JPWO2009104606A1 - Background pattern image embedding method, electronic watermark embedding method, electronic watermark detection method, background pattern image embedding apparatus, electronic watermark embedding apparatus, electronic watermark detection apparatus, program, and computer-readable recording medium - Google Patents

Abstract

It is designed to make it possible to print a tint block more effectively through simpler processing. Erasing pattern information for specifying an erasing pattern that cannot be detected at a resolution lower than a predetermined resolution and a resolution lower than a predetermined resolution However, by combining the remaining pattern information that specifies the remaining pattern that can be detected and the hidden character information that specifies the area to be printed by the disappearing pattern and the remaining pattern according to the hidden character, a copy-forgery-inhibited pattern image that includes the hidden character is obtained. Combining the first process for generating the copy-forgery-inhibited pattern image information, and the original image information representing the original image to be printed using the copy-forgery-inhibited pattern image information and the copy-forgery-inhibited pattern image represented by the copy-forgery-inhibited pattern image information as a background, And a second process for generating copy-forgery-inhibited pattern image insertion original image information indicating an original image in which a copy-forgery-inhibited pattern image including a hidden character is inserted in the background. And output to linters, and outputs the original image you insert a background pattern image that contains the hidden text in the background.

Description

  The present invention relates to a tint block image embedding method, an electronic watermark embedding method, an electronic watermark detection method, an tint block image embedding device, an electronic watermark embedding device, an electronic watermark detection device, a program, and a computer-readable recording medium. Copies the printed matter of documents and images such as certificates, various contracts, and various confidential documents (in this specification, “documents” and “images” are collectively referred to as “documents” as appropriate)) In this case, it is suitable for use in embedding an electronic watermark in an image having a copy-preventing pattern for enabling discrimination between the original printed matter and the copied matter obtained by copying the printed matter with a copying machine. , Copy-forgery-inhibited pattern image embedding method, digital watermark embedding method, digital watermark detection method, copy-forgery-inhibited pattern image embedding device, digital watermark embedding device, digital watermark detection Device, a program, and a computer-readable recording medium.

2. Description of the Related Art Conventionally, as a technique for preventing unauthorized copying of important paper documents, a technique using special copy forgery prevention paper called cherry paper is known.
Here, the cherry paper is a tint block printed paper on which a tint block pattern has been printed in advance, and more specifically, it is difficult to identify with the naked eye, but when copied with a copying machine, it is printed in advance as a tint block pattern. This is a sheet on which special patterns such as “Copy” and “Copy prohibited” are printed in advance.
Such cherry paper is a paper that can be handled in the same way as plain paper in ordinary copiers and printers.
In other words, the cherry paper with the above-mentioned tint block pattern printed in advance can be printed with a normal printer in the same way as plain paper when a document or the like created using a computer is printed with a printer.
When cherry paper on which a document or the like is printed using a printer is copied with a copying machine, the copied material is a copy of a copy-forgery-inhibited pattern printed in advance as a copy-forgery-inhibited pattern. Warning characters will be displayed prominently.
Therefore, when the above-mentioned cherry paper is used, the operator can handle the paper in the same way as plain paper when printing by the printer, and there is an advantage that workability is not impaired.
However, on the other hand, the above-mentioned cherry paper is created by printing paper manufacturer printing a copy-forgery-inhibited pattern on dedicated paper, so if you want to change the background pattern or hidden text content to be printed as a copy-forgery-inhibited pattern There is a problem in that it is necessary to order a new sakura paper print from the paper manufacturer according to the change, and it takes time to obtain the cherry paper reflecting the change.
In addition, since the above-mentioned cherry paper has been subjected to a special background pattern printing process, for example, it is sold for several tens of yen per sheet, and it is pointed out that it is extremely expensive compared to plain paper. It was.

On the other hand, as the performance of computers and printers for general business has improved dramatically in recent years, the development of tint block printing technology that achieves the same effect as using conventional cherry paper using a computer and printer Is making rapid progress.
This technology that uses a computer and a printer to print a background pattern together with a document on plain paper, when printing a document created using a computer, etc., with a printer, such as "Copy", "Copy prohibited", etc. The pattern image in which the characters are hidden is printed as a background of a document to be printed and the like on the text.
Here, FIG. 1A shows “copy” as a background pattern of a document or the like on plain paper by using a tint block printing technique that realizes the same effect as when using cherry paper using a computer and a printer. An example of a printed matter in which a character with a hidden background pattern is overlaid is shown.
As shown in FIG. 1A, even if the printed matter is closely observed with the naked eye, it is difficult to identify the “copy” character hidden in the background pattern printed as the background pattern.
On the other hand, FIG. 1B shows a copy obtained by copying the printed material shown in FIG. 1A with a copying machine.
As shown in FIG. 1B, in the copy, the characters “copy” hidden in the background pattern printed as the background pattern are displayed so that they can be easily identified with the naked eye. It can be easily recognized that it is a copy.
In other words, the tint block printing technology that uses a computer and a printer to achieve the same effect as when using cherry paper does not require the use of special paper such as cherry paper. It was something that could be solved.
As described above, in the tint block printing technology, which is an excellent technology that can solve the problems of cherry paper, it is possible to print the tint block more effectively by simpler processing in order to further improve its performance. The development of a technique that can be performed was desired every day.

In recent years, with the development of computer networks, copyright infringement of electronic data such as image data and audio data has become a problem.
As means for protecting the copyright of electronic data against such copyright infringement of electronic data, for example, various digital watermark information embedding techniques for embedding digital watermark information in electronic data have been developed.
Here, a digital watermark (hereinafter, digital watermark is simply referred to as “watermark” as appropriate) is an information embedding technique that uses redundancy for electronic data such as image data and audio data. This is a technique for embedding information. In general, other information embedded in electronic data such as image data and audio data is referred to as “digital watermark information (watermark information)” or simply “digital watermark (watermark)”.
Such digital watermark information embedding technology is also expected to be applied when a paper document printed with electronic data is illegally leaked. The same effect as when using the above-mentioned cherry paper is used with a computer and a printer. For the background pattern printed as a background pattern of a document or the like by the realized background pattern printing technology, various information about the paper document as a digital watermark, for example, unique information of a printer for identifying the printer that printed the paper document, A copy of the printed matter printed with the copy-forgery-inhibited pattern printing technology by embedding information such as the computer name and IP address that identifies the computer that created the printed document, or the user ID that identifies the user who printed the paper document In the event of a spill, information about the spilled paper document is obtained from the spilled copy. Proposal of technique that can be output has been desired.

  The prior art that the applicant of the present application knows at the time of filing a patent is as described above and is not an invention related to a known literature, so there is no prior art information to be described.

The present invention has been made in view of the various problems of the conventional technology as described above and various requests for the conventional technology. The object of the present invention is more effective by simpler processing. A copy-forgery-inhibited pattern image embedding method, digital watermark embedding method, copy-forgery-inhibited pattern image embedding device, digital watermark embedding device, program, and computer readable image. A recording medium is to be provided.
In addition, an object of the present invention is to provide a digital watermark detection method and digital watermark detection that can acquire digital watermark information from a printed matter in which digital watermark information is embedded in a background pattern by a normal reading device (scanner). An apparatus, a program, and a computer-readable recording medium are provided.

  In order to achieve the above object, according to the present invention, there is provided a tint block image embedding method for inserting a tint block image into a background of an image. The tint block image embedding method includes at least one pixel and at least one predetermined pixel among the pixels. It is composed of at least one or more pixels, and at least one or more predetermined ones among the pixels, and disappearance pattern information that designates an disappearance pattern that is configured by arranging dots in a size that cannot be detected at a resolution lower than a predetermined resolution. The remaining pattern information that specifies the remaining pattern that is configured by arranging dots with a size that can be detected even at a resolution equal to or lower than the predetermined resolution, the erase pattern that the erase pattern information specifies according to the desired hidden character, and the above Specify the area to be printed according to the remaining pattern specified by the remaining pattern information. And the hidden pattern information to generate the copy-forgery-inhibited pattern image information representing the copy-forgery-inhibited pattern image including the hidden character, the copy-forgery-inhibited pattern image information generated by the first process, and the copy-forgery-inhibited pattern image information. A copy-forgery-inhibited pattern image insertion original image showing an original image obtained by combining the copy-forgery-inhibited pattern image including the hidden character and the original image information representing the original image to be printed as a background and inserting the copy-forgery-inhibited pattern image including the hidden character in the background The original image in which the copy-forgery-inhibited pattern image insertion original image information generated by the second process is output to a printer, and the copy-forgery-inhibited pattern image including the hidden characters is inserted into the background. Is output.

  According to the present invention, in a tint block image embedding method for inserting a tint block image with a digital watermark in the background of an image, the tint block image embedding method includes at least one pixel, and at least one predetermined pixel among the pixels is predetermined. This is composed of at least one pixel when the disappearance pattern information for specifying the disappearance pattern and the bit information representing the digital watermark bit information are 0, which is configured by arranging dots with a size that cannot be detected at a resolution less than the resolution of A digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution in at least one or more pixels located in a predetermined region of the array, When the bit information representing the watermark bit information is 1, the at least one or more pixels A digital watermark configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution in at least one or more pixels located in an area having a shape different from the predetermined area in the formed array size The digital watermark remaining pattern information for designating the remaining pattern, the erase pattern designated by the erase pattern information according to the desired hidden character, and the digital watermark remaining pattern designated by the digital watermark remaining pattern information are respectively printed. A first process for generating digital watermark copy-forgery-inhibited pattern image information representing the digital watermark copy-forgery-inhibited pattern image including the hidden character by combining with the designated hidden character information, and the digital watermark copy-forgery-inhibited pattern image information generated by the first process And a digital watermark copy-forgery-inhibited pattern image including the hidden character represented by the digital watermark copy-forgery-inhibited pattern image information as a background A second process of generating original watermark image insertion original image information indicating an original image in which an electronic watermark copy-forgery-inhibited pattern image including the hidden character is inserted into the background; The digital watermark copy-forgery-inhibited pattern image insertion original image information generated by the second process is output to a printer, and the original image in which the digital watermark copy-forgery-inhibited pattern image including the hidden characters is inserted in the background is output. It is a thing.

  In the present invention described above, the predetermined region is a region extending in a predetermined direction in the central region of the array, and the region having a shape different from the predetermined region is the above-described region. In the central region of the array, the region extends in a direction different from the predetermined direction.

  In the present invention described above, the predetermined region is a region shifted in a predetermined direction from the central region of the array, and the region having a shape different from the predetermined region is the above-described region. The area is shifted from the central area of the array in a direction different from the predetermined direction.

  Further, the present invention provides a digital watermark detection method for detecting a digital watermark from an image in which a digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background, and from the image in which the digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background, A first process for extracting an area consisting of a remaining digital watermark pattern constituting an image; and a second process for determining individual digital watermark remaining patterns constituting the area from the area extracted by the first process. For each of the remaining digital watermark patterns determined by the second process, a third detection is performed to detect whether the digital watermark bit information is 0 or 1 based on the arrangement of dots arranged in the remaining digital watermark pattern. It is made to have this processing.

  Further, the present invention is the above-described present invention, wherein the digital watermark remaining pattern is arranged in an array size composed of at least one pixel when bit information representing digital watermark bit information is 0. A digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution in at least one pixel located in a predetermined area of the digital image, and bit information representing digital watermark bit information is 1. Sometimes, in the array size composed of at least one or more pixels, at least one or more pixels located in a region having a shape different from the predetermined region can be detected even at a resolution equal to or lower than the predetermined resolution. And a digital watermark remaining pattern constituted by arranging dots.

  In the present invention described above, the predetermined region is a region extending in a predetermined direction in the central region of the array, and the region having a shape different from the predetermined region is the above-described region. In the central region of the array, the region extends in a direction different from the predetermined direction.

  In the present invention described above, the predetermined region is a region shifted in a predetermined direction from the central region of the array, and the region having a shape different from the predetermined region is the above-described region. The area is shifted from the central area of the array in a direction different from the predetermined direction.

