must be stored in the fixed-length area.

In addition, as a technique related to data compression, there is one described in Patent Document 2.
Japanese Patent No. 3784777 JP 2006-217503 A

  However, when storing characteristic data in a fixed-length area after compression, in the conventional compression method, since the compression rate changes depending on the data content, the compressed characteristic data before update can be stored in the fixed-length area. However, there is a possibility that the updated compressed characteristic data cannot be stored in the fixed-length area. In the conventional compression method, even if the data length of the characteristic data before compression is constant, the maximum value of the data length of the characteristic data after compression is not known. For this reason, it is difficult to determine the fixed length shorter than the data size of the original characteristic data so that the compressed characteristic data can be stored even if only the contents of the characteristic data having the same data amount are updated.

  The present invention has been made in view of the problems described above, and a compressed data structure capable of compressing characteristic data and storing it in a fixed-length data area regardless of the contents of the characteristic data, and the compressed data Characteristic data compression apparatus, characteristic data compression method and characteristic data compression program for compressing characteristic data in a structure, characteristic data decompression apparatus, characteristic data decompression method and characteristic data decompression program for decompressing characteristic data compressed in the compressed data structure Another object of the present invention is to obtain an information processing apparatus and an image processing apparatus that have characteristic data in such a compressed data structure and that are used by being decompressed.

  In order to solve the above problems, the present invention is configured as follows.

  The characteristic data compression apparatus according to the present invention is a characteristic data compression apparatus that compresses characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known. The apparatus includes a difference calculation unit that calculates a difference value from two second numerical values in two adjacent pairs of data for the first numerical value, a difference value that can represent the difference value with a first bit length, Difference classifying means for classifying the difference value that is not expressible by the first bit length and that can be expressed by the second bit length, and the difference value that can be expressed by the first bit length is a difference of the first bit length. Difference data arrangement means for arranging the difference values that can be arranged as data and can be expressed by the second bit length as the second bit length difference data and storing the difference values in the characteristic data area of the compressed characteristic data.

  As a result, since the maximum number of difference values determined to be representable by the second bit length can be specified, the characteristic data can be compressed and stored in the fixed-length data area regardless of the contents of the characteristic data. .

The characteristic data compression apparatus according to the present invention may be as follows in addition to the characteristic data compression apparatus described above. In this case, the second bit length is N times (N: integer) times the first bit length.

  As a result, when the unit bit length of the characteristic data area is the second number of bits, by arranging N pieces of difference data of the first bit length without gaps, Since they have the same bit length, the difference data of the first number of bits can be efficiently arranged in the characteristic data area.

The characteristic data compression apparatus according to the present invention may be as follows in addition to any of the characteristic data compression apparatuses described above. In this case, the difference data arrangement means stores position data indicating the appearance position of one or more second-bit difference data in the position data area of the compressed characteristic data, and the difference data arrangement means Difference data having a bit length of 1 is stored continuously in the characteristic data area, and difference data having a second bit length is stored continuously in the characteristic data area .

  Thereby, since the appearance position of the difference data of the second bit length in the series of difference values is held by the position data, the difference data of the first bit length and the difference data of the second bit length are separated. Even if the data is arranged in the characteristic data area, it is possible to identify which difference value the difference data of the second bit length has by referring to the position data at the time of data expansion. Therefore, the difference data of the first bit length can be arranged more densely than the case where the difference data of the first bit length and the difference data of the second bit length are arranged together.

The characteristic data compression apparatus according to the present invention may be as follows in addition to any of the characteristic data compression apparatuses described above. In this case, the compressed characteristic data includes a number data area for storing number data indicating the number of difference data having the first bit length or the number of difference data having the second bit length.

  As a result, the number of second bit length difference data can be specified, and by extracting only that number of position data from the fixed length position data area, all second bit length differences are extracted. The appearance position of data can be specified reliably.

The characteristic data compression apparatus according to the present invention may be as follows in addition to any of the characteristic data compression apparatuses described above. In this case, the second number of bits is the number of bits that can express any of the second numbers.

  As a result, the difference value can always be expressed by the second number of bits.

  The characteristic data compression method according to the present invention is a characteristic data compression method for compressing characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known. The method includes calculating a difference value from two second numerical values in two adjacent pairs of data with respect to the first numerical value, a difference value capable of expressing the difference value with a first bit length, A difference value that can be expressed by the second bit length and the difference value that can be expressed by the first bit length are arranged as difference data of the first bit length. Arranging differential values that can be expressed by the second bit length as differential data of the second bit length, and storing them in the characteristic data area of the compressed characteristic data. Here, the storing step stores the position data indicating the appearance position of one or a plurality of second bit length difference data in the position data area of the compressed characteristic data, and the storing step includes: The bit length difference data is continuously stored in the characteristic data area, and the second bit length difference data is continuously stored in the characteristic data area.

