JP6105355B2 - Image compression apparatus, image expansion apparatus, and operation control method thereof - Google Patents

Description

  The present invention relates to an image compression apparatus, an image expansion apparatus, and an operation control method thereof.

  Various algorithms for image compression / decompression have been proposed. Non-Patent Document 1 defines PNG (Portable Network Graphics) which is an image format compressed and expanded by a Deflate (deflate) algorithm. Japanese Patent Application Laid-Open No. H10-228561 describes a method in which a fixed-length block unit is cut out from an image, image information and attribute information are compressed in a fixed length, and are combined and stored in a memory. Japanese Patent Application Laid-Open No. 2004-228561 describes that an input image is subjected to entropy coding after wavelet transform, and is divided into tiles associated with the input image, so that only selected tiles are decoded at a desired resolution.

RFC (Request For Comments) 2083

JP 2007-74412 A JP 2006-304345 A

  PNG described in Non-Patent Document 1 can be compressed / expanded only for the entire image, and does not support compression / expansion of only a specific area of a part of the image. In Patent Document 1, since a fixed-length block is compressed at a fixed length, a specific area can be compressed and expanded. However, there is a possibility that lossless compression cannot be performed depending on the data length of the fixed length compression, and the memory consumption may be increased. In the device described in Patent Document 2, an arbitrary region can be easily compressed and expanded, but for that purpose, wavelet transform is required.

  An object of the present invention is to enable only a part of an image to be reversibly compressed and expanded, and to realize high-speed compression / decompression processing.

  An image compression apparatus according to a first aspect of the invention comprises designation means for designating an image area to be compressed in a given original image, division means for dividing an image portion in the image area designated by the designation means into fixed-length block units, Compression means for variable-length compression of each fixed-length divided image block; identifier adding means for adding an identifier including a block identification code for identifying the divided image block to each of the compressed divided image blocks generated by the compression means; Compression processing area information creating means for creating compression processing area information in which each block identification code and position data representing the position occupied by each of the divided image blocks in the original image are stored in association with each other, and the plurality of identifiers Recording control means for recording the compressed divided image block and the compression processing area information on a recording medium; Eteiru.

  The first invention also provides a method suitable for controlling the operation of the image compression apparatus. According to a first aspect of the present invention, there is provided an operation control method for an image compression apparatus, wherein an image area to be compressed is specified by a specifying means in a given original image, and an image portion in the specified image area is divided into fixed length blocks by a dividing means Each of the fixed-length divided image blocks is subjected to variable length compression by the compression means, and an identifier including a block identification code for identifying the divided image block is added to each of the generated compressed divided image blocks by the identifier adding means. The compression processing region information creating means creates compression processing region information in which each block identification code is stored in association with the position data representing the position occupied by each of the divided image blocks in the original image. The compressed divided image block and the compression processing area information are recorded on the recording medium by the recording control means. That.

  According to the first invention, the image portion in the designated image area in the original image is divided in fixed length block units, and each of the fixed length divided image blocks is variable length compressed. Since a plurality of divided image blocks can be subjected to variable length compression in parallel, an image portion in an image area designated at a relatively high speed can be compressed. The designated image area may be the whole or a part of the original image. When the designated image area is a part of the original image, it can be surely compressed at a higher speed than when the entire original image is compressed.

  According to the first aspect of the invention, compression is performed for each divided image block obtained by dividing the designated image area in units of fixed length blocks, so that only arbitrary blocks can be expanded. An identifier including a block identification code that identifies a divided image block used to generate the compressed divided image block is attached to the compressed divided image block. As a result, the correspondence between the divided image block and the compressed divided image block generated by compressing the divided image block becomes clear. Further, compression processing area information is also created in which each of the block identification codes and position data representing the position (arrangement and arrangement) occupied by each of the divided image blocks in the original image are stored in association with each other. When the original divided image block is generated by expanding the compressed divided image block, the display position of the generated divided image block is also clarified. A reversible compression / decompression process including the display position is realized.