  According to another aspect of the present invention, there is provided a tint block image embedding device that inserts a tint block image into a background of an image. The tint block image embedding device includes at least one pixel, and at least one predetermined pixel of the pixels has a predetermined resolution or less Is configured with at least one or more pixels, and a predetermined resolution for at least one or more predetermined pixels among the pixels. The remaining pattern information that specifies the remaining pattern that is configured by arranging dots in a size that can be detected even at the following resolutions, the disappearance pattern that the disappearance pattern information specifies according to the desired hidden character, and the remaining pattern information that specifies Hidden character information that specifies the area to be printed according to the remaining pattern and The copy-forgery-inhibited pattern image generation means for generating copy-forgery-inhibited pattern image information representing the copy-forgery-inhibited pattern image including the hidden character, the copy-forgery-inhibited pattern image information generated by the copy-forgery-inhibited pattern image generation means, and the hidden character represented by the copy-forgery-inhibited pattern image information Image composition for generating a copy-forgery-inhibited pattern image insertion original image information indicating an original image in which the copy-forgery-inhibited pattern image including the hidden character is inserted into the background by combining the copy-forgery-inhibited pattern image with the original image information representing the original image to be printed And outputting the copy-forgery-inhibited pattern image insertion original image information generated by the image composition means to the printer and outputting the original image in which the copy-forgery-inhibited pattern image including the hidden characters is inserted in the background. is there.

  According to another aspect of the present invention, there is provided a tint block image embedding device that inserts a tint block with a digital watermark in the background of an image. The tint block image embedding device includes at least one pixel, and at least one predetermined pixel among the pixels is predetermined. This is composed of at least one pixel when the disappearance pattern information for specifying the disappearance pattern and the bit information representing the digital watermark bit information are 0, which is configured by arranging dots with a size that cannot be detected at a resolution less than the resolution of A digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution in at least one or more pixels located in a predetermined region of the array, When the bit information representing the watermark bit information is 1, the at least one or more pixels A digital watermark configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution in at least one or more pixels located in an area having a shape different from the predetermined area in the formed array size The digital watermark remaining pattern information for designating the remaining pattern, the erase pattern designated by the erase pattern information according to the desired hidden character, and the digital watermark remaining pattern designated by the digital watermark remaining pattern information are respectively printed. The digital watermark copy-forgery-inhibited pattern image generation means for generating digital watermark copy-forgery-inhibited pattern image information representing the digital watermark copy-forgery-inhibited pattern image including the hidden character by combining the hidden character information to be specified, and the digital watermark generated by the digital watermark copy-forgery-inhibited pattern image generation means The watermark copy-forgery-inhibited pattern image information and the electric power including the hidden character represented by the digital watermark copy-forgery-inhibited pattern image information. Digital watermark copy-forgery-inhibited pattern image insertion original image information indicating an original image obtained by combining the original image information representing the original image to be printed with the watermark copy-forgery-inhibited pattern image as a background and inserting the digital watermark copy-forgery-inhibited pattern image including the hidden characters into the background A digital watermark image synthesizing unit for generating the digital watermark copy-forgery-inhibited pattern image insertion original image information generated by the digital watermark image synthesizing unit and outputting the original image information to the printer, and inserting the digital watermark copy-forgery-inhibited pattern image including the hidden characters into the background The original image is output.

  In the present invention described above, the predetermined region is a region extending in a predetermined direction in the central region of the array, and the region having a shape different from the predetermined region is the above-described region. In the central region of the array, the region extends in a direction different from the predetermined direction.

  In the present invention described above, the predetermined region is a region shifted in a predetermined direction from the central region of the array, and the region having a shape different from the predetermined region is the above-described region. The area is shifted from the central area of the array in a direction different from the predetermined direction.

  The present invention also provides an electronic watermark detection apparatus for detecting a digital watermark from an image in which a digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background, and from the image in which the digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background, Extraction means for extracting an area composed of the remaining digital watermark pattern constituting the image, determination means for determining individual digital watermark remaining patterns constituting the area from the area extracted by the extraction means, and determination by the determination means Each of the remaining digital watermark patterns has detection means for detecting whether the digital watermark bit information is 0 or 1 based on the arrangement of dots arranged in the remaining digital watermark pattern. is there.

  Further, the present invention is the above-described present invention, wherein the digital watermark remaining pattern is arranged in an array size composed of at least one pixel when bit information representing digital watermark bit information is 0. A digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution in at least one pixel located in a predetermined area of the digital image, and bit information representing digital watermark bit information is 1. Sometimes, in the array size composed of at least one or more pixels, at least one or more pixels located in a region having a shape different from the predetermined region can be detected even at a resolution equal to or lower than the predetermined resolution. And a digital watermark remaining pattern constituted by arranging dots.

  In the present invention described above, the predetermined region is a region extending in a predetermined direction in the central region of the array, and the region having a shape different from the predetermined region is the above-described region. In the central region of the array, the region extends in a direction different from the predetermined direction.

  In the present invention described above, the predetermined region is a region shifted in a predetermined direction from the central region of the array, and the region having a shape different from the predetermined region is the above-described region. The area is shifted from the central area of the array in a direction different from the predetermined direction.

  The present invention is also a program for causing a computer to execute the tint block image embedding method of the present invention.

  Further, the present invention is a program for causing a computer to execute the digital watermark embedding method of the present invention.

  The present invention is also a program for causing a computer to execute the digital watermark detection method of the present invention.

  Further, the present invention is a program for causing a computer to function as the tint block image embedding device of the present invention.

  Further, the present invention is a program for causing a computer to function as the digital watermark embedding apparatus of the present invention.

  Further, the present invention is a program for causing a computer to function as the digital watermark detection apparatus of the present invention.

  The present invention is also a computer-readable recording medium on which the program according to the present invention is recorded.

Since the present invention is configured as described above, the background pattern can be printed more effectively by simpler processing, and the digital watermark information can be embedded in the background pattern. Excellent effect.
In addition, since the present invention is configured as described above, it is possible to obtain digital watermark information from a printed matter in which digital watermark information is embedded in a background pattern by a normal reading device. Play.

Fig. 1 (a) shows the effect of hiding “copy” on plain paper as a background pattern of a document or the like by using a tint block printing technology that achieves the same effect as when using cherry paper using a computer and a printer. FIG. 1B is an explanatory diagram showing an example of a printed material obtained by overlapping the printed background pattern, and FIG. 1B is an example of a copied material obtained by copying the printed material shown in FIG. It is explanatory drawing which shows. FIG. 2 is a block configuration explanatory diagram showing an example of a system configuration of a tint block image embedding device for carrying out the tint block image embedding method according to the present invention. FIG. 3 is a conceptual explanatory diagram for explaining the configuration of the remaining pattern and the disappearance pattern used when creating the copy-forgery-inhibited pattern image. FIG. 4 (a) is a chart showing the types of pixel array sizes per unit area where small dots are arranged, the number of small dots and the density in each array size, and FIG. 4 (b). FIG. 5 is a conceptual diagram showing the arrangement position of the small dots in each array size of pixels per unit area where the small dots are arranged. FIG. 5A is a chart showing the number and density of large dots when large dots are arranged in an array size of 12 pixels × 12 pixels for the remaining pattern, and FIG. It is a conceptual diagram which shows the arrangement | positioning order at the time of arrange | positioning a large dot to each pixel of the arrangement size of * 12 pixel. FIG. 6 is a flowchart of the tint block image generation processing routine. FIG. 7A is a conceptual explanatory diagram showing a method of creating a disappearing pattern image, and FIG. 7B is a conceptual explanatory diagram showing a method of creating a remaining pattern image, and FIG. (C) is a conceptual explanatory view showing a hidden character image. FIG. 8 is a conceptual explanatory diagram showing a method of generating a tint block image. FIG. 9 is a conceptual explanatory diagram conceptually showing processing when a copy-forgery-inhibited pattern image is embedded in an original image. FIG. 10 is a block configuration explanatory diagram showing an example of a system configuration of a digital watermark copy-forgery-inhibited pattern embedding device for carrying out a method for embedding a copy-forgery-inhibited pattern image having a digital watermark in an original image according to the present invention. FIG. 11 is a conceptual configuration explanatory diagram of the configuration of digital watermark information. FIGS. 12A and 12B are conceptual explanatory diagrams regarding the remaining digital watermark pattern showing the arrangement order when large dots are arranged in each pixel having an arrangement size of 12 pixels × 12 pixels. FIG. 13 is a flowchart of a digital watermark copy-forgery-inhibited pattern image generation processing routine. 14A and 14B are conceptual explanatory diagrams of two types of remaining digital watermark patterns. FIG. 15 is a conceptual explanatory diagram conceptually illustrating a technique for pasting a digital watermark remaining pattern in the process of generating a digital watermark remaining pattern image. FIG. 16 is an explanatory diagram conceptually showing a technique for generating a digital watermark copy-forgery-inhibited pattern image. FIG. 17 is a conceptual explanatory diagram conceptually showing processing when an electronic watermark copy-forgery-inhibited pattern image is embedded in an original image. FIG. 18 is a block configuration explanatory diagram showing an example of a system configuration of a digital watermark detection apparatus for carrying out a method for detecting digital watermark information according to the present invention. FIG. 19 is a flowchart of a digital watermark detection processing routine. FIG. 20A is a conceptual explanatory diagram showing a method of digital watermark detection processing, and FIG. 20B is an enlarged explanatory view of a main part showing an enlarged part of the remaining digital watermark pattern image. It is. FIG. 21 is a conceptual explanatory diagram for explaining the configuration of the remaining pattern and the disappearing pattern used when creating the copy-forgery-inhibited pattern image. FIG. 22 is a conceptual explanatory diagram illustrating a method of generating a tint block image when a hidden type of hidden character is used. 23 (a) and 23 (b) are conceptual explanatory diagrams of two types of remaining digital watermark patterns. FIG. 23 (c) is an enlarged view of a main part showing a part of the remaining digital watermark pattern image. It is explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Background pattern image embedding apparatus 12 Background pattern image generation part 14 Image composition part 16 Printer 100 Digital watermark background pattern image embedding apparatus 102 Digital watermark background pattern image generation part 104 Digital watermark image composition part 106 Printer 200 Digital watermark detection apparatus 202 Image reading apparatus
204 Digital Watermark Detection Unit

Hereinafter, a tint block image embedding method, digital watermark embedding method, digital watermark detection method, tint block image embedding device, digital watermark embedding device, digital watermark detection device, program, and computer-readable recording according to the present invention will be described with reference to the accompanying drawings. An example of the embodiment of the medium will be described in detail.

(1) First embodiment of the present invention (method of embedding a tint block image)
First, FIG. 2 is a block configuration explanatory diagram showing an example of a system configuration of a tint block image embedding device for carrying out the tint block image embedding method according to the present invention as a first embodiment according to the present invention. .
The tint block image embedding device 10 includes a tint block image generating unit 12 that generates a tint block image information 12d indicating a tint block image to be printed as a tint block image on a sheet of paper such as plain paper as a print medium, and a tint block image generated by the tint block image generating unit 12. An image compositing unit 14 that generates information (background pattern image insertion original image information) 14a indicating an original image in which a copy-forgery-inhibited pattern image is inserted by combining information 12d and original image information 18 indicating a document to be printed on the paper surface, And a printer 16 that inputs the copy-forgery-inhibited pattern image insertion original image information 14a generated by the synthesizing unit 14 and prints it on plain paper or the like as the print medium and outputs it as a printed matter such as a paper document. Such a tint block image embedding apparatus 10 can be constructed by a computer system.
More specifically, the copy-forgery-inhibited pattern image generation unit 12 described above includes disappearance pattern information 12a indicating a disappearance pattern (described later), remaining pattern information 12b indicating a remaining pattern (described later), and hidden characters inserted into the background pattern. The hidden character information 12c indicating (described later) is input, and the tint block image information 12d is generated from the disappearing pattern information 12a, the remaining pattern information 12b, and the hidden character information 12c.
The copy-forgery-inhibited pattern image information 12d generated by the copy-forgery-inhibited pattern image generation unit 12 is input to the image composition unit 14, and the image composition unit 14 combines the original image information 18 and the copy-forgery-inhibited pattern image information 12d. Insertion original image information 14a is generated.
Then, the printer 16 performs printing on the medium according to the input copy-forgery-inhibited pattern image original image information 14a, and outputs a printed matter 16a that is a medium on which the original image with the copy-forgery-inhibited pattern image inserted is printed.

