JP2009141918A - Multifunction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multifunction machine in which while having effects of suppressing unauthorized reproduction of a printed material, it can be avoided that it becomes difficult to read an original image. <P>SOLUTION: The multifunction machine comprises: an original image storage means for holding the original image in which a character is imposed on a solid background; a pattern image storage means for holding a pattern image which is an image with which a character string is associated and in which a difference in density between adjacent dots is smaller than the difference in density between the character and the background in the original image; a pattern embedded image generation means for generating a pattern embedded image by repeatedly embedding the same pattern image on the original image of one page so that the character in the original image and the pattern image overlap each other; a print means for printing the pattern embedded image on a sheet; a read data generation means for reading the pattern embedded image printed on the sheet and generating the read data; and a character string discrimination means for discriminating the character string associated with the pattern image that is embedded in the pattern embedded image according to the read data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-function peripheral, and more particularly to an improvement of a multi-function peripheral capable of embedding a copy-forgery-inhibited pattern image in which a character string is associated with a document image in which characters are arranged on a plain background and printing the paper.

  2. Description of the Related Art In recent years, as a technique for suppressing information leakage due to printed matter and copying of the printed matter and tracking the printed matter, a technology for embedding and printing a character string indicating that take-out and copying are prohibited has been proposed. For example, when document data is printed on paper, character strings such as a document name, a printer name, and copy prohibition are embedded as hidden characters in an original image. A hidden character is formed by embedding a character composed of low-resolution dots in a background composed of high-resolution dots. When a printed material in which such hidden characters are embedded is duplicated, duplication of the printed material can be suppressed by removing the high-resolution background to make the hidden characters appear. There is also known a technique for suppressing duplication of a printed matter by adding a background pattern composed of a continuous pattern to a part of a sheet (for example, Patent Document 1). The copy-prevented printed matter described in Patent Document 1 is formed by adding a background pattern in which characters formed with different densities in the background are embedded as a latent image. In this copy-preventing printing, when a printed matter with a copy-forgery-inhibited pattern is copied, duplication is suppressed by utilizing the fact that characters appear due to the density difference between the background and the characters.

  There is also known a technique for improving traceability of printed matter by adding a QR code (registered trademark) in which a character string is encoded to a part of a sheet.

However, in a printing method in which a character string is embedded as a hidden character or latent image, the character is simply embedded as it is, so that the embedded character string may be readable and the original image becomes difficult to read. was there. In addition, in the printing method in which a QR code is added to a part of the paper, there is a problem that the character information for tracking the printed matter can be removed by concealing the code portion and reading the printed matter.
Japanese Unexamined Patent Publication No. 7-76195

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-function machine that can suppress the difficulty of reading a document image while maintaining the effect of suppressing the reproduction of printed matter. In particular, it is an object of the present invention to provide a multi-function machine that makes it difficult to read character information embedded in printed matter. It is another object of the present invention to provide a multifunction machine that can suppress duplication of character information embedded in printed matter. It is another object of the present invention to provide a multi-function machine that can prevent character information that is encoded in a character string and embedded in a printed matter from being read out.

  According to a first aspect of the present invention, there is provided a multi-function peripheral comprising a document image storage means for holding a document image in which characters are arranged on a plain background, and an image associated with a character string, wherein the density difference between adjacent dots is the document. A copy-forgery-inhibited pattern image storage means for holding a copy-forgery-inhibited pattern image storage unit that stores a copy-forgery-inhibited pattern image smaller than the density difference between characters and background in the image, and repeatedly embedding the same copy-forgery-inhibited pattern image in the document image so A tint block embedded image generating unit that generates a tint block embedded image, a printing unit that prints the tint block embedded image on a sheet, and read data generation that reads the tint block embedded image printed on the sheet and generates read data. And character string determination means for determining a character string associated with the copy-forgery-inhibited pattern image embedded in the copy-forgery-inhibited pattern embedded image based on the read data.

