JP2000350044A - Document compressor, document decoder, document compression method, document decoding method and computer-readable recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document compressor that can decode image data of each page of a document, consisting of a plurality of pages and generate data of a smaller size. SOLUTION: This document compressor is constituted so as to generate compression document data 31, that include normal compression data obtained by coding image data of a 1st page as compression data #1 for a 1st page, on the basis of a document of an Mmax page and include difference compression data showing positions and contents of a part of image data of a P-th page different from image data of a (P-1)-th page as compression data #2 to #Mmax for a P-th (P=2 to Mmax) page.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document compression apparatus and a document compression method for generating compressed document data obtained by compressing a document composed of a plurality of pages, and a method for restoring the compressed document data generated by the document compression apparatus and method. The present invention relates to a document restoring device and a document compressing method for performing the same, and a computer-readable recording medium for causing a computer to operate as a document compressing device or a document restoring device.

[0002]

2. Description of the Related Art In a device utilizing digital data, digital data is compressed in order to effectively use a storage area of an auxiliary storage device such as a hard disk device and to shorten information transfer time. Also, in a computer, a document created by various application programs is converted into image data and stored so that the contents can be read by the same application program or output operation such as printing can be easily performed. It has also been done.

[0003]

There are various known compression methods that can be used when a document is converted into image data and stored. However, since the conventional compression method performs compression for each page, when the conventional compression method is used for a certain document including a plurality of pages, the redundancy is high (the compression ratio is not high). ) The compression result was obtained.

Accordingly, a first object of the present invention is to provide compressed document data which can restore the image data of each page of the document based on a document having a plurality of pages, and which has a smaller size than conventional compressed document data. An object of the present invention is to provide a document compression apparatus and a document compression method that can be created.

It is a second object of the present invention to provide a document restoring apparatus and a document restoring method capable of restoring compressed document data created by the document compressing apparatus and method of the present invention.

A third object of the present invention is to provide a computer-readable recording medium which enables a computer to function as such a document compression device or a decompression device.

[0007]

According to a first aspect of the present invention, there is provided a document compression apparatus for encoding compressed image data of a first page of a document to generate compressed normal data of the first page. Creating means, and N-1 pieces of differentially-compressed data each using image data of the second to Nth pages of the document as generated image data and using image data of the immediately preceding page as reference image data, Differential compressed data generating means for generating N-1 differential compressed data indicating the position and content of the portion of the generated image data different from the reference image data; and normal compressed data generated by the normal compressed data generating means. , N-1 difference compressed data created by the difference compressed data creating means, and each normal compressed data And a compressed document data creation means for data and compressed difference data to create a compressed document data including the information indicating whether it relates to one of the pages of the document.

That is, in the document compression apparatus according to the first aspect of the present invention, based on an N page document,
Normal compressed data is included as compressed data for the first page, and compressed data for the Pth page (P = 2 to N) is
Compressed document data including differential compressed data indicating the position and content of a portion of the image data of the Pth page different from the P-1 image data is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Therefore, for a document having many common portions on each page, for example, a document created by spreadsheet software or a fixed document such as an invoice, if the document compression apparatus is used, the document can be converted by a conventional method. As a result, compressed document data smaller in size than data obtained by compression can be obtained.

[0009] The compressed document data creating means constituting the document compressing apparatus includes normal compressed data created by the normal compressed data creating means and N-1 differential compressed data created by the differential compressed data creating means. What kind of form of compressed document data is created as long as it creates compressed document data including information indicating which page of the document each normal compressed data and differential compressed data relate to. It may be. More specifically, the compressed document data creating means may include a normal compressed data file, N-1 differential compressed data files, and which page of the document each normal compressed data and differential compressed data file is related to. The compressed document data may be created from a file containing information indicating the number of compressed compressed data files. The compressed document data may be created. Furthermore, compressed document data in which normal compressed data and N-1 differential compressed data are arranged in the order of page numbers may be created.

[0010] A document compression apparatus according to a second aspect of the present invention comprises a normal compressed data generating means for generating normal compressed data relating to a first page by encoding image data of the first page of the document; N-1 pieces of differentially compressed data using the image data of the second to Nth pages of the document as generated image data and the image data of the first page as reference image data, which is different from the reference image data. Differential compressed data generating means for generating N-1 differential compressed data indicating the position and content of the generated image data, normal compressed data generated by the normal compressed data generating means, and differential compressed data generating means N-1 differential compressed data, and their normal compressed data and differential And a compressed document data generating means for generating a compressed document data reduced data includes information indicating whether it relates to one of the pages of the document.

That is, in the document compression apparatus according to the second aspect of the present invention, based on a document of N pages,
Normal compressed data is included as compressed data for the first page, and compressed data for the Pth page (P = 2 to N) is
Compressed document data including differential compressed data indicating the position and content of a portion of the image data of the Pth page different from the image data of the first page is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Therefore, if the document compression apparatus is used for a document in which each page has many portions in common, for example, a document created by spreadsheet software or a fixed document such as a bill, data obtained by a conventional method can be used. Thus, compressed document data having a smaller size can be obtained.

A document compression apparatus according to a third aspect of the present invention uses differential compressed data in which image data of a certain page of a document is used as generated image data and reference image data is used as image data of a different page. A differential compressed data generating means for generating differential compressed data indicating a position and contents of a part of the generated image data different from the reference image data for all combinations of two pages included in the document; N × created by data creation means
The (N-1) pieces of differentially compressed data are classified into N groups of N-1 pieces of differentially compressed data in which the same image data is used as reference image data. Sum calculating means for calculating the sum of the sizes of the differential compressed data, and encoding the image data used as the reference image data when creating the differential compressed data in the group having the smallest total calculated by the total calculating means. Thus, the normal compression data creation unit that creates the normal compression data for the page represented by the image data, the normal compression data created by the normal compression data creation unit, and the sum calculated by the sum calculation unit N-1 difference compressed data included in the smallest group, their normal compressed data and difference And a compressed document data creation means reduced data to create a compressed document data including information indicating whether it relates to one of the pages of the document.

That is, in the document compression apparatus according to the third aspect of the present invention, based on a document of N pages,
Normal compressed data is included as compressed data for the Xth page, and Pth (P @ X)
X is compressed document data including differential compressed data indicating the position and contents of a portion of the image data of the page different from the image data of the Xth page, and X is selected such that the total size of the differential compressed data is minimized. Compressed document data is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Then, in the present apparatus, the image data commonly used for generating the differential compressed data is selected by the total calculating means or the like so that the total size of the differential compressed data is minimized. Therefore, if the document compression apparatus is used, the second aspect of the present invention is based on a document in which each page has many common portions, for example, a document created by spreadsheet software or a standard document such as an invoice. Can obtain compressed document data having a smaller size than the compressed document data obtained by the document compression apparatus.

A document compression apparatus according to a fourth aspect of the present invention uses differential compressed data in which image data of a certain page of a document is used as generated image data and reference image data which is image data of a different page from the document. A differential compressed data generating means for generating differential compressed data indicating a position and contents of a portion of the generated image data different from the reference image data for all combinations of two pages included in the document; N × created by data creation means
A specifying means for specifying the smallest differential compressed data from the (N-1) differential compressed data; and an image used as reference image data when creating the differential compressed data specified by the specifying means. A normal compressed data generating means for generating normal compressed data for the page represented by the image data by encoding the data; and a standard compressed data generating means for generating the normal compressed data or differential compressed data. The difference compression data having the smallest size was searched for from the difference compression data which was generated as image data, and image data of a page to which normal compression data or difference compression data was not yet associated was generated. The difference compression data is used as the generated image data for its creation. The process of associating the page represented by the used image data with the differential compressed data created by the differential compressed data creating means is performed on all pages except the page to which the normal compressed data of the document is associated. Associating means that repeats until they are associated, normal compressed data created by the normal compressed data creating means, differential compressed data created by the differential compressed data creating means, and associated with each page by the associating means; Includes information indicating which page of the document the normal compressed data and differential compressed data relate to, and information indicating which page image data of each differential compressed data is used as reference image data Create compressed document data Create compressed document data And means.

That is, in the document compression apparatus according to the fourth aspect of the present invention, based on an N page document,
The compressed data for the X-th page includes normal compressed data, and the compressed data for the P-th (P = 1 to X−1, X + 1 to N) pages includes the f-th image data of the P-th page.
A compressed document data including the difference compressed data showing the position and contents of the image data and the different parts of the _P page, X, compression f _P has been selected such that the total size of the compressed difference data is reduced Document data is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Then, in the present apparatus, the image data to be used for generating each differential compressed data is selected by the associating means or the like such that the size of each of the differential compressed data is reduced. Therefore, if the document compression apparatus is used for a document having many common portions on each page, for example, a document created by spreadsheet software or a fixed document such as an invoice, the first to fourth aspects of the present invention are achieved. As a result, compressed document data smaller in size than when the document compression device of the third aspect is used is obtained.

In implementing the document compression apparatus according to the first to fourth aspects of the present invention, the image data of each page except for the page where the normal compressed data is created by the normal compressed data creating means is encoded. With respect to each page except for the page for which the normal compressed data is created by the second normal compressed data creating means for creating N-1 pieces of normal compressed data for each page, Determining means for determining whether or not the size of the differential compressed data is larger than the size of the normal compressed data relating to the page created by the second normal compressed data creating means; For pages for which the size of the differential compressed data is determined to be larger by Compressed document data including normal compressed data created by the second compressed data creating means for the page, further including information indicating a page using the normal compressed data created by the second compressed data creating means. Means for creating data can be employed.

That is, the document compression apparatus may be configured so that normally compressed data is used for pages for which it is not appropriate to use differential compressed data. By adopting such a configuration, a document compression apparatus capable of compressing any document at least at a compression ratio equivalent to that of the related art can be obtained.

Further, as a differential compressed data creating means, the generated image data and the reference image data are compared for each unit data which is data of a predetermined size constituting each image data, so that a plurality of element data can be obtained. Differential compressed data, wherein each element data is an area where one or more unit data of the same content included in the generated image data are continuous, and a corresponding portion of the reference image data has a unit data of the content. , The start position information indicating the start position of the replacement required area, which is an area where no replacement exists, the continuous number information indicating the number of unit data constituting the replacement required area, and the It is also possible to employ a means for creating differential compressed data including replacement data indicating the contents of unit data.

The document to be processed by the document compression apparatus of the present invention may be any document as long as image data can be obtained. The print data may be information that can be converted.

The document restoration apparatus according to the first aspect of the present invention includes normal compressed data relating to the first page of a document and N-1 special compressed data relating to the second to Nth pages of the document, respectively. An apparatus for restoring compressed document data, wherein each piece of special compressed data indicates the position and content of a part of the image data of the related page different from the image data of the previous page. Storage means for storing image data, and decoding means for generating image data representing the first page of the document in the storage means by decoding the normal compressed data relating to the first page contained in the compressed document data. 1
Generating means, first output means for outputting the image data generated in the storage means by the first generation means, and rewriting the contents of the image data stored in the storage means based on the differential compressed data, and obtaining the contents by rewriting. Second output means for sequentially executing the process of outputting the obtained image data on the special compressed data relating to the second to Nth pages included in the compressed document data.

According to the document restoring apparatus, the compressed document data includes the normal compressed data relating to the first page of the document and the N-1 special compressed data relating to the second to N-th pages of the document. , Compressed document data in which each special compressed data indicates the position and content of a part of the image data of the related page different from the image data of the previous page, for example, the document compression apparatus according to the first aspect of the present invention Can be restored.

The first output means and the second output means may output the image data to any place. Specifically, the information may be output to a storage unit, or may be output to a printing device or a communication line.

A document restoring device according to a second aspect of the present invention comprises a storage means for storing image data and a normal compressed data relating to a first page included in the compressed document data, thereby decoding the document. First generating means for generating image data representing the first page in the storage means, first output means for outputting the image data generated in the storage means by the first generation means, and first data in the storage means. Processing for newly generating image data relating to a page, rewriting the generated image data based on the special compressed data, and outputting the image data obtained by the rewriting is performed on the second to Nth pages included in the compressed document data. Second output means for sequentially executing the special compressed data.

According to the document restoring apparatus, the compressed document data includes the normal compressed data on the first page of the document and the N-1 special compressed data on the second through N-th pages of the document. , Compressed document data in which each special compressed data indicates the position and content of a portion of the image data of the associated page different from the image data of the first page, for example, the document compression according to the second aspect of the present invention. The compressed document data created by the device can be decompressed.

According to a third aspect of the present invention, there is provided a document restoring apparatus, comprising: storage means for storing image data; and predetermined decoding of normal compressed data associated with the X-th page included in the compressed document data. Generating means for generating image data representing the X-th page of the document in the storage means by decompressing using the procedure; first output means for outputting the image data generated by the generation means; Generating a copy of the image data related to the X-th page, rewriting the generated copy of the image data based on the differential compressed data, and outputting the image data obtained by the rewriting. The first excluding page X
A second output means for sequentially executing the differentially compressed data on the Nth page.

According to this document restoring apparatus, the document includes normal compressed data on the Xth page of the document and N-1 specially compressed data on the first to Nth pages except the Xth page of the document. Compressed document data, each special compressed data,
Compressed document data indicating the position and content of a portion of the image data of the related page different from the image data of the Xth page, for example, a compressed document created by the document compression apparatus according to the third aspect of the present invention Data can be restored.

In implementing the document restoring apparatus according to the third aspect of the present invention, the first output unit performs processing on the differentially compressed data relating to the X-1 page by the second output unit. , The X + 1-th output by the second output means
It is desirable that the function be performed before the processing on the differentially compressed data relating to the page is executed. That is, it is desirable to be able to output image data in page order.

In implementing the document restoring device according to the first to third aspects of the present invention, when the special compressed data relating to the page to be processed is the normal compressed data, the second output means It is also possible to employ a means for generating image data representing the page in the storage means by decoding the compressed data and outputting the generated image data. When such a second output unit is employed, a document restoring apparatus capable of restoring compressed document data which may include, as special compressed data, normal compressed data whose image data is generated by decoding is obtained. . That is, by using the document decompression devices according to the first to third aspects of the present invention in which the second output means is employed, the first to third aspects of the present invention to which the second normal compressed data creating means and the like are respectively added. The compressed data created by the document compression apparatus according to the third aspect can be restored.

According to a fourth aspect of the present invention, there is provided a document restoring apparatus, comprising: storage means for storing image data; and decoding of normal compressed data related to an X-th page included in compressed document data. A first generation unit for generating image data representing the X-th page of the document in the storage unit; and rewriting the image data stored in the storage unit in accordance with the special compressed data included in the compressed document file. Second generating means for generating image data representing a page to which the special compressed data is related; preparing means for preparing image data to be rewritten by the second generating means in a storage means; Means or both the preparation means and the second generation means, so that the Xth It generates the first to the image data of the N pages except over di-, and a generation-output control means for outputting the image data of the first to N pages generated in the storage means.

According to the document restoring apparatus, the normal compressed data relating to the X-th page of the document, the N-1 special compressed data relating to the first to N-th pages excluding the X-th page of the document, and each special compression data Compressed document data including association information for associating data with another page, and each special compressed data is different from image data of another page associated with the association information of the image data of the associated page Compressed document data indicating the position and content of the part, for example, compressed document data created by the document compression apparatus according to the fourth aspect of the present invention, can be restored.

In implementing the document restoring apparatus according to the fourth aspect of the present invention, special compressed data for which normal compressed data is indicated by the association information as generation / output means is used. In other words, it is possible to adopt a means for generating image data representing a page to which the special compressed data is related in the storage means by decoding the special compressed data.

According to the document restoring apparatus employing the generating / outputting means, the special compressed data which includes the normal compressed data which may generate the image data by decoding may be included as the special compressed data. , And compressed document data including association information including information for associating special compressed data that does not normally use compressed data with another page. That is, by using the document restoring device of the fourth aspect of the present invention employing the above-mentioned generating / outputting means, the document compressing device of the fourth aspect of the present invention to which the second normal compressed data creating means and the like are added The created compressed document data can be restored.

A document compression method according to a first aspect of the present invention is for generating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages. A normal compressed data generating step of generating normal compressed data for the first page by encoding image data of the first page of the document; and an image of the second to Nth pages of the document, respectively. N-1 pieces of differential compressed data using data as generated image data and image data of the immediately preceding page as reference image data, wherein the position of a portion of the generated image data that is different from the reference image data; Differential compression to create N-1 differential compressed data indicating the contents And over data creation step, and usually compressed data created in the normal compression data generating step, was created in the differential compressed data creation step N
A compressed document data generating step of generating compressed document data including one differential compressed data and information indicating which page of the document each of the normal compressed data and the differential compressed data is related to.

That is, in the document compression method according to the first aspect of the present invention, based on N pages of a document,
Normal compressed data is included as compressed data for the first page, and compressed data for the Pth page (P = 2 to N) is
Compressed document data including differential compressed data indicating the position and content of a portion of the image data of the Pth page different from the P-1 image data is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Therefore, if this document compression method is used for a document in which each page has many common portions, for example, a document created by spreadsheet software or a fixed document such as an invoice, the conventional method is used. Thus, compressed document data having a smaller size can be obtained.

A document compression method according to a second aspect of the present invention includes a normal compressed data generating step of generating normal compressed data for a first page by encoding image data of a first page of the document. N-1 pieces of differentially compressed data using the image data of the second to Nth pages of the document as generated image data and the image data of the first page as reference image data, which is different from the reference image data. A differential compressed data generating step of generating N-1 differential compressed data indicating a position and contents of a portion of the generated image data, a normal compressed data generated in the normal compressed data generating step, and a differential compressed data generating step N-1 differentially compressed data created in Data and compressed difference data and a compressed document data creation step of creating a compressed document data including the information indicating whether it relates to one of the pages of the document.

That is, in the document compression method according to the second aspect of the present invention, based on N pages of a document,
Normal compressed data is included as compressed data for the first page, and compressed data for the Pth page (P = 2 to N) is
Compressed document data including differential compressed data indicating the position and content of a portion of the image data of the Pth page different from the image data of the first page is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Therefore, if this document compression method is used for a document in which each page has many common portions, for example, a document created by spreadsheet software or a fixed document such as an invoice, the conventional method is used. Thus, compressed document data of a smaller size can be obtained.