With the above configuration, the operation principle of the copy-forgery-inhibited pattern image embedding device 10 will be described with reference to FIG. 2 and FIGS. 3 to 9 described above, and the method of the copy-forgery-inhibited pattern image embedding process executed by the copy-forgery-inhibited pattern image embedding device 10 will be described. To do.
The disappearance pattern indicated by the disappearance pattern information 12a described above is a copy-forgery-inhibited pattern that cannot be detected at the resolution of the copying machine when the printed material 16a on which the original image with the copy-forgery-inhibited pattern image inserted is copied. It means a tint block pattern having a resolution used when printing an area where an image is not copied and disappears without remaining as copy contents.
The remaining pattern indicated by the remaining pattern information 12b can be detected at the resolution of the copying machine when the printed material 16a in which the copy-forgery-inhibited pattern image is inserted in the background and the original image is printed is copied by the copying machine. This means a tint block pattern having a resolution used when printing a region where a copy-forgery-inhibited pattern image is copied and remains as a copy content.
Furthermore, the hidden character indicated by the hidden character information 12c is not visible to the naked eye from the printed material 16a in which the original image is printed with the copy-forgery-inhibited pattern image inserted in the background. When the printed material 16a on which the original image is printed is copied by a copying machine, the relationship between the area that remains as the copied content that is the area where the remaining pattern is copied and the area where the copied content that is the area where the erased pattern is copied disappears. It means an image such as a character displayed in a state that can be visually recognized with the naked eye. That is, the area to be printed is determined based on the disappearance pattern information 12a and the remaining pattern information 12b according to the hidden character information 12c.

Here, the principle of the tint block image generation process executed in the tint block image embedding device 10 will be described.
That is, the tint block image generation process executed in the tint block image embedding device 10 described above is performed when the tint block image insertion original image information 14a indicating the original image into which the tint block image is inserted is output to a printing medium such as plain paper and printed. The difference between the resolution of the printer 16 to be used and the resolution of a copying machine that copies the printed matter 16a in which the copy-forgery-inhibited pattern image is inserted into the background by the printer 16 and the original image is printed on the printing medium is used.
More specifically, a copying machine has a limit in the ability to read minute dots on an original, and this limit is called the maximum resolution of the copying machine.
Also, in a printer that prints on a medium, the maximum resolution indicating the minimum dot size that can be printed by the printer is set.
Comparing the maximum resolution of these copiers with the maximum resolution of printers, the maximum resolution of copiers is generally lower than the maximum resolution of printers. In the case of copying, the copying machine cannot detect dots of all sizes constituting a document or the like printed on the printed matter, and an area that cannot be detected by the copying machine is generated.

The above-mentioned tint block image embedding device 10 uses the difference between the maximum resolution of the copying machine and the maximum resolution of the printer based on the above-described principle, from dots of a size that can be detected by the copying machine as a pattern constituting the tint block image. The copy-forgery-inhibited pattern image, which is a region in which the remaining pattern is copied, in a copy obtained by copying the printed matter 16a on which the copy-forgery-inhibited pattern image is printed using the copy machine An area that remains without disappearing and an area where the copy-forgery-inhibited pattern image, which is an area where the disappearance pattern is copied, disappear without remaining are generated.

Further, the configuration of the remaining pattern and the disappearing pattern used when creating the copy-forgery-inhibited pattern image will be described with reference to FIG.
In FIG. 3, reference numeral 20 schematically indicates a copy-forgery-inhibited pattern image displayed on the printed matter 16 a printed by the printer 16, that is, a copy-forgery-inhibited pattern image before copying by the copying machine, and reference numeral 22 indicates the printed matter 16 a. The copy-forgery-inhibited pattern image displayed on the copied material, that is, the copy-forgery-inhibited pattern image after copying by the copying machine is schematically shown.
Here, the copy-forgery-inhibited pattern image 20 is composed of dots of two different sizes.
More specifically, an area 20a of alphabet “C” in the copy-forgery-inhibited pattern image 20 is appropriately referred to as a dot having a resolution size that cannot be read by a copying machine (hereinafter referred to as “small dot”). Is printed using an erasure pattern composed of an array.
On the other hand, the background area 20b excluding the area 20a is a remaining pattern formed by arranging dots having a resolution size that can be read by a copying machine (hereinafter referred to as “large dots” as appropriate). Printed using.
When the copy-forgery-inhibited pattern image 20 is copied by a copying machine, a copied copy-forgery-inhibited pattern image 22 is obtained.

That is, the area 20b formed by arranging large dots in the copy-forgery-inhibited pattern image 20 can be read by the copying machine when copied by the copying machine. This is an area 22b where an image remains.
On the other hand, the area 20a configured by arranging small dots in the copy-forgery-inhibited pattern image 20 cannot be read by the copying machine when copied by the copying machine. This is the area 22a where the tint block image disappears.
That is, printing with small dots in the area 20a cannot be read by the copying machine, and the copy-forgery-inhibited pattern image in the area 20a is not copied to the area 22a corresponding to the area 20a in the copied copy-forgery-inhibited pattern image 22a. Then, with the region 22b where the copy-forgery-inhibited pattern image remains as a background, the region 22a in the shape of the alphabet “C” can be visually recognized as a hidden character portion.
Note that the area having the shape of the alphabet “C” corresponding to the area 20a and the area 22a is determined by the range of the area 20a and the area 20b specified by the hidden character information 12c.
As described above, when a printed matter such as a paper document on which the copy-forgery-inhibited pattern image 20 is printed is copied by the copying machine, the area 20b that is the background portion of the copy-forgery-inhibited pattern image composed of large dots is detected by the copying machine. On the other hand, the area 20a that is a hidden character portion composed of small dots is not detected by the copying machine and is therefore erased from the copy, and the hidden character portion is extracted white in the copy, so that the hidden character is clearly visible. Can read.
In addition, by adjusting and selecting each density so that the density of the above-described disappearance pattern (density = area of small dots per unit area / unit area) and the density of the remaining pattern are equal to each other, When the printed matter 16a printed by the printer 16 is visually recognized, the distinction between the area 20a constituted by the disappearing pattern and the area 20b constituted by the remaining pattern can be made difficult to distinguish with the naked eye.

Next, a method for generating the copy-forgery-inhibited pattern image information 12d representing the copy-forgery-inhibited pattern image generated based on the above principle will be described in detail below.
In the present invention, the copy-forgery-inhibited pattern image is configured using the disappearance pattern and the remaining pattern, and the copy-forgery-inhibited pattern image information 12d is generated by combining the disappearance pattern information, the remaining pattern information, and the hidden character information. It is what is done.

First, the disappearance pattern will be described. As described above, the disappearance pattern must be composed of dots (small dots) having a size that cannot be detected by the copying machine.
Specifically, since the maximum resolution of a copying machine is generally lower than the maximum resolution of a printer, for example, the minimum size of dots that can be printed by the printer is used as the size of the dots constituting the disappearance pattern. That's fine.
Here, FIGS. 4A and 4B show a chart and a conceptual diagram regarding the disappearance pattern. That is, FIG. 4A is a chart showing the type of pixel array size per unit area where small dots are arranged, the number of small dots and the density in each array size, and FIG. FIG. 4 is a conceptual diagram showing the arrangement positions of the small dots in each array size of pixels per unit area for arranging the small dots (in FIG. 4B, the pixels on which the small dots are printed are shown in black. Yes.)
In addition, as each array size of pixels per unit area in which small dots are arranged, an array size in which pixels are arranged in 4 rows and 4 columns (4 × 4 pixels), and an array size in which pixels are arranged in 5 rows and 5 columns (5 × 5 pixels), array size with pixels arranged in 6 rows and 6 columns (6 × 6 pixels), array size with pixels arranged in 7 rows and 7 columns (7 pixels × 7 pixels), and pixels arranged in 8 rows and 8 columns The five array sizes (8 pixels × 8 pixels) are used, and the number of small dots arranged in each array size can be selected from 1 to 4.
That is, the user can arbitrarily select a desired density value from the density values shown in FIG.

Here, the one having the highest density among the densities in each array size shown in FIG. 4A has 4 small dots in which 4 small dots are arranged in an array size of 4 pixels × 4 pixels. (See FIGS. 4B and 4B.) On the other hand, the pixel having the lowest density among the array sizes shown in FIG. The number of small dots in which one small dot is arranged in an array size of × 8 pixels is one (see FIGS. 4B and 4B), and the user has such maximum density and minimum density. A disappearance pattern of a desired density is selected between
That is, the user refers to the darkness value shown in FIG. 4 (a) and adjusts the erase pattern shown in FIG. By selecting what is used as a desired disappearance pattern, it is possible to adjust the density of the tint block image to a density suitable for the density of the document printed by the printer 16.
In the present embodiment, the color of the pixel that prints the small dot shown in FIG. 4B is a value 0 (black) out of 256 gradations, and the pixel that does not print the small dot (FIG. 4B). In FIG. 5, the pixel in which the small dots are not printed is shown in white.) The color of the 256 gradations is assumed to be 255 (white).
As described above, the erase pattern for printing the area that disappears after copying is determined by the user's selection in consideration of the arrangement size and density of the erase pattern as described above.

Next, the remaining pattern will be described. As described above, the remaining pattern needs to be composed of dots (large dots) of a size that can be detected by the copying machine.
Specifically, since the maximum resolution of the copying machine is generally lower than the maximum resolution of the printer, the size of the dots constituting the remaining pattern is, for example, smaller than the minimum size of dots that can be printed by the printer. A large size that can be printed by a printer may be used.
In the present embodiment, the array size (12 × 12 pixels) in which pixels are arranged in 12 rows and 12 columns is used as the array size of the minimum structural unit of the remaining pattern.
Here, FIGS. 5A and 5B show charts and conceptual diagrams regarding the remaining patterns. That is, FIG. 5A is a chart showing the number and density of large dots when large dots are arranged in an array size of 12 pixels × 12 pixels for the remaining pattern, and FIG. It is a conceptual diagram which shows the arrangement | positioning order at the time of arrange | positioning a large dot to each pixel of the arrangement size of * 12 pixel.
In FIG. 5B, the numbers described in each pixel represent the order in which the pixels are arranged. Specifically, 32 large dots from “1” to “32” in order. Represents the order of printing.
More specifically, for example, when printing only one large dot, printing is performed only on the pixel indicated as “1” in FIG. 5B, and when printing five large dots. 5B, from the pixel labeled “1” to the pixel labeled “5”, that is, expressed as “1”, “2”, “3”, “4”, and “5”. Print to the selected pixel.
That is, for example, when 16 large dots are arranged within an array size of 12 × 12 pixels, the dots 1 to 16 are represented in black in FIG. All dots other than 16 are represented in white. In this case, since the number of large dots is 16, the density is “0.1111” from FIG.
Here, the number of large dots used in the above remaining pattern is selected from those suitable for the density of the disappearing pattern described above.
That is, the remaining pattern for printing the region remaining after copying is determined by the user selecting the density of the disappearing pattern as described above.
In this embodiment, the color of the pixel that prints a large dot shown in FIG. 5B is a value 0 (black) out of 256 gradations, and the pixel that does not print a large dot (FIG. 5B). In FIG. 2, the pixel in which the small dots are not printed is shown in white.) The color of the 256 gradations is assumed to be 255 (white).