  In this multifunction device, when a copy-forgery-inhibited pattern embedded image is generated from a document image in which characters are arranged on a plain background and a copy-forgery-inhibited pattern image associated with a character string, the characters and the copy-forgery-inhibited pattern image in the document image overlap. As described above, the background pattern embedded image is generated by repeatedly embedding the same background pattern image in the document image. According to such a configuration, since the character information to be embedded in the printed material is embedded as a copy-forgery-inhibited pattern image, it can be difficult to read. Therefore, it is possible to prevent the original image from being difficult to read while maintaining the effect of suppressing the duplication of printed matter. Further, since the copy-forgery-inhibited pattern embedded image is formed so that the characters in the document image and the copy-forgery-inhibited pattern image overlap each other, it is possible to prevent the copy-forgery-inhibited pattern image from being hidden when reading the copy-forgery-inhibited pattern image. Furthermore, since the same copy-forgery-inhibited pattern image is repeatedly embedded in the document image, it is possible to prevent character information from being read when the copy-forgery-inhibited pattern embedded image is read to determine a character string corresponding to the copy-forgery-inhibited pattern image.

  In addition to the above configuration, the MFP according to the second aspect of the present invention includes a copy-forgery-inhibited pattern image generation unit that generates a copy-forgery-inhibited pattern image by encoding a character string and changing the density between adjacent dots. A character string is determined by extracting and decoding the copy-forgery-inhibited pattern image from the read data.

  In addition to the above-described configuration, the MFP according to the third aspect of the present invention may be configured such that the copy-forgery-inhibited pattern image generation unit is configured so that the maximum dot density in the copy-forgery-inhibited pattern image is lower than the character density in the document image. The copy-forgery-inhibited pattern image is generated by changing the density. According to such a configuration, since the density of dots in the copy-forgery-inhibited pattern image embedded in the printed material is lower than the character density in the original image, it is possible to further suppress the original image from being difficult to read due to the copy-forgery-inhibited pattern image.

  In the MFP according to the fourth aspect of the present invention, in addition to the above configuration, the copy-forgery-inhibited pattern image generation unit monotonously decreases the density between adjacent dots in a dot row including at least three dots adjacent in the horizontal direction, or The copy-forgery-inhibited pattern image is generated in a monotonically increasing manner.

  In addition to the above-described configuration, the MFP according to the fifth aspect of the present invention is configured such that the background pattern embedded image generation unit generates the background pattern embedded image by repeatedly embedding the same background pattern image over the entire document image.

  In addition to the above configuration, a multifunction machine according to a sixth aspect of the present invention includes a restored image generation unit that removes the copy-forgery-inhibited pattern image from the read data based on a determination result by the character string determination unit and generates a restored image, and the character Output image generating means for generating a character string embedded image for output by embedding the character string determined by the column determining means in the restored image. According to such a configuration, the character string determined from the copy-forgery-inhibited pattern image is embedded in the restored image obtained by removing the copy-forgery-inhibited pattern image from the read data, and output image data is generated. Duplication of printed matter can be suppressed.

  According to the MFP of the present invention, the character information to be embedded in the printed material is embedded as a copy-forgery-inhibited pattern image, so that it can be difficult to read. Therefore, it is possible to prevent the original image from being difficult to read while maintaining the effect of suppressing the duplication of printed matter. Further, since the copy-forgery-inhibited pattern embedded image is formed so that the characters in the document image and the copy-forgery-inhibited pattern image overlap each other, it is possible to prevent the copy-forgery-inhibited pattern image from being hidden when reading the copy-forgery-inhibited pattern image. Furthermore, since the same copy-forgery-inhibited pattern image is repeatedly embedded in the document image, it is possible to prevent character information from being read when the copy-forgery-inhibited pattern embedded image is read to determine a character string corresponding to the copy-forgery-inhibited pattern image.

  FIG. 1 is a system diagram showing an example of a schematic configuration of an image processing system 1 including a multifunction machine 6 according to an embodiment of the present invention. The image processing system 1 includes a PC (personal computer) 2, a document management server 4, and a multifunction device 6 that can communicate with each other via a communication network 3 such as the Internet or a LAN. The document management server 4 is a server that manages document data created by a terminal device on the communication network 3. For example, the document management server 4 transfers document data in the document data storage unit 5 to the multifunction device 6 based on an instruction from the PC 2. Is performed.

  The multifunction device 6 is an MFP (Multi-Function Peripheral) having a printer function, a scanner function, a facsimile function, and a scanning function, and can selectively execute these functions. The printer function is a function for printing document data on paper. For example, document data transferred from the document management server 4 via the communication network 3 is printed.

