JP5585915B2 - Printed material capable of authenticating authenticity and authentication method of the printed material - Google Patents

Description

  The present invention relates to a printed matter capable of authenticating authenticity for precious printed matter such as banknotes, stock certificates, securities such as bonds, various certificates and important documents, and an authentication method for the printed matter.

  Countermeasures against counterfeiting and alteration are important elements in printed matters such as banknotes, stock certificates, securities such as bonds, various certificates and important documents. There are two methods for preventing counterfeiting and alteration of printed materials: a method of using a design with a lot of geometric patterns in the design, and a method of embedding invisible information in the printed material by some means and reading the invisible information by some means.

  A typical example of the former is one that uses a geometric pattern such as a background pattern, a colored pattern, or a relief pattern that is widely used in the design of securities prints, etc., but forgery or alteration using the geometric pattern. As a preventive measure, there is one in which a pattern is constituted by a set of curved lines having a basically fixed line width as shown in FIG. In domestic banknote manufacturing factories, it is called the “Saimon pattern” and in overseas banknote manufacturing factories, it is also called Guilloche. Such a pattern of line expression is excellent in counterfeiting and has been used with the intention of preventing counterfeiting on banknotes and the like since the 19th century.

  On the other hand, as shown in FIG. 1B, there is a geometric pattern constituted by a set of solid portions in which a printed image line forms a certain area. In domestic banknote factories, when it is formed by an intaglio printing method, it is sometimes called a white pattern.

  These patterns take into account design such as the design of printed matter, and use colors that are difficult to be extracted by a photoengraving device or reproduced by a copying machine, or have a complicated image line configuration for scanning input / output of a copying machine and a scanner. Although the role of anti-counterfeiting has been heightened by generating moire, recently there has been a drawback that the anti-counterfeiting and anti-counterfeiting effect has not been brought about due to the advent of highly functional photoengraving devices or copiers. is there.

  In addition, as shown in FIG. 1C, when formed by the offset printing method, it may be called a grid pattern. The pattern as shown in FIG. 1 (c) is also called a shimultan pattern at overseas banknote factories, and such a surface expression pattern started in the 20th century when offset printing was developed.

  The purpose of preventing the counterfeiting of the pattern shown in FIG. 1C is that the respective contours of a plurality of graphic areas are printed at a constant distance of several hundred μm, and the plurality of graphic areas are different colors. Is being printed by. That is, since the same pattern cannot be expressed unless it has high printing accuracy, it has been considered that there is an anti-duplication effect. However, today, plate making / printing methods having high accuracy such as CTP have been developed, and the effect as a forgery prevention measure applying high printing accuracy has already been lost.

  Therefore, as a solution for such a problem, a machine reading inspection method that can process a large amount and at high speed in authenticity determination is widely adopted. Today's machine-reading inspection methods for printed materials include tributaries such as functional inks such as magnetic ink, infrared reflection absorption ink, and fluorescent ink, and detection of materials such as fibers, materials, and chemicals that form printing media. However, these technologies are caused by specific electromagnetic waves that cannot be detected by humans. Many of these technologies depend on the suitability of materials for producing printed matter, and are only applied to products that are economical in terms of production cost. I can't.

  Further, as a method that does not particularly take into consideration the production cost of the printed matter, there is an optical reading method for a pattern on the printed matter to which a printing material such as visible visible ink can be applied. OCR, OMR, bar code, two-dimensional code, etc. are known as relatively easy optical reading methods, but the figures used in these optical reading methods have no design and are used for existing products. If the design, specification changes are required.

  These optical reading methods are also widely available in the market, and since the codes can be seen as printed lines, there is a risk of decoding and tampering. It is enough.

  Furthermore, there is a series of techniques generally called electronic watermarks as a method for providing reading information without changing the design such as the design by the optical reading method. An electronic watermark is also called a concealed image or a digital watermark, and is a technique for embedding copyright information in a document file or a printed material of a copy function or a DTP technique with advanced functions. As a well-known representative technique for printed materials, there is a method called frequency utilization type.

  Electronic watermarks are said to have little deterioration in frequency characteristics even in duplicates. Recently, digital watermarks are often applied to digital images distributed on the Internet for the purpose of copyright protection. In addition, since it has an effect on printed matter, it is often used for posters.

  It is a continuous gradation (photographic gradation) pattern that an electronic watermark can exert the most effect. Since the continuous tone (photo gradation) pattern is multi-valued image data, there is sufficient redundancy, so not only the frequency-based type but also the pixel replacement type, the pixel space usage type, the quantization error diffusion type, etc. A method is proposed, and there are many literatures and patent applications.

  However, a set of curved lines such as a background pattern, a stencil pattern, and a relief pattern used for securities is basically a binary image, so there is little redundancy and it is difficult to embed an electronic watermark. The problem is that reading accuracy is low due to weak reading signals.

