JP2008245089A - Watermark embedding system, watermarked printing medium output device, and information reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a watermark embedding system capable of easily taking consistency with a processing program of a printing medium both at a watermark information embedding side and at a reading side. <P>SOLUTION: The watermark embedding system 100 is provided with a watermarked printing medium output device 110 and an information reader 120. The watermarked printing medium output device 110 includes: a watermark embedding section 114 for embedding, in an input image, algorithm information defining a procedure of image processing to be executed by the watermark reader 120; and a printing-out section 115 for printing the input image in which a watermark is embedded. The information reader 120 includes: an image input section 121 to which a watermarked image is inputted; an information reading section 122 for reading the algorithm information from the watermarked image; and an image processing section 123 for performing image processing on the watermarked image on the basis of the procedure defined by the algorithm information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a watermark embedding system, a watermarked print medium output device, and an information reading device.

  Conventionally, there has been devised a technique for detecting falsification of a printed document by embedding information in an unreadable format in a document printed on a print medium such as paper and reading the embedded information. For example, Patent Document 1 discloses a method in which index points are arranged in a mesh shape in the entire image of a document to be printed, and image features for each index point are embedded in the image as feature amounts, thereby detecting tampering. Yes. According to this method, when tampering is detected, a printed matter on which a document image is printed is read by a scanner or the like, an index point is detected from the read image, and an image feature for each index point is calculated. Tampering can be detected by comparison.

  Patent Document 2 discloses a method of dividing an image into a plurality of blocks, and calculating and embedding image feature feature amounts in units of blocks. In this method, pattern blocks are generated for all block images, and information is embedded in a printed document by arranging the pattern blocks in the background of the document. When tampering is detected, a block is detected from an image obtained by reading a printed matter with a scanner or the like, and tampering is detected by comparing the image feature of each block with the embedded image feature.

  In such a falsification detection technique, falsification of a printed matter is detected by scanning a printed matter printed by a printer or the like to form an image. Examples of tampering that can be detected include addition and rewriting to a printed material, and erasing using a correction liquid.

  However, since falsification detection of a printed document detects falsification from an image that has passed through printing and scanning, the extent to which deterioration is caused by printing / scanning is considered, and the criteria for determining where to determine falsification are uniquely determined. It is difficult. Therefore, it is desirable to make a falsification determination using a different algorithm depending on the material and use of the printed document. However, in this case, it is necessary to match the algorithm between the printing device and the reading device on the side where information for detecting falsification is embedded, and it may be possible to increase the effort and cost.

  Also, in recent years, the accuracy of tamper detection technology itself has been improving rapidly, and program mismatches between the embedding device and the reading device often occur, making it difficult to always maintain compatibility. Yes. In particular, when a printing device using the latest program is installed, the information cannot be read unless the reading devices at all the sites where the print medium is likely to be distributed are updated. There was a very big problem.

  As a method for updating the program of such an apparatus, there is a method disclosed in Patent Document 3. Japanese Patent Application Laid-Open No. 2004-228561 discloses a method for performing printer firmware version upgrade and various setting item changes in a printer fax multifunction peripheral based on data received by facsimile. According to this method, it is possible to perform maintenance work on the printer-fax multi-function peripheral by transmitting data by facsimile via a communication line, and the maintenance cost can be reduced.

JP 2005-297373 A Japanese Patent Laid-Open No. 2003-264685 JP 2000-316066 A

  On the other hand, in the case of detecting falsification of a print medium using a watermark, there are cases where it is desired to apply a different falsification determination algorithm depending on the material and usage of the print document, as described above. In such a case, it is necessary to rewrite the program on the reading device side for each document to be tampered with. Therefore, in the method of Patent Document 3, it is necessary to send the change data by facsimile at every timing of rewriting the program. In addition, since the maintenance data transmission timing must be linked with the distribution of the print document that is subject to tampering detection, it is difficult to determine the maintenance data transmission timing.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to simplify the consistency of a print medium processing program on both the watermark information embedding side and the reading side. It is an object of the present invention to provide a new and improved watermark embedding system, watermarked print medium output device, and information reading device that can be taken.