Next, processing for generating copy-forgery-inhibited pattern image information having hidden characters will be described with reference to the flowchart of the copy-forgery-inhibited pattern image generation processing routine shown in FIG.
The copy-forgery-inhibited pattern image information 12d having hidden characters is shown in the flowchart of FIG. 6 using the disappearance pattern information 12a indicating the disappearance pattern, the remaining pattern information 12b indicating the remaining pattern, and the hidden character information 12c indicating the hidden character. When the copy-forgery-inhibited pattern image generation processing routine is started by a user instruction or the like, first, the erase pattern information 12a indicating the erase pattern of the density selected by the user is generated. Is used to generate an erasure pattern image that is an image (2040 × 2040 pixel image) composed of pixels of 2040 rows and 2040 columns according to the erasure pattern indicated by the erasure pattern information 12a (step S602).
More specifically, as the disappearance pattern information 12a, for example, from the disappearance patterns shown in FIGS. 4A and 4B, the density 0.0625 of an array size of 4 × 4 pixels in which one small dot is arranged by the user. If the disappearance pattern information 12a is selected, an erase pattern having one small dot in such an array size of 4 × 4 pixels is defined as a minimum constituent unit, and this minimum constituent unit is an area having a size of 2040 × 2040 pixels (hereinafter referred to as an area). This is referred to as a “margin image”.) When pasting on the upper left corner along the row direction, and reaching the right end and pasting one row, it is positioned in the lower row as in the first row. Paste to the next line and repeat it to the bottom line in sequence, pasted to the lower right corner with no gaps and no overlap Create, in which a pattern image disappears it (Fig. 7 (a) (b) referring to.).
As shown in FIGS. 7A and 7B, when the minimum structural unit of the disappearing pattern is pasted on the blank image, it may protrude from the size of 2040 × 2040 pixels.
An erase pattern image having a size of 2040 × 2040 pixels is created as described above, and this erase pattern image is used to create tint block image information.
When the process of step S602 is completed, the process proceeds to the process of step S604, and the remaining pattern information 12b indicating the remaining pattern of the density selected by the user by the same method as the creation of the disappearing pattern image by the process of step S602. Is used to create an image (remaining pattern image) of 2040 pixels × 2040 pixels based on the remaining pattern.
More specifically, as the remaining pattern information 12b, the remaining pattern indicating the remaining pattern having a density suitable for the density of the disappearing pattern used in the process of step S602 from the remaining patterns shown in FIGS. Select the information 12b, paste it on the 2040x2040 pixel blank image so that it proceeds along the row direction from the upper left corner, and when it reaches the right end and finishes pasting one row, it is the same as the first row Paste it to the next line located in the lower row, and repeat it to paste it to the lowermost row in sequence, creating a paste with no gap to the lower right corner and without overlapping. This is the remaining pattern image (see FIGS. 7A and 7B).
For example, when a density of 0.0625 having an array size of 4 × 4 pixels in which one small dot is arranged is selected as the disappearance pattern, the remaining pattern having a density close to the density corresponding to this disappearance pattern is shown in FIG. a) Selection is made with reference to (b).
More specifically, referring to FIGS. 5A and 5B, the density close to the disappearance pattern density of 0.0625 is the remaining pattern, and the remaining pattern has a density of 0. 063 is the remaining pattern.
Therefore, when a 4 × 4 pixel array size density of 0.0625 with one small dot arranged as the disappearing pattern is selected, the remaining pattern with nine large dots arranged in a 12 × 12 pixel array size As a minimum unit and pasted on a 2040 × 2040 pixel blank image so that it proceeds along the row direction from the upper left corner, and when reaching the right end and pasting one row, it is the same as the first row. Paste it to the next line located in the lower row, and repeat it to paste it to the lowermost row in sequence, creating a paste with no gap to the lower right corner and without overlapping. This is the remaining pattern image (refer to FIGS. 7A and 7B).
When the process of step S604 is completed, the process proceeds to step S606, and a hidden character image creation process is performed using the hidden character information 12c.
Here, the hidden character image is created as an image having an array size of 2040 × 2040 pixels (see FIG. 7C) based on the hidden character information 12c indicating a desired hidden character input by the user or the like. What should I do?
When the process in step S606 is completed, the process proceeds to step S608, and a 2040 × 2040 pixel tint block image creation process having hidden characters is performed.
Hereinafter, the tint block image creation processing in step S608 will be described in detail.

FIG. 8 is an explanatory diagram conceptually showing a method for creating a copy-forgery-inhibited pattern image using the disappearing pattern image, the remaining pattern image, and the hidden character image.
Here, reference numeral 30 in FIG. 8 indicates an erasure pattern image having an array size of 2040 × 2040 pixels created in the process of step S602, and reference numeral 32 in FIG. 8 denotes 2040 × 2040 created in the process of step S604. 8 shows a remaining pattern image having an array size of pixels. Reference numeral 34 in FIG. 8 indicates a hidden character image having an array size of 2040 × 2040 pixels created in the process of step S606, and reference numeral 38 in FIG. 8 indicates a tint block image. Represents.
Then, in order to synthesize the disappearing pattern image 30, the remaining pattern image 32, and the hidden character image 34 as one image, the arithmetic processing indicated by reference numeral 36 in FIG. The arithmetic processing shown is performed.
In the present embodiment, as shown in the example shown in FIG. 3, when the copy-forgery-inhibited pattern image is copied, the hidden character portion is copied white, and the hidden character is displayed in white so that the pattern is applied to the background portion. The case where processing is performed will be described.
Here, the calculation processing 36 performs processing for determining the portion represented by the disappearing pattern image 30 and the portion represented by the remaining pattern image 32 in the hidden character image 34 for the input hidden character image 34. In the present embodiment, the character (black) portion 34 a in the hidden character image 34 is output as the disappearing pattern image 30, and the background (white) portion 34 b in the hidden character image 34 is output as the remaining pattern image 32. So that condition is set.
In the arithmetic processing 36 described above, in order to simplify the explanation and facilitate understanding of the present invention, the hidden character image 34 is set as the input image A, the remaining pattern image 32 is set as the input image B, and the disappearing pattern image 30 is set. Will be described as an input image C.
In the calculation processing 36, the following Expression 1 and Expression 2 are calculated. First, according to Expression 1, the area of the numerical value 255 representing the white color of the input image A (white background) is the input image as the output image. Processed to use B.
IF input image A = 255
Output image = input image B Formula 1
As a result, the background portion 34b of the input image A, which is the hidden character image 34, is input to the input image B, which is the remaining pattern image 32 that is copied to the copy and the background pattern remains when the printed matter on which the background portion 34b is printed is copied by the copying machine. It will consist of
Further, according to Expression 2, the area of the numerical value 0 (black character) representing black of the input image A is processed so that the input image C is used as the output image.
IF input image A = 0
Output image = input image C (2)
As a result, the character pattern 34a of the input image A, which is the hidden character image 34, disappears without being copied to the copy and leaving no background pattern when the printed matter on which the character portion 34a is printed is copied by the copying machine. The input image C is formed.
Therefore, by executing the arithmetic processing 36 described above, a tint block image 38 having an array size of 2040 × 2040 pixels is generated, the background portion 38b is constituted by the remaining pattern, and the character portion 38a is constituted by the disappearing pattern. It will be.

When the process of step S608 is completed, the process proceeds to step S610, and the copy-forgery-inhibited pattern image information 12d indicating the copy-forgery-inhibited pattern image 38 having an array size of 2040 × 2040 pixels created in the process of step S608 and the original image information 18 are combined. Then, a process of embedding the copy-forgery-inhibited pattern image 38 in the original image 18a indicated by the original image information 18, that is, a composition process of the original image and the copy-forgery-inhibited pattern image is performed.
FIG. 9 conceptually illustrates a process of combining the copy-forgery-inhibited pattern image information 12 d indicating the copy-forgery-inhibited pattern image 38 and the original image information 18 and embedding the copy-forgery-inhibited pattern image 38 in the original image 18 a indicated by the original image information 18. The figure is shown.
In the process of step S610, first, a 2040 × 2040 pixel copy-forgery-inhibited pattern image generated by the process of step S608 and the original image 18a indicated by the original image information 18 are used as a unit block. The unit block is pasted on the original image information 18 so as to proceed along the row direction from the upper left corner, and when reaching the right end and pasting one row, it is positioned at the lower stage in the same manner as the first row. Pasted to the next line, and then repeatedly pasted to the bottom line, pasting to the lower right corner with no gaps and no overlap, the original image information as the output image The copy-forgery-inhibited pattern image insertion original image in which the copy-forgery-inhibited pattern image 38 is embedded in the original image 18a indicated by 18 is generated. The image information 14a is output to the printer 16.
Then, when the copy-forgery-inhibited pattern image 38 is embedded in the original image 18a indicated by the original image information 18, the calculation process represented by reference numeral 40 in FIG. An area for embedding is specified.
Here, the calculation process 40 will be described using the original image 18a indicated by the original image information 18 as the input D and the copy-forgery-inhibited pattern image 38 as the input E. By performing the calculation of Expression 3 below, the white color of the input D is expressed. The input E is embedded in the area of the numerical value 255 (white margin), and the copy-forgery-inhibited pattern image 38 of the input E is printed.
IF input D = 255
Output = Input E ... Formula 3
That is, since the original image 18a indicated by the original image information 18 has a configuration in which black characters are arranged on a white background, the background in the original image 18a indicated by the original image information 18 is the background pattern image 38 as the input E. Will be printed.
In addition, by performing the calculation of the following expression 4, the numerical value 0 representing black is embedded in the area of the numerical value 0 representing black (black characters) of the input D, and the original image 18a indicated by the original image information 18 The black character portion is printed as it is.
IF input D = 0
Output = 0 Equation 4
That is, since the original image 18a indicated by the original image information 18 has a configuration in which black characters are arranged on a white background, the black characters in the original image 18a indicated by the original image information 18 are printed in black as they are. It will be.
The copy-forgery-inhibited pattern image obtained by combining the copy-forgery-inhibited pattern image 38 thus obtained and the original image 18a indicated by the original image information 18 and replacing the background of the original image 18a indicated by the original image information 18 with the copy-forgery-inhibited pattern image 38. The copy-forgery-inhibited pattern image insertion original image information 14 a indicating the image insertion original image 42 is output by the printer 16 and printed.

When the process of step S610 is completed, the process proceeds to step S612, where the balance between the background tint image density and the density of the hidden characters applied to the printed copy-forgery-inhibited pattern image 42 is checked. If there is no problem, the tint block image generation processing routine ends.
On the other hand, if there is a problem in the check process in step S612, the process returns to step S602, the processes in steps S602 to S610 are executed again, and the copy-forgery-inhibited pattern image insertion original image 42 with an appropriate density is created.

As described above, according to the tint block image embedding method of the present invention, the tint block pattern can be effectively applied to the original image by a simple method.

(2) Second embodiment of the present invention (embedding method of digital watermark copy-forgery-inhibited pattern image)
Next, as a second embodiment according to the present invention, an example of an embodiment relating to a method of embedding a digital watermark copy-forgery-inhibited pattern image which is a copy-forgery-inhibited pattern image having digital watermark information will be described in detail.
Note that the same or equivalent configuration and processing contents as those in the first embodiment according to the present invention are indicated by using the same reference numerals as those in the first embodiment according to the present invention. Detailed description thereof will be omitted as appropriate.

In FIG. 10, as a second embodiment of the present invention, an electronic method for embedding a tint block image having a digital watermark in an original image (hereinafter referred to as “digital watermark tint block embedding method” as appropriate) is implemented. A block configuration explanatory diagram showing an example of a system configuration of an embedding device for a copy-forgery-inhibited pattern image having a watermark (hereinafter appropriately referred to as “digital watermark copy-forgery-embedded device”) is shown.
Compared with the copy-forgery-inhibited pattern image embedding device 10 shown in the first embodiment, the digital watermark copy-forgery-inhibited pattern embedding device 100 shows a digital watermark copy-forgery-inhibited pattern image as a copy-forgery-inhibited pattern image having a digital watermark instead of the copy-forgery-inhibited pattern image generation unit 12. The difference is that the digital watermark copy-forgery-inhibited pattern image generation unit 102 for generating the digital watermark copy-forgery-inhibited pattern image information is provided, and the digital watermark image synthesis unit 104 is provided instead of the image synthesis unit 14.
That is, the digital watermark copy-forgery-inhibited pattern embedding device 100 includes a digital watermark copy-forgery-inhibited pattern image generation unit 102 that generates digital watermark copy-forgery-inhibited pattern image information 102 e, digital watermark copy-forgery-inhibited pattern image information 102 e and original image information 18 generated by the digital watermark copy-forgery-inhibited pattern image generation unit 102. And a digital watermark image synthesis unit 104 that generates information (digital watermark copy-forgery-inhibited pattern image insertion original image information) 104a indicating the original image into which the digital watermark copy-forgery-inhibited pattern image is inserted, and the digital watermark generated by the digital watermark image synthesis unit 104 And a printer 16 for inputting the watermark copy-forgery-inhibited pattern image original image information 104a, printing it on plain paper or the like as the print medium, and outputting it as a printed matter 106 such as a paper document. The embedding device 100 can be constructed by a computer system.
More specifically, the digital watermark copy-forgery-inhibited pattern image generation unit 102 indicates the above-described disappearance pattern information 12a, digital watermark remaining pattern information 102b indicating a digital watermark remaining pattern (described later), hidden character information 12c, and digital watermark. The digital watermark bit information 102d as bit information is input, and the digital watermark copy-forgery-inhibited pattern image information 102e is generated from the disappearance pattern information 12a, the digital watermark remaining pattern information 102b, the hidden character information 12c, and the digital watermark bit information 102d.
Also, the digital watermark copy-forgery-inhibited pattern image information 102e generated by the digital watermark copy-forgery-inhibited pattern image generation unit 102 is input to the digital watermark image combination unit 104 described above, and the digital watermark image combination unit 104 stores the original image information 18 and the digital watermark copy-forgery-inhibited pattern image information 102e. Are combined to generate digital watermark copy-forgery-inhibited pattern image insertion original image information 104a.
Then, the printer 16 performs printing on the medium according to the input digital watermark copy-forgery-inhibited pattern image insertion original image information 104a, and outputs a printed matter 106 as a medium on which the original image with the digital watermark copy-forgery-inhibited pattern image inserted is printed.