  As a result, since the maximum number of difference values determined to be representable by the second bit length can be specified, the characteristic data can be compressed and stored in the fixed-length data area regardless of the contents of the characteristic data. .

  The characteristic data compression program according to the present invention is a characteristic data compression program for compressing characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known. is there. This program is a difference calculation means for calculating a difference value from two second numerical values in two pairs of data adjacent to each other with respect to the first numerical value, and a differential value capable of expressing the difference value with a first bit length. Difference classifying means for classifying the differential value into a differential value that is not expressible by the first bit length and that can be expressed by the second bit length, and the differential value that can be expressed by the first bit length is the first bit length The difference value that can be expressed as the difference data of the second bit length and can be expressed as the difference data of the second bit length is arranged as the difference data having the second bit length and is stored in the characteristic data area of the compressed characteristic data. Here, the difference data arrangement means stores position data indicating the appearance position of one or more second-bit difference data in the position data area of the compressed characteristic data, and the difference data arrangement means Difference data having a bit length of 1 is stored continuously in the characteristic data area, and difference data having a second bit length is stored continuously in the characteristic data area.

  As a result, since the maximum number of difference values determined to be representable by the second bit length can be specified, the characteristic data can be compressed and stored in the fixed-length data area regardless of the contents of the characteristic data. .

The characteristic data decompression device according to the present invention provides a difference value that can be expressed by the first bit length from the difference data of the first bit length in the characteristic data area of the compressed characteristic data generated by the characteristic data compression device. A differential value extracting unit that extracts and extracts a differential value that can be expressed by the second bit length from the differential data of the second bit length, and a characteristic data restoring unit that restores the characteristic data from the extracted differential value. Here, the difference value extracting means reads position data corresponding to the difference data of one or more second bit lengths from the position data area of the compressed characteristic data, and stores the position data of the array of uncompressed characteristic data. The difference value is extracted by inserting the difference data of the second bit length at the indicated appearance position.

  Thereby, the compressed characteristic data stored in the fixed-length data area can be expanded.

Further, characteristic data decompression device according to the present invention, in addition to one of the above characteristic data decompression apparatus may be as follows. In this case, the difference data extraction means reads the number data from the number data area of the compressed characteristic data, specifies the number of the second bit length difference data, and characterizes the number of the second bit length difference data. The number of first difference data is specified from the number of second bit length difference data, and the number of first bit length difference data is read from the characteristic data region.

In the characteristic data decompression method according to the present invention, the difference value that can be expressed by the first bit length from the difference data of the first bit length in the characteristic data area of the compressed characteristic data generated by the above characteristic data compression method. Extracting the difference value that can be expressed by the second bit length from the difference data of the second bit length, and restoring the characteristic data from the extracted difference value. Here, the extracting step reads out one or a plurality of position data corresponding to the difference data of the second bit length from the position data area of the compression characteristic data, and indicates the position data of the array of uncompressed characteristic data The difference value is extracted by inserting the difference data of the second bit length at the appearance position.

  Thereby, the compressed characteristic data stored in the fixed-length data area can be expanded.

The characteristic data decompression program according to the present invention can represent a computer with the first bit length from the difference data of the first bit length in the characteristic data area of the compressed characteristic data generated by the characteristic data compression program. As a difference value extracting means for extracting a difference value and extracting a difference value that can be expressed by the second bit length from the difference data of the second bit length, and a characteristic data restoring means for restoring the characteristic data from the extracted difference value Make it work. Here, the difference value extracting means reads position data corresponding to the difference data of one or more second bit lengths from the position data area of the compressed characteristic data, and stores the position data of the array of uncompressed characteristic data. The difference value is extracted by inserting the difference data of the second bit length at the indicated appearance position.

  Thereby, the compressed characteristic data stored in the fixed-length data area can be expanded.

An information processing apparatus according to the present invention includes a data storage means having characteristic data in a characteristic data area in a compressed data structure of compressed characteristic data generated by the characteristic data compression apparatus, and a characteristic compressed in the characteristic data area And the above characteristic data decompression device for decompressing data.

  As a result, the maximum number of difference values determined to be representable by the second bit length can be specified, so that the characteristic data is compressed and stored in the fixed-length data area regardless of the contents of the characteristic data. Can do. Furthermore, the compressed characteristic data stored in the fixed-length data area can be expanded and used.

An image processing apparatus according to the present invention includes a data storage unit having a gamma correction table in a characteristic data area as characteristic data in any one of the compressed data structures of the compressed characteristic data generated by the characteristic data compression apparatus, and characteristic data And the above characteristic data decompression device for decompressing the compressed gamma correction table in the area.

  As a result, since the maximum number of difference values determined to be expressible by the second bit length can be specified, the gamma correction table is compressed and stored in a fixed-length data area regardless of the contents of the gamma correction table. I can leave. Furthermore, the compressed gamma correction table stored in the fixed-length data area can be expanded and used.