  The scanner function is a function for reading an image printed on paper. The facsimile function is a function for transmitting document data by FAX (facsimile). For example, image data read from a sheet is transmitted to another communication apparatus via a PSTN (Public Switched Telephone Networks) (not shown). The The scan function is a function for transferring image data read from a sheet to another terminal device, and the image data is transferred by designating the terminal device on the communication network 3 as a storage destination.

  In the multifunction device 6, when document data is printed on paper, a copy-forgery-inhibited pattern image associated with a character string for suppressing duplication of printed matter is embedded in the original image and printed.

  FIG. 2 is a block diagram illustrating a configuration example of the multifunction machine 6 in the image processing system 1 of FIG. The multifunction device 6 includes an external interface unit 11, a printer unit 12, a key input unit 13, and a scanner unit 14. The external interface unit 11 is a communication control means for transmitting and receiving data via the communication network 3 or PSTN. For example, the document data transferred from the document management server 4 via the communication network 3 is output to the printer unit 12. Is performed.

  The printer unit 12 is a unit for printing document data on paper, and includes a document image storage unit 21, a background pattern image generation unit 22, a background pattern image storage unit 23, a background pattern embedded image generation unit 24, and a printing unit 25. The document image storage unit 21 is a memory for storing a document image in which characters are arranged on a plain background. For example, document data from the external interface unit 11 is stored as a document image. The characters in the document image are formed by, for example, a large number of dots, and the background is formed as an area where no dots exist.

  Such an original image may be image data read from a sheet or image data received by FAX from another communication device, in addition to the image transferred from the document management server 4.

  The copy-forgery-inhibited pattern image generation unit 22 performs an operation of generating a copy-forgery-inhibited pattern image associated with a character string. The copy-forgery-inhibited pattern image is formed by coding a character string and changing the density between adjacent dots so that the density difference between adjacent dots is smaller than the density difference between characters and background in the document image. In other words, the original image is a monochrome image in which black characters are arranged on a white background, whereas the copy-forgery-inhibited pattern image is a gradation image in which the density gradually changes between adjacent dots.

  Here, in order to prevent the copy-forgery-inhibited pattern image from conspicuous when such a copy-forgery-inhibited pattern image is embedded in the document image, the adjacent dots are set so that the maximum dot density in the copy-forgery-inhibited pattern image is lower than the character density in the document image. A copy-forgery-inhibited pattern image is formed by changing the density between dots.

  The character string to be encoded includes information included in the document data, document data transfer source information, identification information of the multifunction device 6, registration information registered in advance in the multifunction device 6, print information, and multifunction device 6. Operator (operator) information or character information designated by the operator can be considered. The information included in the document data is, for example, a document name, a document creator name, and a document creation date / time included in the header information. The transfer source information is, for example, address information or account information indicating the transfer source of document data.

  The identification information of the multifunction device 6 is, for example, account information or a printer name assigned to the multifunction device 6. As registration information, for example, a character string indicating that copying of a printed matter is prohibited, or a department name indicating a location where the multifunction machine 6 is installed can be considered. The print information is job information when printing document data. For example, the page number, the total number of pages, or the print date and time can be considered.

  The operator information is, for example, an operator name, and is added when an operator who operates the multifunction machine 6 can be identified. As the character information designated by the operator, an arbitrary character string can be designated. For example, the character string is designated based on an input signal from the key input unit 13.

  The tint block image generated by the tint block image generation unit 22 is stored in the tint block image storage unit 23. The background pattern embedded image generation unit 24 performs an operation of repeatedly embedding the same background pattern image in the document image so that characters in the document image and the background pattern image overlap to generate a background pattern embedded image. This background pattern embedded image is formed, for example, by repeatedly embedding the same background pattern image over the entire document image to be printed.

  The printing unit 25 performs an operation of printing the background pattern embedded image generated by the background pattern embedded image generation unit 24 on a sheet.

  The scanner unit 14 is a unit for reading an image printed on paper, and includes a read data generation unit 31, a character string determination unit 32, a restored image generation unit 33, and an output image generation unit 34. The read data generation unit 31 performs an operation of reading the copy-forgery-inhibited pattern embedded image printed on the paper and generating read data. The read data generation unit 31 reads an image with a resolution equal to or higher than the resolution of the copy-forgery-inhibited pattern image embedded in the document image.