  Therefore, the present inventors have described "a printed matter and a discrimination method capable of determining authenticity and a method for embedding information in the printed matter" (Patent Document 1), "a printed matter and a discrimination method capable of determining authenticity, and the printed matter." According to the “embedding method of information” (patent document 2) and “printed material and authentication method of the printed material” (patent document 3), a print image line composed of a free curve group such as a background pattern and a colored pattern is mechanically generated. There has already been filed a printed matter characterized by identification. However, since these inventions are techniques applied only to the chromatic pattern by the line representation shown in FIG. 1 (a), the so-called white chromatic pattern in FIG. It cannot be applied to the pattern of surface expression as shown in Sasame Saimon pattern.

Japanese Patent Application No. 2001-1519 Japanese Patent Application No. 2002-50606 Japanese Patent Application No. 2005-096758

  The present invention has been made in view of the above points, and in a printed matter having artistic properties such as securities composed of securities line drawings and the like, by modulating the line images for securities at a level that humans cannot visually recognize. The purpose is to embed information without losing its artistic effect. In addition, in order to strengthen the signal of information used in the conventional information embedding and reading technology, the solid line processing in which the printed image line forms a fixed area is subjected to line processing that forms an equidistant pitch. To achieve.

  The printed matter capable of authenticating authenticity of the present invention comprises an image having an arbitrary shape on a substrate, the image has a plurality of regions, and the plurality of regions are formed by lines including a curve, The line including the curve has an image line selected from an image line width of 30 μm to 80 μm and a non-image line selected from a non-image line width of 30 μm to 80 μm alternately arranged, A relationship between the selected image line width and the selected non-image line width is formed in a range of 2: 1 to 1: 2, and the plurality of areas are, for each area, the selected image line width and the selected image line width. The selected non-image line width is the same, and the area formed by the lines including the curve is visually recognized at a constant density, and the frequency analysis is performed on the area formed by the lines including the curve. In this case, a predetermined frequency component is extracted.

  The printed matter capable of authenticating authenticity of the present invention comprises an image having an arbitrary shape on a substrate, the image has a plurality of regions, and the plurality of regions are formed by lines including a curve, The line including the curve has an image line selected from an image line width of 30 μm to 80 μm and a non-image line selected from a non-image line width of 30 μm to 80 μm alternately arranged, A relationship between the selected image line width and the selected non-image line width is formed in a range of 2: 1 to 1: 2, and at least one of the plurality of areas includes the selected image line width and the selected image line width Both of the selected non-image line widths are different from the selected image line width and the selected non-image line widths of other regions, and the plurality of regions have image lines per unit area for each of the regions. The area formed by the lines with almost the same area ratio and including the curve is visually recognized at a constant density. Characterized in that the predetermined frequency components when frequency analysis on regions formed with parallel line containing the curve is extracted.

  The line including the curved line of the printed matter capable of authenticating authenticity according to the present invention is a concentric circle or a curved line obtained by extracting a part of the concentric circle.

  The image of the printed matter capable of authenticating authenticity according to the present invention is a dummy composed of a solid print formed at a density equal to the density of a region formed by a line including the curve that is visually recognized by the naked eye. A region is further provided.

  The image of the printed matter capable of authenticating authenticity according to the present invention is characterized by further including a chromatic pattern line.

  An authentication method for a printed matter capable of authenticating authenticity according to the present invention, wherein a processor unit acquires image data including a region formed by lines including the curve, and an image processing unit performs frequency analysis on the image data. And generating a frequency component and authenticating the printed matter capable of authenticating the authenticity by comparing and collating the frequency component with a predetermined frequency component by a determination unit.

  According to the present invention having the above-described configuration, information embedded in a digital device such as a scanner or a copying machine can be detected by a digital device such as a scanner or a copying machine, but the Fourier transform or specific frequency can be detected on the digital device. The embedded information can be analyzed by performing operations such as extraction and inverse Fourier transform.

  In addition, since the image line used in the present invention cannot recognize the information with human vision even in single color printing, the artistic effect of the print image line is not reduced.

  In addition, compared to the technique for embedding and reading invisible information described in the prior art, the signal strength of the information becomes very large because a highly regular segmentation process is given to a highly regular image line. Easy to read.

  Because of these effects, the present invention activates actions such as reading invisible information given to banknotes, securities, various certificates, important documents, etc. with a digital device and stopping the operation of the digital device based on that information. It is effective to make it.