  According to the present invention, the characteristic data can be compressed and stored in the fixed-length data area regardless of the contents of the characteristic data.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a characteristic data compression apparatus according to Embodiment 1 of the present invention. In FIG. 1, an arithmetic processing unit 1 includes a computer (not shown), executes a characteristic data compression program stored in a recording medium (not shown), a difference calculation unit 11, a difference classification unit 12, and a difference data arrangement unit 13. It is a device that realizes.

  The arithmetic processing unit 1 compresses characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known. In particular, in the first embodiment, a gamma correction table used for image processing is compressed. The gamma correction table is characteristic data having a plurality of pairs of input values (first numerical values) and output values (second numerical values). For example, the range of input values and output values of the gamma correction table for gamma correcting 256 gradation (8 bits) image data is 0-255.

  The difference calculation unit 11 is a processing unit that functions as a difference calculation unit that calculates a difference value from two second numerical values in two pairs of data adjacent to each other with respect to the first numerical value. When the second numerical value of the characteristic data is N-bit data, the calculated difference value is temporarily stored in the data storage device 2 as N-bit uncompressed difference data 22. Difference values are calculated in ascending or descending order of the first numerical value, and the difference values are stored as uncompressed difference data 22 in the calculation order. In the first embodiment, the difference value between the output values of two adjacent pairs of data for the input value in the gamma correction table is calculated. For example, when the output value is 0 when the input value is 0 and the output is 7 when the input value is 1, the difference value is 7. In the case of a monotonically increasing characteristic such as a gamma correction table, all difference values are zero or positive. Then, the difference values are calculated in ascending or descending order of the input values, arranged in the calculation order, and the difference values are stored as uncompressed difference data 22.

  The difference classifying unit 12 can express the difference value calculated by the difference calculating unit 11 with a difference value that can be expressed by the first bit length and a second bit length that is not expressible by the first bit length. It is a processing unit that functions as a difference classifying means for classifying the difference values. The difference classification unit 12 stores, as difference attribute data 23, the difference value data 23 that indicates the difference value that is not expressible with the first bit length and that can be expressed with the second bit length (that is, the appearance position). Store in device 2. In the first embodiment, the difference value is classified into a difference value that can be expressed by 4 bits and a difference value that cannot be expressed by 4 bits and can be expressed by 8 bits. That is, it is classified into a difference value of 15 or less and a difference value of 16 or more. Therefore, in the first embodiment, what is the difference value of 16 or more difference values is stored as the difference attribute data 23.

  The difference data array unit 13 is based on the difference attribute data 23 and is not expressible with the first bit length and the uncompressed difference data 22 including the difference value that can be expressed with the first bit length, and with the second bit length. The characteristic data in the compressed characteristic data 24 is specified by specifying the uncompressed differential data 22 including the differential value that can be expressed, and the differential value that can be expressed by the first bit length is made continuous as the differential data of the first bit length. Difference data arrangement means for storing in the area and subsequently storing the difference value that can be expressed by the second bit length as the difference data of the second bit length in the characteristic data area in the compressed characteristic data 24 It is a processing unit that functions as: In the first embodiment, a difference value of 15 or less is stored in the characteristic data area as 4-bit difference data, and a difference value of 16 or more is stored in the characteristic data area as 8-bit difference data.

  Further, the difference data array unit 13 acquires the appearance position of the difference value that cannot be expressed with the first bit length and that can be expressed with the second bit length from the difference attribute data 23, and uses the appearance position as position data. Stored in a fixed-length position data area in the compressed characteristic data 24. In the first embodiment, the difference data array unit 13 acquires all the appearance positions of 16 or more difference values from the difference attribute data 23, and uses the appearance positions as position data for 15 bytes of position data in the compressed characteristic data 24. Store in the area. Here, in the case of the 256 gradation gamma correction table, since the number of difference values is 255, one position data is 8-bit data that can represent the appearance position such as any one of the 0th to 254th. The Therefore, a maximum of 15 pieces of position data are stored in the 15-byte position data area.

  Further, the difference data array unit 13 refers to the difference attribute data 23, acquires the number of difference data having the second bit length, and stores it as number data in the number data area in the compressed characteristic data 24. In the first embodiment, the difference data array unit 13 stores the number of second bit length difference data in the 1-byte number data area in the compressed characteristic data 24 as 1-byte number data.

  Further, the data storage device 2 stores characteristic data 21 to be subjected to compression processing, uncompressed differential data 22 and differential attribute data 23 generated during the processing, and compressed characteristic data 24 that is a processing result. It is. As the data storage device 2, a hard disk drive, RAM, or the like is used as appropriate.