A document compression method according to a third aspect of the present invention is a method for compressing differential data using image data of a certain page of a document as generated image data and reference image data which is image data of a different page from the document. A differential compressed data generating step of generating differential compressed data indicating a position and a content of a part of the generated image data different from the reference image data for all combinations of two pages included in the document; The N × (N−1) difference compressed data created in the data creation step is converted into N using the same image data as the reference image data.
A total calculation step of classifying into N groups of -1 differential compressed data and calculating the total size of the N-1 differential compressed data included in each group; and calculating the total in the total calculating step. A normal compressed data creating step of encoding the image data used as the reference image data at the time of creating the differential compressed data in the group having the smallest sum to create the normal compressed data for the page represented by the image data And the normal compressed data created in the normal compressed data creating step, the N-1 difference compressed data included in the group having the smallest sum calculated in the sum calculation step, the normal compressed data and the difference compressed data Is information about which page of the document And a compressed document data creation step to create a non-compressed document data.

That is, in the document compression method according to the third aspect of the present invention, based on a document of N pages,
The compressed data for the Xth page includes normal compressed data, and the compressed data for the Pth page (P = 1 to X−1, X + 1 to N) includes the Xth page of the image data of the Pth page.
Creates compressed document data including differential compressed data indicating the position and contents of a part different from the image data of the page, wherein X is selected such that the total size of the differential compressed data is minimized. Is done. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. In the document compression method, image data commonly used for generating differential compressed data is selected by processing in a total calculation step or the like such that the total size of such differential compressed data is minimized. Therefore, if this document compression method is used for a document having many common portions on each page, for example, a document created by spreadsheet software or a fixed document such as an invoice, the second aspect of the present invention is achieved.
Thus, compressed document data having a smaller size than the case of using the document compression method according to the aspect can be obtained.

A document compression method according to a fourth aspect of the present invention is a method for compressing differential data using image data of a certain page of a document as generated image data and reference image data which is image data of a different page from the document. A differential compressed data generating step of generating differential compressed data indicating a position and a content of a part of the generated image data different from the reference image data for all combinations of two pages included in the document; A specifying step of specifying the smallest differential compressed data from the N × (N−1) differential compressed data generated in the data generating step; and a step of generating the differential compressed data specified in the specific step. Encodes image data used as reference image data Thus, the normal compressed data creating step for creating the normal compressed data for the page represented by the image data, and the normal compressed data or the differential compressed data for any page already associated with the differential compressed data. The image data is used as the reference image data, and the image data relating to any page to which the normal compressed data or the differential compressed data is not yet associated is selected from among the differential compressed data created as the generated image data. The process of searching for small differential compressed data and associating the searched differential compressed data with the page represented by the image data used as the generated image data in the creation of the compressed differential data of the document All pages except And an associating step that is repeated until any of the differential compressed data created in the differential compressed data creating step is associated with the normal compressed data created in the normal compressed data creating step, and a differential compressed data created in the differential compressed data creating step. The differential compressed data associated with each page in the associating step, information indicating which page of the document the normal compressed data and the differential compressed data relate to, and the image of which page each differential compressed data corresponds to Generating compressed document data including information indicating whether the data is used as reference image data.

That is, in the document compression method according to the fourth aspect of the present invention, based on the document of N pages,
The compressed data for the X-th page includes normal compressed data, and the compressed data for the P-th (P = 1 to X−1, X + 1 to N) pages includes the f-th image data of the P-th page.
A compressed document data including the difference compressed data showing the position and contents of the image data and the different parts of the _P page, X, compression f _P has been selected such that the total size of the compressed difference data is reduced Document data is created. If each page of the document from which the compressed document data is based has many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for that page. Then, in the document compression method, the image data to be used for generating each differential compressed data is selected by the processing in the associating step or the like so that the size of each of the differential compressed data is reduced. Therefore, if the present document compression method is used for a document in which each page has many portions in common, for example, a document created by spreadsheet software or a standard document such as an invoice, the first to third aspects of the present invention are achieved. As a result, compressed document data having a smaller size than when the document compression method of the third aspect is used is obtained.

The document compression method according to the first to fourth aspects of the present invention encodes image data of each page except for the page in which the normal compressed data was created in the normal compressed data creation step, so that each page is encoded. For each page excluding the page where the normal compressed data is created in the second normal compressed data creating step for creating N-1 pieces of normal compressed data and the size of the differential compressed data related to the page, A determination step of determining whether or not the size of the normal compressed data of the page created in the second normal compressed data creation step is larger than the size of the normal compressed data. Differential compression is applied to pages whose size is determined to be larger Indicates compressed compressed document data including normal compressed data created in the second compressed data creation step for the page, in which the normal compressed data created in the second compressed data creation step is used. It may be executed in a form adopting a step of creating compressed document data further including information.

According to the document compression method in which the second normal compressed data creation step is added, compressed document data compressed with a compression ratio at least as high as that of the conventional document can be obtained for any document. Will be obtained.

In the differential compressed data creating step, the generated image data and the reference image data are compared for each unit data which is data of a predetermined size constituting each image data, so that a plurality of element data can be obtained. Differential compressed data, wherein each element data is an area where one or more unit data of the same content included in the generated image data are continuous, and a corresponding portion of the reference image data has a unit data of the content. , The start position information indicating the start position of the replacement required area, which is an area where no replacement exists, the continuous number information indicating the number of unit data constituting the replacement required area, and the A step of creating differential compressed data including replacement data indicating the contents of the unit data may be used.

The document to be processed by the document compression method may be any document as long as a plurality of image data can be obtained. The print data may include printable information.

In the document restoring method according to the first aspect of the present invention, the image data representing the first page of the document is stored in the storage device by decoding the normal compressed data relating to the first page contained in the compressed document data. And a first output step of outputting the image data generated in the storage device in the first generation step, and the contents of the image data stored in the storage device based on the differential compressed data. The process of rewriting and outputting the image data obtained by the rewriting is performed by a second process included in the compressed document data.
To a special output data for the Nth page.

According to this document restoring method, the compressed document data includes normal compressed data relating to the first page of the document and N-1 special compressed data relating to the second to Nth pages of the document. , Compressed document data in which each special compressed data indicates the position and content of a part of the image data of the related page different from the image data of the previous page, for example, the document compression method according to the first aspect of the present invention , The compressed document data created by the device can be restored.

According to the document restoring method of the second aspect of the present invention, the image data representing the first page of the document is stored in the storage device by decoding the normal compressed data relating to the first page contained in the compressed document data. A first generation step of generating image data, a first output step of outputting the image data generated in the storage device in the first generation step, and newly generating image data of a first page in the storage device. Processing of rewriting the compressed image data based on the special compressed data and outputting the image data obtained by the rewriting is sequentially performed on the specially compressed data related to the second to Nth pages included in the compressed document data. A second output step.

According to this document restoring method, the compressed document data includes normal compressed data for the first page of the document and N-1 special compressed data for the second to Nth pages of the document. , Compressed document data in which each special compressed data indicates the position and content of a portion of the image data of the associated page different from the image data of the first page, for example, the document compression according to the second aspect of the present invention. The compressed document data created by the method and apparatus can be decompressed.

In the document restoring method according to the third aspect of the present invention, the normal compressed data associated with the X-th page included in the compressed document data is decompressed by using a predetermined decoding procedure, so that the document is restored. A generating step of generating image data representing the Xth page in the storage device, a first output step of outputting the image data generated in the generating step, and generating a copy of the image data relating to the Xth page in the storage device The process of rewriting a copy of the generated image data based on the differential compressed data and outputting the image data obtained by the rewriting is included in the compressed document data.
A second output step of sequentially performing differential compression data on the first to N-th pages excluding the X-th page.

According to the document restoring method, the document includes normal compressed data on the Xth page of the document and N-1 specially compressed data on the first to Nth pages except the Xth page of the document. Compressed document data, each special compressed data,
Compressed document data indicating the location and content of a portion of the related page image data that is different from the Xth page image data, for example, created by the document compression method and apparatus according to the third aspect of the present invention. Compressed document data can be restored.

In the document restoring method according to the third aspect of the present invention, the first output step includes the step of executing the second output step after performing the processing on the differentially compressed data relating to the X-1 page by the second output step. If the process is performed in a form that functions before the process on the differentially compressed data relating to the X + 1 page is performed, the decompression result can be output in page order.

In executing the document compression method according to the first to third aspects of the present invention, when the specially compressed data relating to the page to be processed is the normally compressed data, the second output step is performed. By decoding the compressed data, image data representing the page may be generated in the storage device, and the generated image data may be output.

According to the document compression methods of the first to third aspects employing the second output step,
Compressed document data, which may include normal compressed data for which image data is generated by decoding as special compressed data, for example, the first to third aspects of the present invention to which a second normal compressed data creating means and the like are added. The compressed document data created by the document compression method according to the first to third aspects of the present invention to which the compressed document data created by the document compression apparatus, the second normal compressed data creation step, and the like are added can be restored.

In a document restoring method according to a fourth aspect of the present invention, image data representing the X-th page of a document is stored by decoding normal compressed data related to the X-th page contained in the compressed document data. A first generating step of generating in the device, and rewriting the image data stored in the storage device in accordance with the special compressed data included in the compressed document file, so that the image data representing the page to which the special compressed data is related A generation step of generating image data, a preparation step of preparing image data to be rewritten in the storage apparatus in the second generation step, and a second generation step or a preparation step and a second generation step according to the association information. , Except for the X-th page in the storage device. Or together with generating the image data of the N pages, and generating and outputting control step of outputting the image data of the first to N pages generated in the storage device.

According to this document restoring method, the normal compressed data relating to the X-th page of the document, the N-1 special compressed data relating to the first to N-th pages excluding the X-th page of the document, and each special compressed data Compressed document data including association information for associating data with another page, and each special compressed data is different from image data of another page associated with the association information of the image data of the associated page Compressed document data indicating the location and content of the part, for example, compressed document data created by the document compression method / apparatus of the fourth aspect of the present invention, can be decompressed.

When the document restoring method according to the fourth aspect of the present invention is executed, the generation and output steps include:
For special compressed data that indicates that normal compressed data is used by the association information, the special compressed data is decoded to store image data representing the page related to the special compressed data. A step of generating in the device may be employed.

According to the document restoring method employing such a generation / output step, compressed document data which may include, as special compressed data, normally compressed data whose image data is generated by decoding, and It is possible to decompress compressed document data including information for identifying special compressed data in which data is used and information for associating special compressed data for which normal compressed data is not used with other pages. it can. That is, by using the document restoring method of the fourth aspect of the present invention in which the above-mentioned generation / output step is adopted, the document compressing apparatus of the fourth aspect of the present invention to which the second normal compressed data creating means and the like are added, The compressed document data created by the document compression method according to the fourth aspect of the present invention to which the second normal compressed data creation step and the like are added can be restored.

The computer readable recording medium of the present invention stores a program for causing a computer to operate as the above-described document compression device or document decompression device of the present invention. Therefore, by using the computer-readable recording medium of the present invention, it is possible to create compressed document data having a smaller size than before, which enables the computer to restore the image data of each page of the original document. Document data can be restored.

[0059]

Embodiments of the present invention will be specifically described below with reference to the drawings.

First, the outline of the hardware configuration and operation of the document compression / decompression device according to the first to seventh embodiments of the present invention will be described with reference to FIG.

As shown, the document compression / decompression device according to each embodiment includes a display 11, an input device 12, a printing device 13, and a control device 14.

The control device 14 includes a control unit 21, a RAM (random access memory) 22, an HDD
(hard disk drive) 23, communication control unit 24, display control circuit 25, interface circuits 26 and 27, CD
-ROM (compact disc read-only memory) drive 2
8 and a bus 29 for interconnecting them.

The display 11 is a device for displaying an image according to the input RGB signals, and is connected to the display control circuit 25 of the control device 14. The display control circuit 25 has a built-in VRAM,
Is a circuit that outputs an RGB signal corresponding to the data stored in the. The input device 12 is a device (keyboard and mouse) used by an operator to input various instructions to the device. The printing device 13 is a device for outputting data on paper. The input device 12 and the printing device 13
It is connected to a bus 29 (control unit 21) via interface circuits 26 and 27 for performing timing control of data transfer with the control unit 21 and the like.

The CD-ROM drive 28 has a CD-RO
M reading device. The communication control unit 24 includes a so-called modem and a network interface circuit. The data transmission lines 18 and 19 (in each embodiment, the public line and the L
AN line). The RAM 22 is a storage device for temporarily storing various data. HDD
Reference numeral 23 denotes a storage device for storing various data in a file and storing the data in the HDD.
system) and various application programs running on the OS. The HDD 23 has C
A document compression / decompression program (details will be described later) installed from the D-ROM 15 via the CD-ROM drive 28 is also stored.

The control unit 21 has a CPU (central processin).
g unit) and a ROM (read only memory) storing a bootstrap program and the like.
When the power is turned on, the control unit 21 (CPU)
HDD 23 according to the bootstrap program in
Is read into a predetermined storage area of the RAM 22. Thereafter, control according to the read OS is started, and when it is detected that an operation for instructing execution of a certain program is performed on the input device 12,
The program in the HDD 23 is read onto the RAM 22, and control according to the read program is started.

That is, the document compression / decompression device according to each of the embodiments is a device realized by installing a document compression / decompression program on a computer (computer system) having a general configuration.

The document compression / decompression program installed in the document compression / decompression device according to each embodiment includes a compression program and a decompression program. The compression program is a program for causing the control unit 21 to execute a compression process for creating a compressed document file capable of restoring a plurality of pages of image data. The decompression program is a program for causing the control unit 21 to execute a decompression process for decompressing and outputting image data based on the compressed document file.

Documents to be subjected to compression processing by the document compression / decompression device according to each embodiment include a document composed of a plurality of image data of the same size (hereinafter referred to as an image document), a document creation program and a table. There is a document created by a calculation program (hereinafter referred to as a normal document). At the time of compression processing on an image document, a plurality of image data constituting the image document are used as they are, and a compressed document file including data capable of restoring the image data is created.
Also, during compression processing on a normal document, a plurality of image data representing a print result of the document is created. Then, a compressed document file is created based on the image data. Note that the document compression / decompression device according to each embodiment can perform compression processing on an image document when instructing execution of a compression program from the OS, and perform compression processing on a normal document when instructing printing from an application program. It is configured to be able to do it. That is,
The compression program functions as both an application program and a kind of printer driver.

Hereinafter, details of the operation of the document compression / decompression device according to the first to seventh embodiments will be sequentially described.

<First Embodiment> First, the structure of a compressed document file created by the document compression / decompression device according to the first embodiment will be described with reference to FIG.

As shown, the compressed document file 31 created by the document compression / decompression device according to the first embodiment includes the number Mmax of compressed data and Mmax pieces of compressed data. When the compressed document file 31 is created (the details will be described later), the number of compressed data Mmax
Is set as the total number of pages of the document to be processed. That is, the compressed document file 31 is a file including the same number of compressed data as the total number of pages of the original document.

The compressed data # 1 included in the compressed document file 31 encodes (compresses) the image data of the first page of the document to be processed by a general procedure.
(Hereinafter also referred to as normal compressed data). On the other hand, each other compressed data #d
(D = 2 to Mmax) is data composed of the element data number Nmax and Nmax element data created on the basis of the image data of the d-th page and the image data of the d-1 page (hereinafter referred to as differential compression). (Also referred to as data). Each element data included in the differential compression data is composed of position data and replacement data.

Hereinafter, the meaning of each data constituting the compressed document file 31 will be described by describing a procedure for creating the compressed document file 31 in the document compression / decompression apparatus.

FIG. 3 is a flowchart of a compression process executed when a compressed document file 31 is created from a document to be processed in the document compression apparatus according to the first embodiment. FIG. 3 is a flowchart of differential compressed data creation processing. As described above, the documents that can be processed by the document compression apparatus include a normal document (a document created by a document creation program or a spreadsheet program) and an image document (a document including a plurality of image data of the same size). However, the illustrated compression process is performed commonly for both documents. However, when the compressed document file 31 is created from the image document, a process of acquiring the file names of a plurality of image data files constituting the image document from the operator is performed before step S101 is executed.

As shown in FIG. 3, during the compression processing, the control unit 21 first sets "1" to a variable M for storing the number of the page being processed (step S10).
1). Then, the image data of the first page of the document to be processed is prepared on the RAM 22 as the image # 1 (step S102). That is, the control unit 21
Normally, when a document is to be processed, image data of a designated resolution is stored in RAM based on print data passed from an application program.
22 and the image data is "1" (= M)
It is managed in a form related to. If the image document is to be processed, the contents of the image data file for the first page are read and stored in the RAM 22 in a form associated with “1”.

After preparing the image # 1 on the RAM 22, the control section 21 stores the number of unit data included in the image # 1 as kmax (step S103).
It should be noted that the unit data is a predetermined size (in the present embodiment,
(1 byte) data.

Thereafter, the control unit 21 creates compressed data # 1 on the RAM 22 by encoding (run-length encoding in this embodiment) the image # 1 on the RAM 22 (step S104). The compressed data # 1 created in this step includes information on its own size and the resolution of the restored image data.

Then, the control section 21 determines whether or not there is a page to be processed (step S105).
When there is a page to be processed (step S10
5; YES), the control unit 21 recognizes the image #M on the RAM 22 as a reference image (step S10).
6). That is, the fact that image #M is used as the reference image is stored. Thereafter, "1" is added to M (step S107), and the image data of the Mth page of the document to be processed is stored in the RAM 22 in the image #M.
(Step S108). Then, the control unit 21 starts differential compressed data creation processing (step S109), which is processing for creating compressed data #M.

As shown in FIG. 4, at the start of the differential compressed data creation process, the control unit 21 sets “1” to a variable k for storing the unit data number of the unit data to be processed, The variable i for counting the number of element data included in the data #M is set to "0" (step S201). The unit data number is information for identifying one unit data from kmax unit data constituting the image data. In the present apparatus, the unit data number “1” is assigned to the head unit data of the image data. Is given.

Thereafter, the control unit 21 transmits the unit data #k of the image #M and the reference image (that is, the image #M).
-1) is compared with the unit data #k (step S202)
Then, when the unit data #k of the image #M matches the unit data #k of the reference image (step S203;
YES), "1" is added to k (step S206).
Then, it is determined whether or not k is equal to or smaller than kmax (step S207).

On the other hand, if the unit data #k of the image #M does not match the unit data #k of the reference image (step S203; NO), the control unit 21 adds "1" to i (step S203). Step S204). And k,
The unit data #k of the image #M is stored as the position data and the replacement data of the element data #i of the compressed data #M (step S205). In other words, the position data constituting the element data is data indicating the position of the unit data of the image data for which compressed data is to be created, which has a different content from the image data used as the reference image. The replacement data is data indicating the contents of the unit data at that position in the image data for which compressed data is to be created.

Thereafter, the control unit 21 adds “1” to k (step S206), and then determines whether k is equal to or smaller than kmax (the number of unit data included in the image # 1 acquired in step S103). Is determined (step S20).
7). If k is equal to or smaller than kmax (step S207; YES), the process returns to step S202 to start the process for the next unit data. On the other hand, k is kma
If it exceeds x (step S207; YES), that is, the comparison of the unit data #kmax is performed in step S202.
If the processing has been performed in step S208, the value of i at that time is stored as the number of element data Nmax of the compressed data #M (step S208), and the differential compressed data creation processing ends.