  In order to solve the above problems, according to one aspect of the present invention, a watermarked print medium output device that outputs a watermarked print medium in which a watermark representing predetermined information is embedded, and the watermarked print medium embedded in the watermarked print medium There is provided a watermark embedding system comprising an information reading device for reading information. The watermarked print medium output device includes a watermark embedding unit that embeds a watermark representing algorithm information that defines a processing procedure of image processing executed by the watermark reading device in an input image, and a watermark that prints the input image in which the watermark is embedded. And a print output unit for outputting a printed print medium. In addition, the information reading device includes an image input unit that receives a watermarked image read from a watermarked print medium, an information reading unit that reads algorithm information from the watermarked image, and algorithm information for the watermarked image. An image processing unit that executes image processing based on the processed procedure.

  With this configuration, it is possible to distribute different image processing algorithms for each print medium at the same time as the print medium to be processed, and on the receiving side of the print medium, image processing using the algorithm embedded in the print medium Can be executed. Accordingly, the image processing algorithm executed on the reading side can be updated simultaneously with the distribution of the print medium, and errors due to omission of program update on the reading device side can be prevented. In addition, since the program on the reading device side can be updated via the print medium, the cost for updating the program can be reduced.

  The watermark embedding unit embeds algorithm information defining image processing for performing falsification detection on the watermarked print medium and image feature information indicating the image feature of the input image in the input image. Based on the processing procedure defined by the information, image features may be extracted from the watermarked image, and the tampered detection of the watermarked print medium may be performed by comparing the extracted image features with the image feature information.

  Further, the algorithm information may include information defining a criterion for determining whether or not tampering is detected in the tampering detection by the image processing unit, and the image processing unit may perform tampering detection based on the criterion. .

  Further, the algorithm information may include information defining processing contents to be executed next in accordance with a processing result at an intermediate stage of image processing.

  Further, the algorithm information may include information for executing image processing defined by other algorithm information.

  The algorithm information may include information for calling and executing an arbitrary program stored in the information reading device.

  The information reading device further includes an algorithm information storage unit that stores algorithm information read from the watermarked image, and the image processing unit executes image processing defined by the algorithm information stored in the algorithm information storage unit. You may do it.

  The information reading device may update the algorithm information stored in the algorithm information storage unit with the algorithm information read from the watermarked image.

  In order to solve the above problem, according to another aspect of the present invention, there is provided a watermarked print medium output device that outputs a watermarked print medium in which a watermark representing predetermined information is embedded. A watermarked print medium comprising: a watermark embedding unit that embeds a watermark representing algorithm information that defines a processing procedure of processing in an input image; and a print output unit that outputs a watermarked print medium printed with the input image embedded with the watermark An output device is provided.

  The watermark embedding unit may embed algorithm information defining image processing for performing falsification detection on the watermarked print medium and image feature information indicating the image feature of the input image in the input image.

  In addition, the algorithm information may include information defining a determination criterion for determining whether or not tampering is detected in tampering detection.

  Further, the algorithm information may include information defining processing contents to be executed next in accordance with a processing result at an intermediate stage of image processing.

  Further, the algorithm information may include information for executing image processing defined by other algorithm information.

  The algorithm information may include information for calling and executing an arbitrary program.

  In order to solve the above problem, according to another aspect of the present invention, there is provided an information reading device for reading information embedded in a watermarked print medium, wherein a watermarked image read from the watermarked print medium is input. An image input unit, an information reading unit that reads image information that defines image processing on the watermarked image from the watermarked image, and image processing that is performed on the watermarked image based on the processing procedure defined by the algorithm information. An information reading device including an image processing unit to be executed is provided.

  The information reading unit reads algorithm information defining image processing for performing falsification detection on the watermarked print medium and image feature information indicating the image feature of the input image from the watermarked image. Based on the processing procedure defined by the algorithm information, image features may be extracted from the watermarked image, and falsification detection of the watermarked print medium may be performed by comparing the extracted image features with the image feature information. .

  The algorithm information may include information defining a criterion for determining whether or not tampering is performed in the tampering detection process, and the image processing unit may perform tampering detection based on the criterion.