  The characteristic data 21 is data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known. In the first embodiment, the characteristic data 21 is a gamma correction table. The gamma correction table has as many pairs of input values and output values as the number of input values, that is, the range of input values. For example, when the input value range is 0 to 255, the gamma correction table has 256 pairs of data. In this case, since the range of the output value is limited to 0 to 255, it is known that the minimum value that the output value can take is 0 and the maximum value that the output value can take is 255.

  The uncompressed difference data 22 is data having a second bit length including the difference value calculated by the difference calculation unit 11. In the first embodiment, one uncompressed differential data 22 is 8-bit data. For example, when a difference value is calculated for a 256-gradation gamma correction table, 255 uncompressed difference data 22 are generated.

  The difference attribute data 23 is data including what number difference value (that is, the appearance position) the difference value that cannot be expressed by the first bit length and can be expressed by the second bit length is. The difference attribute data 23 has one piece of position data indicating one appearance position as many as the number of difference values that cannot be expressed by the first bit length and can be expressed by the second bit length. One piece of position data is data having a second bit length. In the first embodiment, one piece of position data is 8-bit data.

  The compressed characteristic data 24 is data having compressed characteristic data in a fixed-length characteristic data area, position data in a fixed-length position data area, and number data in a fixed-length number data area.

  FIG. 2 is a diagram showing an example of the data format of the compressed characteristic data 24 in the first embodiment. In the first embodiment, a gamma correction table having 256 gradations (that is, 8 bits) is compressed. Here, since the first bit length is 4 bits, the second bit length is 8 bits, the minimum value of the output value is 0, and the maximum value of the output value is 255, the characteristic data area 24a The length is a fixed length of 135 bytes, and the length of the position data area 24b is a fixed length of 15 bytes. The number data area 24c is 1 byte.

  Since the maximum value of the output value is 255, the number of difference values of 16 or more is 15 at the maximum. Therefore, the length of the position data area 24b is 15 bytes. When the number of difference values of 16 or more is 15, the area length for storing 8-bit difference data including the difference values of 16 or more is 15 bytes (= 15 × 8 bits), and the difference value of 15 or less The area length for storing the 4-bit difference data including is 120 bytes (= (255-15) × 4 bits). For this reason, it is sufficient that the length of the characteristic data area 24a is 135 bytes (= 15 + 120 bytes). Further, since the maximum number of 8-bit difference data is 15, one byte is sufficient for the number data area 24c. As described above, in the first embodiment, the compressed characteristic data 24 is data having a fixed length of 151 bytes (135 + 15 + 1 bytes). When storing a 256-gamma gamma correction table without compression, a 256-byte storage area is required. If the gamma correction table is stored with this compressed data structure, it is fixed at about 41% less than the non-compressed table. A long storage area is sufficient.

  Next, the operation of the above apparatus will be described. FIG. 3 is a flowchart for explaining the operation of the characteristic data compression apparatus according to the first embodiment.

  The difference calculation unit 11 sequentially calculates the difference value from the second numerical value in the two adjacent pairs of data for the first numerical value in the series of paired data (step S1). Since the paired data having the characteristic input value and the output value are arranged in ascending order of the input value, a difference value between the output values of the two consecutive pairs of data is calculated. These difference values are temporarily stored in the data storage device 2 as uncompressed difference data 22.

  FIG. 4 is a diagram illustrating an example of gamma correction characteristics based on the gamma correction table according to the first embodiment. In FIG. 4, the characteristic is represented by a continuous curve, but actually, the characteristic data by the table is a set of discrete points. In the first embodiment, a gamma correction table having a range of input values and output values of 0 to 255 is used as characteristic data. Therefore, in the first embodiment, since there are 256 pairs of data, 255 difference values are calculated. In the ascending order of input values, the output values of the gamma correction table are G (0), G (1),..., G (254), G (255), and the difference values are DG (0), DG ( In the case of 1),..., DG (254), each difference value DG (i) is calculated by the following equation.

DG (i) = G (i + 1) −G (i), i = 0, 1,.
Next, the difference classifying unit 12 uses a difference value that can be expressed in the first bit length as a difference value in the uncompressed difference data 22 and a second bit length that cannot be expressed in the first bit length. Differences that are classified into expressible difference values and that are not expressible with the first bit length and that can be expressed with the second bit length among the uncompressed differential data 22 arranged in ascending or descending order of the input values The appearance position of the value is stored in the data storage device 2 as the difference attribute data 23 (step S2). In the first embodiment, the difference classifying unit 12 sequentially refers to the uncompressed difference data 22 arranged in ascending or descending order of input values, and what is the difference value of 16 or more difference values? Is stored as difference attribute data 23. That is, the element number in the array for the difference value having a value of 16 or more out of a series of difference value arrays calculated along the ascending or descending order of the input values is stored as the difference attribute data 23.