After executing the differential compressed data creation process (FIG. 3: step S109), the control unit 21 discards the reference image (image # M-1) on the RAM 22 (step S110). That is, the storage area used for storing the image # M-1 is released so that it can be used for storing other data. Then, the control unit 21 determines in step S
Returning to 105, it is determined whether or not there is a page to be processed.

If there is a page to be processed (step S105; YES), the control unit 21 performs the processing of steps S106 to S110 on the next page. Then, when the processing for all pages of the processing target document is completed (step S105; NO), the number of compressed data Mmax (the value of M at that time) obtained by the processing up to that point, the compressed data # 1 to A compressed document file 31 is created in the HDD 23 using #Mmax (step S111). Then, the unnecessary data on the RAM (image #Mmax and compressed data # 1)
To #Mmax) (not shown), and the compression process ends.

The operation of the document compression / decompression apparatus according to the first embodiment at the time of compression processing will be described below with reference to FIG. 5, taking as an example a case where a normal document whose total number of pages is “3” is to be processed. Will be described more specifically.

The processing shown in FIG. 5A is performed on the print data of the first page. That is, an image # 1 having contents corresponding to the print data is created on the RAM 22, and the compressed image # 1 creates compressed data # 1 which is normally compressed data. Further, based on the size of the image # 1, the total number kmax of unit data constituting the image # 1 is recognized.

The processing shown in FIG. 5B is performed on the print data of the second page. That is, an image # 2 corresponding to the print data is created on the RAM 22. And the newly created image # 2,
By comparison with the already created image # 1, compressed data # 2, which is differential compression data of image # 2 using image # 1 as a reference image, is created.

The same procedure is performed on the print data of the third page. That is, as shown in FIG. 5C, the image data of the previous page (image #
Image # 3 according to print data with 2) left
Is created on the RAM 22. Then, by comparing image # 3 with image # 2, compressed data # 3, which is differential compression data of image # 3 using image # 2 as a reference image, is created. Then, the number of compressed data Mmax obtained by the processing up to that time and the compressed data # 1 to
The compressed document file 31 including # 3 is stored in the HDD 2
3 is created.

Next, the procedure for restoring the compressed document file 31 in the document compression / decompression device according to the first embodiment will be described with reference to FIGS. FIG. 6 is a flowchart of a decompression process executed by the document compression / decompression device, and FIG. 7 is a flowchart of a differential compression data decompression process executed during the decompression process.

As shown in FIG. 6, at the time of restoration processing, the control unit 21 first acquires restoration processing conditions from the operator (step S301). More specifically, in this step, the control unit 21 acquires a restoration processing condition including a file name of the compressed document file to be restored, restoration page range designation information, output destination designation information, and the like. The restoration page range designation information is information for designating a page range for restoration (output), and includes a restoration start page number Ps and a restoration end page number Pe (≧ Ps). The output destination designation information is information for designating the output destination of the restoration result (image data of the Ps to Pe pages). The output destination designation information includes the HDD 23
(Or an auxiliary storage device of another device), information for designating a file to be saved, information for designating output to the printing device 13, and information for designating fax transmission can be set. .

After obtaining the decompression processing conditions, the control unit 21 sets "1" to a variable M for storing the compressed data number of the compressed data to be processed (step S302). As is clear from the procedure for creating the compressed document file 31 described above, the compressed data with the compressed data number m is data for restoring the image data of the m-th page. It is also information indicating the page number of the image data obtained by the above.

After setting "1" to M, the control unit 21
The number of compressed data Mmax included in the compressed document file 31 for which restoration is instructed is obtained (step S).
303). That is, by reading data of a predetermined size from a file having a file name given as a decompression processing condition, the number of compressed data Mmax is obtained. Although not shown, immediately after this step, the control unit 21 determines whether or not valid (processable) restoration page range designation information is given (this processing is performed). This is because the validity of the restored page range designation information has not been checked in step S301).
Specifically, it is determined whether or not Mmax <Pe, and whether or not Ps> Mmax. If Mmax <Pe, Pe is determined.
Is set to Mmax, and then step S304 is executed. If Ps> Mmax, the restoration process ends.

In step S304, control unit 21
Is the compressed data # 1 in the compressed document file 31
To generate an image # 1 on the RAM 22. At the time of processing in this step, the control unit 21 sets the compressed data # 1 set at the head of the compressed data # 1.
1 is used, and information including the resolution of the image data represented by the compressed data # 1 is used.

Thereafter, the control section 21 determines whether or not M is equal to or greater than Ps (step S305). If M is less than Ps (step S305; NO), the control unit 2
In step S308, the process proceeds to step S308. On the other hand, if M is equal to or greater than Ps (step S305; YES), the control unit 21
Outputs the image #M on the RAM 22 to the output destination specified by the output destination specifying information (step S3).
06). That is, when the output to the HDD 23 is instructed, the M-th data is stored in the HDD 23 based on the image #M.
Create an image data file for the page. If printing has been instructed, the interface circuit 2 causes the printing device 13 to print the image #M.
7 is supplied with image #M. If FAX transmission has been instructed, image #M is supplied to communication control unit 24. If FAX transmission has been instructed, the first
Before outputting the image data of the page, processing for connecting the transmission destination and the line is performed.

Output of Image #M (Step S306)
Thereafter, the control unit 21 determines whether M <Pe holds (step S307). If M <Pe holds (step S307; NO), the process proceeds to step S308.

In step S308, the control unit 21
Recognizes image #M as a reference image. Then, "1" is added to M (step S309), and a differential compressed data restoration process (step S3) for generating an image #M based on the reference image and the compressed data #M.
Execute 10).

As shown in FIG. 7, at the time of differential compressed data decompression processing, the control unit 21 first obtains the number Nmax of element data of the compressed data #M (step S401). The acquisition of the element data number Nmax is performed by reading the data at the next position of the processed data from the compressed document file 31. For example, at the time of differential compressed data restoration processing executed when M = 2, compressed data # 1 in the compressed document file 31 (step S304)
The data of a predetermined size existing at the next position of (processed in (1)) is read out as the element data number Nmax.

After obtaining the number Nmax of element data, the control unit 21
Sets "1" to a variable i for storing an element data number (step S402), and determines whether or not the value of i is equal to or smaller than Nmax (step S403). The value of i is Nmax
If it is below (step S403; YES), the control unit 21 sends the element data #i of the compressed data #M (the position data and the replacement data) from the compressed document file 31.
Is acquired (step S404). That is, data of a predetermined size existing at the next position of already processed data in the compressed document file 31 is acquired as element data #i.

Thereafter, the control section 21 changes the unit data of the position indicated by the acquired position data of the reference image (image # M-1) stored in the RAM 22 to the acquired replacement data (step S405). ). That is, the content of the reference image is rewritten so that the replacement data becomes unit data having the position data as the unit data number of the reference image. Thereafter, "1" is added to i (step S406), and the process returns to step S403 to compare the changed value of i with Nmax. And i ≦ Nmax
Is satisfied (step S403; YES), the processing of steps S404 to S406 is executed again,
When i ≦ Nmax is not satisfied (step S40)
3; NO), that is, when the processing on the element data #Nmax is performed in steps S404 and S405, the differential compressed data restoration processing ends.

After the differential compressed data decompression processing (FIG. 6, step S310), the control unit 21 executes the processing from step S305 again. The control unit 21 repeats such processing, and when M <Pe is not satisfied (step S307; NO), that is, in step S310, image data relating to the Pe (= M) page is created, and in step S306, When the output is performed, the output image #M is discarded (step S).
311) Then, the restoration processing ends.

Hereinafter, restoration of a compressed document file 31 created based on a three-page document will be described.
The contents of the restoring process executed by the document compression apparatus will be further described by taking as an example a case where the restoration page range is specified as all pages (Ps = 1, Pe = 3) and a case where the restoration of only the third page is specified. This will be specifically described. In any case, it is assumed that the HDD 23 is specified as the output destination.

In the former case, the processing of the procedure as schematically shown in FIG. 8 is performed, and the image data of the first to third pages is output.

That is, as shown in FIG. 8A, first, the number of compressed data Mma of the compressed document file 31 is
x (in this case, 3) is recognized. Also, compressed data # 1 which is normal compressed data is decompressed, and image # 1 is generated on RAM 22. Then, M (= 1) ≧ Ps
Since (= 1) holds, in step S306,
That image # 1 is the HD that is the designated output destination
Output to D23.

Thereafter, since M <Pe holds, after image #M is recognized as the reference image, M becomes “2”.
(Steps S308 and S309). Then, since the differential compressed data decompression process is performed on the compressed data # 2, as shown in FIG.
1 is rewritten to image # 2. Also, M (= 2)
Since ≧ Ps holds, an image data file of the image # 2 is created in the HDD 23.

Also in step S307 performed after the output of image # 2, since M (= 2) <Pe (= 3) holds, image # 2 is recognized as the reference image. Then, after M is changed to “3”, the differential compressed data decompression process is executed, so that the image # 2 is rewritten to generate the image # 3 as shown in FIG. Since M> Ps, an image data file of the image # 3 is created in the HDD 23, and
Since (= 3) <Pe (= 3) is no longer satisfied,
The restoration processing ends.

On the other hand, when the output of only the third page has been instructed (Ps = Pe = 3), the process of the procedure schematically shown in FIG. 9 is performed, and only the image data of the third page is output. Is output.

That is, as shown in FIG. 9A, first, the number of compressed data Mma of the compressed document file 31 is
x (in this case, 3) is recognized. Step S3
At 04, the compressed data # 1, which is normally compressed data, is decompressed, and an image # 1 is generated on the RAM 22.
Then, since M (= 1) ≧ Ps (= 3) is not established, the image # 1 is not output, and step S3 is performed.
The process from 08 is executed.

In the processing from step S308, FIG.
The processing as shown in (2) is performed. That is, after image # 1 is recognized as the reference image, M is changed to “2”. Then, the reference data (image #
1) is rewritten according to the compressed data # 2, and an image # 2 is generated. Also in step S305 executed after generation of the image # 2, since M (= 2) ≧ Ps is not established, the processing from step S308 is executed without outputting the image # 2.

In the processing from step S308 in this case, after image # 2 is recognized as the reference image, M is changed to "3" and the differential compressed data restoration processing is executed. As a result, as shown in FIG.
Image # 3 is generated based on the reference data (image # 2). Further, since M (= 3) ≧ Ps (= 3) is satisfied, the image # 3 is output. And M <P
Since e does not hold, the restoration process ends.

That is, since each difference compressed data in the compressed document file 31 created by the document compression / decompression apparatus is based on the image data of the previous page as the reference image, the compressed data #P
In order to decompress the compressed data # P-1, the result of decompression of the compressed data # P-1 is required. Since the compressed data that can be independently restored is only the compressed data # 1, as described above,
The compressed data # 1 to # 3 are sequentially decompressed, and the decompression result of the compressed data # 3 is output.

As described above, in the document compression / decompression device according to the first embodiment, a compressed document file 31 including one piece of normal compressed data and N-1 pieces of differentially compressed data is created. If the pages of the document to be processed have many common portions, the size of the differential compressed data for a certain page is smaller than the size of the normal compressed data for the page. Therefore, if the document compression / decompression device is used for a document having many common portions on each page, for example, a document created by spreadsheet software or a fixed document such as an invoice, the document compression / decompression device is higher than before. Data (compressed document file) compressed at the compression rate is obtained.

<Second Embodiment> FIG. 10 shows the structure of a compressed document file 32 created by a document compression / decompression device according to a second embodiment. As illustrated, the compressed document file 32 includes management data including the number Mmax of compressed data and head position data # 2 to #Mmax, and Mmax pieces of compressed data.

The head position data # 2 to #Mmax are data representing the head positions of the compressed data # 2 to #Mmax, respectively, as a relative address from the head of the compressed document file 32. Note that the reason why the head position data for the compressed data # 2 to #Mmax exists,
The reason why the head position data for No. 1 does not exist will be described later. The compressed data # 1 is normal compressed data obtained by encoding the image data of the first page of the processing target document, like the compressed data # 1 in the compressed document file 31. Also, compressed data #d
(D = 2 to Mmax) is the compressed document file 31
Similarly to the compressed data #d, the differential compressed data is composed of the element data number Nmax and the Nmax element data, which represents the difference between the two pieces of image data. However, the compressed data #d in the compressed document file 32 is data representing the difference between the image data of the d-th page and the image data of the first page.

The procedure for creating a compressed document file 32 in the document compression / decompression apparatus according to the second embodiment will be described below.

FIG. 11 is a flowchart of a compression process executed in the document compression / decompression device according to the second embodiment. This compression processing corresponds to FIG.
That is, the compression processing shown in FIG. 11 is commonly executed for normal / image documents. However, the compressed document file 32
Is generated, before step S501 is executed, a process of acquiring the file names of a plurality of image data files constituting the image document from the operator is performed.

As shown in the figure, the control unit 21
Sets "1" to a variable M for storing the number of the compressed data being processed (step S50).
1). Next, the image data of the first page of the document to be processed is prepared on the RAM 22 as the image # 1 and the reference image (step S502). That is, 1 used as the reference image and image # 1
One image data is prepared on the RAM 22.

Next, the control section 21 sets the image # 1 (=
The number of unit data included in the reference image) is stored as kmax (step S503). After that, the control unit 21
Creates compressed data # 1 on the RAM 22 by compressing (run-length encoding in this embodiment) the image # 1 created in step S502 (step S504). Then, it is determined whether there is a page to be processed (step S505).

When there is a page to be processed (step S505; YES), the control unit 21 adds “1” to M (step S506), and stores the image of the Mth page of the document to be processed in the RAM 22. The data is prepared as an image #M (step S607). Then, a differential compressed data creation process (step S508) is executed. The differential compressed data creation processing executed in step S508 is the same as the processing described with reference to FIG. That is, in step S508, the image #
M and the contents of the reference image are compared for each unit data, and compressed data #M including information indicating a portion where the contents are different is created.

Processing for creating differential compressed data (step S50)
After the end of 8), the control unit 21 discards the image #M on the RAM 22 (step S509). That is, the storage area of the image #M created in step S507 is released so that it can be used for storing other data. Then, the control unit 21 returns to step S505, and determines whether or not there is any page to be processed.

The control section 21 repeats such processing for each page to be processed. Then, when the processing for all pages constituting the processing target document is completed (step S505; NO), the sizes of the compressed data # 1 to #M obtained by the series of processing and the size of the management data (M value Function), the compressed data # 2 to #
The head position data of M is created (step S510).
Thereafter, the number of compressed data Mmax (the value of M at that time), the head position data # 2 to #Mmax, the compressed data # 1
Compressed document file 32 containing ~ Mmax
The data is created in D23 (step S511), and unnecessary data is discarded from the RAM 22 (not shown), and the compression process ends.

Hereinafter, taking as an example a case where a normal document whose total number of pages is "3" is to be processed, the compressed document file 32 of the document compression / decompression device according to the second embodiment will be described with reference to FIG. The creation procedure will be described more specifically.

For the print data of the first page, as shown in FIG. 12A, an image # 1 is created in the RAM 22 based on the print data, and the image # 1 is created.
1 is compressed data # 1 which is normally compressed data
Is created. Also, based on the size of Image # 1,
The unit data number kmax constituting the image # 1 is recognized.

For the print data of the second page, as shown in FIG. 12B, while the image # 1 is left, the image data # 2 corresponding to the print data is stored in the RAM 22. Created above. Then, by comparing the image # 2 with the image # 1, compressed data # 2, which is differential compressed data, is created.

For the print data of the third page, as shown in FIG. 13C, while the image # 1 remains, the image data # 3 corresponding to the print data is stored in the RAM 22. The compressed data # 3 is created by comparing the image # 3 with the image # 1. Then, management data (the number of compressed data Mmax and head position data # 2 to #Mmax) and compressed data # 1 to #M created based on the information obtained by the processing up to that time
3 is stored in the HDD 23
Created within.

Next, the procedure for restoring the compressed document file 32 in the document compression / decompression device will be described.

FIG. 13 shows a flow chart of the decompression process executed when the compressed document file 32 is decompressed in the document compression / decompression device. FIG. 14 shows a flow chart of the differential compression data decompression process executed at the time of decompression process. Show.

As shown in FIG. 13, at the time of restoration processing, the control unit 21 first acquires restoration processing conditions from the operator (step S601). This step includes step S3
It is the same as 01. That is, in step S601, the control unit 21 acquires a restoration processing condition including the file name of the compressed document file to be restored, restoration page range designation information, output destination designation information, and the like.

Thereafter, the control unit 21 determines whether the management data (the number of compressed data Mmax and the start position data # 2 to #Mma) contained in the compressed document file 32 instructed to be decompressed are
x) is obtained (step S602). That is, after obtaining data of a predetermined size existing at the head of the compressed document file 32 as compressed data Mmax, Mmax-1 pieces of data of a predetermined size following the data are obtained as head position data # 2 to #Mmax. I do. Although not shown, immediately after this step, the control unit 21 determines whether or not Mmax <Pe and whether or not Ps> Mmax. If Mmax <Pe, P
e is set to Mmax, and step S603 is started. If Ps> Mmax, the restoration process ends.

At step S603, the control unit 21
Is the compressed data # 1 in the compressed document file 32
To generate an image # 1 on the RAM 22. That is, the compressed data # 1 including data related to its own size, which exists immediately after the management data, is read and decompressed. As described above, since the compressed data # 1 is data that is read together with the management data, the head position data of the compressed data # 1 is not set in the compressed document file 32.

Thereafter, the control unit 21 sets Ps to a variable M for storing a compressed data number to be processed.
(Step S604). Then, the control unit 21 determines whether or not M is “1” (Step S605).

When M is not "1" (step S6)
05; NO), that is, if Ps> 1, the control unit 21 generates a copy of the image # 1 to be used as the reference image on the RAM 22 (step S60).
6). If M = Pe, the control unit 21 recognizes the image # 1 itself as a reference image without generating a copy of the image # 1 in step S606.

After execution of step S606, the control unit 21
Executes the differential compression data restoration process (step S607). As shown in FIG. 14, at the start of the differential compressed data decompression process, the control unit 21 recognizes the head of the compressed data #M based on the head position data #M and obtains the number Nmax of element data of the compressed data #M ( Step S701). Next, the control unit 21 sets “1” to the variable i (Step S
702), and it is determined whether the value of i is equal to or smaller than Nmax (step S703). If the value of i is equal to or smaller than Nmax (step S703; YES), the control unit 21 acquires the element data #i (the position data and the replacement data) of the compressed data #M from the compressed document file 32 (step S704). ). That is, data of a predetermined size existing at the next position of the already processed data in the compressed document file 32 is obtained as element data #i.