In the above configuration, the principle of the digital watermark copy-forgery-inhibited pattern image will be described with reference to FIG. 10 and FIG. 11 to FIG. Will be described.
Here, the digital watermark remaining pattern indicated by the digital watermark remaining pattern information 102b described above is the resolution of the copying machine when the printed matter 106 on which the original image inserted with the digital watermark copy-forgery-inhibited pattern image is printed is copied by the copying machine. This means a ground tint pattern having a resolution used when printing an area where a digital watermark ground tint image is copied and remains as a copy content.
In the present embodiment, the digital watermark bit information 102d is embedded in the digital watermark remaining pattern information 102b.
The digital watermark bit information 102d described above represents the digital watermark information 108, which is information that the user wants to embed as an electronic watermark in the original image, as bit information.

Here, the digital watermark information 108 will be described in detail with reference to a conceptual configuration explanatory diagram conceptually showing the configuration of the digital watermark information 108 shown in FIG.
In this embodiment, the contents embedded in the original image as a digital watermark can be configured by a maximum of 16 sets of digital watermark information 108.
As will be described later, since the area of the content information 108b indicating the content of the digital watermark set in the digital watermark information 108 is 8 bytes, the capacity of the content embedded in the original image as the digital watermark is 128 at the maximum. Bytes (= 8 bytes × 16 sets).
The digital watermark information 108 includes 4-byte header information 108a, content information 108b indicating the content of the 8-byte digital watermark, and 2-byte CRC code information 108c.
The header information 108a is composed of a predetermined character as a special recognition character, for example, 3-byte fixed character information 108aa for storing "ABC" and 1-byte set number information 108ab representing a set of the digital watermark information 108. It is what has been.
The number of sets represented by the set number information 108ab is 16 (0 to 15) at the maximum as described above.
Next, the digital watermark content information 108b is an area in which information to be embedded in the original image as a digital watermark is stored. As described above, the digital watermark content information 108b has a capacity of 8 bytes. By using it, it is possible to embed information having a capacity of 128 bytes in the original image as a digital watermark.
The CRC code 108c is information for detecting a 2-byte error generated from the 8-byte digital watermark content 108b.
The digital watermark bit information 102d is obtained by expressing the digital watermark information 108 as a bit string such as “0100111...” Using 0 and 1 as described above. 102 is input.

Next, a method for generating the digital watermark copy-forgery-inhibited pattern image information 102e representing the digital watermark copy-forgery-inhibited pattern image will be described in detail below.
In the present invention, the digital watermark copy-forgery-inhibited pattern image is configured using an erasure pattern and a digital watermark remaining pattern, and the erasure pattern information 12a, the digital watermark remaining pattern information 102b, the hidden character information 12c, and the digital watermark bit. The digital watermark copy-forgery-inhibited pattern image information 102e is generated by combining the information 102d.
Since the disappearance pattern is the same as the disappearance pattern in the first embodiment, detailed description thereof will be omitted.

Next, a digital watermark remaining pattern will be described. This digital watermark remaining pattern needs to be composed of dots (large dots) of a size that can be detected by the copying machine, similarly to the remaining pattern in the first embodiment. is there.
Specifically, since the maximum resolution of the copying machine is generally lower than the maximum resolution of the printer, the size of the dots constituting the digital watermark remaining pattern is, for example, the smallest size of dots that can be printed by the printer. Larger than the size printable by the printer may be used.
In the present embodiment, as the array size of the minimum structural unit of the remaining digital watermark pattern, as described later, an array size (12 × 12 pixels) in which pixels are arranged in 12 rows and 12 columns is used. A predetermined number of large dots are arranged in pixels of this arrangement size according to the density.
The number of large dots is selected so that the remaining digital watermark pattern has a density suitable for the density of the selected erase pattern, and a predetermined number of black dots are arranged within 12 pixels × 12 pixels.

Here, the remaining digital watermark pattern has the same configuration as the remaining pattern in the first embodiment described above, but the remaining pattern in the first embodiment described above only for the position where the large dot is arranged. Is different.
Accordingly, the density corresponding to the number of large dots to be arranged is the same as the remaining pattern in the first embodiment described above, and therefore the chart shown in FIG. 5A is used for the remaining digital watermark pattern. it can.
More specifically, FIGS. 12 (a) and 12 (b) are conceptual explanatory diagrams regarding the remaining digital watermark pattern, and are arranged when a large dot is arranged in each pixel having an arrangement size of 12 pixels × 12 pixels. The order is shown.
That is, in the second embodiment, as the remaining watermark pattern, two types of remaining watermark patterns, that is, the remaining watermark pattern shown in FIG. 12A and the remaining watermark pattern shown in FIG. Is provided.
In FIGS. 12A and 12B, the numbers described in each pixel indicate the order in which the pixels are arranged. Specifically, 32 numbers from “1” to “32” in order. Represents the order of printing the large dots.
More specifically, for example, when only one large dot is printed, printing is performed only on the pixel indicated as “1” in FIGS. 12A and 12B, and five large dots are printed. In the case, in FIG. 12 (a) (b), from the pixel labeled “1” to the pixel labeled “5”, that is, “1”, “2”, “3”, “4” and Print on the pixel labeled “5”.
That is, for example, when 16 large dots are arranged within an array size of 12 × 12 pixels, the dots 1 to 16 in FIG. 12A and 12B are represented in black, All dots other than the numbers 1 to 16 are represented in white. In this case, since the number of large dots is 16, the density is “0.1111” from FIG.

By the way, as described above, the remaining watermark patterns include two types of remaining watermark patterns, that is, the remaining watermark pattern 110 shown in FIG. 12A and the remaining watermark pattern 112 shown in FIG. Is provided.
More specifically, in the digital watermark remaining pattern 110 shown in FIG. 12A, the large dot group 110a that is positioned at the center of the arrangement size of 12 × 12 pixels has a row direction of the arrangement size of 12 × 12 pixels. This is an electronic watermark remaining pattern arranged so as to extend in the horizontal direction in FIG.
On the other hand, in the digital watermark remaining pattern 112 shown in FIG. 12B, the large dot group 112a that is positioned at the center of the arrangement size of 12 × 12 pixels is arranged in the column direction of the arrangement size of 12 × 12 pixels (FIG. 12). This is a digital watermark remaining pattern arranged so as to extend in the vertical direction in (b).
Therefore, the remaining digital watermark pattern 110 and the remaining digital watermark pattern 112 are different from each other in the shape of the large dot group 110a and the large dot group 112a arranged at the center of each pattern. Can be easily read.
In the present embodiment, by utilizing such a point that when the digital watermark remaining pattern 110 and the digital watermark remaining pattern 112 are read by the scanner, both can be easily discriminated. The digital watermark remaining pattern 110 shown in (a) represents “0” of the digital watermark bit information 102d, while the digital watermark residual pattern 112 shown in FIG. 12B is “1” of the digital watermark bit information 102d. ".
Contrary to the above, it is assumed that the remaining digital watermark pattern 110 shown in FIG. 12A represents “1” of the digital watermark bit information 102d, while the remaining digital watermark pattern 112 shown in FIG. 12B. However, it is needless to say that the digital watermark bit information 102d may represent “0”.
Note that the number of large dots used for the above-described digital watermark remaining pattern is to select a dot suitable for the density of the disappearance pattern described above.
That is, the digital watermark remaining pattern for printing the area remaining after copying is determined by the user selecting the density of the disappearing pattern as described above.
In this embodiment, the color of the pixel that prints a large dot shown in FIGS. 12A and 12B is a value 0 (black) out of 256 gradations, and the pixel that does not print a large dot (FIG. 12). In (a) and (b), the pixel in which the small dots are not printed is shown in white.) The color of 256 gradations is assumed to be 255 (white).

Next, processing for generating digital watermark copy-forgery-inhibited pattern image information will be described with reference to the flowchart of the digital watermark copy-forgery-inhibited pattern image generation processing routine shown in FIG.
The digital watermark copy-forgery-inhibited pattern image information 102e uses the disappearance pattern information 12a indicating the disappearance pattern, the remaining watermark information 102b indicating the remaining watermark pattern, the hidden character information 12c, and the watermark bit information 102d. 13 is generated by executing the electronic watermark copy-forgery-inhibited pattern image processing routine shown in the flowchart of FIG. 13, and when the digital watermark copy-forgery-inhibited pattern image processing routine is started by a user instruction or the like, first, the density selected by the user disappears. Using the disappearance pattern information 12a indicating the pattern, an erase pattern image that is an image (2040 × 2040 pixel image) composed of pixels of 2040 rows and 2040 columns is performed by the disappearance pattern indicated by the disappearance pattern information 12a (step) S1302 .
Since the processing content in step S1302 is the same as the processing content in step S602 described above, detailed description thereof will be omitted.
In step S1302, the same pattern as the disappearing pattern image 30 shown in FIG. 8 is created.
When the process of step S1302 is completed, the process proceeds to step S1304, using the remaining watermark information 102b and the watermark bit information 102d indicating the remaining watermark pattern corresponding to the density of the erased pattern image 30. Then, a 2040 pixel × 2040 pixel image (digital watermark remaining pattern image) is created by the digital watermark remaining pattern.
More specifically, first, as in the case of creating the remaining pattern image in the process of step S604 in the first embodiment, as the digital watermark remaining pattern information 102b, FIG. 5A and FIG. Among the remaining digital watermark patterns shown in b), the remaining digital watermark pattern information having a density suitable for the density of the erased pattern used in step S1302 and indicating the remaining digital watermark pattern representing the bit string of the digital watermark bit information 102d Select 102b and paste it on the blank image of 2040 x 2040 pixels so that it proceeds along the row direction from the upper left corner. When it reaches the right end and finishes pasting one row, the bottom row is the same as the first row. Is pasted to the next row located at, and repeated to the bottom row in sequence, Without clearance to, and create what was attached to non-overlapping, which is intended to be electronic watermark remaining pattern image.
For example, when a density of 0.0625 having a 4 × 4 pixel array size in which one small dot is arranged is selected as the disappearance pattern, the large dot in the remaining pattern having a density close to the density corresponding to the disappearance pattern is selected. The number is selected with reference to FIG.
Specifically, referring to FIG. 5 (b), the density close to the disappearance pattern density of 0.0625 is the remaining pattern, and the remaining pattern is the remaining density of 0.063 in which nine large dots are arranged in an array size of 12 × 12 pixels. It becomes a pattern.
Accordingly, when a density of 0.0625 having an array size of 4 × 4 pixels in which one small dot is arranged is selected as an erasure pattern, a digital watermark in which nine large dots are arranged in an array size of 12 × 12 pixels Paste the remaining pattern on the 2040x2040 pixel margin image so that it proceeds along the row direction from the upper left corner, and when it reaches the right end and finishes pasting one row, it is the same as the first row Paste it on the next line located in the lower row, repeat it and paste it to the lowermost row sequentially, with no gap to the lower right corner and pasted so that there is no overlap In this case, the bit value is set so as to correspond to the bit string indicated by the digital watermark bit information 102d in order. In the case of “0”, the digital watermark remaining pattern 114 (see FIG. 14A) using the digital watermark remaining pattern 110 representing the bit information “0” shown in FIG. When the value is “1”, the digital watermark remaining pattern 116 (see FIG. 14B) using the digital watermark remaining pattern 112 representing the bit information “1” shown in FIG. 12B is used. To.
Here, in the digital watermark remaining pattern 114, the shape of the large dot group 114a arranged in the center thereof is vertically long, whereas the digital watermark remaining pattern 116 is in the large dot group 116a arranged in the center thereof. Since the shape of the large dot group 114a and the large dot group 116a is detected, the bit information indicated by the remaining digital watermark pattern is “0” or “1”. Can be determined.
As described above, the digital watermark remaining pattern 114 and the digital watermark remaining pattern 116 are pasted into the array size of 2040 × 2040 pixels so as to proceed in the row direction from the upper left corner, and reach the right end to reach 1 Once the line is pasted, it will be pasted to the next line located in the lower row in the same way as the first row, and it will be repeated and pasted to the bottom row in sequence, with no gap to the lower right corner, and The digital watermark remaining pattern image is generated by being pasted so as not to overlap. The pasting method will be described below with reference to FIG.