  Next, based on the difference attribute data 23, the difference data array unit 13 is not expressible with the first bit length and the uncompressed difference data 22 including the difference value that can be expressed with the first bit length, and the second data The uncompressed differential data 22 including the differential value that can be expressed by the bit length is specified. Then, the differential data array unit 13 expands the differential values that can be expressed by the first bit length as differential data of the first bit length, and stores them continuously in the characteristic data area 24a in the compressed characteristic data 24. (Step S3), the differential value that can be expressed by the second bit length is developed as the differential data of the second bit length, and stored in the characteristic data area 24a in the compressed characteristic data 24 (step S4). ). FIG. 5 is a diagram for explaining the bit length of the difference data in the first embodiment. In the first embodiment, a difference value of 15 or less is stored in the characteristic data area 24a as 4-bit difference data as shown in FIG. 5A, and a difference value of 16 or more is shown in FIG. 5B. Thus, it is stored in the characteristic data area 24a as 8-bit difference data. Further, as shown in FIG. 5C, in units of 8 bits, two 4-bit difference data are stored in succession, followed by 4-bit difference data followed by 8-bit difference data. Stored. For this reason, when there are an odd number of 4-bit difference data, 4-bit padding data (insignificant data with all bit values set to 1 or the like) is added after the last 4-bit difference data. .

  In the first embodiment, as shown in FIG. 5A, since a difference value of 15 or less is stored as 4-bit difference data, two difference values are stored in an 8-bit area. In the first embodiment, since the difference between the minimum value and the maximum value is 255, the difference value is originally expressed as 8-bit data. However, as shown in FIG. For, the amount of data is compressed.

  Further, the difference data array unit 13 acquires the appearance position of the difference value that is not expressible with the first bit length and that can be expressed with the second bit length from the difference attribute data 23, and sets the appearance position to the second The data is expanded into bit length position data and stored in the fixed length position data area 24b in the compressed characteristic data 24 (step S5). Position data corresponding to each difference data of the second bit length is stored in the position data area 24b in the same order as the arrangement order of the difference data of the second bit length in the characteristic data area 24a. Thereby, the difference data of the second bit length and the position data are associated with each other. In the first embodiment, the difference data array unit 13 acquires all the appearance positions of 16 or more difference values from the difference attribute data 23, and stores the appearance positions in the position data area 24b as position data.

  Further, the difference data array unit 13 refers to the difference attribute data 23, acquires the number of second bit length difference data, expands the second bit length number data, and stores the second bit length difference data in the compressed characteristic data 24. The number is stored in the number data area 24c (step S6). In the first embodiment, the difference data array unit 13 stores the number of 8-bit difference data in the number data area 24c as 1-byte number data.

  FIG. 6 is a diagram showing a specific example of the compressed characteristic data 24 in the first embodiment. In the compressed characteristic data 24 shown in FIG. 6, in the 135-byte characteristic data area 24a, 253 pieces of 4-bit difference data and 4-bit padding data are first stored, and subsequently, two pieces of 8-bit difference data are stored. Stored. The remaining part of the characteristic data area 24a is filled with padding data. In the 15-byte position data area 24b following the characteristic data area 24a, two position data indicating the appearance positions of two 8-bit difference data are stored. The remaining portion of the position data area 24b is filled with padding data. In the 1-byte number data area 24c subsequent to the position data area 24b, number data indicating the number of 8-bit difference data (two in this case) is stored. Thus, according to this compressed data structure, the 256-gamma gamma correction table is always the compressed characteristic data 24 having a fixed length regardless of the contents of the characteristics.

  As described above, according to the first embodiment, since the maximum number of difference values determined to be expressible with the second bit length can be specified, the characteristic data is compressed regardless of the contents of the characteristic data. It can be stored in a fixed length data area.

  Further, according to the first embodiment, the data structure used for the compressed characteristic data 24 is the difference calculated from the two second numerical values in the two adjacent pair data for the first numerical value of the pair data. A fixed-length characteristic data area 24a for storing a plurality of differential data having values is provided. In this data structure, the difference value determined to be expressible by the first bit length is stored in the characteristic data area 24a as the differential data having the first bit length, and is not expressible by the first bit length. The difference value determined to be expressible with the second bit length is stored in the characteristic data area 24a as the difference data with the second bit length. As a result, since the maximum number of difference values determined to be representable by the second bit length can be specified, the characteristic data can be compressed and stored in the fixed-length data area regardless of the contents of the characteristic data. . Also, since the amount of information is not lost during compression, it can be compressed and decompressed reversibly.

  Further, according to the first embodiment, the second bit length is N times the first bit length. Thereby, when the unit bit length of the characteristic data area 24a is the second number of bits, the difference data of one second bit length is arranged by arranging N pieces of difference data of the first bit length without any gaps. Therefore, the difference data of the first number of bits can be efficiently arranged in the characteristic data area 24a.