  An algorithm information storage unit that stores algorithm information read from the watermarked image may be further included, and the image processing unit may execute image processing defined by the algorithm information stored in the algorithm information storage unit.

  The information reading device may update the algorithm information stored in the algorithm information storage unit with the algorithm information read from the watermarked image.

  As described above, according to the present invention, it is possible to easily achieve consistency of a print medium processing program on both the watermark information embedding side and the reading side.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  First, a watermark embedding system according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a schematic configuration of a watermark embedding system 100 according to an embodiment of the present invention.

  As shown in FIG. 1, the watermark embedding system 100 according to the present embodiment includes a watermarked print medium output device 110 and an information reading device 120. The watermark embedding system 100 according to the present embodiment uses a print medium in which a watermark representing information defining an algorithm for detecting falsification of the print medium (hereinafter referred to as algorithm information) is embedded, and the print medium (watermarked print medium). This is characterized in that the falsification of the print medium can be detected on the receiving side. Hereinafter, each device constituting the watermark embedding system 100 will be described.

(Watermarked print medium output device 110)
First, the watermarked print medium output device 110 will be described.
The watermarked print medium output apparatus 110 is an apparatus that outputs a watermarked print medium 10 that is printed by embedding algorithm information that defines an algorithm for falsification detection processing in a document image. As shown in FIG. 1, the watermarked print medium output device 110 includes a document image storage unit 111, an image feature extraction unit 112, an algorithm information storage unit 113, a watermark embedding unit 114, and a print output unit 115. Is done.

(Document image storage unit 111)
The document image storage unit 111 is a storage unit that stores one or more document images printed out by the watermarked print medium output device 110. The stored document image is image data representing a state in which the document is printed on a print medium such as paper. The document image may be a black and white binary image (background is composed of white pixels, printed characters and figures are composed of black pixels), or may be a multi-valued image.

(Image feature extraction unit 112)
The image feature extraction unit 112 is a functional unit that extracts image features of document images stored in the document image storage unit 111. The image feature extraction unit 112 divides the document image into n block images and extracts the image features of each block image. The extracted image features are encoded and given to the watermark embedding unit 114. The image feature extraction method and the extracted image feature used here are, for example, the extraction method and the image feature in the image feature extraction technique described in Patent Document 2 (Japanese Patent Laid-Open No. 2003-264665) described above. Also good. Note that the image feature extraction technique disclosed in the same document is merely an example of the image feature extraction technique used in the image feature extraction unit 112 according to the present embodiment. Omitted.

  In addition, it goes without saying that other image features and image feature extraction methods may be adopted in realizing the image feature extraction unit 112. For example, character information included in a document image may be extracted as an image feature. In this case, for example, the position and size of characters printed on paper and the character code may be extracted as image feature amounts.

(Algorithm information storage unit 113)
The algorithm information storage unit 113 is a storage unit that stores algorithm information that defines a processing procedure of document image alteration detection processing. 2-6 is explanatory drawing which shows an example of algorithm information. As shown in FIGS. 2 to 6, the algorithm information is a kind of program that defines various image processes for detecting falsification together with a processing order, and is composed of a plurality of instructions that can be interpreted by a reading-side apparatus. The Each instruction may be expressed by a unique numerical value or the like for each instruction and converted into a binary code or the like. The algorithm information may be, for example, a byte code of Java (registered trademark).

  For example, the algorithm information in FIG. 2 includes 1 to 3 byte codes indicating 10 instructions arranged according to the execution order of processing. The instructions may be for calling and executing a general-purpose image processing program, such as instructions in order 1 to 3, or a branch defining the execution order, such as an instruction in order 9. It may be an instruction or a conditional branch instruction such as instructions in order 5 and 7. Further, as in the order 6 instruction, the process state may be stored in a register or memory, or the stored content may be changed.

  3 and 4 show a modification of the algorithm information of FIG. The algorithm information shown in FIGS. 3 and 4 defines a falsification detection process using the same image features as the algorithm information of FIG. 2, and only the instruction in order 5 is different from the algorithm information of FIG. For example, in the example of FIG. 3, the threshold value for determining the tampering of the block image is set to a value different from the algorithm information of FIG. In the example of FIG. 4, unlike the examples of FIGS. 2 and 3, the square difference is used as an object to be compared with a threshold value for falsification determination.