That is, FIG. 15 shows a conceptual explanatory diagram conceptually illustrating a method of pasting a digital watermark remaining pattern used when generating a digital watermark remaining pattern image. Are pasted in the order of the bit string indicated by the digital watermark bit information 102d so that the bit value of the bit string indicated by the digital watermark bit information 102d matches the bit information indicated by the remaining digital watermark pattern.
That is, the remaining digital watermark pattern 114 indicating the bit information “0” or the remaining digital watermark pattern 116 indicating the bit information “1” in the order of the arrangement of 0 or 1 constituting the digital watermark bit information 102 d is set to 2040 × 2040. Paste on the margin image of the pixel array size so that it proceeds along the line direction from the upper left corner, and when it reaches the right end and finishes pasting one line, the next line located in the lower row is the same as the first line. It is pasted on a line, and it is repeatedly pasted to the bottom line in sequence, and it is pasted to the lower right corner with no gap and no overlap.
Specifically, if the bit string indicated by the digital watermark bit information 102d is, for example, “0100110...” As shown in FIG. 15, the first bit value of the bit string is “0”. First, the digital watermark remaining pattern pasted on the blank image having the array size of 2040 × 2040 pixels becomes the digital watermark remaining pattern 114 representing the bit information “0”, and the blank image having the array size of 2040 × 2040 pixels. Located in the upper left corner.
Next, since the second bit value of the bit string is “1”, the second watermark remaining pattern to be pasted on the blank image having the array size of 2040 × 2040 pixels second represents the bit information “1”. The digital watermark remaining pattern 116 is arranged adjacent to the right side of the first digital watermark remaining pattern 114.
Then, the same processing as described above is repeated, and the digital watermark pattern 114 or the digital watermark pattern 116 respectively corresponding to 0 or 1 of the bit string indicating the digital watermark bit information 102d is placed on a blank image having an array size of 2040 × 2040 pixels. By arranging them in order, a digital watermark remaining pattern image is generated.
When the process of step S1304 is completed, the process proceeds to step S1306, and a hidden character image creation process is performed using the hidden character information 12c.
Here, the hidden character image is a 2040 × 2040 pixel image based on the hidden character information 12c indicating the desired hidden character input by the user, as in the process of step S606 in the first embodiment. What is necessary is just to produce as an image of an array size (refer FIG.7 (c)).
When the process of step S1306 is completed, the process proceeds to step S1308, where a 2040 × 2040 pixel digital watermark copy-forgery-inhibited pattern image having hidden characters is created.
Hereinafter, the tint block image creation processing in step S1308 will be described in detail.

FIG. 16 is an explanatory diagram conceptually showing a technique for creating a digital watermark copy-forgery-inhibited pattern image using an erased pattern image, a digital watermark remaining pattern image, and a hidden character image.
Here, reference numeral 30 in FIG. 16 indicates an erasure pattern image having an array size of 2040 × 2040 pixels created in the process of step S1302, and reference numeral 118 in FIG. 16 denotes 2040 × 2040 created in the process of step S1304. 8 shows a digital watermark remaining pattern image having an array size of pixels. Reference numeral 34 in FIG. 8 indicates a hidden character image having an array size of 2040 × 2040 pixels created in the process of step S1306. Reference numeral 122 in FIG. Represents a watermark pattern image.
Then, in order to synthesize the disappearance pattern image 30, the digital watermark remaining pattern image 118, and the hidden character image 34 as one image, the arithmetic processing indicated by reference numeral 120 in FIG. 6 is performed.
In the present embodiment, as in the example shown in FIG. 3, when the digital watermark copy-forgery-inhibited pattern image is copied, the hidden character portion is copied white, and the hidden character is outlined so that the background portion is patterned. A case where processing is performed so as to be displayed in will be described.
Here, the arithmetic processing 120 performs processing for determining the portion represented by the disappearing pattern image 30 and the portion represented by the remaining digital watermark pattern image 118 in the hidden character image 34 for the input hidden character image 34. In the present embodiment, the character (black) portion 34a in the hidden character image 34 is output as the disappearing pattern image 30, and the background (white) portion 34b in the hidden character image 34 is output as the remaining digital watermark pattern image. The condition is set so that the data is output at 118.
In the arithmetic processing 120 described above, in order to simplify the explanation and facilitate the understanding of the present invention, the hidden character image 34 is set as the input image F, the digital watermark remaining pattern image 118 is set as the input image G, and the disappearance pattern. The image 30 will be described as an input image H.
In the calculation process 120, the following Expression 5 and Expression 6 are calculated. First, according to Expression 5, the area of the numerical value 255 representing the white color of the input image F (white background) is the input image as the output image. Processed to use G.
IF input image F = 255
Output image = input image G Expression 5
As a result, the background portion 34b of the input image F, which is the hidden character image 34, is input as the digital watermark remaining pattern image 118 in which the copy-forgery-inhibited pattern image is copied to the copy when the printed matter on which the background portion 34b is printed is copied by the copying machine. The image G is composed.
Further, according to Expression 6, the area of 0 (black character) representing the black color of the input image F is processed so that the input image H is used as the output image.
IF input image F = 0
Output image = input image H Expression 6
As a result, the character pattern 34a of the input image F, which is the hidden character image 34, disappears without being copied to the copied material and leaving no background pattern when the printed material on which the character portion 34a is printed is copied by the copying machine. The input image H is formed.
Therefore, by executing the arithmetic processing 120 described above, a digital watermark copy-forgery-inhibited pattern image 122 having an array size of 2040 × 2040 pixels is generated, its background portion 122b is constituted by a digital watermark remaining pattern, and its character portion 122a is an erase pattern. It is comprised by.

When the process of step S1308 is completed, the process proceeds to step S1310, and digital watermark copy-forgery-inhibited pattern image information 102e indicating the digital watermark copy-forgery-inhibited pattern image 122 having an array size of 2040 × 2040 pixels created in the process of step S1308 and original image information 18 and the process of embedding the digital watermark copy-forgery-inhibited pattern image 122 in the original image 18a indicated by the original image information 18, that is, the synthesis process of the original image and the digital watermark copy-forgery-inhibited pattern image.
FIG. 17 conceptually illustrates a process of synthesizing the digital watermark copy-forgery-inhibited pattern image information 102 e indicating the copy-forgery-inhibited pattern image 122 and the original image information 18 and embedding the copy-forgery-inhibited pattern image 122 in the original image 18 a indicated by the original image information 18. An explanatory diagram is shown.
The process executed in step S1310 is the same as the process executed in step S610 in the first embodiment described above.
That is, in FIG. 17, the digital watermark copy-forgery-inhibited pattern image information 102e indicating the digital watermark copy-forgery-inhibited pattern image 122 and the original image information 18 are combined, and the digital watermark copy-forgery-inhibited pattern image 122 is embedded in the original image 18a indicated by the original image information 18. An explanatory diagram conceptually showing the processing is shown.
In the process of step S1310, first, the 2040 × 2040 pixel digital watermark copy-forgery-inhibited pattern image 122 and the original image 18a indicated by the original image information 18 created in step S1308 are used. When an image is a unit block, this unit block is pasted on the original image 18a indicated by the original image information 18 so as to proceed along the row direction from the upper left corner, and when reaching the right end and pasting one line is completed, 1 Paste it to the next line located in the lower row in the same way as the line, and repeat it to paste it to the lowermost row in sequence, with no gaps to the lower right corner and without overlapping. In addition, an electronic watermark copy-forgery-inhibited pattern image insertion original image in which the digital watermark copy-forgery-inhibited pattern image 122 is embedded in the original image 18a indicated by the original image information 18 as an output image. Is generated, and the electronic watermark copy-forgery-inhibited pattern image insertion original image information 104 a indicating the original digital watermark copy-forgery-inhibited pattern image insertion original image is output to the printer 16.
Then, when embedding the digital watermark copy-forgery-inhibited pattern image 122 in the original image 18a indicated by the original image information 18, the arithmetic processing represented by reference numeral 124 in FIG. An area for embedding the watermark copy-forgery-inhibited pattern image 122 is designated.
Here, the calculation process 124 will be described using the original image 18a indicated by the original image information 18 as the input I and the digital watermark copy-forgery-inhibited pattern image 122 as the input J. By calculating the following Expression 7, In the area of the numerical value 255 (white margin) representing the input J, the input J digital watermark copy-forgery-inhibited pattern image 122 is printed.
IF input I = 255
Output = input J ... 7
That is, since the original image 18a indicated by the original image information 18 has a configuration in which black characters are arranged on a white background, the background in the original image 18a indicated by the original image information 18 is an electronic watermark copy-forgery-inhibited pattern image as an input J. 122 is printed.
Further, by performing the calculation of Expression 8 below, the numerical value 0 representing black is embedded in the area of the input I representing black (black characters), and the original image information 18 indicates the original image 18a. The black character portion is printed as it is.
IF input I = 0
Output = 0 Equation 4
That is, since the original image 18a indicated by the original image information 18 has a configuration in which black characters are arranged on a white background, the black characters in the original image 18a indicated by the original image information 18 are printed in black as they are. It will be.
The digital watermark copy-forgery-inhibited pattern image 122 generated by combining the digital watermark copy-forgery-inhibited pattern image 122 thus obtained and the original image 18a indicated by the original image information 18 is replaced with the digital watermark copy-forgery-inhibited pattern image 122. The copy-forgery-inhibited pattern image insertion original image information 104a indicating the copy-forgery-inhibited pattern image insertion original image 126 is output from the printer 16 and printed.

When the process of step S1310 is completed, the process proceeds to step S1312, and the balance between the density of the background digital watermark pattern image and the density of the hidden characters applied to the printed digital watermark pattern image insertion original image 126 is checked. If there is no problem in the check, the digital watermark copy-forgery-inhibited pattern image generation processing routine is terminated.
On the other hand, if there is a problem in the check process in step S1312, the process returns to step S1302, and the process in steps 1302 to S1310 is executed again to create the digital watermark copy-forgery-inhibited pattern image insertion original image 126 having an appropriate density.

As described above, according to the digital watermark copy-forgery-inhibited pattern image embedding method according to the present invention, it becomes possible to embed digital watermark information in a copy-forgery-inhibited pattern, and the digital watermark is effectively added to the original image by a simple method. A tint block pattern can be applied.

(3) Third embodiment according to the present invention (method for detecting digital watermark information from an original image into which a digital watermark copy-forgery-inhibited pattern image is inserted)
Next, a method for detecting digital watermark information embedded in the original image information 18 from the digital watermark copy-forgery-inhibited pattern image insertion original image 126 by the method described in the second embodiment of the present invention will be described.