  Further, according to the first embodiment, the position data is stored in the fixed-length position data area 24b. The characteristic data area 24a stores the difference data of the first bit length continuously and stores the difference data of the second bit length continuously. As a result, when data is expanded, the difference data can be rearranged by specifying the difference data of the second bit length difference data according to the appearance position. Can be separated from the difference data of the second bit length. For this reason, the difference data of the first bit length can be arranged more densely than the case where the difference data of the first bit length and the difference data of the second bit length are arranged together.

  Further, according to the first embodiment, the number data is stored in the number data area 24c. As a result, the number of differential data having the second bit length can be specified. Therefore, by extracting only the number of position data from the fixed-length position data area 24b, all the second bit lengths can be specified. It is possible to reliably specify the appearance position of the difference data.

Further, according to the first embodiment, the second number of bits is the number of bits that can represent all the second numerical values. As a result, the difference value can always be expressed by the second number of bits.
Embodiment 2. FIG.
The characteristic data decompression apparatus according to the second embodiment of the present invention is an information processing apparatus that decompresses the compressed characteristic data generated by the characteristic data compression apparatus according to the first embodiment and generates original characteristic data. For example, such a characteristic data expansion device may be incorporated in an image processing device that performs image processing using a gamma correction table.

  FIG. 7 is a block diagram showing a configuration of the characteristic data decompression apparatus according to Embodiment 2 of the present invention. In FIG. 7, an arithmetic processing unit 51 is a device that incorporates a computer (not shown) and executes a characteristic data decompression program stored in a recording medium (not shown) to realize a data extraction unit 61 and a data conversion unit 62. .

  The data extraction unit 61 extracts a difference value that can be expressed by the first bit length from the difference data of the first bit length in the compressed characteristic data generated by the characteristic data compression device according to the first embodiment, 2 is a processing unit that functions as a difference value extraction unit that extracts a difference value that can be expressed by a second bit length from difference data having a bit length of 2. In the second embodiment, the data extraction unit 61 extracts a difference value that can be expressed in 4 bits from the 4-bit difference data in the compressed characteristic data, and extracts a difference value that can be expressed in an 8-bit length from the 8-bit difference data. To do.

  The data conversion unit 62 is a processing unit that functions as a characteristic data restoration unit that restores characteristic data from the extracted difference value.

  The data storage device 52 also stores compressed characteristic data 71 to be decompressed, uncompressed differential data 72 generated in the middle of processing, and original characteristic data as a processing result, stored in a fixed-length storage area. 73 is a device for storing 73. The compressed characteristic data 71 is the same as the compressed characteristic data 24 in the first embodiment. The characteristic data 73 is the same as the characteristic data 21 in the first embodiment. As the data storage device 52, a rewritable nonvolatile recording medium (hard disk drive, NVRAM: Non-Volatile RAM, etc.), RAM, or the like is used as appropriate. In the second embodiment, the compressed characteristic data 71 is stored in advance in a fixed-length storage area in the NVRAM 81 that is a rewritable nonvolatile memory, and the uncompressed differential data 72 is stored in the RAM 82. The characteristic data 73 is stored in the RAM 82. Furthermore, in the second embodiment, the gamma correction table is expanded as the characteristic data 73, stored in the RAM 82, and used for image processing by an image processing unit (not shown).

  Next, the operation of the above apparatus will be described. FIG. 8 is a flowchart for explaining the operation of the characteristic data decompression apparatus according to the second embodiment.

  The data extraction unit 61 reads the number data from the compressed characteristic data 71 and specifies the number of difference data having the second bit length (step S11). In Embodiment 2, the data extraction unit 61 specifies the number of 8-bit difference data. As shown in FIG. 2, since the position of the number data area 24c is known, the data extracting unit 61 may read the number data from the position.

  Next, the data extraction unit 61 identifies the number of first bit length difference data from the number of second bit length difference data, and uses the first bit length difference data as characteristic data. Read from the area 24a (step S12). The first bit length difference data is converted into second bit length difference data, and stored as uncompressed difference data 72 in the same order as stored in the characteristic data area 24a. Here, only the bit length is converted, and the data value does not change. In the second embodiment, the data extraction unit 61 subtracts the number of 8-bit difference data from the total difference data number to identify the number of 4-bit difference data, and the number of 4-bit difference data is stored in the characteristic data area 24a. Read from the beginning. At this time, the two 4-bit difference data may be read as 8-bit data, and the two difference values may be specified from the upper 4 bits and the lower 4 bits. However, if the number of 4-bit difference data is an odd number, the last padding data portion is discarded.

  Further, the data extraction unit 61 reads the difference data having the second bit length from the characteristic data area 24a by the specified number (step S13). The difference data having the second bit length is stored as uncompressed difference data 72 as it is. At this time, the data extraction unit 61 reads the position data corresponding to the difference data of the second bit length from the position data area 24b of the compressed characteristic data 71, and the position data of the position data of the array of the uncompressed characteristic data 72 is read. The difference data having the second bit length is inserted at the indicated appearance position. Thereby, the differential data before compression is restored. That is, difference data arranged in the order along the ascending or descending order of the first values is obtained.