  The position data representing the position in the original image occupied by the divided image block may be included in an identifier added to each compressed divided image block. An image compression apparatus according to a second aspect of the invention comprises designation means for designating an image area to be compressed in a given original image, division means for dividing an image portion in the image area designated by the designation means into fixed-length block units, Each of the fixed-length divided image blocks is compressed by variable length compression, and each of the compressed divided image blocks generated by the compression means includes a block identification code for identifying the divided image block and the divided image block in the original image. An identifier adding means for adding an identifier including position data representing the occupied position, and a recording control means for storing the plurality of compressed divided image blocks with identifiers in a recording medium.

  According to a second aspect of the present invention, there is provided a method for controlling an operation of an image compression apparatus, wherein an image area to be compressed is specified by a specifying means in a given original image, and an image portion in the specified image area is divided into fixed length blocks by a dividing means. Each of the fixed-length divided image blocks is subjected to variable length compression by a compression unit, and each of the generated compressed divided image blocks includes a block identification code for identifying the divided image block and the divided image block in the original image. An identifier including position data representing the occupied position is added by an identifier adding means, and the plurality of compressed divided image blocks with identifiers are recorded on a recording medium by a recording control means.

  According to the second invention, as in the first invention, the image portion in the designated image area in the original image is divided in units of fixed-length blocks, and each of the divided image blocks is variable-length compressed. Since a plurality of divided image blocks can be subjected to variable length compression in parallel, an image portion in an image area designated at a relatively high speed can be compressed. If the designated image area is a part of the original image, high-speed compression can be surely achieved as compared with the case where the entire original image is compressed. It is possible to expand only arbitrary blocks.

  The compression means performs variable length compression on each of the divided image blocks using, for example, an LZ77 (Lempel-Ziv 77) algorithm and Huffman coding.

  Preferably, the image compression device includes a thumbnail image generating unit that generates a thumbnail image obtained by reducing the original image, and a plurality of thumbnail images corresponding to each of a plurality of divided image blocks of the original image. Clickable thumbnail image generating means for generating a clickable thumbnail image in which each of the image blocks is associated with the block identification code and capable of selecting an image block is provided, and the recording medium recording means stores the clickable thumbnail image on the recording medium. To record. The clickable thumbnail image can be used to select (designate) a block to be decompressed from among a plurality of compressed divided image blocks recorded on the recording medium.

  Preferably, the compressed image device is provided with a clickable thumbnail image reading means for reading the clickable thumbnail image from the recording medium and an image block in the clickable thumbnail image selected according to a given request. According to the identification code, there is provided a compressed divided image block reading means with identifier for reading the compressed divided image block with identifier including the block identification code as an identifier.

  The present invention also provides an image expansion device that expands the compressed divided image block generated in the above-described image compression device. An image expansion apparatus according to the present invention has an input means for inputting a block identification code for specifying a divided image block to be expanded, an image part in at least a part of an image area of an original image is divided into fixed length blocks, Each of the fixed-length divided image blocks is subjected to variable length compression, and each of the compressed divided image blocks subjected to variable length compression is assigned an identifier including a block identification code for identifying the divided image block. Reading means for reading the compressed divided image block with identifier having the block identification code input by the input means from the recording means in which the divided image block is recorded, and the compression included in the read compressed divided image block with identifier An expansion unit is provided for expanding the divided image block.

  An operation control method suitable for controlling the image decompression apparatus according to the present invention is such that a block identification code for specifying a divided image block to be decompressed is input by an input means, and an image portion in at least a part of the image area of the original image is input. Are divided into fixed-length block units, each of the fixed-length divided image blocks is variable-length compressed, and each of the compressed divided image blocks subjected to variable-length compression is given an identifier including a block identification code for identifying the divided image block The compressed compressed image block with identifier having the input block identification code is read out from the recording means in which the compressed compressed image block with identifier is recorded, and is included in the read compressed compressed image block with identifier. The compressed divided image block is decompressed by decompression means.