Thereafter, the control unit 21 transmits the reference image (copy of image # 1) stored in the RAM 22.
The unit data at the position indicated by the acquired position data is changed to the acquired replacement data (step S705). Then, "1" is added to i (step S706), and the process returns to step S703 to determine whether or not the processing for the last element data has been completed by comparing the changed value of i with Nmax. I do.

The control unit 21 determines that all rewrites according to the Nmax element data have been completed (step S703; N
O), that is, when the rewriting of the reference image to the image #M is completed by repeating the above processing, the differential compressed data decompression processing ends.

Returning to FIG. 13, the description of the restoration processing will be continued.
After generating the image #M by executing the differential compressed data decompression processing (step S607), the control unit 21
The image #M on the file 22 is output to the output destination specified by the output destination specifying information (step S608). afterwards,
If M is not "1", the image #M is discarded (step S609). That is, when image data of a page other than the first page is output, the storage area of the image data is released.

Thereafter, the control section 21 adds "1" to M (step S610), and determines whether M> Pe is satisfied (step S611). And M> Pe
Is not established (Step S611; NO)
Then, the process returns to step S606 to start processing for restoring the next compressed data. If the value of M for which the value of Ps is set in step S604 is “1” (step S605), the control unit 21 proceeds to step S606.
The processing from step S608 is executed without executing S607.

The control unit 21 completes the restoration and output of the image #Pe, that is, when the value obtained by adding “1” to the compressed data number M related to the output image data exceeds Pe (step S611; YES). ), RAM 22
Discard the image # 1 remaining on the top (Step S61)
2) Then, the restoration processing ends.

Hereinafter, restoration of a compressed document file 32 created based on a three-page document will be described.
The contents of the restoration process will be described more specifically by taking as an example a case where the restoration page range is specified as all pages (Ps = 1, Pe = 3) and a case where restoration of only the third page is designated.
In any case, the output destination is HDD2
It is assumed that 3 is specified.

In the former case, the processing of the procedure as schematically shown in FIG. 15 is performed, and the image data of the first to third pages is output.

First, as shown in FIG. 15A, management data (the number of compressed data Mmax and the start position data # 2 to #Mmax) of the compressed document file 32 are obtained.
Then, the compressed data # 1 which is the normal compressed data in the compressed document file 32 is expanded, and the image # 1 is generated on the RAM 22. Then, Ps (= 1) in M
Is set, “YE” is set in step S605.
A branch is made to the S "side. As a result, an image data file for the image # 1 is created in the HDD 23 which is the designated output destination.

Thereafter, the processing as shown in FIG. 15 (2) is performed. That is, M (= 2) to which "1" is added
On the other hand, since M> Pe does not hold, a reference image which is a copy of the image # 1 is generated on the RAM 22. Then, the reference image (copy of image # 1) is rewritten according to compressed data # 2, and image # 2 is generated. Further, output of the image # 2 (in this case, creation of an image data file for the image # 2) is performed.

Thereafter, image # 2 is discarded, and the value of M is changed to "3". And M> Pe does not hold,
Since M = Pe holds, the image # 1 itself is recognized as the reference image, as shown in FIG.
Image # 3 is generated by differential compressed data decompression processing using the reference image and compressed data # 3. Then, the output of the image # 3 is performed.

Thereafter, image # 3 is discarded, and the value of M is changed to "4". As a result, M (= 4) <Pe
Since (= 3) does not hold, after the image # 1 is discarded, the restoration processing is terminated.

On the other hand, when the output of only the third page is instructed (Ps = Pe = 3), first, the processing as shown in FIG. 16A is performed. That is, step S602
, The management data of the compressed document file 32 (the number of compressed data Mmax and the head position data # 2 to #Mma
x) is obtained. Also, in step S603,
The compressed data # 1 is decompressed and the image #
1 is generated.

Then, since Ps (= 3) is set for M, the processing from step S606 is executed. As a result, as shown in FIG. 16 (2), differential compressed data decompression processing is performed on compressed data # 3 using image # 1 as a reference image, and the reference image (image # 1) is converted into image # 3. You. And that image # 3
Is output.

That is, each differential compressed data in the compressed document file 32 created by the present document compression / decompression apparatus uses the image data of the first page as a reference image. Therefore, if the compressed data # 1 and the compressed data #P can be read, the image data of the P-th page can be restored. Even if there is no start position data # 2 to #Mmax, if each compressed data is read out sequentially as in the first embodiment, compressed data # 1 and compressed data #P can be obtained. However, when the processing is performed in such a procedure, time is consumed for reading unnecessary compressed data.
In the compressed document file 32, compressed data # 2
The top position data for #Mmax is set.

As described above, even in the document compression / decompression device according to the second embodiment, a compressed document including one piece of normal compressed data and N−1 pieces of differentially compressed data for an N page document A file is created. Therefore, for a document having many portions in which each page has a common part, for example, a document created by spreadsheet software or a standard document such as an invoice,
If this document compression / decompression device is used, the document can be stored at a higher compression ratio than in the past, similarly to the document compression / decompression device according to the first embodiment.

Further, in the document compression / decompression apparatus, the image data of the first page is used as a reference image when creating each difference compressed data. For this reason, the document compression / decompression device is a device capable of decompressing the compressed document file 32 from an intermediate page at a higher speed than the document compression / decompression device according to the first embodiment.

<Third Embodiment> FIG. 17 shows the structure of a compressed document file 33 created by the document compression / decompression device according to the third embodiment. As shown in the figure, the compressed document file 33 is composed of management data including the number Mmax of compressed data, page numbers # 1 to #Mmax, and top position data # 2 to #Mmax, and Mmax pieces of compressed data.

The page numbers # 1 to #Mmax are respectively
This is information indicating which page of the compressed data # 1 to #Mmax is the compressed data related to the image data. The head position data # 2 to #Mmax are respectively compressed data #
2 to #Mmax are data representing relative addresses from the beginning of the compressed document file 33.

The compressed data # 1 is normal compressed data obtained by encoding image data, like the compressed data # 1 in the compressed document files 31 and 32.
However, the compressed data # 1 in the compressed document file 33 is data obtained by encoding the image data of the page indicated by the page number # 1.

The compressed data #d (d = 2 to Mmax) is the compressed data # 2 to #M in the compressed document file 32.
Like max, differential image data created by using image data obtained by restoring compressed data # 1 as a reference image. However, since the image data obtained by decompressing the compressed data # 1 is the image data of the page indicated by the page number # 1 as described above, each compressed data #d has the reference image corresponding to the page number # 1. Are the image data of the page (not limited to the first page), and the image data of the page indicated by the page number #d is obtained by the restoration. In other words, the compressed data #d in the compressed document file 32 is data in which the reference image is the image data of the first page, and d is the data representing the page number of the image data obtained by the decompression. On the other hand, in the compressed data #d in the compressed document file 33 created by the document compression / decompression device of the present embodiment, the reference image is not limited to the image data of the first page, and d is obtained by the decompression. The data does not necessarily indicate the page number of the image data to be obtained.

Hereinafter, referring to FIG. 18 to FIG.
A procedure for creating the compressed document file 33 in the document compression / decompression device according to the embodiment will be described. FIG. 18 shows the document compression / data compression according to the third embodiment.
FIG. 20 is a flowchart of a compression process executed when a compressed document file 33 is created in the decompression device.
9 is a flowchart of a differential compressed data compression process and a compressed data selection process executed at the time of the compression process, respectively. Also,
The compression processing shown in FIG. 18 corresponds to FIG. 4, and is executed commonly for normal / image documents. Then, when the compressed document file 32 is created from the image document, step S8
Before the execution of 01, a process of acquiring the file names of a plurality of image data files constituting the image document from the operator is performed.

As shown in FIG. 18, at the start of the compression process,
The control unit 21 controls the first to M-th documents to be processed.
The image data of the page is created as images # 1 to #Mmax (step S801). In this step, the control unit 21 recognizes the number kmax of element data of the image data. After that, the control unit 21
Variables X and Y, which are operands of differential compressed data creation processing
Are set to "1" and "2", respectively (step S80).
2) Then, the differential compressed data creation processing (step S803)
To start.

As shown in FIG. 19, at the time of differential compressed data creation processing, the control unit 21 first sets “1” as a variable k for storing a unit data number and sets a variable k for counting the number of element data. The variable i is set to “0” (step S
901). Next, the unit data #k of the image #X is compared with the unit data #k of the image #Y (step S).
902).

If the unit data #k of the image #X does not match the unit data #k of the image #Y (step S903; NO), the control unit 21 adds "1" to i (step S903). S904). Then, the unit data #k of k and the image #X are used as the position data and the replacement data of the element data #i of the compressed data #Y_X (compressed data in which the image #X is restored using the image #Y as a reference image). It is stored (step S905). Also,
k and the unit data #k of the image #Y are converted into compressed data #
The position data and the replacement data of the element data #i of X_Y are stored (step S906). Then, “1” is added to k (step S907).

On the other hand, if the unit data #k of the image #X matches the unit data #k of the image #Y (step S903; YES), the control unit 21 proceeds to step S903.
Steps S90 and S904 are not performed
Execute 7.

After changing the value of k in step S907, the control unit 21 sets the value of k to the number kmax of element data.
It is determined whether it is the following (step S908). If the value of k is equal to or smaller than kmax (step S9)
08; YES), the process returns to step S902, and the process is performed on the next unit data.

The control section 21 repeats such processing for each unit data. When the value of k is no longer than kmax (step S908; NO), the control section 21 replaces the value of i at that time with the compressed data. #X_Y, compressed data #Y_X
(Step S90).
9). Then, the differential compressed data creation processing ends.

As shown in FIG. 18, after execution of the differential compressed data creation processing (step S803), the control unit 21
Adds "1" to Y (step S804). Then, it is determined whether or not Y exceeds Mmax (step S).
805) If Y has not exceeded Mmax (step S805; NO), the process returns to step S803,
The compressed difference data creation process is executed for the updated Y value.

As a result of repeating such processing,
When Y exceeds Mmax (Step S805; YE)
S), that is, using image #X as a reference image,
When the creation of the differential compressed data for the images # X + 1 to #Mmax is completed, the control unit 21 adds “1” to X (step S806). Next, Y is set to X + 1 (step S807), and it is determined whether or not X <Mmax is satisfied (step S808).

If X <Mmax is satisfied (step S808; YES), the control unit 21 executes the processing from step S803 again. On the other hand, X <Mma
If x is not satisfied (step S808; N
O), that is, each X from "1" to "Mmax-1"
When the processing of steps S803 to S805 has been performed on compressed data, the compressed data selection processing (step S809) is started.

As shown in FIG. 20, at the start of the compressed data selection processing, the control unit 21 determines that Mmax × (Mmax−1) compressed data obtained in the processing up to that point will be used. For each of images # 1 to Mmax, Mmax-1 created using the image as a reference image
Calculate the total size of the compressed data (step S
1001). Next, the control unit 21 specifies the image #Z that minimizes the total size of the compressed data when used as the reference image (step S1002). After that, compressed data of the image #Z is created by encoding the image #Z (step S1003).
Then, the compressed data of the image #Z and the compressed data #Z_
Management data for creating j (j = 1 to Z-1, Z + 1 to Mmax) as compressed data # 1 to #Mmax, respectively, is created (step S1004). Next, a compressed document file having the created management data and including compressed data of image #Z and data compressed data #Z_j (j = 1 to Z-1, Z + 1 to Mmax) as compressed data # 1 to #Mmax, respectively. After the creation (step S1005), the compressed data selection processing and the compression processing are completed.

Hereinafter, the procedure for creating the compressed document file 33 in the document compression / decompression device according to the third embodiment will be described more specifically, taking as an example a case where a document having a total number of pages of “5” is to be processed. explain.

In this case, since Mmax = 5, when the compressed data selection process is started, 20 (= 5 × 4)
Pieces of compressed data have been created. Step S1001
Then, the compressed data is divided into five groups according to the image data used as the reference image, and the total size of the four compressed data belonging to each group is calculated. That is, this step S100
In the processing up to 1, for example, information as shown in FIG. 21 is collected. In FIG. 21, the numerical values (1, 2, etc.) shown in the leftmost column are the page numbers (hereinafter, referred to as reference page numbers) of the image data used as the reference images, and The numbers shown are
The page number of the image data compared with the reference image (hereinafter, referred to as a generated page number). And
The numerical value described at the place where the reference page number is X and the generated page number is Y is the size (arbitrary unit) of the compressed data #X_Y.

In the processing up to step S1001, FIG.
If the information as shown in (1) is collected, step S10
In 02, image # 3 having a total of "11" is specified. In the following step S1004, the page numbers # 1 to #Mmax are 3 (= Z), 1, 2,
4 and 5, and the head position data # 2 to #Mmax are determined based on the size of each compressed data (management data is created). Then, in step S1005, as shown in FIG. 22, the number of compressed data Mmax is “5”, and the page numbers # 1 to # 5 (P _{1 to} P _{5 in the} figure) are 3, 1,. is 2,4,5, (in the _figure, D 2 to D ₅₎ the head position data # 2 to # 5 defined than the size of the compressed data has a management data having a normal compressed data of the third page, A compressed document file 33 including compressed data # 3_1, # 3_2, # 3_4, and # 3_5 as compressed data # 1 to # 5, respectively, is created.

Next, the operation of the document compression / decompression device according to the present embodiment when decompressing the compressed document file 33 will be described.

FIG. 23 shows a flowchart of the restoration process executed when the document 33 to be processed is restored. As illustrated, at the time of restoration processing, the control unit 21 first acquires restoration processing conditions from the operator (step S1101). This step is the same as steps S301 and S601. That is, in step S1101, the control unit 21 acquires a restoration processing condition including the file name of the compressed document file to be restored, restoration page range designation information, output destination designation information, and the like.

Thereafter, the control unit 21 determines whether the management data (the number of compressed data Mmax, the page numbers # 1 to #Mmax,
First position data # 2 to #Mmax are acquired (step S)
1102). That is, the compressed document file 33
Of the predetermined size existing at the beginning of the compressed data Mma
After obtaining as x, Mmax pieces of data of a predetermined size following the data are obtained as page numbers # 1 to #Mmax. Further, following the page number #Mmax, Mmax-1
Data of the predetermined size are transferred to the head position data # 2 to #M.
Get as max.

Although not shown, the control unit 21
Determines immediately after step S1102 whether or not Mmax <Pe and whether or not Ps> Mmax. And M
If max <Pe, Mmax is set to Pe, and step S1103 is started. If Ps> Mmax, the restoration process ends. That is, Ps ≦ Pe ≦
The process of each step described below is performed under the condition of Mmax.

In step S1103, the control unit 21 determines whether the compressed data # 1 in the compressed document file 33
To generate an image # 1 on the RAM 22. Thereafter, the control unit 21 sets Ps to the variable P (step S1104), and sets the P-th page compressed data number (compressed data number of the compressed data whose page number is P) to the variable M (step S1105). . That is, m with page number # m = P is found, and the found m is M
Set to. Then, the control unit 21 determines whether P is equal to or less than Pe (step S1106).

When P is less than Pe (step S1)
106; YES), the control unit 21 determines whether or not P matches P ₁ (page number # 1) (step S).
1107). That is, it is determined whether or not the image # 1 created in step S1103 relates to a page to be restored this time. If P does not match with the _{P 1} (step S1107; NO), the control unit 2
1 generates a copy of the image # 1 to be used as a reference image on the RAM 22 (step S1109).
If P = Pe holds, the control unit 21 recognizes the image # 1 on the RAM 22 as a reference image without generating a copy of the image # 1 in step S1109.

Then, a differential compressed data decompression process (step S1110) is executed. The difference compressed data decompression process executed in step S1110 is the same as that described with reference to FIG.

After generating the image #M, that is, the image data of the P-th page by executing the differential compressed data restoring process, the control unit 21 sets the image #M on the RAM 22 to the image #M.
Is output to the output destination specified by the output destination specification information (step S1111). Then, after discarding the image #M (step S1112), “1” is added to P (step S1113). After that, step S1105
And the above processing is performed on the P whose value has been changed.

[0175] Step S1104, the value in S1113 is set, if the modified P is coincident with _{P 1} (step S1107; YES), the control unit 21, the output destination specified image # 1 on the RAM Output (Step S1
108). Thereafter, the process proceeds to step S1113, and after the value of P is changed, the processing from step S1105 is executed.

When P ≦ Pe is not satisfied as a result of repeating such processing (step S1106; NO), the control section 21 discards unnecessary image data (step S1106). (Not shown), and then terminate the restoration process.

As described above, in the document compression / decompression device according to the third embodiment, the document compression / decompression device according to the third embodiment compresses a document including N pages in the same manner as the document compression / decompression device according to the second embodiment. Data # 1
A compressed document file 33 including N-1 pieces of differentially compressed data created using the image # 1 obtained by the decompression as a reference image is created. However, the image data serving as the basis of the compressed data # 1 is not fixed to the image data of the first page, and is selected so that the total size of the N-1 difference compressed data is minimized.

Therefore, if the present document compression / decompression apparatus is used for a document in which each page has many portions in common, for example, a document created by spreadsheet software or a standard document such as an invoice, As a result, compressed document data of a smaller size can be obtained than when the document compression / decompression device according to the second embodiment is used.

In the document compression / decompression device, image data of a specific page is used as a reference image when creating each difference compressed data. For this reason, the document compression / decompression device can perform decompression (output) from a middle page of the compressed document file 33 as in the document compression / decompression device of the second embodiment.
This is an apparatus that can perform faster than the document compression / decompression apparatus according to the first embodiment.

<Fourth Embodiment> FIG. 24 shows the structure of a compressed document file 34 created by a document compression / decompression device according to a fourth embodiment. As shown in the figure, the compressed document file 34 has a compressed data number Mmax, page numbers # 1 to #Mmax, and a reference page number #.
It is composed of management data including 2 to #Mmax and head position data # 2 to #Mmax, and Mmax pieces of compressed data.

The page numbers # 1 to #Mmax are respectively
This is information indicating which page of the compressed data # 1 to #Mmax is the compressed data related to the image data. The reference page numbers # 2 to #Mmax are the compressed data #
2 to #Mmax are information indicating which page of image data is compressed data created using the reference image as the reference image. In addition, the head position data # 2 to #Mmax respectively indicate the head positions of the compressed data # 2 to #Mmax relative to the head of the compressed document file 34, similarly to the head position data in the compressed document files 32 and 33. This is data represented by an address.