  Then, the data conversion unit 62 restores the characteristic data 73 from the uncompressed characteristic data 72 (step S14). The restored characteristic data 73 is stored in the RAM 82. In the case of the gamma correction table of the second embodiment, since the output value when the input value is 0 is 0, the output value when the input value is 1 is the value of the first difference data. . Next, the output value when the input value is 2 is a value obtained by adding the value of the second difference data to the value of the first difference data. In this way, the output value at each input value is calculated sequentially. In this way, in the case of characteristic data whose output value for the minimum input value is not known, an area for storing the output value for the minimum input value is provided in the compressed characteristic data 71, and the output value is stored at the time of compression. The output value for the minimum input value may be determined by storing in that area and referring to the output value at the time of decompression.

  As described above, according to the second embodiment, the compressed characteristic data stored in the fixed-length data area can be expanded as in the first embodiment.

  Further, according to the second embodiment, since the compressed characteristic data 71 has a fixed-length data format, it is not necessary to change the length of the storage area when the compressed characteristic data 71 is updated. For example, when the output value of the gamma correction table, that is, the characteristic is changed, it can be surely updated to a new gamma correction table.

  Each embodiment described above is a preferred example of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. It is.

  For example, in the first embodiment, the number data indicates the number of difference data having the second bit length, but may be the number of difference data having the first bit length. In that case, the number of difference data having the second bit length may be obtained by subtracting the number of difference data having the first bit length from the total number of difference data.

  In each of the above embodiments, the gamma correction table of 8 bits, that is, 256 gradations is used as the characteristic data 21 and 73 as an example. However, the gamma correction table of other even bits (2M bits) is used as the characteristic data 21 and 73. Of course. In that case, the second bit length is 2M, and the first bit length is M. The characteristic data is not limited to the gamma correction table, and may be, for example, a measurement value correction table or a calibration table.

  In the first embodiment, the difference value is temporarily stored as the uncompressed difference data 22, and then it is determined whether or not the difference value can be expressed by the first bit length. Before storing the value as uncompressed difference data 22, it may be determined whether or not the difference value can be expressed by the first bit length.

  The present invention is applicable to, for example, a gamma correction table of an image processing apparatus.

It is a block diagram which shows the structure of the characteristic data compression apparatus which concerns on Embodiment 1 of this invention. 6 is a diagram illustrating an example of a data format of compressed characteristic data according to Embodiment 1. FIG. 4 is a flowchart for explaining the operation of the characteristic data compression apparatus according to the first embodiment. 6 is a diagram illustrating an example of gamma correction characteristics based on a gamma correction table according to Embodiment 1. FIG. 6 is a diagram for explaining a bit length of difference data in Embodiment 1. FIG. 6 is a diagram illustrating a specific example of compressed characteristic data according to Embodiment 1. FIG. It is a block diagram which shows the structure of the characteristic data expansion | extension apparatus which concerns on Embodiment 2 of this invention. 10 is a flowchart for explaining the operation of the characteristic data decompression apparatus according to the second embodiment.

Explanation of symbols

11 Difference calculation part (difference calculation means)
12 Difference classification part (difference classification means)
13 Difference data array part (difference data array means)
24a Characteristic data area 24b Position data area 24c Number data area 52 Data storage device (data storage means)
61 Data extraction unit (difference value extraction means)
62 Data converter (characteristic data restoration means)

Claims (12)