It is the figure which showed the example of the line drawing for securities used for securities, bills, etc. It is explanatory drawing which showed the FFT pattern obtained by inputting the image of the printed matter which has three figure area | regions with an optical scanner, and also Fourier-transforming. FIG. 4 is an explanatory diagram showing one intensity peak in an FFT pattern obtained by inputting an image of a printed matter having three graphic regions with an optical scanner and further performing Fourier transform. It is explanatory drawing by which the two intensity peaks were shown by the FFT pattern obtained by inputting the image of the printed matter which has three figure area | regions with an optical scanner, and also Fourier-transforming. It is explanatory drawing by which the three intensity peaks were shown by the FFT pattern obtained by inputting the image of the printed matter which has three figure area | regions with an optical scanner, and also Fourier-transforming. FIG. 5 is an explanatory diagram in which one intensity peak is shown by an FFT pattern obtained by inputting an image of a printed matter having three ring-shaped graphic regions with an optical scanner and further performing Fourier transform. It is explanatory drawing by which the two intensity peaks were shown by the FFT pattern obtained by inputting the image of the printed matter which has three ring-shaped figure areas with an optical scanner, and also Fourier-transforming. It is explanatory drawing by which the three intensity peaks were shown with the FFT pattern obtained by inputting the image of the printed matter which has three ring-shaped figure area | regions with an optical scanner, and also Fourier-transforming. It is a pattern block diagram which has one type of figure area group among several figure areas. FIG. 6 is an explanatory diagram showing one intensity peak in an FFT pattern obtained by inputting an image of a printed matter having a plurality of graphic regions with an optical scanner and further performing Fourier transform. It is a pattern block diagram which has two types of graphic area groups among several graphic areas. It is explanatory drawing by which the two intensity peaks were shown by the FFT pattern obtained by inputting the image of the printed matter which has a some figure area | region with an optical scanner, and also Fourier-transforming. It is a pattern block diagram which has three types of graphic area groups among several graphic areas. It is explanatory drawing by which the three intensity peaks were shown with the FFT pattern obtained by inputting the image of the printed matter which has a some figure area | region with an optical scanner, and also Fourier-transforming. It is explanatory drawing by which the three intensity peaks were shown by the FFT pattern obtained by inputting the image of the printed matter which has three types of graphic areas which consist of texts, such as a character and a number, with an optical scanner, and also Fourier-transforming it. . It is explanatory drawing shown by the drawing method of the line group comprised by the straight line and curve which have the same drawing line width based on the line which comprises a pentagon. Three intensity peaks appear in the FFT pattern obtained by inputting an image with an optical scanner for a printed matter having three types of graphic regions composed of straight lines and curves forming an arithmetic sequence in an arbitrary graphic region, and further performing Fourier transform. It is shown explanatory drawing. It is a figure which shows the authentication method of the printed matter which can authenticate authenticity. It is a figure which shows the example which gave the chromatic pattern to the image of the printed matter which can authenticate authenticity.

  Embodiments of the present invention will be described below in detail with reference to the drawings based on examples. The line drawing for securities used for securities, banknotes, etc. is composed of a plurality of lines made of curves or straight lines as shown in FIG. In the present invention, an image line that constitutes such a line drawing for securities is referred to as a fine line.

  In addition, as for the pattern of line expression shown in FIG. 1 (a), it is possible to mechanically identify the fine line by the prior art, but it is shown in FIG. 1 (b) or FIG. 1 (c). It was not possible to mechanically recognize the surface expression pattern. Therefore, a fine line was applied to provide a desired spatial frequency in the surface expression pattern. The principle will be described with a simple graphic example.

  For example, the pattern shown in FIG. 2A is a 1024 × image in which three graphic areas 1a, 1b, and 1c printed on the printed matter 1 with the same printing color are input with an optical scanner at a resolution of 1200 dpi. It is an 8-bit grayscale image consisting of 1024 pixels. FIG. 2B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. In addition, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is overlaid on the fourth quadrant of the FFT pattern in FIG. In the pattern configuration shown in FIG. 2, there is no significant feature in the spatial frequency.

  The pattern shown in FIG. 3A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The graphic region 1a on the printed material 1 is arranged with concentric circles having 50 μm width lines having a distance d1 of 100 μm. Since the concentric circles forming the graphic region 1a are thin lines, the visual density is uniform. It seems to keep the surface. Furthermore, the graphic area 1b and the graphic area 1c are printed in the same print color as the graphic area 1a. FIG. 3B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. As in FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. As shown in the frequency intensity graph of FIG. 3B, the inverse spatial distance q1 of the intensity peak can be seen. This is because the interval d1 appears on the inverse space. Regarding the inverse spatial distance of the intensity peak on the FFT pattern, when various parameters related to image input, that is, when the graphic area 1a on the printed matter 1 is 50 μm wide and the interval d1 of 100 μm is the actual spatial distance, If the number of pixels on one side and the resolution of the image are known, it can be easily calculated by equation (1).

  As shown in the calculation of Formula 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles provided in the graphic region 1a shown in FIG. 3A is shown in FIG. As shown, it appears 217 pixels from the center of the FFT pattern.