  According to the present invention, it is possible to expand only an arbitrary block among the compressed divided image blocks generated by being compressed by the image compression apparatus. A divided image block obtained by expanding the compressed divided image block for the desired image portion can be acquired. When a plurality of block identification codes are input, a plurality of compressed divided image blocks are expanded. In this case, high-speed decompression processing can be realized by decompressing a plurality of compressed divided image blocks in parallel.

  A computer-readable program suitable for the above-described image compression apparatus and image expansion apparatus operation control method and a recording medium (CD-ROM, DVD-ROM, semiconductor memory, etc.) on which the program is recorded can also be provided.

It is a block diagram which shows the whole structure of an image compression / decompression system. It is a block diagram which shows the electric constitution of an image server. It is a block diagram which shows the electric constitution of a client computer. The image compression process will be described using specific images. It is a flowchart which shows the flow of the image compression process in an image server. The compressed divided image block with an identifier is shown. The state of generation of a clickable thumbnail image is shown. The image expansion process will be described using a specific image. It is a flowchart which shows each process of an image server and a client computer in an image expansion process. The other example of the compression division | segmentation image block with an identifier is shown.

  FIG. 1 is a block diagram showing the overall configuration of an image compression / decompression system.

  The image compression / decompression system includes an image server 2 and a plurality of client computers 3 connected to a network (Internet, LAN, etc.) 1. In this embodiment, as will be described later, the image server 2 performs image compression processing, and the client computer 3 performs compression image expansion processing.

  FIG. 2 is a block diagram showing an electrical configuration of the image server 2.

  The image server 2 includes a control device 4 that performs overall control of the image server 2. The control device 4 includes an image input unit (such as an input port) 5 that receives input of image data, an operation unit 6 including a keyboard, a mouse, and the like. A display device 7 for displaying an image, a memory 8 for temporarily storing data, a predetermined program and data such as an operating system are stored, and compressed image data created by the image server 2 as described later is stored A storage device (such as a hard disk) 9 and a communication device 10 for transmitting and receiving data via the network 1 are connected.

  The control device 4 further includes a compression encoding unit 11 that compresses image data, a compression processing region information creation unit 12 that creates compression processing region information described later, and a clickable thumbnail image creation unit that creates a clickable thumbnail image described later. 13 are connected to each other.

  The compression encoding unit 11 compresses image data using a combination of the LZ77 algorithm and Huffman encoding. If a slide window having a predetermined length including a dictionary portion is sequentially slid from the head with respect to the data sequence of the image data by the LZ77 algorithm, and the data sequence having a predetermined pattern included in the slide window has appeared before, the data sequence Is replaced with a predetermined code. Encoding by the Huffman code including the code replaced by the LZ77 algorithm is performed.

  The compression encoding unit 11 can compress only a part of the input original image. As will be described later, an image portion to be compressed is first divided into a plurality of fixed-length blocks, and each fixed-length divided image block is subjected to variable-length compression. The compression processing area information creation unit 12 generates compression processing area information for specifying the position (arrangement and arrangement) in the original image occupied by each of the plurality of divided image blocks compressed by the compression encoding unit 11. Details of the compression processing area information will be described later.

  The clickable thumbnail image creation unit 13 adds the compression processing area information created by the above-described compression processing area information creation unit 12 to the thumbnail image obtained by reducing the original image, and adds it to each of the plurality of divided image blocks of the original image. A clickable thumbnail image capable of selecting a plurality of image blocks in the corresponding thumbnail image is generated. A compressed divided image block to be decompressed is designated by the clickable thumbnail image. Details of the clickable thumbnail image will also be described later.

  FIG. 3 is a block diagram showing the electrical configuration of the client computer 3.

  The client computer 3 includes a control device 21 that comprehensively controls the entire computer. The control device 21 includes an input device (keyboard, mouse, etc.) 14, a display device 15, a memory 16, a storage device 17, and a communication device 18. It is connected. Further, the expansion unit 19 and the image integration unit 20 are connected to the control device 21.