The compressed data # 1 is normal compressed data obtained by encoding image data, like the compressed data # 1 in the compressed document files 31-33.
The compressed data #d (d = 2 to Mmax) is differential compressed data created based on two image data having the same configuration as the compressed data #d in the compressed document files 31 to 33. However, as is apparent from having management data including a page number and a reference page number, the compressed data # 1 in the compressed document file 34 was obtained by encoding the image data of the page indicated by the page number # 1. Data. The compressed data #d (d = 2 to Mmax) is the reference page number #
The image data of the page indicated by page number #d, which is created using the image data of the page indicated by d as the reference image, can be restored.

Hereinafter, a procedure for creating the compressed document file 34 in the document compression / decompression device according to the fourth embodiment will be specifically described.

The compression processing executed by the document compression / decompression device according to the present embodiment includes a compression process (FIGS. 18 to 20) executed by the document compression / decompression device according to the third embodiment and a compressed data selection process. Only the content of the is different. For this reason,
The procedure for creating the compressed document file 34 in the document compression / decompression apparatus will be described focusing on the compressed data selection processing.

FIG. 25 shows a flowchart of the compressed data selection processing executed in the document compression / decompression device according to the fourth embodiment. It should be noted that the flow chart shown is Mmax ≧
3 shows only the processing performed when the condition 3 is satisfied (in the case of Mmax = 2, step S1212 is executed immediately after step S1205).

As shown in the figure, at the start of the compressed data selection processing, the control unit 21 determines the size of the Mmax × (Mmax−1) pieces of compressed data (differential compressed data) obtained by the previous processing. Is specified and the reference page number a and the generated page number b are obtained (step S1201). Note that the compressed data #x_
Since the size of y is equal to the size of the compressed data #y_x, there are 2n (n is a natural number) compressed data having the smallest size among the Mmax × (Mmax-1) compressed data. In step S1201, among the 2n pieces of compressed data, those for which the reference page number <the generated page number is satisfied are specified as compressed data for obtaining a and b. When there are a plurality of such compressed data, the one having the smallest reference page number is specified as the compressed data for acquiring a and b.

After obtaining a and b, the control section 21 compresses the image data of the page number a (image #a) to generate compressed data # 1 which is compressed data to be arranged immediately after the management data. (Step S1202). Also, a is stored as page number # 1 (step S1).
1203). Further, the fact that the compressed data #a_b is used as the compressed data # 2 is stored (step S1204).
Then, a and b are stored as reference page number # 2 and page number # 2, respectively (step S1205).

Thereafter, the control section 21 sets "3" to a variable m for storing the compressed data number to be processed (step S1206). Then, among the compressed data whose reference page number is any of page numbers # 1 to # m-1 and whose generated page number is not any of page numbers # 1 to # m-1, compressed data having the smallest size Is specified (step S1207). When there are a plurality of pieces of compressed data having the minimum size, the control unit 21 specifies one piece of compressed data in the following procedure. When the reference page number is page number # 1 (the generation page number of the compressed data # 1) among the plurality of minimum-sized compressed data, the compressed data is compressed to the minimum size. Specify as data. If none of the reference page numbers is page number # 1, the compressed data with the smallest generated page number (a plurality of pieces, if any, any of them) is specified as the compressed data of the minimum size. .
The processing content of this step will be more specifically described later with reference to other drawings.

Then, the fact that the specified compressed data is used as compressed data #m is stored (step S12).
08). Also, the reference page number of the specified compressed data,
The generated page numbers are stored as a reference page number #m and a page number #m, respectively (step S1209).

Thereafter, it is determined whether or not m <Mmax is satisfied (step S1210), and if it is satisfied (step S1210; YES), “1” is added to m (step S1211). Then, the processing of steps S1207 to S1209 is executed for the changed m.

The control section 21 repeats such processing. When m <Mmax is not satisfied (step S1210; NO), the control section 21 uses various information obtained in the processing up to that point to generate a compressed document. The file 34 is created (step S1212). Then, the compressed data selection process and the decompression process are completed.

Hereinafter, the procedure of creating the compressed document file 34 in the document compression / decompression device according to the fourth embodiment will be described more specifically, taking as an example a case where a document whose total number of pages is “5” is to be processed. explain.

In this case, since Mmax = 5, there are 20 (= 5 × 4) pieces of compressed data at the start of the compressed data selection process. Here, it is assumed that the size of the compressed data is as shown in FIG. In FIG. 26, the numerical values (1, 2, etc.) shown in the leftmost column are reference page numbers (page numbers of image data used as reference images), and the numerical values shown in the top row are , Generated page number (page number of image data obtained by restoration). The numerical value described at the place where the reference page number is X and the generated page number is Y is the size (arbitrary unit) of the compressed data #X_Y.

In this case, the compressed data # 3_4 and the compressed data # 4_3 are the compressed data of the minimum size. Also, the reason that the reference page number is smaller than the generated page number is
This is compressed data # 3_4. Therefore, step S12
In 01, a = 3 and b = 4. In steps S1202 and S1203, the compressed data # 1 is created by compressing the image # 3, and the fact that the page number # 1 is "3" is stored. Step S12
In 04, compressed data # 3_4 is stored as compressed data # 2. In step S1205, the reference page number # 2 and the page number # 2 are respectively
"3" and "4" (compressed data # 2 is data for restoring the image data of the fourth page using the image data of the third page as a reference image) is stored.

Step S12 executed when m = 3
07, the reference page numbers are page numbers # 1 to # 2 (=
m-1), and the compressed data having the smallest size is specified from the compressed data whose generated page number is not any of the page numbers # 1 and # 2. That is, in this case, as schematically shown in FIG. 27, compressed data of the minimum size is searched from among the unshaded compressed data, and as a result, compressed data # 3_2 is specified. . In the illustrated case, there is only one piece of compressed data of the minimum size. For example, if both the sizes of the compressed data # 3_2 and the compressed data # 3_5 are the minimum size “2”, the reference page number Is the page number #
1 (that is, "3") compressed data # 3_
2 specifies the compressed data of the minimum size. Also,
When both the sizes of the compressed data # 4_2 and the compressed data # 4_5 are the minimum size, since the reference page number is not the page number # 1 (that is, “3”), the generated page number is smaller. Small compressed data # 4_2
Is specified as the minimum-size compressed data.

Then, in step S1208, it is stored that the compressed data # 3_2 is used as the compressed data # 3. In step S1209, the reference page number # 3 and the page number # 3 are "3" and "2", respectively.
Is stored.

Step S12 executed when m = 4
07, the reference page number is one of page numbers # 1 to # 3, and the generated page number is page numbers # 1 to # 3.
The compressed data having the smallest size is specified from among the compressed data other than the above. That is, in this case, FIG.
As shown schematically, compressed data of the minimum size is searched from among the compressed data not shaded, and as a result, compressed data # 2_1 is specified. Then, in step S1208, it is stored that the compressed data # 2_1 is used as the compressed data # 4. In step S1209, it is stored that the reference page number # 4 and the page number # 4 are "2" and "1", respectively.

Step S12 executed when m = 5
07, the reference page number is one of page numbers # 1 to # 4, and the generated page number is page numbers # 1 to # 4.
The compressed data having the smallest size is specified from among the compressed data other than the above. That is, as schematically shown in FIG. 29, compressed data of the minimum size is searched from among the compressed data not shaded. in this case,
Although the compressed data # 1_5 and the compressed data # 3_5 are the minimum-sized compressed data, the compressed data # 3_5 is
Since the data can be restored by directly using the result of restoration of the compressed data # 1, the compressed data # 3_5 is specified as the compressed data of the minimum size.

In step S1208, it is stored that the compressed data # 3_5 is used as the compressed data # 5. In step S1209, the reference page number # 5 and the page number # 5 are "3" and "5", respectively.
Is stored.

In step S1210 performed thereafter, since m <Mmax is not established, a branch to the “NO” side is performed. Then, in step S1212,
Based on the information obtained so far, a compressed document file 34 having the contents schematically shown in FIG. 30 is created.

Next, the operation of the document compression / decompression device according to the present embodiment when decompressing the compressed document file 34 will be described.

FIG. 31 shows a flowchart of the restoration processing executed when the processing target document 34 is restored.
9 shows a flowchart of a reference image creation process executed during the restoration process. As shown in FIG. 31, during the restoration process, the control unit 2
In step S1301, first, a restoration process condition is obtained from the operator. This step corresponds to step S30
1, the same as S601 and the like. That is, the control unit 2
In step S1101, 1 obtains restoration processing conditions including the file name of the compressed document file to be restored, restoration page range designation information, output destination designation information, and the like.

Thereafter, the control unit 21 determines whether the management data (the number of compressed data Mmax, the page numbers # 1 to #Mmax,
Reference page numbers # 2 to #Mmax, start position data # 2
#Mmax) (step S1302). Further, immediately after step S1302, the control unit 21 sets Mmax
It is determined whether or not <Pe, and whether or not Ps> Mmax. If Mmax <Pe, Pe is set to Mmax.
Is set, and step S1303 is started. If Ps> Mmax, the restoration process ends.

In step S1303, control unit 21
Is the compressed data # 1 in the compressed document file 34
To generate an image # 1 on the RAM 22. Thereafter, the control unit 21 sets Ps as a variable P (step S1304), and sets a P-th page compressed data number (compressed data number of the compressed data whose page number is P) as a variable M (step S1305). . That is, m with page number # m = P is found, and the found m is M
Set to. Thereafter, the control unit 21 determines whether or not the image #M has been restored (the image #M exists in the RAM 22) (step S1306).

If image #M has been restored (step S1306; YES), control proceeds to step S1311, where control unit 21 stores image #M on the RAM, which is the image data of page P, in the output destination designation information. Output to the output destination specified by. On the other hand, if the image #M has not been restored (step S1306; YES), the control unit 21 sets a reference image required for restoring the image #M on the RAM 22 as a reference image. The image creation processing (step S1308) is started.

[0206] As shown in FIG. 32, when the reference image creation process, the control unit 21, first, the "0" to the variable j, the _{R M} page compression data number in the array variable m (j) (page number A compressed data number matching the reference page number #M is set (step S1401). Next, it is determined whether or not the image #m (j) has been restored (step S1402).

When the image #m (j) has not been restored (step S1402; NO), the control unit 21
Is added to (step S1403). And
r is the reference page number #m (j-1), and
The page compression data number is set in the array variable m (j) (step S1404). After that, step S1402
And the above processing is executed for the new j value.

If image #m (j) has been restored (step S1402; YES), control unit 21
Proceeds to step S1411 to determine whether j = 0. That is, it is determined whether or not the processing of steps S1402 to S1404 has been completed without executing step S1404 (whether or not image #m (0) has been restored).

If j = 0 is not satisfied (step S141)
1; NO), the control unit 21 generates a copy of the image #m (j) as a reference image (step S1412).
Then, the compressed differential data restoration process (step S1413) is executed. The differential compressed data restoration processing performed in this step is the same as the differential compressed data restoration processing described with reference to FIG. 14 except that m (j−1) is used instead of M. That is, in step S1413, a part of the reference image is rewritten in accordance with the compressed data #m (j-1), so that the image #m (j
-1) is generated.

Thereafter, the control unit 21 performs the process of reducing the value of j by "1" (step S1414), and then executes the processes from step S1411 again on j whose value has been changed. Then, when j = 0 holds (step S
1411; YES), the reference image creation processing ends.

Returning to FIG. 31, description of the restoration processing will be continued. After execution of the reference image creation processing (step S1308), the control unit 21 generates a copy of the image #m (0) created (or already existing) created by the reference image creation processing as a reference image (step S13).
09). Then, the differential compressed data creation processing (step S
1310). The differential compressed data creation processing performed in this step is exactly the same as that described with reference to FIG. That is, in step S1310, the reference image is rewritten based on the compressed data #M, and the image #M which is the image data of the P-th page is rewritten.
Is created.

Thereafter, the control section 21 outputs the image #M on the RAM 22 to the designated output destination (step S1311). Next, “1” is added to P (step S1311). If P does not exceed Pe (step S1312; NO), step S130 is performed.
Returning to 5, the above-mentioned processing is executed again for P whose value has been changed. Then, when P = Pe + 1 (step S1312; YES), a process (not shown) of discarding unnecessary image data is performed, and the restoration process is terminated.

Hereinafter, a case where restoration of all pages of the compressed document file 34 shown in FIG. 30 is instructed will be described as an example.
The decompression process executed by the document compression / decompression device according to the fourth embodiment will be described more specifically.

In this case, in step S1302, image # 1, which is image data of the third page, is generated on RAM 22. Then, step S13
04, in S1305, P is set to Ps value “1”, and M is set to compressed data number “4” whose page number is “1”. Then, step S16
Since the determination of 06 is made and the image # 4 has not been restored, the reference image creation processing is started.

Step S140 of reference image creation processing
In 1, the j is set to “0” and the m (0) is set to “2” which is the compressed data number of the compressed data used to restore the image data used as the reference image when the image # 4 is restored. Then, step S1402 is executed,
Since the image # 2 has not been restored, a branch is made to the “NO” side. As a result, j is changed to “1” and m
In (1), “1” which is a compressed data number of image data (image # 1) used as a reference image when decompressing image # 2 is set. Thereafter, step S1402 is executed again, and since the image # 1 has been restored, the branch to the “YES” side is performed.

That is, as schematically shown in FIG. 33A, only the image # 1 exists in the RAM 22,
Step S1411 is executed in a state where (0) = 2, m (1) = 1, and j = 1. In the case shown in FIG. 33A, since j = 1, branching to the “NO” side is performed in step S1411.

Therefore, by executing step S1412, as shown in FIG. 33B, image # 1 (= m
A state where the copy (reference image) of (1)) exists is formed. Then, in step S1413, since the differential compressed data decompression process is performed on the compressed data # 2 (= m (0)), as shown in FIG.
A state is formed in which the image # 1 and the image # 2 which is the image data of the fourth page exist on the AM 22. Thereafter, the value of j is reduced by "1", so that j = 0. Therefore, the reference image creation processing ends, and steps S1309 to S1311 are executed.

In step S1309, as shown in FIG. 33D, a copy of image # 2 (= m (0)) is created as a reference image. Subsequent step S131
0, the copy is rewritten based on the compressed data # 4 (= M). As a result, as shown in FIG. 33 (E), the image # 1, the image # 2,
A state is established in which image # 4, which is the image data of the first page, exists. And that image # 4
(Image data of the first page) is output to the specified output destination.

Thereafter, P is changed to "2", and step S13 is executed to output the image data of the second page.
The processing from 05 is executed again.

In this case, in step S1305, M
Is set to the second page compression data number “3”. Image # 3 does not exist on RAM 22 (FIG. 33)
(E)), the reference image creation process is started,
In m (0), “1” which is the _RM-th page compressed data number
Is set. Then, step S1402 is executed, but since image # 1 (= m (0)) exists on the RAM 22, the processing from step S1411 is started without performing steps S1403 and S1404. That is, as schematically shown in FIG. 34A, in a state where the images # 1, # 2, and # 4 exist in the RAM 22 and m (0) = 1 and j = 0, step S1 is executed.
411 is executed.

Since j = 0, a branch is made to the "YES" side in step S1411. That is, the processing from step S1309 is started. As a result, FIG.
As shown in FIG. 4 (B), image # 1 (= m (0))
Is made as a reference image. Then, since the copy is rewritten based on the compressed data # 3 (= M), as shown in FIG.
Above, a state is formed in which images # 1, 2, 4 and image # 3, which is image data of the second page, exist. Then, the image # 3 (image data of the second page) is output to the specified output destination, and the P value is changed to “3”.

At the time of the process after P = 3, in step S1305, the third page compressed data number “1” is set in M. Then, since the image # 1 has been restored, the output of the image # 1 (step S
1311) is performed. In the subsequent process for P = 4, since the image # 2, which is the image data of the fourth page, already exists in the RAM 22, steps S1308 to S1310 are not executed, and the process from step S1311 is not executed. Is executed.

At the time of processing for P = 5, “5” is set to M in step S1305. Since image # 5 has not been restored, a reference image creation process is performed, and in step S1401, j = 0,
m (0) = 1. Since the image # 1 (= m (0)) has been restored, the images # 1 to # 4 exist in the RAM 22 as schematically shown in FIG.
In the state where (0) = 1 and j = 0, step S1411
Is executed.

Since j = 0, a branch is made to the "YES" side in step S1411. That is, the reference image creation processing is terminated without executing steps S1412 to S1414, and steps S1309 to S1309.
1311 is executed. In step S1309, FIG.
As shown in FIG. 5 (B), image # 1 (= m (0))
Is made as a reference image. Then, in step S1310, the compressed data # 5 of the copy
Image # 5 is generated by rewriting based on (= M). As a result, as shown in FIG.
A state in which images # 1 to # 4 and image # 5 which is the image data of the fifth page exists on M22. Then, the image # 5 is output to the specified output destination. Thereafter, P becomes “6”, and the restoration processing is terminated.

As described above, in the document compressing / decompressing apparatus according to the fourth embodiment, a compressed document including one piece of normal compressed data and N-1 pieces of differentially compressed data for an N page document A compressed document file, which is a file and is determined for each differential compressed data so that the size of image data used as a reference image is minimized, is created.

Therefore, if the present document compression / decompression apparatus is used for a document in which each page has many portions in common, for example, a document created by spreadsheet software or a standard document such as an invoice, 1 to
As a result, a compressed document file 34 having a smaller size than when the document compression / decompression device according to the third embodiment is used is obtained.

<Fifth Embodiment> FIG. 36 shows the structure of a compressed document file 35 created by a document compression / decompression device according to a fifth embodiment. As shown in the figure, the compressed document file 35 has a number Mmax of compressed data, type flags # 2 to #Mmax,
It is composed of management data consisting of 1 to #Mmax and Mmax pieces of compressed data.

The type flag #d (d = 2 to Mmax) is data indicating whether the compressed data #d is normal compressed data or differential compressed data. That is, the compressed document file 35 is a file in which compressed data # 2 to #Mmax may include normal compressed data. The type-specific flag is 1-bit data, and the type flags # 2 to #Mmax are stored in a storage area of a byte number corresponding to the Mmax value (“INT ((Mmax -2) / 8) +1 "byte storage area). Start position data # 1 to #Mmax
Are data representing the start positions of the compressed data # 1 to #Mmax as relative addresses from the start of the compressed document file 35, respectively. Note that, unlike the compressed document files 32 to 34, the reason why the head position data # 1 is included in the compressed document file 35 will be described later.

The procedure for creating a compressed document file 35 in the document compression / decompression device according to the fifth embodiment will be described below with reference to FIGS. 37 and 38. FIG. 37 is a flowchart of a compression process executed in the document compression / decompression apparatus, and FIG. 38 is a flowchart of a differential compressed data creation process executed at the time of the compression process.