  The pattern shown in FIG. 4A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The graphic area 1a on the printed material 1 is arranged with concentric circles having a 50 μm wide image line having a distance d1 of 100 μm, and the graphic area 1b is having a 57 μm wide image line having a concentric circle line having a distance d2 of 113 μm. The concentric circles that are arranged and constitute the graphic region 1a and the graphic region 1b are thin lines, so that they appear to have a uniform density by visual observation. Furthermore, the graphic area 1c is printed in the same print color as the graphic area 1a and the graphic area 1b. FIG. 4B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern of FIG. 4B. As shown in the frequency intensity graph of FIG. 4B, the inverse spatial distance q1 and the inverse spatial distance q2 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles in the graphic region 1a shown in FIG. 4A is shown in FIG. 4B. As shown, it appears 217 pixels from the center of the FFT pattern. Further, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the lines of the concentric circles provided in the graphic region 1b shown in FIG. 4A is an FFT pattern as shown in FIG. 4B. It appears at a position of 192 pixels from the center of.

  The pattern shown in FIG. 5A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The graphic area 1a on the printed material 1 is arranged with concentric circles having a 50 μm wide image line having a distance d1 of 100 μm, and the graphic area 1b is having a 57 μm wide image line having a concentric circle line having a distance d2 of 113 μm. The graphic area 1c is arranged as a concentric circle having 65 μm wide lines having a spacing d3 of 130 μm, and the concentric circles constituting the graphic area 1a, the graphic area 1b and the graphic area 1c are thin lines. Therefore, it looks like a surface maintaining a uniform density by visual inspection. FIG. 5B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. As shown in the frequency intensity graph of FIG. 5B, the inverse spatial distance q1, the inverse spatial distance q2, and the inverse spatial distance q3 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles provided in the graphic region 1a shown in FIG. 5A is shown in FIG. As shown, it appears 217 pixels from the center of the FFT pattern. Further, the inverse spatial distance q2 of the intensity peak caused by the space d2 between the lines of the concentric circles provided in the graphic region 1b shown in FIG. 5A is an FFT pattern as shown in FIG. 5B. It appears at a position of 192 pixels from the center of. Further, the inverse spatial distance q3 of the intensity peak caused by the interval d3 between the drawing lines of the concentric circles provided in the graphic region 1c shown in FIG. 5A is an FFT pattern as shown in FIG. 5C. It appears at a position of 167 pixels from the center of.

  As described above, by including concentric circles in an arbitrary graphic area, the spatial frequency characteristics of the concentric circles are shown as intensity peaks in the FFT pattern. Note that the position of the intensity peak varies depending on the interval between the drawing lines of the concentric circles. The difference in pattern can be identified by the difference in the position of the intensity peak in this FFT pattern. The print colors used for the graphic region group 1a, the graphic region group 1b, and the graphic region group 1c may be the same color or may be different from each other. Further, the printing color is not limited at all. Furthermore, the number of graphic area groups is not limited at all.

  For example, the pattern shown in FIG. 6A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The printed product 1 has three circular graphic areas, and the central graphic area 1a is arranged by concentric circles having 50 μm-wide image lines having a distance d1 of 100 μm to form the graphic area 1a. Since the concentric circles are thin lines, they appear to have a uniform density by visual inspection. Similarly, in the ring-shaped graphic region 1b and graphic region 1c, 50 μm-wide image lines are arranged as concentric circles having a distance d1 of 100 μm, and the concentric circles constituting the graphic region 1a are thin lines. Then it looks like a surface with a uniform density. FIG. 6B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. As in FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. 6B. As shown in the frequency intensity graph of FIG. 6B, the inverse spatial distance q1 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles in the graphic area 1a shown in FIG. 6A is shown in FIG. 6B. As shown, it appears 217 pixels from the center of the FFT pattern.

  The pattern shown in FIG. 7A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The printed product 1 has three circular graphic areas, and the central graphic area 1a is arranged by concentric circles having 50 μm-wide image lines having a distance d1 of 100 μm to form the graphic area 1a. Since the concentric circles are thin lines, they appear to have a uniform density by visual inspection. On the other hand, in the ring-shaped graphic region 1b and graphic region 1c, 57 μm-wide image lines are arranged as concentric circles having a distance d2 of 113 μm, and the concentric circles constituting the graphic region 1b and graphic region 1c are finely drawn. Since it is a line, it can be visually observed as a surface with a uniform density. FIG. 7B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. As in FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. 7B. As shown in the frequency intensity graph of FIG. 7B, the inverse spatial distance q1 and the inverse spatial distance q2 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles provided in the graphic region 1a shown in FIG. 7A is shown in FIG. 7B. As shown, it appears 217 pixels from the center of the FFT pattern. Furthermore, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the lines of the concentric circles provided in the graphic region 1b shown in FIG. 7A is an FFT pattern as shown in FIG. 7B. It appears at a position of 192 pixels from the center of.