  On the other hand, the algorithm information shown in FIG. 5 defines processing for performing falsification detection using image features different from the algorithm information shown in FIGS. That is, while the algorithm information shown in FIGS. 2 to 4 uses the feature amount calculated from the frequency spectrum, the algorithm information shown in FIG. 5 uses the position and size of characters included in the target image, the character code, etc. Information. In this way, by setting a standard for judging alteration for each algorithm information and embedding it in the print medium, it is possible to distribute a falsification detection algorithm having a different judgment standard together with the print medium subject to the alteration detection. .

  Further, the algorithm information may include an instruction for calling and executing another algorithm information to which an identifier is assigned, as in the example illustrated in FIG. For example, when applying a falsification detection method that differs depending on a page, identifiers are assigned and embedded in a plurality of algorithm information, and each page is designated with an identifier of algorithm information applied to that page, as shown in FIG. Such algorithm information may be embedded. Thereby, it is possible to omit the same algorithm from being embedded in each page. Or, in the case of a document consisting of multiple pages, it is redundant to embed algorithm information on all pages, so embed algorithm information only on the first page such as a cover page and embed only image feature information on other pages. May be.

(Watermark embedding unit 114)
The watermark embedding unit 114 replaces the image feature information extracted by the image feature extraction unit 112 and arbitrary algorithm information acquired from the algorithm information storage unit 113 with an optically readable watermark pattern, and converts the document image This is a functional unit that is embedded in the background of a document image acquired from the storage unit 111. As the watermark pattern used here, for example, a pattern generated by using the technique described in Japanese Patent No. 3628312 may be used. The watermark pattern disclosed in this document represents a wave having an arbitrary wavelength and direction by the arrangement of dots (black pixels). Note that the watermark pattern generated by the method disclosed in this document is merely an example of the watermark pattern used in the watermark embedding unit 114 according to the present embodiment, and thus detailed description thereof is omitted. Needless to say, other watermark pattern generation techniques may be employed in generating the watermark pattern.

(Print output unit 115)
The print output unit 115 is an output device such as a printer, prints the document image in which the watermark is embedded by the watermark embedding unit 114, and outputs the watermarked print medium 10.

  The configuration of the watermarked print medium output apparatus 110 has been described above. Each unit of the image feature extraction unit 112 and the watermark embedding unit 114 may be configured by software in which a program module capable of executing the above-described functions is installed in an information processing apparatus such as a computer, or each of the above-described units. You may comprise by hardware, such as a processor which can perform a function. Further, the document image storage unit 111 and the algorithm information storage unit 113 may be configured by various storage media such as a semiconductor memory, an optical disk, and a magnetic disk, for example.

(Example of watermarked print media output processing)
Next, an example of the watermarked print medium output process executed by the watermarked print medium output apparatus 110 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the watermarked print medium output process executed by the watermarked print medium output apparatus 110 according to this embodiment.

  First, in step S200, the image feature extraction unit 112 acquires a document image stored in the document image storage unit 111.

  Next, in step S202, the image feature extraction unit 112 divides the input document image into n small blocks. In this way, by dividing the document image into a plurality of block images and embedding the image features for each block image together with the position in the block image, it is possible to specify which portion of the document has been tampered with when tampering is detected. . Further, the position can be specified in detail as the number of blocks n to be divided increases. Note that the size of each block image may be a fixed value or a value that varies depending on the position in the original document image.

  Next, in step S204, the image feature extraction unit 112 extracts the image features of each block. The image feature extraction method and the extracted image feature used here are, for example, the extraction method and the image feature in the image feature extraction technique described in Patent Document 2 (Japanese Patent Laid-Open No. 2003-264665) described above. Also good. Alternatively, the position and size of characters included in the document image, the character code, and the like may be extracted as image features.

  In step S206, algorithm information to be embedded in the document image is acquired from the algorithm information storage unit 113. This algorithm information defines a processing procedure of image processing for detecting falsification of a document. One or more pieces of algorithm information may be acquired. In the case of embedding a plurality of algorithm information, for example, information obtained by assigning an identifier to each algorithm information and algorithm information specifying an identifier of algorithm information applied to each page may be embedded.