  The decompression unit 19 performs a process of decompressing the compressed divided image block generated in the image server 2 and returning it to the original divided image block. An algorithm (LZ77 algorithm and Huffman coding) corresponding to the compression encoding unit 11 that generates the compressed divided image block in the image server 2 is also implemented in the decompression unit 19 of the client computer 3. The divided image blocks generated by being expanded by the expansion unit 19 are integrated by the image integration unit 20, and the integrated image is displayed on the display device 15.

  FIG. 4 explains the image compression processing in the image server 2 described above using specific images. FIG. 5 is a flowchart showing the flow of image compression processing in the image server 2.

  Data representing an image to be compressed (original image 30) is input from the image input unit 5 of the image server 2 (step 61) and temporarily stored in the memory 8. Data representing the original image 30 stored in the memory 8 is given to the display device 7, whereby the original image 30 is displayed on the display screen of the display device 7 (see the original image 30 on the upper left side of FIG. 4).

  A part (or all) of the original image 30 displayed on the display device 7 is designated by the user of the image server 2 using the operation unit 6 (step 62). In FIG. 4, a designated region 31 in the original image 30 is indicated by hatching (see the original image 30 in the upper center of FIG. 4). The image part in the designated area 31 is treated as an image part to be compressed.

  The image portion in the designated area 31 is divided into fixed-length blocks (step 63). The data size of the fixed-length block can be set arbitrarily. The number of divisions varies according to the data size of the fixed-length block, the size of the designated area 31 (number of pixels), and the like. In this embodiment, an example in which an image portion in the designated area 31 is divided into six fixed-length blocks will be described. Each of the image portions obtained by dividing the image portion in the designated area 31 into six fixed-length blocks is hereinafter divided into image blocks 31A, 31B, 31C, 31D, 31E, and 31F (see the original image 30 on the upper right side of FIG. 4). Call it. Since it has a fixed length, the data sizes of the divided image blocks 31A, 31B, 31C, 31D, 31E, and 31F are the same.

  Each of the fixed-length divided image blocks 31A, 31B, 31C, 31D, 31E, and 31F is given to the compression encoding unit 11 of the image server 2 described above, and is variable-length compressed in parallel (step 64). As described above, the compression encoding unit 11 uses a combination of the LZ77 algorithm and Huffman encoding. Six compressed divided image blocks 32A, 32B, 32C, 32D, 32E, and 32F (see the lower part of FIG. 4) are generated. By compressing using a combination of the LZ77 algorithm and Huffman coding, the data amounts of the six compressed divided image blocks are generally different (variable length). As variable length compression processing using a combination of the LZ77 algorithm and Huffman coding, Deflate processing is known. For example, PNG (Portable Network Graphics) format image data is generated.

  The compression processing region information creation unit 12 creates compression processing region information 34 including data specifying the position in the original image 30 occupied by each of the six divided image blocks 31A to 31F compressed by the compression encoding unit 11. (Step 65). The compression processing area information 34 is schematically shown in the lower part of FIG. The compression processing area information 34 includes data representing codes (block IDs) I to VI specifying each of the six divided image blocks 31A to 31F, and an original image occupied by each of the divided image blocks 31A to 31F specified by the block ID. Data representing the position in 30. The compression processing area information 34 can be created in a table format.

  Next, identifiers f1 to f6 are assigned to the compressed divided image blocks 32A to 32F, respectively (step 66).

  FIG. 6 shows an identifier-attached compressed divided image obtained by adding an identifier f1 to a compressed divided image block 32A generated by compressing a divided image block 31A that is one of the six divided image blocks 31A to 31F described above. A block (also called a chunk) 33A is shown.

  The compressed divided image block 33A with an identifier is generated by adding an identifier f1 to the header of the compressed divided image block 32A. The identifier f1 is a block ID that identifies the data size of the compressed divided image block 32A and the divided image block 31A used to generate the compressed divided image block 32A (in the case of the divided image block 31A, the block ID is “I”). )including. Based on the block ID included in the identifier f1 and the above-described compression processing area information 34 (see the lower part of FIG. 4), it is possible to determine which area of the original image 30 is the compressed divided image block 32A. it can. Generation of a compressed divided image block with an identifier is performed in, for example, the compression encoding unit 11.