  The pattern shown in FIG. 8A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The printed material 1 has three circular graphic areas, and the central graphic area 1a is arranged by concentric circles having 50 μm-wide image lines having a distance d1 of 100 μm, and a ring-shaped graphic area 1b. Is arranged with concentric circles having a width of 57 μm and an interval d2 of 113 μm, and the ring-shaped graphic area 1c is arranged with a concentric circle of lines having a width of 65 μm and an interval d3 of 130 μm. The concentric circles constituting 1a, the graphic area 1b, and the graphic area 1c are thin lines, so that they can be visually observed as surfaces having a uniform density. FIG. 8B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. As in FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. 8B. As shown in the frequency intensity graph of FIG. 8B, the inverse spatial distance q1, the inverse spatial distance q2, and the inverse spatial distance q3 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the lines of the concentric circles provided in the graphic region 1a shown in FIG. 8A is shown in FIG. 8B. As shown, it appears 217 pixels from the center of the FFT pattern. Further, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the drawing lines of the concentric circles provided in the graphic region 1b shown in FIG. 8A is the center of the FFT pattern as shown in FIG. 8B. To 192 pixels. Further, the inverse spatial distance q3 of the intensity peak caused by the interval d3 between the drawing lines of the concentric circles provided in the graphic region 1c shown in FIG. 8A is an FFT pattern as shown in FIG. 8C. It appears at a position of 167 pixels from the center of.

  As described above, by including concentric circles in an arbitrary graphic area, the spatial frequency characteristics of the concentric circles are shown as intensity peaks in the FFT pattern. Note that the position of the intensity peak varies depending on the interval between the drawing lines of the concentric circles. The difference in pattern can be identified by the difference in the position of the intensity peak in this FFT pattern. The print colors used for the graphic region group 1a, the graphic region group 1b, and the graphic region group 1c may be the same color or may be different from each other. Further, the printing color is not limited at all. Furthermore, the number of graphic area groups is not limited at all.

  The present invention has a plurality of fine lines having regularity in the graphic area of the surface expression, so that it can be identified in a high-resolution input image by a digital device such as a scanner or a copying machine, but it is visually recognized by humans. By assigning difficult fine and regular parts, analyzing the correlation of the intervals of line drawings for digital securities on the obtained printed matter, and identifying the information embedded in the printed matter, it is possible to determine authenticity It is possible to perform actions such as stopping the operation of a digital device such as a copying machine used for counterfeiting based on the information.

(1) Embodiment 1
The first embodiment is an example in which an effect is obtained even if a graphic region including concentric circles has an arbitrary region shape and arrangement. The first embodiment will be described in detail with reference to the drawings.

  As described above, the pattern shown in FIG. 1B is an example of a pattern composed of surface representations, and is composed of a geometric pattern composed of a set of solid portions in which a printed image line forms a certain area, and is a white pattern pattern. Sometimes called. In addition, the pattern shown in FIG. 1C is an example of a pattern composed of a surface expression, which is also called a sash pattern or shimultan pattern. It is. For example, as shown in the pattern configuration diagram having a plurality of graphic areas in FIG. 9, the graphic area group 2a includes all of the patterns shown in FIG. FIG. 10A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the printed material 1 having the pattern configuration shown in FIG. 9 with an optical scanner at a resolution of 1200 dpi. The graphic area group 2a arranged in a grid pattern on the printed material 1 is arranged by concentric circles having a 50 μm width image line having a distance d1 of 100 μm, and the concentric circle lines constituting the graphic area group 2a are thin line images. Because of this, it looks visually as if it had a uniform density. Although the center of the concentric circle is the center of the entire pattern shown in FIG. 10A, the effect of the present invention is not hindered wherever the center of the concentric circle is.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the drawing lines of the concentric circles provided in the graphic region group 2a shown in FIG. 10A is shown in FIG. As shown in FIG. 5, the pixel appears at a position of 217 pixels from the center of the FFT pattern.

  The pattern configuration diagram of FIG. 11 includes two types of graphic area groups including a graphic area group 2a and a graphic area group 2b in the pattern shown in FIG. FIG. 12A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the printed material 1 having the pattern configuration shown in FIG. 11 with a resolution of 1200 dpi by an optical scanner. The graphic area group 2a arranged in a grid pattern on the printed matter 1 is arranged by concentric circles having 50 μm wide image lines having a distance d1 of 100 μm, and the graphic area group 2a arranged in a grid pattern is 57 μm wide. Are arranged in concentric circles having an interval d2 of 113 μm, and the concentric circles constituting the graphic region group 2a and the graphic region group 2b are thin image lines. . Although the center of the concentric circle is the center of the entire pattern shown in FIG. 12A, the effect of the present invention is not hindered wherever the center of the concentric circle is. FIG. 12B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern of FIG. As shown in the frequency intensity graph of FIG. 12B, the inverse spatial distance q1 and the inverse spatial distance q2 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the drawing lines of the concentric circles included in the graphic region group 2a shown in FIG. 12A is shown in FIG. As shown in FIG. 5, the pixel appears at a position of 217 pixels from the center of the FFT pattern. Further, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the lines of the concentric circles provided in the graphic region group 2b shown in FIG. 12A is an FFT as shown in FIG. 12B. It appears at a position of 192 pixels from the center of the pattern.