  Next, in step S208, the watermark embedding unit 114 converts the image feature information extracted in step S204 and the algorithm information acquired in step S206 into a watermark pattern, and uses it as the background of the document image acquired in step S200. Embed. The watermark embedding unit 114 encodes both image feature information and algorithm information, and replaces these codes with an optically readable watermark pattern. As the watermark pattern used here, for example, a pattern generated by using the technique described in Japanese Patent No. 3628312 may be used.

  Here, for example, in the case of a document consisting of a plurality of pages, it is redundant to embed algorithm information in all pages. Therefore, algorithm information is embedded only in the first page such as a cover, and only image feature information is stored in other pages. It may be embedded. In addition, when applying a falsification detection method that differs depending on the page, a plurality of pieces of algorithm information each assigned an identifier are embedded together in the first page, and each page contains an identifier for the algorithm information applied to that page. Information for designating may be embedded.

  In step S210, the watermark-embedded document image is printed by an output device such as a printer, and the watermarked print medium 10 is output.

  The configuration and operation of the watermarked print medium output apparatus 110 have been described above. With this configuration, it is possible to distribute a falsification detection algorithm that differs for each print medium at the same time as the print medium to be falsified. Accordingly, the falsification detection algorithm embedded in the print medium can be applied at the falsification detection process on the side receiving the print medium, and the falsification detection algorithm can be matched between the distribution side and the reception side of the print medium. it can.

(Information reading device 120)
Next, the information reading device 120 will be described.
The information reading device 120 is a device that reads the watermark printed on the watermarked print medium 10 to obtain algorithm information, and detects falsification of the print medium based on the algorithm defined in the algorithm information. As shown in FIG. 1, the information reading device 120 includes a document image input unit 121, an information reading unit 122, an alteration detection unit 123, an algorithm information storage unit 124, and a general-purpose library storage unit 125.

(Document Image Input Unit 121)
The document image input unit 121 includes a device such as a scanner that can read an optical image, and reads a watermarked image printed on the watermarked print medium 10. The read watermarked image may be provided with a function of performing image processing such as rotation correction and noise removal, and a function of cutting out a portion related to embedded image feature information from the read image. The read watermarked image is input to the information reading unit 122 and the falsification detection unit 123.

(Information reading unit 122)
The information reading unit 122 is a functional unit for reading information embedded in the watermarked image input by the document image input unit 121. The information reading unit 122 reads a watermark embedded in a watermarked image input from the document image input unit 121 and decodes image feature information and algorithm information. As a method for reading information from a watermarked image, for example, a technique described in Japanese Patent No. 3628312 may be used. The read image feature information and algorithm information are input to the falsification detection unit 123.

  The information reading unit 122 may store the read algorithm information in the algorithm information storage unit 124. For example, when the same algorithm information is used for a plurality of watermarked images, or when a plurality of algorithm information is embedded in one watermarked image, it is necessary to store the read algorithm information. Because there is. Further, the information reading unit 122 may replace part or all of a program or the like already stored in the algorithm information storage unit 124 with the read algorithm information. As a result, the read algorithm information can be used to update the program of the reading device.

(Falsification detection unit 123)
The falsification detection unit 123 is a functional unit for detecting falsification of a watermarked image input from the document image input unit 121. The falsification detection unit 123 is an example of an image processing unit according to the present invention.

  The falsification detection unit 123 performs a falsification detection process on the watermarked image input from the document image input unit 121 based on the algorithm information read by the information reading unit 122. The falsification detection unit 123 extracts image features from the watermarked image in accordance with the image processing procedure defined by the algorithm information. The image feature extraction method used here is the same method used in the image feature extraction unit 112 of the watermarked print medium output apparatus 110. Further, the tampering detection unit 123 compares the extracted image feature with the image feature information read by the information reading unit 122, and determines whether or not tampering has occurred based on the comparison result. As a calculation method used for comparison of image features and a condition for determination, those defined by algorithm information are used.