As shown in FIG. 37, at the time of compression processing, the control section 21 first sets "1" to a variable M for storing the page number of the page being processed (step S1501). Then, the image data of the first page of the document to be processed is stored in the RAM as image # 1.
22 (step S1502). That is,
When called from the application program, in this step, image data corresponding to the print data passed from the application program is created on the RAM 22 in a form associated with “1” (= M). When a document composed of a plurality of image data is being compressed, the contents of the image data file for the first page are read out, and “1” is stored in the RAM 22.
(= M).

After preparing the image # 1 on the RAM 22, the control unit 21 stores the number of unit data included in the image # 1 as kmax (step S150).
3). Thereafter, the control unit 21 performs run-length encoding on the image # 1 on the RAM
Compressed data # 1 is created above (step S150)
4). Then, it is determined whether there is a page to be processed (step S1505).

If there are pages to be processed (step S1505; YES), the control unit 21 executes a compressed data creation process (step S1506).

As shown in FIG. 38, at the time of the compressed data creation processing, the control section 21 recognizes that the image #M existing on the RAM 22 is used as a reference image (step S1601). Next, “1” is added to M (step S1602), and “1” is set to the type flag #M (step S1603).

Then, the image data of the Mth page of the document to be processed is stored in the RAM 22 as an image #M.
It is prepared above (step S1604), and executes differential compressed data creation processing (step S1604). The difference compressed data creation processing executed in this step is exactly the same as that described with reference to FIG. 14, and a description thereof will be omitted.

After creating the compressed data #M by executing the difference compressed data creation processing, the control unit 21 discards the image # M-1 used as the reference image (step S1606). Then, normal compressed data of the image #M is created (step S1607), and the size S _{RLE of} the created normal compressed data is compared with the size _SD of the compressed data #M created in the differential compressed data creating process (step S1607). Step S1608).

If S _RLE < _SD (step S
1608; NO), the control unit 21
The normal compressed data of M is discarded (step S1609),
The compressed data creation processing ends. On the other hand, when the size of the normal compressed data is smaller (step S1608;
YES), the control unit 21 discards the compressed data #M created in the differential compressed data creation process, and proceeds to step S16.
The normal compressed data created in step 07 is set as compressed data #M (step S1610). Then, the value of the type flag #M is changed to “0” (step S1611), and the compressed data creation processing ends.

[0237] As shown in FIG.
Executes this compressed data creation process (step S1506) for each page to be processed, and when there are no more pages to be processed (step S1505; NO),
The compressed document file 36 is created based on the information obtained so far (step S1513), and the compression process ends.

Next, a procedure for restoring the compressed document file 36 in the document compression / decompression device according to the present embodiment will be described.

FIGS. 39 and 40 show flow charts of the decompression processing executed in the document compression / decompression apparatus. As shown in FIG. 39, at the time of restoration processing, the control unit 21 first acquires restoration processing conditions from the operator (step S1).
701). The restoration processing conditions obtained in this step are as follows:
This is the same as the restoration processing condition in each embodiment described above.

After obtaining the restoration processing conditions, the control unit 21 obtains management data (the number of compressed data Mmax, type flags # 2 to #Mmax, and top position data # 1 to #Mmax) of the compressed document file to be processed (see FIG. 4). Step S170
2). Then, the type flag # 1 is set to “0”, and Ps (decompression start page number) is set in a variable M for storing the compressed data number of the compressed data to be processed.
(Step S1703). As is clear from the compression procedure already described, the compressed data of a certain compressed data number in the compressed document file 35 is data obtained by compressing image data of a page number equal to the compressed data number. This value of M is processed (restored)
Is a value that also represents the page number of the image data that is to be executed.

Thereafter, control unit 21 determines whether or not the value of type flag #M is "0" (step S170).
4). If the value of the type flag #M is not “0” (step S1704; NO), the control unit 21 decreases the value of M by “1” (step S1705). Then, the process returns to step S1704, where the value of the type flag #M is “0”.
Is determined.

When the type flag # M = 0 is found by the processing of steps S1704 and S1705 (step S1704; YES), the control unit 21 determines the position indicated by the head position data #M in the compressed document file 35. Then, an image #M is created on the RAM 22 by decompressing the compressed data #M existing in the storage area from (step S1706).

Thereafter, the control unit 21 determines whether or not the value of M matches Ps (step S1707). If the value does not match (step S1707; NO), the image # M is recognized as a reference image (step S1708). Then, "1" is set to M
Are added (step S1709), and the differential compressed data decompression process (step S1710) is executed. The differential compressed data decompression processing performed in this step is the same as that already described with reference to FIG.

After executing the differential compressed data restoration processing, the control unit 21 returns to step S1707, and determines whether or not M is equal to Ps. If they do not match (step S1707; NO),
The processing of steps S1708 to S1710 is executed, and if they match (step S1707; YES),
The image #M on the RAM 22 is output to the output destination specified by the output destination specification information (step S1711).

Thereafter, the control section 21 determines whether or not M <Pe holds (FIG. 40: step S1721).
If M <Pe (step S1721;
To “YES”, “1” is added to M (step S17)
22). Then, it is determined whether or not the type flag #M is “1”, and when it is not “1” (step S172)
3; NO), the image # M-1 on the RAM 22 is recognized as a reference image (step S1724). Then, an image #M is created on the RAM 22 by executing the differential compressed data restoring process (step S1725).

If the type flag #M is "1" (step S1723; YES), the control section 21 discards the image # M-1 (step S1726). Then, by expanding the compressed data #M, the RAM 22 is expanded.
An image #M is created above (step S1727).
That is, the compressed data # whose type flag #M is “1”
M is normal compressed data that does not require a reference image. Therefore, the image # M-1 is discarded, and the image # M-1 is discarded.
In order to obtain M, the compressed data #M is expanded.

Step S1725 or step S1
After creating the image #M in 727, the control unit 21 outputs the image #M to the designated output destination (step S1728). Returning to step S1721, it is determined whether or not the output image #M is the image of the last page specified by the restored page range specification information, and if it is the image of the last page (step S1721).
1721; YES), the unnecessary image data is discarded (not shown), and the restoration processing ends.

As described above, in the document compressing / decompressing apparatus according to the fifth embodiment, a compressed document file containing compressed data for the first to Nth pages is provided for an N page document. The normal compressed data of the image data of the first page is used as the compressed data for the first page, and the compressed data of the image data of the page and the normal compressed data of the previous page are used as the compressed data for each page after the second page. A compressed document file is created using the smaller size data of the difference compressed data created using the image data as the reference image. That is, for a page for which it is not appropriate to use differential compressed data, a compressed document file 35 using normal compressed data is created.

Therefore, if the document compression / decompression device is used, whatever document is processed, the document can be compressed at least at the same compression ratio as the conventional one. Then, for a document in which each page has many common portions, the document can be compressed at a higher compression ratio than before.

The compressed document file 35
Is a file in which normal compressed data may be used in place of differential compressed data. Therefore, even if compressed data # 1 is not read, restoration of a target page can be performed.
It is a file that can be output. In the document compression / decompression apparatus according to the present embodiment, the start position of all the compressed data is set so that the processing can be performed in the same procedure in all cases including the case where reading of the compressed data # 1 is not necessary. The data is included in the compressed document file 35.

<Sixth Embodiment> FIG. 41 shows the structure of a compressed document file 36 created by a document compression / decompression device according to a sixth embodiment. As shown in the drawing, the compressed document file 36 includes a compressed data number Mmax, page numbers # 1 to #Mmax, and a reference page number #.
It is composed of management data including 2 to #Mmax and head position data # 1 to #Mmax, and Mmax pieces of compressed data.

The page numbers # 1 to #Mmax are respectively
This is information indicating which page of the compressed data # 1 to #Mmax is the compressed data related to the image data. The reference page numbers # 2 to #Mmax are the compressed data #
2 to #Mmax are information indicating whether the data is normal compressed data or differential compressed data by "0". When the reference page numbers # 2 to #Mmax are not “0”, the information indicating the page number of the compressed data # 2 to #Mmax is the compressed data created as the reference image, respectively. Has become. The start position data # 1 to #Mmax are data representing the start position of the compressed data # 1 to #Mmax, respectively, as a relative address from the start of the compressed document file 36.

As is apparent from the provision of the management data as described above, the compressed data # 1 in the compressed document file 36 is data obtained by encoding the image data of the page indicated by the page number # 1. ing.
The compressed data #d having the reference page number #d that is not “0” restores the image data of the page indicated by the page number #d created using the image data of the page indicated by the reference page number #d as the reference image. It is possible to compress differential data. It should be noted that the differential compressed data has exactly the same configuration as the differential compressed data in the compressed document files 31 to 35. Then, the compressed data #d whose reference page number #d is “0”
Is the normal compressed data of the image data of the page indicated by the page number #d.

The compression processing executed by the document compression / decompression device according to the present embodiment includes a compression process (FIGS. 18 to 20) executed by the document compression / decompression device according to the third embodiment, and a compressed data selection process. Only the content of the is different. For this reason,
A procedure for creating the compressed document file 36 in the document compression / decompression apparatus will be described focusing on the compressed data selection processing.

FIGS. 42 and 43 show flowcharts of compressed data selection processing executed by the document compression / decompression device according to the sixth embodiment. As shown in FIG. 42, at the time of the compressed data selection processing, the control unit 21 first sets the images # 1 to #M
By compressing max, normal compressed data # 1 to #Mmax are respectively generated (step S1801). Next, the control unit 21 obtains the obtained Mmax × (Mmax−1)
The difference compression data having the smallest size is specified from the difference compression data, and the reference page number a and the generated page number b are obtained (step S1801). In addition,
Since the size of the compressed data #x_y is equal to the size of the compressed data #y_x, among the Mmax × (Mmax−1) pieces of compressed data, 2n (n
Is a natural number). In this step S1801,
Out of the 2n pieces of compressed data, those satisfying the reference page number <the generated page number are specified as compressed data for acquiring a and b. Further, when there are a plurality of such compressed data, the one having the smallest reference page number is specified as the compressed data for acquiring a and b.

After the acquisition of a and b, the control unit 21 stores that the normal compressed data #a is used as the compressed data # 1 (step S1803). Also, if the page number # 1 is a
Is stored (step S1804).

After that, the control unit 21 sets the differential compression data #
The size Sa_b of a_b and the size S of normal compressed data #b
b is compared (step S1805). And Sa_b
<If Sb is satisfied (Step S1805; YE)
S) stores that the differential compressed data #a_b is used as the compressed data # 2 (step S1806).
Further, it is stored that the reference page number # 2 and the page number # 2 are a and b, respectively (step S180).
7). On the other hand, when Sa_b <Sb is not satisfied (step S1805; NO), the fact that the normal compressed data #b is used as the compressed data # 2 is stored (step S1808). Further, it stores that the reference page number # 2 and the page number # 2 are 0 and b, respectively (step S1809).

After determining reference page number # 2 and page number # 2 in step S1807 or S1809, control unit 21 sets variable m to "3" (FIG. 4).
3: Step S1811). The difference compressed data having the smallest size is selected from the differential compressed data in which the reference page number is any of page numbers # 1 to # m-1 and the generated page number is not any of page numbers # 1 to # m-1. The compressed data #x_y is specified (step S1807). If there are a plurality of compressed data of the minimum size, the control unit 2
1 specifies one piece of compressed data in the following procedure. When the reference page number is page number # 1 among a plurality of minimum-size compressed data, the compressed data is specified as the minimum-size compressed data. When there is no reference page number of page number # 1, the number of compressed data required for restoration (details will be described later) is the smallest (a plurality of compressed data, if any, any of them). ) Is specified as the minimum size compressed data.

Thereafter, the control unit 21 sets the differential compression data #
x_y size Sx_y and normal compressed data #y size S
y is compared (step S1813). If Sx_y <Sy holds (step S1813; YES),
The fact that the difference compressed data #x_y is used as the compressed data #m is stored (step S1814). Further, the reference page number # 2 and the page number # 2 are respectively represented by x and y.
Is stored (step S1815). on the other hand,
If Sx_y <Sy is not satisfied (step S18)
13; NO), the normal compressed data #y is
m is stored (step S181).
6). Also, the reference page number # 2 and the page number # 2 are
It stores that they are 0 and y, respectively (step S1).
817).

After determining the reference page number #m and the page number #m in step S1815 or S1817, the control unit 21 determines whether or not m <Mmax is satisfied (step S1818). In this case (step S1818; YES), “1” is added to m (step S1819). Then, the processing from step S1812 is executed again on the changed m.

The control section 21 repeats such processing, and when m <Mmax is not satisfied (step S1818; NO), the control section 21 uses various information obtained in the processing up to that point to generate a compressed document. The file 36 is created (step S1820). Then, the compressed data selection process and the compression process are completed.

Hereinafter, the procedure for restoring the compressed document file 36 in the document compression / decompression apparatus according to the sixth embodiment will be described with reference to FIGS. 44 and 45. FIG. 44 shows a document compression / data compression process according to the sixth embodiment.
FIG. 45 is a flowchart of a restoration process executed by the restoration device, and FIG.
9 is a flowchart of a reference image creation process executed at the time of a restoration process.

As shown in FIG. 44, at the time of restoration processing, the control unit 21 first acquires restoration processing conditions from the operator (step S1901). This step includes step S
301, S601 and the like.

Thereafter, the control unit 21 determines whether the management data (the number of compressed data Mmax, the page numbers # 1 to #Mmax,
Reference page numbers # 2 to #Mmax, start position data # 1
#Mmax) (step S1902). Although not shown, the control unit 21 determines in step S190
Immediately after Step 2, it is determined whether or not Mmax <Pe, and whether or not Ps> Mmax. When Mmax <Pe, Pe is set to Mmax, and then step S1903 is performed.
To start. If Ps> Mmax, the restoration process ends.

At step S1903, control unit 21
Sets Ps to the variable P. After that, the control unit 21
In the variable M, the P-th page compressed data number (the page number is P
Is set (compressed data number of the compressed data) (step S1904). That is, m with page number # m = P is determined, and the determined m is set to M. Thereafter, the control unit 21 determines that the image #M has been restored (image #M
Is determined on the RAM 22) (step S1905).

If the image #M has been restored (step S1905; YES), the control unit 21 proceeds to step S1911, and stores the image #M on the RAM, which is the image data of the Pth page, in the output destination designation information. Output to the output destination specified by. On the other hand, if the image #M is not already restored (step S1905; YES), the control unit 21, (in the figure, _{R M)} reference data number #M determines whether or not "0" (step S190
6).

If the reference data number #M is "0" (step S1906; YES), the compressed data #M which is normally compressed data is expanded,
Image #M is generated on RAM 22 (step S1)
907). Then, the process proceeds to step S1911 to output the image #M.

If the reference data number #M is not "0" (step S1906; NO), a reference image which is a process for preparing a reference image required for restoring the image #M on the RAM 22 is prepared. The creation process (step S1908) is started.

[0269] As shown in FIG. 45, when the reference image creation process, the control unit 21, first, the "0" to the variable j, the _{R M} page compression data number in the array variable m (j) (page number A compressed data number matching the reference page number #M is set (step S2001). Next, it is determined whether or not the image #m (j) has been restored (step S2002).

If image #m (j) has not been restored (step S2002; NO), control unit 21 determines whether reference page number #m (j) is "0" (step S2002). S2003). And reference page number #
When m (j) is “0” (Step S2003;
YES), the compressed data #m which is the normal compressed data
An image #m (j) is created on the RAM 22 by expanding (j) (step S2004).

If the reference page number #m (j) is not “0” (step S2003; NO), the control unit 21
Adds “1” to j (step S2005). Then, when r is the reference page number #m (j-1), the r-th page compressed data number is set to the array variable m (j) (step S2006). Then, step S2
Returning to 002, the above-described processing is executed for a new j value.

If image #m (j) has been restored (step S2002; YES), control unit 2
The process advances to step S2011 to determine whether or not j = 0.

If j = 0 is not satisfied (step S201)
1; NO), the control unit 21 generates a copy of the image #m (j) as a reference image (step S2012).
Then, the differential compressed data restoration processing (step S2013) is executed. The differential compressed data restoration processing performed in this step is the same as the differential compressed data restoration processing described with reference to FIG. 14 except that m (j−1) is used instead of M. That is, in step S2013, a part of the reference image is rewritten in accordance with the compressed data #m (j-1), so that the image #m (j
-1) is generated.

Thereafter, the control unit 21 performs the process of reducing the value of j by “1” (step S2014), and then executes the process from step S2011 again on j whose value has been changed. Then, when j = 0 holds (step S
2011; YES), the reference image creation processing ends.

Returning to FIG. 44, description of the restoration processing will be continued. After executing the reference image creation processing (step S1908), the control unit 21 generates a copy of the image #m (0) created (or already existing) created by the reference image creation processing as a reference image (step S19).
09). Then, the differential compressed data creation processing (step S
1910). The differential compressed data creation processing performed in this step is exactly the same as that described with reference to FIG. That is, in step S1910, the reference image is rewritten based on the compressed data #M, and the image #M which is the image data of the P-th page is rewritten.
Is created.

After that, the control section 21 outputs the image #M on the RAM 22 to the designated output destination (step S1911). Next, “1” is added to P (step S1911), and if P has not exceeded Pe (step S1912; NO), step S190 is performed.
Returning to 5, the above-mentioned processing is executed again for P whose value has been changed. Then, when P = Pe + 1 (step S1912; YES), the unnecessary image data is discarded (not shown), and the restoration processing ends.

As described above, in the document compression / decompression device according to the sixth embodiment, a compressed document file containing compressed data for the first to N-th pages is provided for the N-page document. For a page including at least one piece of normal compressed data and capable of creating differential compressed data smaller in size than the normal compressed data, a compressed document file using the differential compressed data is created.

Therefore, if the document compression / decompression device is used, whatever document is processed, the document can be compressed at least at the same compression ratio as the conventional one. Then, for a document having many common portions on each page, the document can be compressed at a higher compression ratio than the document compression / decompression device of each of the above-described embodiments and the same type of conventional device.

<Seventh Embodiment> A document compression / decompression device according to a seventh embodiment is a modification of the document compression / decompression device according to the first embodiment.

FIG. 46 shows the structure of a compressed document file 37 created by the document compression / decompression device according to the seventh embodiment. As is apparent from the figure, the compressed document file 37 has the element data number Nmax.
, And Nmax pieces of element data including replacement start position data, replacement number data, and replacement data, respectively.

Hereinafter, the meaning of each data constituting the element data will be described by describing the compression / decompression operation of the document compression / decompression apparatus. Note that the overall operation of the document compression / decompression device is the same as that of the document compression / decompression device according to the first embodiment. The device will be described.

FIGS. 47 and 48 show flowcharts of differential compressed data creation processing executed by the document compression / decompression apparatus.