  Returning to FIG. 5, in the clickable thumbnail image creation unit 13, a thumbnail image that is a reduced image of the original image 30 is generated, and the clickable thumbnail image is generated by applying the compression processing area information 34 to the generated thumbnail image. (Step 67).

  FIG. 7 shows how the clickable thumbnail image 30SC is generated. For ease of understanding, the thumbnail image 30S and the clickable thumbnail image 30SC are shown enlarged in FIG.

  The clickable thumbnail image 30SC is generated by applying data representing the positions in the original image of the plurality of divided image blocks included in the compression processing area information 34 to the thumbnail image 30S as a clickable map. As described above, the compression processing area information 34 includes data representing the positions of the six divided image blocks 31A to 31F in the original image 30 (see the lower part of FIG. 4). By applying the position data of the six divided image blocks 31A to 31F to the thumbnail image 30S of the original image 30, six image blocks corresponding to the six divided image blocks 31A to 31F of the original image 30, respectively. Are defined in the thumbnail image 30S, so that the clickable thumbnail image 30SC includes six clickable areas CA. The clickable thumbnail image 30SC is used for selecting an expansion area in the client computer 3, as will be described later.

  The compressed divided image blocks with identifiers 33A to 33F and the clickable thumbnail image 30SC are stored in the storage device 9, and the compression process for the original image 30 is thereby completed. Through the same processing, a set of the compressed divided image block with identifier and the clickable thumbnail image can be stored in the storage device 9 for other original images. Of course, data representing the original image 30 (original image data) may be stored in the storage device 9 in addition to the set of the compressed divided image block with identifier and the clickable thumbnail image.

  The clickable thumbnail image 30SC does not have to be created in advance and stored in the storage device 9, but may be created when a request is received from the client computer 3, as will be described later. In this case, the storage device 9 of the image server 2 stores the compressed divided image blocks 33A to 33F with identifiers and the compression processing area information 34. In addition, the thumbnail image 30S of the original image 30 may be stored in the storage device 9.

  FIG. 8 illustrates image expansion processing in the client computer 3 using specific images. FIG. 9 is a flowchart showing the processing flow of the image server 2 and the client computer 3 in the image expansion processing.

  For example, a plurality of image file names are displayed on the display device 15 of the client computer 3. An image file name to be decompressed is selected by the user of the client computer 3 from the displayed image file names (step 71). Here, the following description will be made assuming that the file name of the original image 30 is selected. A request for the original image 30 is transmitted from the client computer 3 to the image server 2.

  The image server 2 reads data representing the clickable thumbnail image 30SC for the selected original image 30 from the storage device 9 and transmits it to the client computer 3 (step 81). A clickable thumbnail image 30SC is displayed on the display screen of the display device 15 of the client computer 3 (see the left side of FIG. 8).

  In the clickable thumbnail image 30SC to be displayed, the above-described clickable area CA is surrounded by a broken line. Instead of the broken line, for example, the clickable area CA may be clearly shown by reducing the brightness. As described above, the clickable thumbnail image 30SC is defined with six clickable areas CA. From among the six clickable areas CA divided, the user of the client computer 3 designates an area (decompression area) for which expansion is desired (desired to obtain image data with good resolution) (step 72). Here, it is assumed that three of the six clickable areas CA are designated. In FIG. 8, the three designated clickable areas CA are indicated by hatching. Block IDs corresponding to the three clickable areas CA indicated by hatching are I, III, and V, respectively (see the compression processing area information 34 in FIG. 7).

  The block IDs for the designated decompression area, here I, III and V, are transmitted from the client computer 3 to the image server 2. The image server 2 reads out the compressed compressed image blocks 33A, 33C, 33E with identifiers including the received block IDs (I, III, and V) as identifiers from the storage device 9 and transmits them to the client computer 3 (step 82).