  The character string discriminating unit 32 performs an operation of extracting a tint block image from the embedded tint block image based on the read data from the read data generating unit 31 and discriminating a character string associated with the tint block image. . For example, the character string is determined by decoding a copy-forgery-inhibited pattern image extracted from the read data.

  The restored image generating unit 33 performs an operation of removing the copy-forgery-inhibited pattern image from the read data based on the determination result by the character string determining unit 32 and generating a restored image. The output image generation unit 34 performs an operation of embedding the character string determined by the character string determination unit 32 in the restored image to generate image data for output. This output image data is, for example, a character string embedded image in which a character string decoded from a tint block image is embedded in a restored image.

  For example, the output image data is output to the printing unit 25 and printed on paper. Alternatively, the fax is transmitted to another communication apparatus via the external interface unit 11. Alternatively, the data is transferred to another terminal device at the storage destination via the external interface unit 11.

  FIG. 3 is a diagram showing an example of an operation at the time of printing in the multifunction machine 6 of FIG. 2, and shows a state in which a background pattern embedded image 51 is formed by embedding a background pattern image 44 in the document image 41. . This document image 41 is image data for each page to be printed, and characters 43 are arranged on a plain background 42 having a rectangular shape.

  The copy-forgery-inhibited pattern image 44 is formed by gently changing the density between adjacent dots. Specifically, the density between adjacent dots is such that the density difference between adjacent dots in the vertical and horizontal directions at a predetermined resolution is smaller than the density difference between the character 43 and the background 42 in the document image 41. The tint block image 44 is formed by changing. The resolution when changing the density between adjacent dots is, for example, 200 dpi (dot per inch).

  In this way, the tint block image 44 is formed as a density difference code pattern in which a character string is encoded using a density difference between adjacent dots. If the tint block image 44 is viewed by paying attention to a dot row composed of three or more dots adjacent in the horizontal direction, at least for such a dot row, the density decreases monotonously between adjacent dots or increases monotonously. It is supposed to be. Also, with respect to the vertical dot row, similarly to the horizontal dot row, the density monotonously decreases or increases monotonously between adjacent dots. That is, the two-dimensional density distribution indicating the density of each dot constituting the copy-forgery-inhibited pattern image 44 has density values that change stepwise in the vertical and horizontal directions.

  Here, it is assumed that dots are arranged on a white background having a square shape, and the maximum value of the density difference between adjacent dots is smaller than the density difference between the character 43 and the background 42 in the document image 41. Further, it is assumed that the maximum dot density in the copy-forgery-inhibited pattern image 44 is lower than the character density in the document image 41.

  The tint block embedding image 51 is formed by repeatedly embedding the tint block image 44 in such a document image 41. The copy-forgery-inhibited pattern image 44 is repeatedly embedded in the document image 41 in a predetermined direction. In this example, it is repeatedly embedded in the vertical direction 52 and the horizontal direction 53. Specifically, the tint block embedded image 51 is formed by arranging the tint block image 44 over the entire document image 41 without gaps and without overlapping each other.

  Here, the vertical direction 52 and the horizontal direction 53 in the background pattern embedded image 51 are a transport direction when transporting a sheet and a direction perpendicular to the transport direction, respectively.

  FIG. 4 is a diagram showing an example of an operation at the time of reading in the multi function device 6 of FIG. 2, and shows a state in which a sheet on which the copy-forgery-inhibited pattern embedding image 51 is printed is read and output by facsimile. Yes. When the copy-forgery-inhibited pattern embedded image 51 is printed on paper, it is printed at a resolution of 600 dpi, for example.

  When the multifunction device 6 reads a sheet on which such a copy-forgery-inhibited pattern image 51 is printed, the image is read at a resolution higher than the resolution of the copy-forgery-inhibited pattern image 44, that is, at a resolution of 200 dpi or more.

  When the multifunction peripheral 6 reads the background pattern embedded image 51 printed on the paper, the background pattern image is extracted from the background pattern embedded image 51, and the character string associated with the background pattern image is determined. Then, output image data is generated based on the determination result.

  When printing the output image data, the character string “copy prohibited” 62 indicating that copying of the printed matter is prohibited and the department name “accounting department” indicating the installation location of the multifunction machine 6 are used as the restored image. The embedded character string embedded image 61 is generated as an output image.