  The pattern configuration diagram of FIG. 13 includes three types of graphic area groups including a graphic area group 3a, a graphic area group 3b, and a graphic area group 3c in the pattern shown in FIG. FIG. 14A is an 8-bit grayscale image composed of 1024 × 1024 pixels in which the printed material 1 having the pattern configuration shown in FIG. 13 is input by the optical scanner with a resolution of 1200 dpi. The graphic area group 3a arranged in a grid pattern on the printed matter 1 is arranged with concentric circles having 50 μm-width image lines having a distance d1 of 100 μm, and the graphic area group 3b has image lines having a width of 57 μm and an interval of 113 μm. The graphic region group 3c is arranged with concentric circles having a width of 65 μm and an interval d3 of 130 μm, and the graphic region group 3a, the graphic region group 3b, and the graphic region group 3c are arranged. Since the concentric circles that make up are thin lines, they appear to be a surface with a uniform density by visual inspection. FIG. 14B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed and displayed in the fourth quadrant of the FFT pattern of FIG. As shown in the frequency intensity graph of FIG. 14B, the inverse spatial distance q1, the inverse spatial distance q2, and the inverse spatial distance q3 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the drawing lines of the concentric circles included in the graphic region group 3a shown in FIG. 14A is shown in FIG. As shown in FIG. 5, the pixel appears at a position of 217 pixels from the center of the FFT pattern. Furthermore, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the lines of the concentric circles provided in the graphic region group 3b shown in FIG. 14A is the FFT as shown in FIG. 14B. It appears at a position of 192 pixels from the center of the pattern. Further, the inverse spatial distance q3 of the intensity peak caused by the interval d3 between the lines of the concentric circles provided in the graphic region group 3c shown in FIG. 14A is the FFT as shown in FIG. 14B. It appears at a position of 167 pixels from the center of the pattern.

  As described above, by including concentric circles in an arbitrary graphic area, the spatial frequency characteristics of the concentric circles are shown as intensity peaks in the FFT pattern. Note that the position of the intensity peak varies depending on the interval between the drawing lines of the concentric circles. The difference in pattern can be identified by the difference in the position of the intensity peak in this FFT pattern. The print colors used for the graphic area group 3a, the graphic area group 3b, and the graphic area group 3c may be the same color or may be different from each other. Further, the printing color is not limited at all.

(2) Embodiment 2
The second embodiment is an example in which the effect is exhibited even if the graphic region including the concentric circles is a character. The second embodiment will be described in detail with reference to the drawings.

  The pattern configuration diagram of FIG. 15 includes three types of graphic area groups including a graphic area group 3a, a graphic area group 3b, and a graphic area group 3c representing text such as letters and numbers. FIG. 15A is an 8-bit grayscale image composed of 1024 × 1024 pixels in which the printed material 1 having the pattern configuration shown in FIG. 15 is input by the optical scanner with a resolution of 1200 dpi. A graphic region group 3a composed of English letters “A” and numbers “1” on the printed matter 1 is arranged with concentric lines consisting of 50 μm wide image lines having a distance d1 of 100 μm. The graphic area group 3b consisting of the numeral “2” is arranged in a concentric circle consisting of 57 μm-wide image lines having a spacing d2 of 113 μm, and the graphic area consisting of the English letter “C” and the numeral “3” on the printed matter 1. In the group 3c, 65 μm wide lines are arranged in concentric circles having an interval d3 of 130 μm, and the concentric circles constituting the graphic area group 3a, the graphic area group 3b, and the graphic area group 3c are thin lines. Visually it looks like a surface with a uniform density. FIG. 15B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern in FIG. As shown in the frequency intensity graph of FIG. 15B, the inverse spatial distance q1, the inverse spatial distance q2, and the inverse spatial distance q3 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse spatial distance q1 of the intensity peak caused by the interval d1 between the drawing lines of the concentric circles provided in the graphic region group 3a shown in FIG. 15A is shown in FIG. As shown in FIG. 5, the pixel appears at a position of 217 pixels from the center of the FFT pattern. Further, the inverse spatial distance q2 of the intensity peak caused by the interval d2 between the lines of the concentric circles provided in the graphic region group 3b shown in FIG. 15A is an FFT as shown in FIG. 15B. It appears at a position of 192 pixels from the center of the pattern. Further, the inverse spatial distance q3 of the intensity peak caused by the interval d3 between the lines of the concentric circles included in the graphic region group 3c shown in FIG. 15A is the FFT as shown in FIG. 15B. It appears at a position of 167 pixels from the center of the pattern.