As shown in FIG. 47, at the time of the differential compressed data creation processing, the control unit 21 sets “1” to k and “0” to i.
Is set to “0” for L (step S2101). Then, the unit data #k of the image #M (hereinafter also referred to as D) is compared with the unit data #k of the reference image (step S2102).

If the two match (step S21)
03; YES), the control unit 21 adds “1” to k (step S2110). Then, it is determined whether or not k is equal to or smaller than kmax. If k is equal to or smaller than kmax (step S2111; YES), the processing from step S2102 is executed again.

If D and unit data #k of the reference image do not match (step S2103; NO),
The control unit 21 determines whether or not L is “0” (Step S2104). When L is “0” (step S2104; YES), the control unit 21 sets k to the variable ks.
Is set to "1" for L, D for variable Dold, and k for kold (step S2109), and the flow advances to step S2110.

On the other hand, if L is not "0" (step S2104; NO), the control unit 21 determines whether D = Dold and k = kold + 1 hold (step S2105). If the condition is satisfied (step S2105; YES), “1” is added to L and k is set to kold (step S2106). Then, the process proceeds to step S2110.

If either (or both) of D = Dold and k = kold + 1 do not hold (step S2
105; NO), the control unit 21 adds "1" to the variable i (step S2107). Then, the values of ks, L, and Dold at that time are stored as respective elements of the replacement data #i (step S2108). Then, the processing from step S2109 is executed.

The control section 21 repeats such processing until the processing for all the unit data in the image #M is completed. Then, when the processing for all the unit data is completed (step S2111; NO), FIG.
As shown in FIG. 8, it is determined whether or not L = 0 (step S2112). If L = 0 is not satisfied (step S2112; NO), the control unit 21 adds “1” to i (step S2113), and replaces ks, L, and Dold with each element (replacement start position) of the element data #i. (Data, replacement number data, replacement data) (step S211).
4). Then, the value of i is stored as the number of element data Mmax of the compressed data #M (step S2115), and the differential compressed data creation processing ends. On the other hand, if L = 0 (step S2112; YES), the control unit 21 executes step S2115 without changing the i value or the like, and ends the differential compressed data creation processing.

The processing in steps S2112 to S2114 is performed to include element data relating to the last unit data of the image #M in the differential compressed data when the last unit data is different from the corresponding unit data of the reference image. It has been done.

That is, at the time of differential compressed data creation processing in the document compression / decompression device according to the present embodiment, the image #M is composed of continuous unit data having the same contents from portions different from the reference image. Is searched for, the information (replacement start position data ks) representing the head element data of each such part, the number of unit data constituting the part (replacement number data L), and the Difference compressed data including element data composed of the content of the unit data (replacement data D) is created.

The differential compressed data created in this manner is restored by the differential compressed data restoring process shown in FIG.

That is, the control unit 21 first obtains the number Nmax of element data of the compressed data #M (step S22).
01). Next, "1" is set to a variable i for storing the element data number (step S2202), and it is determined whether or not the value of i is equal to or smaller than Nmax (step S220).
3). When the value of i is equal to or smaller than Nmax (step S22)
03; YES), the control unit 21 acquires the element data #i (replacement position data ks, replacement number data L, replacement data D) of the compressed data #M from the compressed document file 37 (step S2204).

Thereafter, the control unit 21 changes the continuous L unit data starting from the position indicated by ks of the reference image stored in the RAM 22 to the replacement data D (step S2205). Then, i is "1"
Is added (Step S2206), and then Step S2
Returning to 203, the changed value of i is compared with Nmax.
If i ≦ Nmax is satisfied (step S2)
203; YES), the processing of steps S404 to S406 is executed again, and if i ≦ Nmax is not satisfied (step S2203; NO), that is, the processing for all the element data of the compressed data #M is completed Then, the differential compression data decompression process ends.

The compressed document file 37 created by the document compression / decompression device according to the present embodiment
The size of one of the element data is larger than the size of the element data in the compressed document file 31 by the amount including the continuous number data. However, when the continuous number data is q (≧ 2), the part represented by q element data in the compressed document file 31 is represented by one element data in the main compressed document file 37. Will be. Therefore,
If the image #M includes a portion different from the reference image and composed of continuous unit data having the same content at a certain ratio or more, the compressed document file 37 is It becomes a small file. The image data of a document created by spreadsheet software or a standard document such as an invoice usually includes many such portions.
Therefore, if this document compression / decompression device is used,
The document can be compressed at a higher compression ratio than the document compression / decompression device according to the first embodiment.

<Modifications> The document compression / decompression device of each embodiment can perform various modifications. For example, as the differential compressed data having the configuration used in the document compression / decompression device of the seventh embodiment is used,
The document compression / decompression devices of the second to sixth embodiments can be modified. In addition, the technique used in the document compression / decompression apparatus according to the fifth and sixth embodiments (usually using compressed data for a page where it is not appropriate to use differential compressed data) is described in the second and third embodiments. Can be applied to the document compression / decompression device according to.

Further, the document compression / decompression device of each embodiment creates one file as a compression result, but the device may be configured so that a file is created for each page. Further, the document compression / decompression device of each embodiment is a device in which run-length encoding is used to create normal compressed data. However, the normal compression data is created by another encoding procedure. Of course, it may be.

Although the document compression / decompression device of each embodiment is realized by installing a predetermined program in a computer, the document compression / decompression device is manufactured by manufacturing an IC capable of performing the above-described processing. , A document compression / decompression device may be realized. Further, a document compression / decompression device may be realized as a function of a printing device, a facsimile device, or a multifunction peripheral.

[0298]

According to the document compression apparatus and the document compression method of the present invention, a document composed of a plurality of pages of image data can be compressed at a high compression rate. Further, according to the document decompression device and the document decompression method of the present invention, it is possible to decompress the compressed data obtained by the document compression device and the document compression method of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a hardware configuration of a document compression / decompression device according to each embodiment.

FIG. 2 is an explanatory diagram of a compressed document file created by the document compression / decompression device according to the first embodiment.

FIG. 3 is a flowchart of a compression process executed in the document compression / decompression device according to the first embodiment.

FIG. 4 is a flowchart of differential compressed data creation processing executed in the document compression / decompression device according to the first embodiment.

FIG. 5 is an explanatory diagram of a compression process performed in the document compression / decompression device according to the first embodiment.

FIG. 6 is a flowchart of a decompression process executed in the document compression / decompression device according to the first embodiment.

FIG. 7 is a flowchart of differential compressed data decompression processing executed in the document compression / decompression device according to the first embodiment.

FIG. 8 is an explanatory diagram of a decompression process executed in the document compression / decompression device according to the first embodiment.

FIG. 9 is an explanatory diagram of a decompression process executed in the document compression / decompression device according to the first embodiment.

FIG. 10 is an explanatory diagram of a compressed document file created by a document compression / decompression device according to a second embodiment.

FIG. 11 is a flowchart of a compression process executed in the document compression / decompression device according to the second embodiment.

FIG. 12 is an explanatory diagram of a compression process performed in the document compression / decompression device according to the second embodiment.

FIG. 13 is a flowchart of a decompression process executed in the document compression / decompression device according to the second embodiment.

FIG. 14 is a flowchart of differential compressed data decompression processing executed in the document compression / decompression device according to the second embodiment.

FIG. 15 is an explanatory diagram of a decompression process executed in the document compression / decompression device according to the second embodiment.

FIG. 16 is an explanatory diagram of a decompression process executed in the document compression / decompression device according to the second embodiment.

FIG. 17 is an explanatory diagram of a compressed document file created by the document compression / decompression device according to the third embodiment.

FIG. 18 is a flowchart of a compression process performed in the document compression / decompression device according to the third embodiment.

FIG. 19 is an explanatory diagram of differential compressed data creation processing executed in the document compression / decompression device according to the third embodiment.

FIG. 20 is a flowchart of compressed data selection processing executed in the document compression / decompression device according to the third embodiment.

FIG. 21 is a diagram illustrating a compression process performed in the document compression / decompression device according to the third embodiment.

FIG. 22 is a diagram showing an example of a compressed document file created by the document compression / decompression device according to the third embodiment.

FIG. 23 is an explanatory diagram of a decompression process executed in the document compression / decompression device according to the third embodiment.

FIG. 24 is an explanatory diagram of a compressed document file created by the document compression / decompression device according to the fourth embodiment.

FIG. 25 is a flowchart of a compressed data selection process executed in the document compression / decompression device according to the fourth embodiment.

FIG. 26 is a diagram illustrating a compression process performed in the document compression / decompression device according to the fourth embodiment.

FIG. 27 is a diagram illustrating a compression process performed in the document compression / decompression device according to the fourth embodiment.

FIG. 28 is a diagram illustrating a compression process performed by the document compression / decompression device according to the fourth embodiment.

FIG. 29 is a diagram illustrating a compression process performed in the document compression / decompression device according to the fourth embodiment.

FIG. 30 is a diagram showing an example of a compressed document file created by the document compression / decompression device according to the fourth embodiment.

FIG. 31 is an explanatory diagram of a decompression process performed in the document compression / decompression device according to the fourth embodiment.

FIG. 32 is an explanatory diagram of a reference image creation process executed in the document compression / decompression device according to the fourth embodiment.

FIG. 33 is a view for explaining a decompression process executed in the document compression / decompression device according to the fourth embodiment.

FIG. 34 is a diagram for explaining a decompression process performed in the document compression / decompression device according to the fourth embodiment.

FIG. 35 is a diagram illustrating a decompression process performed by the document compression / decompression device according to the fourth embodiment.

FIG. 36 is an explanatory diagram of a compressed document file created by the document compression / decompression device according to the fifth embodiment of the present invention.

FIG. 37 is a flowchart of a compression process executed in the document compression / decompression device according to the fifth embodiment.

FIG. 38 is a flowchart of compressed data creation processing executed in the document compression / decompression device according to the fifth embodiment.

FIG. 39 is a flowchart of a decompression process executed in the document compression / decompression device according to the fifth embodiment.

FIG. 40 is a flowchart following FIG. 39 of the decompression processing executed in the document compression / decompression device according to the fifth embodiment.

FIG. 41 is a configuration diagram of a compressed document file created by a document compression / decompression device according to a sixth embodiment.

FIG. 42 is a flowchart of compressed data selection processing executed in the document compression / decompression device according to the sixth embodiment.

FIG. 43 shows a compressed data selection process executed in the document compression / decompression device according to the sixth embodiment;
FIG.

FIG. 44 is a flowchart of a decompression process executed in the document compression / decompression device according to the sixth embodiment.

FIG. 45 is a flowchart of a reference image creation process executed in the document compression / decompression device according to the sixth embodiment.

FIG. 46 is a configuration diagram of a compressed document file created by the document compression / decompression device according to the seventh embodiment.

FIG. 47 is a flowchart of differential compressed data creation processing executed in the document compression / decompression device according to the seventh embodiment.

FIG. 48 is a flowchart following FIG. 47 of differential compressed data creation processing executed in the document compression / decompression device according to the seventh embodiment.

FIG. 49 is a flowchart of differential compressed data decompression processing executed in the document compression / decompression device according to the seventh embodiment.

[Explanation of symbols]

 Reference Signs List 11 display 12 input device 13 printing device 14 control device 15 CD-ROM 21 control unit 22 RAM 23 HDD 24 communication control unit 25 display control circuit 26 interface circuit 28 CD-ROM 29 bus 31-37 compressed document file

Claims (36)