  The client computer 3 that has received the compressed divided image blocks 33A, 33C, and 33E with identifiers supplies them to the decompression unit 19, where they are decompressed in parallel (step 73). As described above, the decompression unit 19 uses a combination of the LZ77 algorithm and Huffman coding. The compressed divided image blocks 32A, 32C, 32E included in the compressed divided image blocks 33A, 33C, 33E with identifiers are decompressed in parallel to generate data representing the divided image blocks 31A, 31C, 31E. (See FIG. 8).

  The generated data representing the three divided image blocks 31A, 31C, 31E is given to the image integration unit 20 of the client computer 3 and integrated (combined), and an image 40 represented by the integrated image data is displayed. It is displayed on the device 15 (step 74). The arrangement at the time of integration of the three divided image blocks 31A, 31C, and 31E is matched with the arrangement of block images corresponding to the three divided image blocks 31A, 31C, and 31E in the clickable thumbnail image 30SC. On the display device 15 of the client computer 3, an image portion 40 (an image obtained by integrating the divided image blocks 31A, 31C, 31E) of only the decompression area designated by the user is displayed with high definition (see FIG. 8).

  FIG. 10 shows another example of the compressed divided image block 33A1 with an identifier, and shows a data structure corresponding to FIG. In the compressed divided image block 33A with an identifier shown in FIG. 6, the identifier f1a is based on the divided image block 31A used for generating the compressed divided image block 32A in addition to the data size and block ID of the compressed divided image block 32A. The difference is that data including the position occupied in the image 30 is included. When the original divided image block 31A is generated by decompressing the compressed divided image block 32A by including the position data representing the position in the original image 30 occupied by the divided image block 31A in the identifier f1a, the generated divided image is generated. The display position (arrangement and arrangement) of the block 31A can be specified by the identifier f1a.

  In the above-described embodiments, the case where the image server 2 performs image compression and the client 3 performs decompression of the compressed image has been described. However, it is also possible to cause one computer system to perform both image compression and decompression of the compressed image. it can. In the above-described embodiment, the image server 2 includes the compression encoding unit 11, the compression processing area information generation unit 12, and the clickable thumbnail image generation unit 13, and the client 3 includes the expansion unit 19 and the image integration unit 20. Although an example has been described, it goes without saying that the processing of each piece of hardware may be realized by processing using software (computer program). In this case, a program that causes the computer (control device 4) to function as the compression encoding unit 11, the compression processing area information creation unit 12, and the clickable thumbnail image creation unit 13 is stored in the storage device 9 of the image server 2, and the computer ( A program for causing the control device 21) to function as the expansion unit 19 and the image integration unit 20 is stored in the storage device 17 of the client computer 3.

2 Image server (image compression device)
3 Client computer (image expansion device)
9,17 Storage device
10, 18 Communication device
11 Compression encoder
12 Compression processing area information creation part
13 Clickable thumbnail image generator
19 Extension
30 Original image
30S thumbnail image
30SC Clickable thumbnail image
31 Specified area
31A, 31B, 31C, 31D, 31E, 31F Split image block
32A, 32B, 32C, 32D, 32E, 32F compression divided image block
33A, 33B, 33C, 33D, 33E, 33F Identifier / compressed divided image block f1, f1a, f2, f3, f4, f5, f6 identifier
34 Compression processing area information

Claims (10)