  The falsification detection unit 123 may use algorithm information input from the information reading unit 122, or may read and use algorithm information stored in the algorithm information storage unit 124. For example, when only the identifier of the algorithm information to be applied is embedded in the watermarked image currently being processed, the falsification detection unit 123 reads the corresponding identifier from the algorithm information storage unit 124 before performing the falsification detection processing. May be read out.

(Algorithm information storage unit 124)
The algorithm information storage unit 124 is a storage unit that stores algorithm information read by the information reading unit 122. One or more algorithm information may be stored. When storing a plurality of algorithm information, each algorithm information may be given an identifier so that they can be distinguished from each other.

(General library storage unit 125)
The general-purpose library storage unit 125 is a storage unit that stores a program group having a general-purpose image processing function as a library. For example, when the algorithm information includes an instruction for calling a program having a general-purpose image processing function such as image binarization or division, the falsification detection unit 123 reads the corresponding program from the general-purpose library storage unit 125. The module can be called and executed.

  The configuration of the information reading device 120 has been described above. Each unit of the information reading unit 122 and the falsification detection unit 123 may be configured by software in which a program module capable of executing each function described above is installed in an information processing apparatus such as a computer, or each function described above. May be configured by hardware such as a processor capable of executing the above. The algorithm information storage unit 124 and the general-purpose library storage unit 125 may be configured by various storage media such as a semiconductor memory, an optical disk, and a magnetic disk, for example.

(Example of information reading process)
Next, an example of information reading processing executed by the information reading device 120 according to the present embodiment will be described based on FIG. Here, FIG. 8 is a flowchart showing a flow of information reading processing from a watermarked print medium executed by the information reading apparatus 120 according to the present embodiment.

  First, in step S220, a watermarked image is input from the document image input unit 121. The document image input unit 121 may perform image processing such as rotation correction, enlargement / reduction, and noise removal on the input image.

  Next, in step S222, the information reading unit 122 reads algorithm information and image feature information from the watermarked image. In step S224, the algorithm information read in step S222 is stored in the algorithm information storage unit 124.

  In step S226, the falsification detection unit 123 executes falsification detection processing on the watermarked image. An example of the falsification detection process executed here will be described using examples of algorithm information shown in FIGS.

  FIG. 9 is a flowchart showing the flow of processing when falsification detection processing is performed based on the algorithm information shown in FIG. The tampering detection unit 123 sequentially interprets the algorithm information shown in FIG. 2 from the top, and executes processing according to the included instructions.

  First, in step S230, the falsification detection unit 123 executes binarization of the image. Here, a general-purpose program module having a function of binarizing an image is called from the general-purpose library storage unit 125 and executed.

  Next, in step S232, the falsification detection unit 123 divides the image into blocks having a predetermined size. Here, as in step S230, the corresponding program module may be called from the general-purpose library storage unit 125 and executed.

  Next, in step S234, a two-dimensional Fourier transform is executed in units of divided blocks. In step S236, a feature amount is calculated from the frequency spectrum, and a difference between the calculated value and the feature amount of the block read in step S222 is obtained.

  Next, in step S238, it is determined whether or not there is any falsification from the comparison result in step S236. Here, if the difference between the two values is 5 or less, it is determined not to be falsified, and if it is greater than 5, it is determined to be falsified. If the difference is 5 or less, the falsification detection unit 123 skips the algorithm information by 2 bytes and executes the instruction of order 7 in step S242.

  On the other hand, if the difference is greater than 5, in step S240, a mark indicating that tampering has been detected is assigned to the block.

  Next, in step S242, it is determined whether or not the processing of all blocks has been completed. If not completed, the algorithm information is returned by 14 bytes, and the process is repeated from step S234. If completed, the algorithm information is skipped by 2 bytes and the process is terminated. When the falsification detection process is completed, the process returns to FIG. 8 again, and the falsification detection result is output in step S228.

  Here, when the falsification detection process is executed using the algorithm information shown in FIG. 3, it is determined in step S238 of FIG. When the algorithm information shown in FIG. 4 is used, the square difference of the feature amount is obtained in step S236, and it is determined whether or not there is any falsification using the threshold value 20 in step S238.