In FIG. 18, as a third embodiment according to the present invention, a method of detecting digital watermark information from the digital watermark copy-forgery-inhibited pattern image insertion original image 126 (hereinafter referred to as “digital watermark detection method” as appropriate) is implemented. 1 is a block configuration explanatory diagram showing an example of a system configuration of a digital watermark detection apparatus (hereinafter appropriately referred to as “digital watermark detection apparatus”).
This digital watermark detection apparatus 200 reads an image displayed on a paper document 130 having a digital watermark and a character-hidden copy-forgery-inhibited pattern image, such as a printed matter printed with the digital watermark copy-forgery-inhibited pattern insertion original image 126 or a copy of the printed matter. 202 and a digital watermark detection unit 204 that detects digital watermark information 204a based on an image read by the image reading device 202, and can be constructed by a computer system.
In this embodiment, as the image reading device 202, a scanner generally used for image reading is used.

With the above configuration, a process for detecting the digital watermark information 204a from the paper document 130 by the digital watermark detection apparatus 200 will be described in detail with reference to FIGS. 18 and 19 to 20 described above.
That is, FIG. 19 shows a flowchart representing a digital watermark detection processing routine for detecting the digital watermark information 204a from the paper document 130 by the digital watermark detection apparatus 200, and FIGS. 20 (a) and 20 (b). , conceptual diagram illustrating conceptually the digital watermark detection process is shown.
When this digital watermark detection processing routine is started by a user instruction or the like, first, the image 206 displayed on the paper document 130 is read by the image reading device 202 to obtain image information of the image 206, and the digital watermark is obtained. The detection unit 204 performs processing for detecting the digital watermark information 204a from the acquired image information. First, an area composed only of the remaining digital watermark pattern in the image 206 from the acquired image information. 206a to be acquired (step S1902).
That is, the image 206 includes various areas such as an area 206a composed only of the remaining digital watermark pattern, an area 206b including a hidden character display, or an area 206c including an original image display. Only the region 206a composed only of the remaining watermark pattern is cut out and acquired manually or automatically.
When the process of step S1902 is completed, the process proceeds to the process of step S1904, and the process of determining the position of each remaining digital watermark pattern is performed from the area 206a of only the remaining digital watermark pattern acquired in the process of step S1902.
That is, by extracting halftone dots that serve as reference positions for the remaining digital watermark patterns at the four corners of each remaining digital watermark pattern from the remaining digital watermark pattern area 206a obtained in step S1902, the area 206a is extracted. determining the position of each electronic watermark remaining pattern disposed on.
Here, the halftone dot means a large dot arranged in each pixel located in the four corner areas of the remaining digital watermark pattern. In the remaining digital watermark pattern, as shown in FIGS. In addition, large dots are set in the four corner areas of the digital watermark remaining pattern.
Here, FIG. 20B shows an enlarged explanatory view of a main part showing a part of the remaining digital watermark pattern image.
As shown in FIG. 20B, large dots arranged in the four corner areas of each digital watermark remaining pattern constitute a halftone dot, and serve as a reference when determining the position of the remaining digital watermark pattern. The position of the remaining digital watermark pattern is determined with reference to this reference position.
Even if it is not possible to extract halftone dots at all four corners in each digital watermark remaining pattern, for example, if halftone dots at three corners or two corners can be extracted, the digital watermark remaining pattern is determined. it may be to determine the position.
When the process of step S1904 is completed, the process proceeds to step S1906, and the remaining digital watermark pattern whose position is determined in the process of step S1904 is the remaining digital watermark pattern 114 or the remaining digital watermark pattern 116. In the case of the digital watermark remaining pattern 114, it is determined that the bit information is “0”, and “1” is detected as the bit information. The bit information is determined to be “1”, and “0” is detected as the bit information.
That is, by determining the position of the remaining digital watermark pattern whose position has been determined in the processing of step S1904, the center position of the remaining digital watermark pattern located at the center of each halftone dot can be determined. By determining the shape of the large dot group located in the position area, the digital watermark remaining pattern whose position is determined in the processing of step S1904 is the digital watermark remaining pattern 114 or the digital watermark remaining pattern 116. Can be determined.
In other words, in the present embodiment, if the large dot group located in the central region of the remaining watermark pattern is a horizontally long shape, it can be determined that the remaining watermark pattern 114, while the remaining watermark pattern If the large dot group located in the central area is vertically long, it can be determined that the digital watermark remaining pattern 116 is present, and if it is the digital watermark remaining pattern 114, it is determined that the bit information is “0”. Thus, “1” is detected as the bit information. On the other hand, if it is the digital watermark remaining pattern 116, it is determined that the bit information is “1”, and “0” is detected as the bit information.
As described above, in the example shown in FIG. 20A, the digital watermark bit information 208 of the bit string “0100110...” Can be detected.
When the process of step S1906 is completed, the process proceeds to the process of step S1908. By obtaining header information and CRC information from the detected digital watermark bit information 208, the entire watermark information is detected, and the digital watermark detection processing routine is ended. .
Therefore, the digital watermark information 204a embedded in the digital watermark copy-forgery-inhibited pattern image document 126 can be detected by executing the digital watermark detection processing routine.

As described above, the digital watermark embedding method and the digital watermark detection method according to the present invention make it possible to embed digital watermark information in an original image by a simple method, and further detect the digital watermark information by a copying machine. Since it is configured using a possible pattern, it is possible to maintain digital watermark information without disappearing from the document even after copying.
Furthermore, since the digital watermark information is converted into bit information and embedded in the original image, it is possible to detect the digital watermark information without requiring a special device for detection.

The above-described embodiment can be modified as described in (1) to (5) below.
(1) The specific numerical values shown in the above-described embodiments are merely examples, and it goes without saying that these numerical values may be appropriately selected when the present invention is embodied.
(2) In the above-described embodiment, the background pattern image is configured such that the background pattern characters appear white. However, the present invention is not limited to this, and the background pattern characters are configured to appear on a white background. It is also possible to use the copy-forgery-inhibited pattern image.

More specifically, the copy-forgery-inhibited pattern image 20 shown in FIG. 3 is configured such that the region 20a that becomes the alphabet “C” of the hidden character portion is configured by the disappearing pattern, and the region 20b that is the background is configured by the remaining pattern. However, as in the copy-forgery-inhibited pattern image 300 shown in FIG. 21, the background region 300a is configured by the disappearing pattern, and the region 300b that is the alphabet “C” of the hidden character portion is configured by the remaining pattern. You may do it.
In this case, in the copy obtained by copying the printed matter on which the copy-forgery-inhibited pattern image 300 shown in FIG. 21 is copied by the copying machine, the area 300a constituted by the disappearing pattern is not detected by the copying machine, On the other hand, the area 300b composed of the remaining pattern is detected by the copying machine and copied as the area 302b in FIG. Unlike the example shown, the hidden character is copied as a raised character.
Further, a method for creating a tint block image using such a hidden type hidden character will be described in detail with reference to FIG.
That is, FIG. 22 is an explanatory diagram conceptually showing a method of creating a tint block image using the above-described type of hidden character using the disappearing pattern image, the remaining pattern image, and the hidden character image. ing.
Here, reference numeral 30 in FIG. 8 indicates an erasure pattern image having an array size of 2040 × 2040 pixels created in the process of step S602, and reference numeral 32 in FIG. 8 denotes 2040 × 2040 created in the process of step S604. 8 shows a remaining pattern image having an array size of pixels. Reference numeral 34 in FIG. 8 indicates a hidden character image having an array size of 2040 × 2040 pixels created in the process of step S606, and reference numeral 38 in FIG. 8 indicates a tint block image. Represents.
Then, in order to synthesize the disappearing pattern image 30, the remaining pattern image 32, and the hidden character image 34 as one image, the arithmetic processing indicated by reference numeral 304 in FIG. The arithmetic processing shown is performed.
Here, the arithmetic processing 304 performs processing for determining the portion represented by the disappearing pattern image 30 and the portion represented by the remaining pattern image 32 in the hidden character image 34 for the input hidden character image 34. In the example shown in FIG. 22, the character (black) portion 34 a is output as the remaining pattern image 32 in the hidden character image 34, and the background (white) portion 34 b is erased in the hidden character image 34 as the pattern image 30. The conditions are set to output.
In the arithmetic processing 304 described above, in order to simplify the explanation and facilitate understanding of the present invention, the hidden character image 34 is set as the input image A, the remaining pattern image 32 is set as the input image B, and the disappearing pattern image 30 is set. Will be described as an input image C.
In the calculation processing 36, the following Expression 9 and Expression 10 are calculated. First, according to Expression 9, the area of the numerical value 255 representing the white color of the input image A (white background) is the input image as the output image. Processed to use C.
IF input image A = 255
Output image = input image C Expression 9
As a result, the background pattern 34b of the input image A, which is the hidden character image 34, disappears without a copy-forgery-inhibited pattern remaining on the copy when the printed matter on which the background portion 34b is printed is copied by the copying machine. The input image C is formed.
Further, according to Expression 10, a region of 0 (black characters) representing black in the input image A is processed so that the input image B is used as the output image.
IF input image A = 0
Output image = input image B Equation 10
As a result, the character portion 34a of the input image A, which is the hidden character image 34, is input to the input image B, which is the remaining pattern image 32 which is copied to the copy and the background pattern remains when the printed matter on which the character portion 34a is printed is copied by the copying machine. It will consist of
Therefore, by executing the arithmetic processing 304 described above, a tint block image 306 having an array size of 2040 × 2040 pixels is generated, the character portion 306a is constituted by the remaining pattern, and the background portion 306b is constituted by the disappearing pattern. It will be.
When the generated tint block image 306 is combined with the original image 18a indicated by the original image information 18 by the same method as in the first embodiment, an original image into which a tint block image having a pattern of embossing is inserted is inserted. Obtainable.
(3) In the second embodiment according to the present invention, the remaining digital watermark pattern 110 and the remaining digital watermark pattern 112 shown in FIGS. 12A and 12B are used as the configuration of the remaining digital watermark pattern representing bit information. However, the present invention is not limited to this. Of course, an electronic device having another configuration can be used as long as it has an easily understandable configuration and can discriminate bit information “0” or bit information “1”. A watermark remaining pattern may be used.
That is, in the digital watermark remaining pattern 110 shown in FIG. 12A, the large dot group 110a located in the central region of the array size is configured to extend in the row direction (lateral direction) as a predetermined direction. On the other hand, in the digital watermark remaining pattern 112 shown in FIG. 12B, the large dot group 112a located in the central region of the array size extends in the row direction (vertical direction) as a predetermined direction. For example, the large dot group 110a and the large dot group 112a may be inclined and extended in different directions.
Further, as remaining digital watermark patterns of other configurations, for example, a remaining digital watermark pattern 400 such as a remaining digital watermark pattern 400 shown in FIG. 23A and a remaining digital watermark pattern 402 shown in FIG. The large dot group 400a and the large dot group 402a of the digital watermark remaining pattern 402 may be arranged so as to be shifted in different directions from the central region of the array size.
Here, it is assumed that the remaining digital watermark pattern 400 indicates bit information “0” and the remaining digital watermark pattern 402 indicates bit information “1”.
When the digital watermark information composed of the digital watermark remaining pattern 400 and the digital watermark remaining 402 is detected by the same method as described above, each digital watermark is detected in the same manner as the digital watermark detection method in the present embodiment. Detection is performed based on the four halftone dots of the remaining pattern.
FIG. 23C shows an enlarged explanatory view of a main part when a digital watermark remaining pattern image is created with a digital watermark remaining pattern 400 and a digital watermark remaining pattern 42.
For the large dot group 400a or large dot group 402a located in the center area with reference to the halftone dot, the large dot group 400a located below the center position is determined as bit information “0”, and from the center position. The large dot group 402a located on the upper side is also determined as bit information “1”.
As described above, the remaining digital watermark pattern 110 shown in FIG. 12A represents “1” of the digital watermark bit information 102d, while the remaining digital watermark pattern 112 shown in FIG. Of course, “0” of the digital watermark bit information 102d may be represented, and similarly, the digital watermark remaining pattern 400 shown in FIG. 23A represents “1” of the digital watermark bit information 102d. On the other hand, the digital watermark remaining pattern 402 shown in FIG. 23B may of course represent “0” of the digital watermark bit information 102d.
In addition, when “1” and “0” of the digital watermark bit information 102d indicated by the pair of digital watermark remaining patterns are inverted as described above, the digital watermark bit information is also determined in step S1906 of the digital watermark detection process. Inversion is performed according to the inversion.
(4) In the above-described embodiment, when the position of the remaining digital watermark pattern is determined, the position is determined based on the halftone dots located at the four corners of each remaining digital watermark pattern. Of course, the present invention is not limited to this, and a large dot is always arranged at a predetermined position in each remaining digital watermark pattern, and the position of each remaining digital watermark pattern is determined based on the large dot. May be performed.
(5) You may make it combine suitably the embodiment shown above and the modification shown in said (1) thru | or (4).