  When the output image data is transmitted by FAX, a character string “FAX prohibited” 64 indicating that copying of the printed matter is prohibited, and a department name “Accounting Department” indicating the installation location of the multifunction machine 6 are restored images. A character string embedded image 63 embedded in is generated as an output image.

  Steps S101 to S105 in FIG. 5 are flowcharts showing an example of an operation at the time of printing in the multifunction machine 6 in FIG. First, the embedded background pattern image generation unit 24 develops the original image data read from the original image storage unit 21 in a printing memory (step S101), and refers to a setting value as to whether to add a background pattern image (step S101). Step S102).

  At this time, for example, if the addition of the copy-forgery-inhibited pattern image is selected by the operator, the copy-forgery-inhibited pattern embedded image is generated by superimposing the copy-forgery-inhibited pattern image on the original image and printed on paper (steps S103 and S104).

  On the other hand, if the addition of the copy-forgery-inhibited pattern image is not selected, the document image is printed on the paper as it is (step S105).

  Steps S201 to S207 in FIG. 6 are flowcharts showing an example of an operation at the time of reading in the multifunction machine 6 in FIG. First, the read data generation unit 31 reads an image printed on a sheet and generates read data (step S201).

  Next, the character string discriminating unit 32 determines whether or not a copy-forgery-inhibited pattern image is embedded based on the read data (step S202). If the copy-forgery-inhibited pattern image is embedded, the operator's operation content is checked, and the copy-forgery-inhibited pattern image is checked. A character string corresponding to the image is determined (steps S203 and S204). For example, the copy-forgery-inhibited pattern image is extracted from the embedded copy-forgery-inhibited pattern image by decoding the developed copy-forgery-inhibited pattern image in the original image, and decoded.

  The restored image generation unit 33 removes the background pattern from the read data based on the determination result of the character string, and generates a restored image (step S205). The output image generation unit 34 adds the decoded character string to the restored image, and generates output image data (step S206). At this time, if the copy of the read data is selected by the operator, the character string “copy prohibited” indicating that the copy of the printed matter is prohibited is added to the restored image.

  When the FAX transmission of the read data is selected by the operator, a character string “FAX prohibited” indicating that copying by FAX transmission of the printed matter is prohibited is added to the restored image. When the scan transfer of the read data is selected by the operator, a character string “scan prohibited” indicating that copying by the scan transfer of the printed matter is prohibited is added to the restored image.

  On the other hand, when the copy-forgery-inhibited pattern image is not embedded, the read data is directly output as output image data. Such output image data is subjected to output processing in accordance with the operation mode selected by the operator. That is, if the copy of the read data is selected, the output image data is printed on the paper.

  Further, when the FAX transmission of the read data is selected, the output image data is FAX transmitted. If scan transfer of read data is selected, the output image data is transferred to another terminal device at the storage destination.

  According to the present embodiment, the character information to be embedded in the printed matter is embedded as the copy-forgery-inhibited pattern image 44, which makes it difficult to read. Therefore, it is possible to prevent the original image 41 from being difficult to read while maintaining the effect of inhibiting the reproduction of printed matter. Further, since the copy-forgery-inhibited pattern embedded image 51 is formed so that the characters 43 in the document image 41 and the copy-forgery-inhibited pattern image 44 overlap each other, when the copy-forgery-inhibited pattern embedded image 51 is read, the copy-forgery-inhibited pattern image 44 is hidden and read. Can be prevented. Further, since the same copy-forgery-inhibited pattern image 44 is repeatedly embedded in the document image 41, it is possible to prevent character information from being read when the copy-forgery-inhibited pattern embedded image 51 is read to determine a character string corresponding to the copy-forgery-inhibited pattern image 44. .

  In addition, since the output image data is generated by embedding the character string determined from the copy-forgery-inhibited pattern image 44 in the restored image obtained by removing the copy-forgery-inhibited pattern image 44 from the read data, a copy of the printed matter on which the copy-forgery-inhibited pattern embedded image 51 is printed is generated. Can be suppressed.

  In this embodiment, an example in which a copy-forgery-inhibited pattern image to be embedded in a document image is formed as a result of character string encoding has been described. However, the present invention is not limited to this. For example, a plurality of copy-forgery-inhibited pattern images may be stored in advance in association with character strings and selectively embedded in the document image.