  On the other hand, an example in which falsification detection is executed using the algorithm information shown in FIG. 5 will be described based on FIGS. Here, FIG. 10 is a flowchart showing the flow of processing when falsification detection processing is performed based on the algorithm information shown in FIG. FIG. 11 is an explanatory diagram for explaining the falsification detection process shown in FIG. 10.

  First, in step S250, the falsification detection unit 123 executes binarization of the image. Here, a general-purpose program module having a function of binarizing an image is called from the general-purpose library storage unit 125 and executed.

  Next, in step S <b> 252, the falsification detection unit 123 acquires the coordinates, size, and character code for one character from the image feature information read by the information reading unit 122. In the image feature information, for example, as shown in FIG. 11, as the image feature amount of the character “A”, the coordinate value (x, y) indicating the character position, the character size (w, h), “A” Character code 3042 (hexadecimal number).

  Next, in step S254, character recognition is performed from an image in a range corresponding to the coordinate value (x, y) and size (w, h). In the example of FIG. 11, the first candidate “A” and the second candidate “O” are obtained as the recognition result of the character “A”.

  Next, in step S256, the result obtained by character recognition is compared with the character code included in the image feature information. Here, if it matches with the top two candidates by character recognition, it is determined that there is no falsification. In the case of the example in FIG. 11, since the first candidate of the character recognition result matches, it is determined that there is no falsification. In this case, the falsification detection unit 123 skips the algorithm information by 2 bytes and executes the instruction of order 6 in step S260.

  On the other hand, if the top two candidates of the character recognition result do not match the character code included in the image feature information, a mark indicating that alteration has been detected is added to the character in step S258.

  Next, in step S260, it is determined whether all blocks have been processed. If not completed, the algorithm information is returned by 14 bytes, and the process is repeated from step S254. If completed, the algorithm information is skipped by 2 bytes and the process is terminated.

  In this way, the alteration detection algorithm can be easily changed on the reading device side simply by reading and executing the algorithm information embedded in the print medium.

  The configuration and operation of the information reading device 120 have been described above. With this configuration, the side receiving the print medium can always detect falsification using the same algorithm as the information embedding side by applying the algorithm embedded in the print medium to the falsification detection process. Further, since the falsification detection processing program can be updated by distributing the print medium, the cost for updating the program can be reduced. Further, even when it is desired to change the falsification detection processing algorithm applied to each print document or page, the algorithm can be easily changed.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, the algorithm information embedded in the print medium has been described as for falsification detection. However, the present invention is not limited to such an example, and defines image processing other than falsification detection for a watermarked image. It may be.

It is a block diagram which shows schematic structure of the watermark embedding system concerning one Embodiment of this invention. It is explanatory drawing which shows an example of algorithm information. 3 shows a modification of the algorithm information shown in FIG. 3 shows a modification of the algorithm information shown in FIG. It is explanatory drawing which shows the example of other algorithm information. It is explanatory drawing which shows the example of other algorithm information. It is a flowchart which shows the flow of the output process of the watermarked printing medium performed by the watermarked printing medium output device. It is a flowchart which shows the flow of the information reading process from the watermarked printing medium performed by the information reading apparatus. It is a flowchart which shows the flow of a process at the time of performing a falsification detection process based on the algorithm information shown in FIG. It is a flowchart which shows the flow of a process at the time of performing a falsification detection process based on the algorithm information shown in FIG. It is explanatory drawing for demonstrating the alteration detection process shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Print media with watermark 100 Watermark embedding system 110 Print output device with watermark 111 Document image memory | storage part 112 Image feature extraction part 113 Algorithm information memory | storage part 114 Watermark embedding part 115 Print output part 120 Information reader 121 Document image input part 122 Information Reading unit 123 Tampering detection unit 124 Algorithm information storage unit 125 General-purpose library storage unit

Claims (19)