[Claims] 1. A document compression apparatus for generating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages, comprising: Normal compressed data generating means for generating normal compressed data relating to the first page by encoding the image data of the first page; and image data of the second to Nth pages of the document as generated image data, respectively. N-1 difference compressed data using the image data of the immediately preceding page as reference image data, and N-1 pieces of positions and contents of the portion of the generated image data different from the reference image data Differential compressed data creating means for creating differential compressed data of: The normal compressed data created by the normal compressed data creating means, the N-1 differential compressed data created by the differential compressed data creating means, and each of the normal compressed data and the differential compressed data relate to any page of the document. A compressed document data creating unit for creating compressed document data including information indicating whether the document is a document. 2. A document compression apparatus for creating, based on a document including first to Nth pages, compressed document data capable of restoring image data of the first to Nth pages of the document, the document compression apparatus comprising: Normal compressed data generating means for generating normal compressed data relating to the first page by encoding the image data of the first page; and image data of the second to Nth pages of the document as generated image data, respectively. And the first
N using page image data as reference image data
Differential compressed data creating means for creating (N-1) differential compressed data that is -1 differential compressed data and indicates a position and a content of a portion of the generated image data that is different from the reference image data; The normal compressed data created by the normal compressed data creating means, the N-1 differential compressed data created by the differential compressed data creating means, and the normal compressed data and the differential compressed data are stored in any page of the document. And a compressed document data creating unit for creating compressed document data including information indicating whether the document is compressed. 3. A document compression apparatus for creating compressed document data based on a document including first to Nth pages and capable of restoring image data of the first to Nth pages of the document, the document compression apparatus comprising: A difference compressed data in which image data of a certain page is used as generated image data, and image data of a different page is used as reference image data, and a position of a portion of the generated image data which is different from the reference image data. And the differential compressed data indicating the contents
Differential compressed data generating means for generating a combination of pages; and N × (N-
1) The differential compressed data is classified into N groups of N-1 differential compressed data in which the same image data is used as reference image data, and N-1 differential compressed data included in each group are classified. Total calculating means for calculating the total size of the compressed data; and encoding of image data used as reference image data when creating differential compressed data in a group having the smallest total calculated by the total calculating means. The normal compressed data creating means for creating normal compressed data for the page represented by the image data, the normal compressed data created by the normal compressed data creating means, and the sum calculated by the sum calculating means N-1 differentially compressed data included in the smallest group and their normal compressed data Document compression apparatus data and compressed difference data is characterized by comprising a compressed document data generating means for generating a compressed document data including information indicating whether it relates to one of the pages of the document. 4. A document compression apparatus for creating, based on a document including first to Nth pages, compressed document data capable of restoring image data of the first to Nth pages of the document, the document compression apparatus comprising: A difference compressed data in which image data of a certain page is used as generated image data, and image data of a different page is used as reference image data, and a position of a portion of the generated image data which is different from the reference image data. And the differential compressed data indicating the contents
Differential compressed data generating means for generating a combination of pages; and N × (N-
1) Identifying means for identifying the differential compressed data having the smallest size among the differential compressed data, and encoding the image data used as the reference image data when creating the differential compressed data identified by the identifying means. The normal compressed data creating means for creating the normal compressed data associated with the page represented by the image data, and any one of the pages to which the normal compressed data or the differential compressed data has already been associated. The difference compression data having the smallest size among the difference compression data in which the image data is used as the reference image data and the image data of any page to which the normal compression data or the difference compression data is not yet associated is generated image data. Searches the data and compares the searched differential compressed data Creating a process for associating a page represented by image data used as generated image data with the differential compressed data creating means for all pages of the document except the page to which the normal compressed data is associated An associating unit that repeats until any of the differential compressed data is associated, the normal compressed data created by the normal compressed data creating unit, and the normal compressed data created by the differential compressed data creating unit, and Differential compressed data associated with each page, information indicating which page of the document the normal compressed data and differential compressed data relate to, and which page of image data each differential compressed data is based on. Information indicating whether the data is used as image data. Document compression apparatus characterized by comprising a compressed document data generating means for generating a non-compressed document data. 5. A second method for creating N-1 pieces of normal compressed data for each page by encoding image data of each page except for the page for which the normal compressed data is created by the normal compressed data creating means. For each page except for the page for which the normal compressed data is created by the normal compressed data creating means, the size of the differential compressed data relating to the page is created by the second normal compressed data creating means. And determining means for determining whether the size of the compressed data is larger than the size of the normal compressed data for the page. The compressed document creation means determines that the differential compressed data is larger in size by the determining means. Page, the second compressed data creation for the page is performed instead of the differential compressed data. Generating compressed document data including normal compressed data created by the means, and further including information indicating a page using the normal compressed data created by the second compressed data creating means. 5. The document compression apparatus according to claim 1, wherein: 6. The differential compressed data creating means compares the generated image data with the reference image data for each unit data, which is data of a predetermined size constituting each image data, to generate generated image data. The start position of the replacement required area, which is an area where one or more unit data of the same content is included and is continuous and the corresponding part of the reference image data does not have the unit data of the content, is included. Includes a plurality of element data consisting of start position information indicating the number of unit data constituting the required replacement area, continuous number information indicating the number of unit data constituting the required replacement area, and replacement data indicating the content of the unit data used in the required replacement area 6. The document compression apparatus according to claim 1, wherein differential compression data is created. 7. The document compression apparatus according to claim 1, wherein the document is print data including information that can be converted into image data of first to Nth pages. 8. Compressed document data including normal compressed data relating to the first page of a document and N-1 special compressed data relating to the second to Nth pages of the document, wherein each special compressed data is A document restoring device for restoring compressed document data indicating a position and a content of a portion of image data of a related page different from image data of a previous page, and storing the image data. Means for generating image data representing a first page of the document in the storage means by decoding normal compressed data relating to a first page included in the compressed document data; The image data generated in the storage means by the first generation means is output. The compressed document data includes a first output unit that outputs the compressed document data, and a process of rewriting the content of the image data stored in the storage unit based on the difference compressed data and outputting the image data obtained by the rewriting. A document decompressing apparatus, comprising: second output means for sequentially executing special compressed data on second to Nth pages. 9. Compressed document data including normal compressed data relating to a first page of a document and N-1 special compressed data relating to the second to Nth pages of the document, respectively. Is a document restoring device for restoring compressed document data indicating a position and contents of a portion of the image data of a related page different from the image data of the first page, and for storing the image data And a first generation unit for generating image data representing a first page of the document in the storage unit by decoding normal compressed data related to a first page included in the compressed document data. Image data generated in the storage means by the first generation means First output means for outputting image data relating to the first page in the storage means, rewriting the generated image data based on special compressed data, and outputting image data obtained by the rewriting. And a second output unit for sequentially executing the special compressed data on the second to Nth pages included in the compressed document data. 10. Compressed document data including normal compressed data on the Xth page of a document and N-1 special compressed data on the 1st to Nth pages except the Xth page of the document, respectively. A document restoring device for restoring compressed document data in which each special compressed data indicates a position and a content of a portion of the image data of a related page different from the image data of the Xth page; Storage means for storing data; and decompressing the normal compressed data associated with the Xth page included in the compressed document data by using a predetermined decoding procedure, thereby obtaining the Xth page of the document. Generating means for generating image data to be represented in the storage means; A first output unit for outputting the generated image data, a copy of the image data relating to the X-th page is generated in the storage unit, and the generated copy of the image data is rewritten based on the differential compressed data. Second output means for sequentially executing a process of outputting image data on differentially compressed data related to the first to Nth pages excluding the Xth page included in the compressed document data. Document restoration device characterized by the above-mentioned. 11. The first output means, after the second output means performs a process on the differentially compressed data relating to the (X-1) th page, outputs the X + th data by the second output means.
11. The document restoring apparatus according to claim 10, wherein the apparatus functions before a process for differentially compressed data relating to one page is executed. 12. The compressed document data is data that may include, as special compressed data, normal compressed data for which image data is generated by decoding, wherein the second output unit is configured to perform special compression on a page to be processed. If the data is normally compressed data, the image data representing the page is generated in the storage unit by decoding the normally compressed data, and the generated image data is output. The document restoration device according to any one of claims 8 to 11. 13. The normal compressed data relating to the Xth page of the document, N-1 special compressed data relating to the first to Nth pages excluding the Xth page of the document, and each special compressed data is associated with another page. Compressed document data including association information, and the position and content of a portion of the image data of the associated page that differs from the image data of another page associated with the association information A document restoring device for restoring compressed document data, the storage device for storing image data, and decoding the normal compressed data related to the X-th page included in the compressed document data Storing the image data representing the X-th page of the document in the storage means. A first generating means for generating the image data stored in the storage means in accordance with the special compressed data included in the compressed document file, whereby image data representing a page to which the special compressed data is related A generating means for generating image data to be rewritten by the second generating means in the storage means; and a second generating means or the preparing means according to the association information. By causing both the and the second generating means to function, image data of the first to Nth pages excluding the Xth page is generated in the storage means, and the first to the nth pages generated in the storage means are generated. A document restoration device comprising: a generation / output control unit that outputs N pages of image data. 14. The compressed document data may include, as special compressed data, normal compressed data for which image data is generated by decoding, and information for identifying special compressed data using normal compressed data. , Data that includes association information including information that associates special compressed data for which normal compressed data is not used with another page. The generation / output unit uses the normally compressed data according to the association information. Decoding the special compressed data to indicate that the special compressed data is associated with the special compressed data to generate image data representing a page related to the special compressed data in the storage unit. The document restoration device according to claim 13. 15. A document compression method for creating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages, comprising: A normal compressed data generating step of generating normal compressed data for the first page by encoding the image data of the first page;
N-1 difference compressed data in which image data of the second to Nth pages of the document are used as generated image data and image data of the immediately preceding page is used as reference image data, and is different from the reference image data. A differential compressed data generating step of generating N-1 differential compressed data indicating a position and a content of the generated image data portion; a normal compressed data generated in the normal compressed data generating step; Compressed document data including N-1 difference compressed data created in the data creation step and information indicating which page of the document the respective normal difference compressed data and the difference compressed data are related to is created. A compressed document data creating step. Document compression method. 16. A document compression method for creating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages, comprising: A normal compressed data generating step of generating normal compressed data relating to the first page by encoding the image data of the first page; and generating image data of the second to Nth pages of the document as generated image data, respectively. And the first
N using page image data as reference image data
Differential compressed data generating step of generating N-1 differential compressed data indicating the position and contents of a part of the generated image data which is different from the reference image data, wherein the differential compressed data is -1 differential compressed data; The normal compressed data created in the normal compressed data creation step, the N-1 difference compressed data created in the difference compressed data creation step, and the normal compressed data and the difference compressed data are stored in any page of the document. A compressed document data creating step of creating compressed document data including information indicating whether the document is related to the document. 17. A document compression method for creating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages, comprising: A difference compressed data in which image data of a certain page is used as generated image data, and image data of a different page is used as reference image data, and a position of a portion of the generated image data which is different from the reference image data. And the differential compressed data indicating the contents
A differential compressed data generating step for generating a combination of pages; and N × (N
-1) differentially compressed data are classified into N groups of N-1 differentially compressed data in which the same image data is used as reference image data, and N-1 number of differentially compressed data included in each group are classified. A sum calculating step for calculating the sum of the sizes of the differential compressed data; and encoding the image data used as the reference image data when creating the differential compressed data in the group having the smallest total calculated in the total calculating step. By this means, a normal compressed data creation step of creating normal compressed data for the page represented by the image data, the normal compressed data created in the normal compressed data creation step, and a total calculated in the total calculation step N- included in the group with the smallest
A step of generating compressed document data including one piece of differential compressed data and information indicating which page of the document the normal differential compressed data and the differential compressed data are related to; A document compression method characterized by the following. 18. A document compression method for creating compressed document data capable of restoring image data of the first to Nth pages of a document based on the document including the first to Nth pages, comprising: A differential compressed data in which image data of a certain page is used as generated image data, and reference image data which is image data of a different page, and the difference of the generated image data which is different from the reference image data. A differential compressed data generating step of generating differential compressed data indicating a position and contents for all combinations of two pages included in the document; and N × (N
-1) a specifying step of specifying differential compression data having the smallest size from among the differential compression data; and image data used as reference image data when creating the differential compression data specified in this specific step. A normal compressed data creating step of creating normal compressed data associated with the page represented by the image data by encoding; and image data relating to the page to which the normal compressed data or differential compressed data has already been associated. Searching for differentially compressed data having the smallest size from differentially compressed data that has been generated as image data relating to a page to which reference compressed image data or differentially compressed data has not yet been associated as reference image data, The compressed difference data that was created The process of associating the page represented by the image data used as the compressed data with any of the pages created in the differential compressed data creating step for all pages of the document except for the page associated with the normal compressed data An associating step that repeats until the differential compressed data is associated with the normal compressed data created in the normal compressed data creating step, and a corresponding page created in the differential compressed data creating step and associated with each page in the associating step Attached differential compressed data, information indicating which page of the document the normal compressed data and differential compressed data relate to, and which page of image data each differential compressed data uses as reference image data. Information that indicates Document compression method, which comprises a compressed document data creation step of creating a compressed document data including and. 19. A second method for creating N-1 pieces of normal compressed data for each page by encoding image data of each page except the page for which the normal compressed data was created in the normal compressed data creating step. In the normal compressed data creating step, for each page except the page in which the normal compressed data was created in the normal compressed data creating step, the size of the differential compressed data related to the page is created in the second normal compressed data creating step. A determination step of determining whether the size of the compressed data is larger than the size of the normal compressed data for the page. The compressed document creation step determines that the difference compressed data is larger in size in the determination step. Page, instead of the compressed differential data, Compressed document data including the normal compressed data created in the second compressed data creating step, the compressed document further including information indicating a page using the normal compressed data created in the second compressed data creating step 19. The document compression method according to claim 15, wherein data is created. 20. The differential compressed data creating step includes: comparing the generated image data with the reference image data for each unit data, which is data of a predetermined size constituting each image data; A start area indicating a start position of a replacement required area, which is an area in which one or more unit data of the same content is continuous and a corresponding part of the reference image data does not include the unit data of the content. Position information, continuous number information indicating the number of unit data constituting the required replacement area,
20. The compressed differential data including a plurality of element data including replacement data indicating the contents of unit data used in the required replacement area. Document compression method. 21. The document according to claim 1, wherein the first to Nth documents are
21. The document compression method according to claim 15, wherein the print data is print data including information that can be converted into image data of a page. 22. Compressed document data including normal compressed data relating to the first page of a document and N-1 special compressed data relating to the second to Nth pages of the document, wherein each special compressed data is A document restoring method for restoring compressed document data indicating a position and a content of a portion of the image data of a related page different from the image data of the previous page, wherein the document data is included in the compressed document data. A first generating step of generating image data representing the first page of the document in the storage device by decoding the normal compressed data relating to the first page in the storage device; and generating the image data in the storage device in the first generating step. A first output step of outputting the compressed image data; The process of rewriting the contents of the image data stored in the storage device based on the data and outputting the image data obtained by the rewriting is performed by a special compression for the second to Nth pages included in the compressed document data. A second output step of sequentially executing data on the document. 23. Compressed document data including normal compressed data relating to the first page of a document and N-1 special compressed data relating to the second to Nth pages of the document, respectively. Is a document restoring method for restoring compressed document data indicating a position and a content of a portion of the image data of a related page different from the image data of the first page, wherein the document data is included in the compressed document data. A first generation step of generating image data representing the first page of the document in the storage device by decoding the normal compressed data related to the first page, A first output step of outputting the generated image data; The processing of newly generating image data relating to the first page in the storage device, rewriting the generated image data based on the special compressed data, and outputting the image data obtained by the rewriting is included in the compressed document data. A second output step of sequentially executing the special compressed data for the second to Nth pages. 24. Compressed document data including normal compressed data relating to the Xth page of the document and N-1 special compressed data relating to the first to Nth pages excluding the Xth page of the document, respectively. A document restoration method for restoring compressed document data in which each special compressed data indicates a position and a content of a portion of the image data of a related page different from the image data of the Xth page, Generating image data representing the X-th page of the document in the storage device by expanding the normal compressed data associated with the X-th page included in the compressed document data using a predetermined decoding procedure. Step and a first output step for outputting the image data generated in the generation step. Generating a copy of the image data relating to the X-th page in the storage device, rewriting the generated copy of the image data based on the differential compression data, and outputting the image data obtained by the rewriting. A second output step of sequentially executing differential compression data on the first to Nth pages excluding the Xth page included in the compressed document data. 25. In the first output step, after the processing on the differentially compressed data relating to the (X−1) th page by the second output step is performed, the processing on the differentially compressed data regarding the (X + 1) th page by the second output step is performed. 25. The method of claim 24, wherein the method functions before the is executed. 26. The compressed document data is data which may include, as special compressed data, normal compressed data for which image data is generated by decoding, wherein the second output step includes a special compression for a page to be processed. When the data is normally compressed data, the image data representing the page is generated in the storage device by decoding the normally compressed data, and the generated image data is output. Item 22
26. The document restoring method according to claim 25. 27. The normal compressed data relating to the Xth page of the document, N-1 special compressed data relating to the first to Nth pages excluding the Xth page of the document, and each special compressed data is associated with another page. Compressed document data including association information, and the position and content of a portion of the image data of the associated page that differs from the image data of another page associated with the association information A document restoration method for restoring compressed document data, the method comprising: decoding X-th page of the document by decoding normal compressed data related to X-th page included in the compressed document data. A first generation step of generating image data to be represented in a storage device; A second generation step of rewriting the stored image data in accordance with the special compressed data included in the compressed document file to generate image data representing a page to which the special compressed data is related; A preparing step of preparing image data to be rewritten in the second generating step; and, by making the second generating step or both of the preparing step and the second generating step function according to the association information, A generation / output control step of generating first to Nth page image data except for the Xth page in the storage device and outputting the first to Nth page image data generated in the storage device; A document restoration method comprising: 28. The compressed document data may include, as special compressed data, normal compressed data for which image data is generated by decoding, and information for identifying special compressed data using normal compressed data. , Data including association information including information for associating special compressed data for which normal compressed data is not used with another page, wherein the generation / output step uses normal compressed data according to the association information. Decoding the special compressed data for the special compressed data indicating that the special compressed data is associated with the special compressed data to generate image data representing a page related to the special compressed data in the storage device. The document restoration method according to claim 27. 29. A computer, based on a document consisting of pages 1 to N,
An apparatus for creating compressed document data capable of restoring image data of the first to Nth pages of the document, wherein the image data of the first page of the document is encoded to perform normal compression on the first page. Normal compressed data generating means for generating data; and N-1 pieces of image data for each of the second to Nth pages of the document as generated image data and the image data of the immediately preceding page as reference image data. Differential compressed data creating means for creating N-1 pieces of differential compressed data that are differential compressed data and indicate positions and contents of portions of the generated image data that are different from the reference image data; Means for generating the normal compressed data and the differential compressed data Compressed document data for creating compressed document data including N-1 pieces of differentially compressed data created by the means, and information indicating which page of the document the respective normal compressed data and difference compressed data relate to. A computer-readable recording medium that records a program for causing the apparatus to function as an apparatus including a creating unit. 30. A computer, based on a document consisting of pages 1 to N,
An apparatus for creating compressed document data capable of restoring image data of the first to Nth pages of the document, wherein the image data of the first page of the document is encoded to perform normal compression on the first page. Normal compressed data generating means for generating data, wherein the image data of the second to Nth pages of the document are generated image data;
N using page image data as reference image data
Differential compressed data creating means for creating (N-1) differential compressed data that is -1 differential compressed data and indicates a position and a content of a portion of the generated image data that is different from the reference image data; The normal compressed data created by the normal compressed data creating means, the N-1 differential compressed data created by the differential compressed data creating means, and the normal compressed data and the differential compressed data are stored in any page of the document. A computer-readable recording medium storing a program for causing the apparatus to function as an apparatus including compressed document data creating means for creating compressed document data including information indicating whether the information is related to the program. 31. A computer, based on a document consisting of pages 1 to N,
An apparatus for creating compressed document data capable of restoring image data of the first to Nth pages of the document, wherein image data of a certain page of the document is generated image data, and a different page of the document is generated. Difference compressed data that is reference image data that is image data and that is different from the reference image data and that indicates the position and content of the portion of the generated image data that is different from the reference image data, for all two pages included in the document And N × (N−N) generated by the differential compressed data generating means.
1) The differential compressed data is classified into N groups of N-1 differential compressed data in which the same image data is used as reference image data, and N-1 differential compressed data included in each group are classified. Sum calculation means for calculating the sum of the sizes of the compressed data; and encoding of the image data used as the reference image data when creating the difference compressed data in the group having the smallest sum calculated by the sum calculation means. The normal compressed data creating means for creating normal compressed data for the page represented by the image data, the normal compressed data created by the normal compressed data creating means, and the sum calculated by the sum calculating means N-1 differentially compressed data included in the smallest group and their normal compressed data And a compressed document data creating means for creating compressed document data including information indicating which page of the document the difference compressed data is related to. recoding media. 32. A computer, based on a document consisting of pages 1 to N,
What is claimed is: 1. A document compression apparatus for creating compressed document data capable of restoring image data of first to Nth pages of a document, wherein image data of a certain page of said document is generated image data and is different from said image data. Differential compressed data that is reference image data that is image data of a page, and differential compressed data that indicates the position and content of a part of the generated image data that is different from the reference image data, Differential compressed data generating means for generating a combination of two pages, and N × (N-
1) Identifying means for identifying the differential compressed data having the smallest size among the differential compressed data, and encoding the image data used as the reference image data when creating the differential compressed data identified by the identifying means. The normal compressed data creating means for creating the normal compressed data associated with the page represented by the image data, and any one of the pages to which the normal compressed data or the differential compressed data has already been associated. Search for differential compressed data having the smallest size from differential compressed data in which image data is used as reference image data and image data relating to a page to which normal compressed data or differential compressed data is not yet associated is generated image data. Then, the searched differential compressed data is The process of associating the page represented by the image data used as the compressed data with any of the pages created by the differential compressed data creating unit on all pages of the document except the page associated with the normal compressed data Associating means that repeats until the differential compressed data is associated with the normal compressed data created by the normal compressed data creating means, and each page created by the differential compressed data creating means and associated with each page by the associating means. Attached differential compressed data, information indicating which page of the document the normal compressed data and differential compressed data relate to, and which page of image data each differential compressed data uses as reference image data. Compressed document containing information indicating whether the Recorded computer-readable recording medium a program for functioning as a device and a compressed document data creation means for creating a cement data. 33. A computer comprising: normally compressed data for a first page of a document;
Each of the compressed document data includes N-1 special compressed data relating to the second to Nth pages of the document, each special compressed data being different from the image data of the previous page of the image data of the associated page. For restoring compressed document data indicating the position and contents of a portion of the compressed document data, comprising: storage means for storing image data; and normal compression relating to a first page included in the compressed document data. First generating means for generating image data representing a first page of the document in the storage means by decoding data; and outputting the image data generated in the storage means by the first generating means. First output means, and an image stored in the storage means based on the differential compressed data A second output unit for sequentially executing a process of rewriting data contents and outputting image data obtained by the rewriting on special compressed data relating to the second to Nth pages included in the compressed document data; And a computer-readable recording medium storing a program for causing the apparatus to function as an apparatus having the following. 34. A computer comprising: normally compressed data for a first page of a document;
Compressed document data including N-1 special compressed data for the second to Nth pages of the document, each of the special compressed data being the image data of the first page of the image data of the associated page A document restoring device for restoring compressed document data indicating a position and contents of a part different from the above, comprising: storage means for storing image data; and a first means included in the compressed document data. First generating means for generating image data representing a first page of the document in the storage means by decoding normal compressed data relating to a page; and an image generated in the storage means by the first generating means. First output means for outputting data, and the first page in the storage means. A process of generating new image data, rewriting the generated image data based on the special compressed data, and outputting the image data obtained by the rewriting is performed on the second to Nth pages included in the compressed document data. A computer-readable recording medium on which a program for functioning as a device having a second output unit for sequentially executing special compressed data is recorded. 35. A computer comprising: normally compressed data for page X of the document;
Compressed document data including N-1 special compressed data for the first to Nth pages except the Xth page of the document, each of the special compressed data being an image data of the associated page. An apparatus for restoring compressed document data indicating the position and contents of a part different from the image data of the X page, comprising: storage means for storing image data; Generating means for generating, in the storage means, image data representing the X-th page of the document by decompressing the normal compressed data associated with the X-th page using a predetermined decoding procedure; A first output unit for outputting the image data generated in the step (c), and the X-th page in the storage unit. The process of generating a copy of the image data, rewriting the generated copy of the image data based on the differential compressed data, and outputting the image data obtained by the rewriting, includes processing the X-th page included in the compressed document data. A computer-readable recording medium in which a program for functioning as a device including second output means for sequentially executing differential compressed data relating to first to Nth pages to be excluded is recorded. 36. A computer comprising: normally compressed data for page X of the document;
Compressed document data including N-1 special compressed data relating to the first to N-th pages except the X-th page of the document, and association information for associating each special compressed data with another page; Is a device for restoring compressed document data indicating the position and content of a portion of the image data of a related page that is different from the image data of another page associated with the association information, Storage means for storing image data; and decoding the normal compressed data associated with the X-th page contained in the compressed document data, thereby storing the image data representing the X-th page of the document in the storage means. First generating means for generating image data in the storage means, and compressing the image data stored in the storage means. A second generation unit for generating image data representing a page to which the special compressed data is related by rewriting in accordance with the special compressed data included in the document file; and an image rewritten in the storage unit by the second generation unit. A preparing means for preparing data, and the second generating means, or both the preparing means and the second generating means are operated in accordance with the association information, so that the X-th page is stored in the storage means. A program for generating an image data of the first to Nth pages excluding, and a generation / output control unit for outputting the image data of the first to Nth pages generated in the storage unit; A computer-readable recording medium on which is recorded.