  In a characteristic data compression apparatus for compressing characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known to generate compressed characteristic data,
  Difference calculating means for calculating a difference value from two of the second numerical values in the two pairs of data adjacent to each other with respect to the first numerical value;
  A difference classification means for classifying the difference value into a difference value that can be expressed by a first bit length and a difference value that is not expressible by the first bit length and can be expressed by a second bit length;
  The difference value that can be expressed by the first bit length is arranged as difference data of the first bit length, and the difference value that can be expressed by the second bit length is set as difference data of the second bit length. Difference data arrangement means for storing in the characteristic data area of the compressed characteristic data,
  With
  The difference data arrangement means stores position data indicating an appearance position of one or a plurality of difference data of the second bit length in a position data area of the compressed characteristic data,
  The difference data arrangement means stores the difference data of the first bit length continuously in the characteristic data area, and stores the difference data of the second bit length continuously in the characteristic data area. about,
Characteristic data compression device characterized by   The compressed characteristic data includes a number data area of the compressed characteristic data including number data indicating the number of difference data having the first bit length or the number of difference data having the second bit length. The characteristic data compression apparatus according to claim 1.   The characteristic data compression apparatus according to claim 1, wherein the second bit length is an integral multiple of the first bit length.   4. The characteristic data compression apparatus according to claim 1, wherein the second number of bits is a number of bits that can represent all of the second numerical values. 5.   In a characteristic data compression method for compressing characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known to generate compressed characteristic data,
  Calculating a difference value from two of the second numerical values in the two pairs of data adjacent to each other for the first numerical value;
  Classifying the difference value into a difference value that can be represented by a first bit length and a difference value that is not representable by the first bit length and that can be represented by a second bit length;
  The difference value that can be expressed by the first bit length is arranged as difference data of the first bit length, and the difference value that can be expressed by the second bit length is set as difference data of the second bit length. And storing in the characteristic data area of the compressed characteristic data;
  With
  The storing step stores one or a plurality of position data indicating an appearance position of the difference data of the second bit length in a position data area of the compressed characteristic data;
  The storing step stores the difference data of the first bit length continuously in the characteristic data area, and stores the difference data of the second bit length continuously in the characteristic data area. ,
The characteristic data compression method characterized by the above-mentioned.   A characteristic data compression program for compressing characteristic data having a plurality of pair data of a first numerical value and a second numerical value whose minimum value and maximum value are known to generate compressed characteristic data in a computer ,
  The computer,
  Difference calculating means for calculating a difference value from two of the second numerical values in the two pairs of data adjacent to each other with respect to the first numerical value;
  Difference classification means for classifying the difference value into a difference value that can be expressed by a first bit length and a difference value that is not expressible by the first bit length and can be expressed by a second bit length; and
  The difference value that can be expressed by the first bit length is arranged as difference data of the first bit length, and the difference value that can be expressed by the second bit length is set as difference data of the second bit length. Difference data array means for storing in the characteristic data area of the compressed characteristic data,
  Function as
  The difference data arrangement means stores position data indicating an appearance position of one or a plurality of difference data of the second bit length in a position data area of the compressed characteristic data,
  The difference data arrangement means stores the difference data of the first bit length continuously in the characteristic data area, and stores the difference data of the second bit length continuously in the characteristic data area. about,
Characteristic data compression program characterized by   5. From the first bit length difference data to the first bit length in the characteristic data area of the compressed characteristic data generated by the characteristic data compression device according to claim 1. A differential value extracting means for extracting a differential value that can be expressed and extracting a differential value that can be expressed by the second bit length from the differential data of a second bit length;
  Characteristic data restoring means for restoring the characteristic data from the extracted difference value;
  With
  The difference value extraction means reads position data corresponding to one or a plurality of difference data of the second bit length from the position data area of the compressed characteristic data, and the position data of the array of uncompressed characteristic data The difference value is extracted by inserting the difference data of the second bit length at the appearance position indicated by
A characteristic data decompression device characterized by that.   The difference data extraction means reads the number data from the number data area of the compressed characteristic data, identifies the number of the difference data having the second bit length, and determines the number of second bit length difference data as the difference data. It reads from the characteristic data area, specifies the number of first difference data from the number of difference data of the second bit length, and reads the number of difference data of the first bit length from the characteristic data area. The specific data decompression device according to claim 7.   A differential value that can be expressed by the first bit length is extracted from the differential data of the first bit length in the characteristic data area of the compressed characteristic data generated by the characteristic data compression method according to claim 5; Extracting a difference value that can be expressed by the second bit length from the difference data having a bit length of 2;
  Restoring the characteristic data from the extracted difference value;
  With
  The extracting step reads out one or a plurality of position data corresponding to the difference data of the second bit length from the position data area of the compression characteristic data, and extracts the position data of the array of uncompressed characteristic data. The difference value is extracted by inserting the difference data of the second bit length into the appearance position shown
The characteristic data decompression method characterized by the above-mentioned.   Computer
  Extracting a differential value that can be expressed by the first bit length from the differential data of the first bit length in the characteristic data area of the compressed characteristic data generated by the characteristic data compression program according to claim 6; A differential value extracting means for extracting a differential value that can be expressed by the second bit length from the differential data of the second bit length; and
  Characteristic data restoring means for restoring the characteristic data from the extracted difference value;
  Function as
  The difference value extraction means reads position data corresponding to one or a plurality of difference data of the second bit length from the position data area of the compressed characteristic data, and the position data of the array of uncompressed characteristic data The difference value is extracted by inserting the difference data of the second bit length at the appearance position indicated by
Characteristic data decompression program characterized by that.   Data storage means having characteristic data in a characteristic data area in a compressed data structure of compressed characteristic data generated by the characteristic data compression device according to any one of claims 1 to 4,
  The characteristic data decompression device according to claim 7, wherein the characteristic data that is compressed in the characteristic data area is decompressed.
  An information processing apparatus comprising:   5. A data storage means having a gamma correction table as characteristic data in a characteristic data area in a compressed data structure of compressed characteristic data generated by the characteristic data compression apparatus according to claim 1. When,
  The characteristic data expansion device according to claim 7, wherein the gamma correction table that is compressed in the characteristic data area is expanded.
  An image processing apparatus comprising:

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