A watermark embedding system comprising: a watermarked print medium output device that outputs a watermarked print medium in which a watermark representing predetermined information is embedded; and an information reading device that reads information embedded in the watermarked print medium,
The watermarked print medium output device comprises:
A watermark embedding unit that embeds a watermark representing algorithm information defining a processing procedure of image processing executed in the watermark reading device in an input image;
A print output unit that outputs a watermarked print medium on which the input image in which the watermark is embedded is printed;
Including
The information reader is
An image input unit for inputting a watermarked image obtained by reading the watermarked print medium;
An information reading unit for reading the algorithm information from the watermarked image;
An image processing unit that performs image processing on the watermarked image based on a processing procedure defined by the algorithm information;
A watermark embedding system comprising: The watermark embedding unit embeds the algorithm information defining the image processing for performing falsification detection on the watermarked print medium and image feature information indicating an image feature of the input image in the input image,
The image processing unit extracts an image feature from the watermarked image based on a processing procedure defined by the algorithm information, and compares the extracted image feature with the image feature information to thereby print the watermarked print. The watermark embedding system according to claim 1, wherein tampering detection of the medium is performed. The algorithm information includes information defining a criterion for determining whether or not tampering is detected in the tampering detection by the image processing unit,
The watermark embedding system according to claim 2, wherein the image processing unit detects falsification based on the determination criterion.   The watermark embedding system according to claim 1, wherein the algorithm information includes information defining processing contents to be executed next in accordance with a processing result in an intermediate stage of the image processing. .   5. The watermark embedding system according to claim 1, wherein the algorithm information includes information for executing image processing defined by the other algorithm information.   The watermark embedding system according to claim 1, wherein the algorithm information includes information for calling and executing an arbitrary program stored in the information reading device. The information reading device further includes an algorithm information storage unit that stores the algorithm information read from the watermarked image,
The watermark embedding system according to claim 1, wherein the image processing unit executes image processing defined by the algorithm information stored in the algorithm information storage unit.   8. The watermark embedding system according to claim 7, wherein the information reading device updates the algorithm information stored in the algorithm information storage unit with the algorithm information read from the watermarked image. A watermarked print medium output device for outputting a watermarked print medium embedded with a watermark representing predetermined information,
A watermark embedding unit that embeds a watermark representing algorithm information defining a processing procedure of predetermined image processing in an input image;
A print output unit that outputs a watermarked print medium on which the input image in which the watermark is embedded is printed;
A watermarked print medium output device comprising:   The watermark embedding unit embeds the algorithm information defining the image processing for performing falsification detection on the watermarked print medium and image feature information indicating the image feature of the input image in the input image. The watermarked print medium output device according to claim 9.   11. The watermarked print medium output apparatus according to claim 10, wherein the algorithm information includes information defining a determination criterion for determining whether or not falsification is detected in the falsification detection.   The watermarked printing according to any one of claims 9 to 11, wherein the algorithm information includes information defining a processing content to be executed next according to a processing result in an intermediate stage of the image processing. Media output device.   13. The watermarked print medium output device according to claim 9, wherein the algorithm information includes information for executing image processing defined by the other algorithm information.   14. The watermarked print medium output apparatus according to claim 9, wherein the algorithm information includes information for calling and executing an arbitrary program. An information reading device for reading information embedded in a watermarked print medium,
An image input unit for inputting a watermarked image obtained by reading a watermarked print medium;
Information reading unit that reads algorithm information defining image processing for the watermarked image from the watermarked image;
An image processing unit that performs image processing on the watermarked image based on a processing procedure defined by the algorithm information;
An information reading apparatus comprising: The information reading unit reads from the watermarked image the algorithm information that defines the image processing for performing falsification detection on the watermarked print medium, and image feature information indicating an image feature of the input image,
The image processing unit extracts an image feature from the watermarked image based on a processing procedure defined by the algorithm information, and compares the extracted image feature with the image feature information to thereby print the watermarked print. The information reading apparatus according to claim 15, wherein tampering detection of the medium is performed. The algorithm information includes information defining a determination criterion for determining whether or not falsification is performed in the falsification detection process,
The information reading apparatus according to claim 16, wherein the image processing unit detects falsification based on the determination criterion. An algorithm information storage unit for storing the algorithm information read from the watermarked image;
The information reading apparatus according to claim 15, wherein the image processing unit executes image processing defined by the algorithm information stored in the algorithm information storage unit.   19. The information reading apparatus according to claim 18, wherein the information reading apparatus updates the algorithm information stored in the algorithm information storage unit with the algorithm information read from the watermarked image.

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