  Thus, by including concentric circles in the graphic area representing text such as letters and numbers, the characteristics of the spatial frequency of the concentric circles are shown as intensity peaks in the FFT pattern. Note that the position of the intensity peak varies depending on the interval between the drawing lines of the concentric circles. The difference in pattern can be identified by the difference in the position of the intensity peak in this FFT pattern. The print colors used for the graphic area group 3a, the graphic area group 3b, and the graphic area group 3c may be the same color or may be different from each other. Further, the printing color is not limited at all. Furthermore, the number of graphic area groups is not limited at all.

(3) Embodiment 3
FIG. 16A shows, for example, a line (hereinafter referred to as α) composed of straight lines and curves that form an arithmetic sequence around the pentagon and have the same line width as the pentagon, based on the line that forms the pentagon. It shows how to draw groups). First, in the line drawing constituting the anti-counterfeit pattern of the present invention, the α line formed around the pentagon shown in FIG. 16 is a line drawing by quantitative continuous expansion, that is, the outer circumference of the pentagonal line segment is circled using a circle R having a radius r. When the circle R is circulated in a state where the outer periphery of each pentagonal line segment and the outer periphery of the circle R are in contact with each other, the center of the circle R is obtained at a position equal to the locus drawn. Accordingly, the distance d between the line segments α1, α2, and α3 outward from the pentagon is equal to the locus drawn by the center of the circle R having the radius r. Therefore, by sequentially increasing α rays, an α ray group composed of straight lines and curves forming an outward progression from the triangle group is formed, and if the α rays are continuously drawn in the outward direction, the outermost side The α line located at approximates a perfect circle.

  FIG. 16B shows a pattern created according to the drawing method of the α ray group when the radius r of the circle R is set to r = 130 μm. As can be seen from the created pattern, a straight line drawing and a curved line drawing that form an equidistant sequence by a locus drawn by a center line of a circle R having a radius r = 130 μm that is in contact with a pentagon formed by ten vertices P1 to P10. Lines are united and patterned.

  The pattern shown in FIG. 17A is an 8-bit grayscale image composed of 1024 × 1024 pixels obtained by inputting the print 1 with an optical scanner at a resolution of 1200 dpi. The graphic region 4a on the printed material 1 is formed with an α line group composed of straight lines and curved lines that form an even number sequence consisting of an interval d1 of 100 μm with a 50 μm wide image line, and the graphic region 4b has a 57 μm wide image line. Α line group is formed which consists of a straight line and a curve forming an even number sequence consisting of an interval d2 of 113 μm, and the graphic region 4c is a straight line and a curve which forms an image line of 65 μm width and forming an equality sequence consisting of an interval d3 of 130 μm. Is formed, and the α line group composed of straight lines and curves constituting the graphic sequence 4a, the graphic area 4b, and the graphic area 4c is a thin line, so it has a uniform density visually. It seems to keep the surface. FIG. 17B is an FFT pattern obtained by Fourier transforming the pattern shown in FIG. Similarly to FIG. 2, in order to explain the feature of the spatial frequency in an easy-to-understand manner, a frequency intensity graph is superimposed on the fourth quadrant of the FFT pattern of FIG. As shown in the frequency intensity graph of FIG. 17B, the inverse spatial distance q1, the inverse spatial distance q2, and the inverse spatial distance q3 of the intensity peak can be seen.

  As shown in the calculation of Equation 1, the inverse of the intensity peak caused by the interval d1 between the lines of the α ray group composed of the straight lines and the curves forming the arithmetic progression provided in the graphic region 4a shown in FIG. The spatial distance q1 appears at a position of 217 pixels from the center of the FFT pattern as shown in FIG. Furthermore, the inverse spatial distance q2 of the intensity peak caused by the space d2 between the lines of the α ray group composed of the straight lines and the curves forming the arithmetic progression provided in the graphic region 4b shown in FIG. As shown in b), it appears at a position of 192 pixels from the center of the FFT pattern. Further, the inverse spatial distance q3 of the intensity peak caused by the space d3 between the lines of the α ray group composed of the straight lines and the curves forming the arithmetic progression provided in the graphic region 4c shown in FIG. As shown in c), it appears at a position of 167 pixels from the center of the FFT pattern.

  As described above, by including an α ray group composed of straight lines and curves forming an arithmetic progression in an arbitrary graphic region, the characteristics of the spatial frequency of the straight lines and curves are shown as intensity peaks in the FFT pattern. Note that the position of the intensity peak varies depending on the interval between the lines of the α-ray group composed of straight lines and curves forming an arithmetic progression. The difference in pattern can be identified by the difference in the position of the intensity peak in this FFT pattern. The print colors used for the graphic region group 4a, the graphic region group 4b, and the graphic region group 4c may be the same color or may be different from each other. Further, the printing color is not limited at all. Furthermore, the number of graphic area groups is not limited at all. In addition, the design of the graphic region group (pattern, image) is not particularly limited, such as letters, numbers, symbols, and patterns.