  INDUSTRIAL APPLICABILITY The present invention can be used when embedding a copy-forgery-inhibited pattern having a hidden character as a background of an important document, embedding a digital watermark in a copy-forgery-inhibited pattern, or detecting a digital watermark embedded in a copy-forgery-inhibited pattern. It is.

Claims (23)

In a background pattern image embedding method for inserting a background pattern into an image background,
An erasure pattern that designates an erasure pattern that is composed of at least one pixel and that is configured by arranging dots in at least one or more predetermined pixels of the pixel with a size that cannot be detected at a resolution lower than a predetermined resolution. Information and
A remaining pattern that is configured by at least one pixel and that specifies a remaining pattern in which dots are arranged in a size that can be detected even at a resolution lower than a predetermined resolution on at least one predetermined pixel among the pixels. Information and
The hidden character information specifying the area to be printed by the erase pattern specified by the erase pattern information and the remaining pattern specified by the remaining pattern information according to a desired hidden character is combined to include the hidden character A first process for generating copy-forgery-inhibited pattern image information representing a copy-forgery-inhibited pattern image;
The copy-forgery-inhibited pattern image information generated by the first process and the copy-forgery-inhibited pattern image including the hidden characters represented by the copy-forgery-inhibited pattern image information are combined with original image information representing an original image to be printed, and the background is combined. A second process of generating a copy-forgery-inhibited pattern image insertion original image information indicating an original image into which the copy-forgery-inhibited pattern image including the hidden character is inserted;
A copy-forgery-inhibited pattern image embedding method, wherein the copy-forgery-inhibited pattern image insertion original image information generated by the second processing is output to a printer, and the original image in which the copy-forgery-inhibited pattern image including the hidden characters is inserted into the background is output. In a tint block image embedding method for inserting a tint block with a digital watermark in the background of an image,
An erasure pattern that designates an erasure pattern that is composed of at least one pixel and that is configured by arranging dots in at least one or more predetermined pixels of the pixel with a size that cannot be detected at a resolution lower than a predetermined resolution. Information and
When bit information representing digital watermark bit information is 0, at least one pixel located in a predetermined region of the array has a resolution equal to or lower than a predetermined resolution in an array size composed of at least one pixel However, when a digital watermark remaining pattern configured by arranging dots in a detectable size is specified and the bit information representing the digital watermark bit information is 1, the array size configured by the at least one or more pixels is included. A digital watermark that designates a digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution on at least one pixel located in an area having a shape different from the predetermined area The remaining pattern information,
Combining the erased pattern designated by the erased pattern information according to the desired hidden character and the hidden character information designating the area to be printed by the digital watermark remaining pattern designated by the digital watermark remaining pattern information, and A first process for generating digital watermark copy-forgery-inhibited pattern image information representing a digital watermark copy-forgery-inhibited pattern image including hidden characters;
Digital watermark copy-forgery-inhibited pattern image information generated by the first processing and original image information representing an original image to be printed using the digital watermark copy-forgery-inhibited pattern image including the hidden character represented by the digital watermark copy-forgery-inhibited pattern image information as a background. A second process of generating electronic watermark copy-forgery-inhibited pattern image insertion original image information indicating an original image obtained by combining and inserting the digital watermark copy-forgery-inhibited pattern image including the hidden character in the background;
The electronic watermark copy-forgery-inhibited pattern image insertion original image information generated by the second processing is output to a printer, and the original image in which the digital watermark copy-forgery-inhibited pattern image including the hidden characters is inserted in the background is output. Watermark embedding method. The digital watermark embedding method according to claim 2,
The predetermined region is a region extending in a predetermined direction in the central region of the array,
The digital watermark embedding method, wherein the region having a shape different from the predetermined region is a region extending in a direction different from the predetermined direction in the central region of the array. The digital watermark embedding method according to claim 2,
The predetermined region is a region shifted from the central region of the array in a predetermined direction,
The digital watermark embedding method, wherein the region having a shape different from the predetermined region is a region shifted from a central region of the array in a direction different from the predetermined direction. In a digital watermark detection method for detecting a digital watermark from an image in which a digital watermark copy-forgery-inhibited pattern image including a hidden character is inserted in the background,
A first process of extracting a region consisting of a remaining digital watermark pattern constituting the copy-forgery-inhibited pattern image from an image in which a digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background;
A second process for determining individual digital watermark remaining patterns constituting the area from the area extracted by the first process;
A third watermark for detecting whether the digital watermark bit information is 0 or 1 based on the arrangement of dots arranged in the digital watermark remaining pattern for each digital watermark remaining pattern determined by the second process And a digital watermark detection method. The digital watermark detection method according to claim 5, wherein
When the bit information representing the digital watermark bit information is 0, the digital watermark remaining pattern has at least one or more pixels located in a predetermined region of the array in an array size composed of at least one or more pixels. When the digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution and the bit information representing the digital watermark bit information is 1, the digital watermark is composed of at least one pixel. The remaining digital watermark pattern is configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution in at least one pixel located in an area having a shape different from the predetermined area And a digital watermark detection method. The digital watermark detection method according to claim 6.
The predetermined region is a region extending in a predetermined direction in the central region of the array,
The region having a shape different from the predetermined region is a region extending in a direction different from the predetermined direction in the central region of the array. The digital watermark detection method according to claim 6.
The predetermined region is a region shifted from the central region of the array in a predetermined direction,
The region having a shape different from the predetermined region is a region shifted from a central region of the array in a direction different from the predetermined direction. In a tint block image embedding device that inserts a tint block into the background of an image,
An erasure pattern that designates an erasure pattern that is composed of at least one pixel and that is configured by arranging dots in at least one or more predetermined pixels of the pixel with a size that cannot be detected at a resolution lower than a predetermined resolution. Information and
A remaining pattern that is configured by at least one pixel and that specifies a remaining pattern in which dots are arranged in a size that can be detected even at a resolution lower than a predetermined resolution on at least one predetermined pixel among the pixels. Information and
The hidden character information specifying the area to be printed by the erase pattern specified by the erase pattern information and the remaining pattern specified by the remaining pattern information according to a desired hidden character is combined to include the hidden character A tint block image generating means for generating tint block image information representing the tint block image;
The copy-forgery-inhibited pattern image information generated by the copy-forgery-inhibited pattern image generation unit and the original image information representing the original image to be printed using the copy-forgery-inhibited pattern image including the hidden characters represented by the copy-forgery-inhibited pattern image information as a background are synthesized, Image compositing means for generating copy-forgery-inhibited pattern image insertion original image information indicating the original image into which the copy-forgery-inhibited pattern image including the hidden character is inserted, and
A copy-forgery-inhibited pattern image embedding device, wherein the copy-forgery-inhibited pattern image insertion original image information generated by the image synthesizing unit is output to a printer, and the original image in which the copy-forgery-inhibited pattern image including the hidden characters is inserted into the background is output. In a tint block image embedding device that inserts a tint block with a digital watermark in the background of an image,
An erasure pattern that designates an erasure pattern that is composed of at least one pixel and that is configured by arranging dots in at least one or more predetermined pixels of the pixel with a size that cannot be detected at a resolution lower than a predetermined resolution. Information and
When bit information representing digital watermark bit information is 0, at least one pixel located in a predetermined region of the array has a resolution equal to or lower than a predetermined resolution in an array size composed of at least one pixel However, when a digital watermark remaining pattern configured by arranging dots in a detectable size is specified and the bit information representing the digital watermark bit information is 1, the array size configured by the at least one or more pixels is included. A digital watermark that designates a digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution on at least one pixel located in an area having a shape different from the predetermined area The remaining pattern information,
Combining the erased pattern specified by the erased pattern information according to the desired hidden character and the hidden character information specifying the area to be printed by the digital watermark remaining pattern specified by the digital watermark remaining pattern information, and Digital watermark copy-forgery-inhibited pattern image generating means for generating digital watermark copy-forgery-inhibited pattern image information representing a digital watermark copy-forgery-inhibited pattern image including hidden characters;
Original image information representing an original image to be printed with the digital watermark copy-forgery-inhibited pattern image information generated by the digital watermark copy-forgery-inhibited pattern image generation means and the digital watermark copy-forgery-inhibited pattern image including the hidden character represented by the digital watermark copy-forgery-inhibited pattern image information as a background. Digital watermark image synthesis means for generating digital watermark copy-forgery-inhibited pattern image insertion original image information indicating an original image in which the digital watermark copy-forgery-inhibited pattern image including the hidden character is inserted in the background, and
The digital watermark copy-forgery-inhibited pattern image insertion original image information generated by the digital watermark image synthesis unit is output to a printer, and the original image in which the digital watermark copy-forgery-inhibited pattern image including the hidden characters is inserted in the background is output. Digital watermark embedding device. The digital watermark embedding apparatus according to claim 10.
The predetermined region is a region extending in a predetermined direction in the central region of the array,
The region having a shape different from the predetermined region is a region extending in a direction different from the predetermined direction in the central region of the array. The digital watermark embedding apparatus according to claim 10.
The predetermined region is a region shifted from the central region of the array in a predetermined direction,
The area having a shape different from the predetermined area is an area shifted from a central area of the array in a direction different from the predetermined direction. In a digital watermark detection apparatus for detecting a digital watermark from an image inserted in the background with a digital watermark copy-forgery-inhibited pattern image including hidden characters,
Extraction means for extracting an area consisting of a remaining digital watermark pattern constituting the copy-forgery-inhibited pattern image from an image in which a digital watermark copy-forgery-inhibited pattern image including hidden characters is inserted in the background;
Confirming means for confirming individual digital watermark remaining patterns constituting the area from the area extracted by the extracting means;
Detecting means for detecting whether the digital watermark bit information is 0 or 1 based on the arrangement of dots arranged in the digital watermark remaining pattern for each digital watermark remaining pattern determined by the determination means An electronic watermark detection apparatus characterized by the above. The digital watermark detection apparatus according to claim 13.
When the bit information representing the digital watermark bit information is 0, the digital watermark remaining pattern has at least one or more pixels located in a predetermined region of the array in an array size composed of at least one or more pixels. When the digital watermark remaining pattern configured by arranging dots in a size that can be detected even at a resolution equal to or lower than a predetermined resolution and the bit information representing the digital watermark bit information is 1, the digital watermark is composed of at least one pixel. The remaining digital watermark pattern is configured by arranging dots in a size that can be detected even at a resolution equal to or lower than the predetermined resolution in at least one pixel located in an area having a shape different from the predetermined area And a digital watermark detection apparatus. The digital watermark detection apparatus according to claim 14,
The predetermined region is a region extending in a predetermined direction in the central region of the array,
An area having a shape different from the predetermined area is an area extending in a direction different from the predetermined direction in the central area of the array. The digital watermark detection apparatus according to claim 14,
The predetermined region is a region shifted from the central region of the array in a predetermined direction,
An area having a shape different from that of the predetermined area is an area shifted from a central area of the array in a direction different from the predetermined direction.   A program for causing a computer to execute the tint block image embedding method according to claim 1.   The program for making a computer perform the electronic watermark embedding method of any one of Claim 2, 3 or 4.   A program for causing a computer to execute the electronic watermark detection method according to any one of claims 5, 6, 7 and 8.   A program for causing a computer to function as the tint block image embedding device according to claim 9.   A program for causing a computer to function as the digital watermark embedding device according to claim 10.   The program for functioning a computer as a digital watermark detection apparatus of any one of Claim 13, 14, 15, or 16.   A computer-readable recording medium in which the program according to any one of claims 17, 18, 19, 20, 21, or 22 is recorded.