  In the present embodiment, an example in which a copy-forgery-inhibited pattern image is removed from the read data to generate a restored image, and the decoded image of the copy-forgery-inhibited pattern image is embedded in the restored image has been described. The present invention is not limited to this. For example, the subsequent processing method of the read data may be changed based on the decoding result of the tint block image.

  Specifically, as a result of the character string determination unit 32 decoding the copy-forgery-inhibited pattern image, for example, when copying of a printed material is prohibited, printing of read data is prohibited, and copying of the printed material is not prohibited It is conceivable that the print data is permitted to be printed. Or, as a result of decoding the copy-forgery-inhibited pattern image, if the FAX transmission of the printed material is prohibited, the FAX transmission of the read data is prohibited. If the FAX transmission of the printed material is not prohibited, the FAX transmission of the read data is permitted. It is conceivable to configure so as to.

1 is a system diagram showing an example of a schematic configuration of an image processing system 1 including a multifunction machine 6 according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration example of a multifunction machine 6 in the image processing system 1 of FIG. 1. FIG. 4 is a diagram illustrating an example of an operation at the time of printing in the multifunction machine 6 of FIG. 2, in which a copy-forgery-inhibited pattern image 51 is formed by superimposing a document image 41 and a copy-forgery-inhibited pattern image 44. FIG. 6 is a diagram illustrating an example of an operation at the time of reading in the multifunction machine 6 of FIG. 2, and illustrates a state when a copy-forgery-inhibited pattern embedded image 51 is read and output as a copy and transmitted by FAX. 3 is a flowchart illustrating an example of an operation at the time of printing in the multifunction machine 6 of FIG. 2. 3 is a flowchart illustrating an example of an operation at the time of reading in the multifunction machine 6 of FIG. 2.

Explanation of symbols

1 Image processing system 2 PC
3 Communication Network 4 Document Management Server 6 Multifunction Machine 11 External Interface Unit 12 Printer Unit 13 Key Input Unit 14 Scanner Unit 21 Original Image Storage Unit 22 Background Pattern Image Generation Unit 23 Background Pattern Image Storage Unit 24 Background Pattern Embedding Image Generation Unit 25 Printing Unit 31 Read data generation unit 32 Character string determination unit 33 Restored image generation unit 34 Output image generation unit 41 Original image 44 Background pattern image 51 Background pattern embedded image 61, 63 Character string embedded image

Claims (6)

Document image storage means for holding a document image in which characters are arranged on a plain background;
A copy-forgery-inhibited pattern image storage means for holding a copy-forgery-inhibited pattern image that is an image associated with a character string and in which a density difference between adjacent dots is smaller than a density difference between characters and background in the document image;
A tint block embedding image generation means for generating a tint block embedded image by repeatedly embedding the same tint block image in the document image so that characters in the original image and the tint block image overlap.
Printing means for printing the tint block embedded image on paper;
Read data generation means for reading the copy-forgery-inhibited pattern embedded image printed on paper and generating read data;
And a character string discriminating means for discriminating a character string associated with the tint block image embedded in the tint block embedded image based on the read data. A copy-forgery-inhibited pattern image generating means for generating a copy-forgery-inhibited pattern image by encoding a character string and changing the density between adjacent dots;
2. The multi-function peripheral according to claim 1, wherein the character string discriminating unit discriminates a character string by extracting and decoding the copy-forgery-inhibited pattern image from the read data.   The copy-forgery-inhibited pattern image generating means generates the copy-forgery-inhibited pattern image by changing the density between adjacent dots so that the maximum dot density in the copy-forgery-inhibited pattern image is lower than the character density in the document image. The multifunction device according to claim 2.   The copy-forgery-inhibited pattern image generation means generates the copy-forgery-inhibited pattern image by monotonously decreasing or increasing monotonously between adjacent dots for a dot row composed of at least three dots adjacent in the horizontal direction. The multifunction device according to claim 2.   2. The multifunction peripheral according to claim 1, wherein the copy-forgery-inhibited pattern embedded image generation unit generates the copy-forgery-inhibited pattern embedded image by repeatedly embedding the same copy-forgery-inhibited pattern image over the entire document image. A restored image generating means for removing the copy-forgery-inhibited pattern image from the read data based on a determination result by the character string determining means and generating a restored image;
2. An MFP according to claim 1, further comprising output image generation means for generating a character string embedded image for output by embedding the character string determined by the character string determination means in the restored image. .