A specifying means for specifying an image area to be compressed in the given original image;
A dividing means for dividing the image portion in the image area specified by the specifying means into fixed-length blocks;
Compression means for variable-length compression of each fixed-length divided image block;
Identifier adding means for adding an identifier including a different block identification code for specifying each of the divided image blocks to each of the compressed divided image blocks generated by the compression means;
Compression processing region information creating means for creating compression processing region information in which each of the block identification codes and position data representing the position occupied by each of the divided image blocks in the original image are stored in association with each other, and the plurality of identifiers Recording control means for recording the attached compressed divided image block and the compression processing area information on a recording medium;
An image compression apparatus comprising: A specifying means for specifying an image area to be compressed in the given original image;
A dividing means for dividing the image portion in the image area specified by the specifying means into fixed-length blocks;
Compression means for variable-length compression of each fixed-length divided image block;
Adding an identifier containing a position data representing each said divided image block occupies positions in different block identification code and the original image to identify the respective divided image blocks compressed divided image blocks generated by the compression means Identifier adding means for recording, and recording control means for storing the plurality of compressed compressed image blocks with identifiers in a recording medium,
An image compression apparatus comprising: Input means for inputting a block identification code for specifying a divided image block to be expanded;
An image portion in at least a part of the image area of the original image is divided into fixed-length block units, each of the fixed-length divided image blocks is variable-length compressed, and each of the compressed divided image blocks that are variable-length compressed A block identification code input by the input means from the recording means in which the compressed divided image blocks with identifiers are recorded, to which identifiers including mutually different block identification codes specifying each of the divided image blocks are given. Reading means for reading compressed divided image blocks with identifiers, and decompressing means for expanding compressed divided image blocks included in the read compressed divided image blocks with identifiers,
An image expansion apparatus comprising: The compression means performs variable length compression on each of the divided image blocks using the LZ77 algorithm and Huffman coding.
The image compression apparatus according to claim 1. The decompression means decompresses the compressed divided image block using the LZ77 algorithm and Huffman coding.
The image expansion device according to claim 3. Thumbnail image generation means for generating a thumbnail image obtained by reducing the original image, and each of the plurality of image blocks of the thumbnail image corresponding to each of the plurality of divided image blocks of the original image and the block identification code Clickable thumbnail image generation means for generating a clickable thumbnail image that can select an image block,
The recording control means is for recording the clickable thumbnail image on the recording medium.
The image compression apparatus according to claim 1. Clickable thumbnail image reading means for reading the clickable thumbnail image from the recording medium according to a given request, and the block identification code according to a block identification code given by selecting an image block in the clickable thumbnail image A compressed divided image block with identifier for reading out the compressed divided image block with an identifier including the identifier from the recording medium,
The image compression apparatus according to claim 6. Specify the image area to be compressed in the given original image by specifying means,
The image part in the specified image area is divided into fixed-length blocks by dividing means,
Each of the fixed-length divided image blocks is compressed by variable length compression means,
Each of the generated compressed divided image blocks, an identifier that includes a different block identification code identifying the respective divided image blocks, adds the identifier adding means,
The compression processing region information creating means creates compression processing region information stored in association with each of the block identification codes and position data representing the position occupied by each of the divided image blocks in the original image,
Recording the plurality of compressed compressed image blocks with identifiers and the compression processing area information on a recording medium by a recording control means;
An operation control method for an image compression apparatus. Specify the image area to be compressed in the given original image by specifying means,
The image part in the specified image area is divided into fixed-length blocks by dividing means,
Each of the fixed-length divided image blocks is compressed by variable length compression means,
Each of the generated compressed divided image blocks in different block identification code and the original image to identify the respective divided image block identifier and a position data representing the position of the divided image blocks is occupied by an identifier adding means Add
Recording the plurality of compressed compressed image blocks with identifiers on a recording medium by a recording control means;
An operation control method for an image compression apparatus. A block identification code for specifying a divided image block to be expanded is input by an input means,
An image portion in at least a part of the image area of the original image is divided into fixed-length block units, each of the fixed-length divided image blocks is variable-length compressed, and each of the compressed divided image blocks that are variable-length compressed identifier that includes a different block identification code identifying the respective divided image blocks is assigned, from the recording means such with identifier compressed divided image blocks is recorded, compressed with an identifier having a block identification code entered Read the divided image block by the reading means,
Decompressing the compressed divided image block included in the read compressed divided image block with identifier by the decompressing means;
An operation control method for an image expansion apparatus.

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