  The present invention is a technique for embedding invisible information or an image consisting of lines of a group of lines composed of concentric circles at regular intervals or straight and curved lines forming an arithmetic progression. On the other hand, since the image forming means for printing by today's digital copying machine is generally operated at 600 dpi or less, the image line structure shown in the present embodiment is a solid pattern in a copy form. End up. As a result, the information to be embedded can be made secret information, and the effect of preventing forgery is improved.

  In order for a figure region formed of a line including a curve to be visually recognized as a solid shape with the naked eye, an image line selected from an image line width of 30 μm to 80 μm and a non-image line width of 30 μm to 80 μm The non-image lines selected from the inside are alternately arranged, and the relationship between the selected image line width and the selected non-image line width needs to be formed in the range of 2: 1 to 1: 2. Being visually recognized by the naked eye means that the image line and the non-image line are difficult to distinguish, and the area formed by the image line and the non-image line is visually recognized at a constant density by the naked eye. Note that the standard of the image line width and the non-image line width is derived from the resolution in general human vision based on physiological knowledge. In the Landolt ring target used in the visual acuity test, the minimum readable threshold that is simply converted under certain conditions (distance 250 mm, visual acuity 1.0) is about 73 μm in slit width. That is, when the line width of 30 μm to 80 μm and the non-line width are 80 μm or more, each line is visible independently, and a region formed by lines including a curve is visually recognized with a solid shape. become unable. Moreover, there is a possibility that the counterfeiter may be duplicated by a highly functional digital imaging process or the like, and the anti-counterfeit effect is reduced. On the other hand, when the image line width and the non-image line width of 30 μm to 80 μm are 30 μm or less, there may be a problem in reproducibility in the offset printing method. That is, in the transfer of ink from the printing plate to the printing substrate, the expansion of the image line is unavoidable due to the physical flow characteristics caused by the printing pressure (also called dot gain in the printing industry). For example, when the expansion of the image line spreads by 10 μm around the image line, if the non-image line width is designed to be 20 μm, the image lines are naturally combined. This is because it is impossible to express concentric circles at regular intervals or straight lines and curves forming an arithmetic sequence. In addition, the relationship between the selected image line width and the selected non-image line width is 2: 1 to 1: 2, because the difference between the image line and the non-image line is clarified, and the frequency intensity at the spatial frequency. Is to increase

  Further, it is more effective if the image area ratio per unit area of each of the plurality of regions is substantially equal. In this case, “substantially equal” means that the relative area ratio per unit area of each region is in the range of 95% to 105%. The outline of the region may be formed by an image line. However, making the relative area ratio substantially equal is a measure to make it difficult to judge that information is given to the lines including the curves at first glance, and to improve the aesthetics. There is no effect on identifying the embedded information. Therefore, the relative area ratios of the plurality of regions do not necessarily have to be substantially equal. Further, the plurality of regions may have different print colors.

  With the above configuration, since the area formed by a line including a curve is visually recognized by the naked eye, it cannot be determined that information is added to the line including the curve at first glance. Excellent prevention effect. In addition, when a frequency analysis is performed on an area formed by lines including a curve, a predetermined frequency component is extracted, so that it is possible to determine authenticity.

  As shown in FIG. 18, the authentication method for a printed matter capable of authenticating authenticity is obtained by acquiring image data including an area formed by lines including a curve by a processor unit and performing frequency analysis on the image data by an image processing unit. The frequency component is generated, and the determination unit can perform authentication of the printed matter that can be determined as authenticity by comparing and comparing the frequency component with a predetermined frequency component.

  Since the frequency component is a component of a region formed by lines including a curve, it is possible to extract a frequency component that is clearer than before, so erroneous recognition of a predetermined frequency component in comparison verification There is nothing to do.

The line including the curve is preferably a concentric line or a curved line obtained by extracting a part of the concentric line. A clear frequency component can be obtained by using a concentric circle or a curved line from which a part of the concentric circle is extracted.

  An image to be formed on a printed matter that can be identified as authenticity is formed with a line that includes a curved line that is visually recognized by the naked eye, in addition to a region that is visually recognized by the naked eye that is formed with a line including curved lines. It is possible to further include a dummy area made of solid printing formed at the same density as that of the other area. For example, the graphic area 1b and the graphic area 1c shown in FIG. 3 are dummy areas for the graphic area 1a. The graphic area 1c shown in FIG. 4 is a dummy area for the graphic area 1a and the graphic area 1b. Further, as shown in FIG. 19, it is possible to further include a line drawing pattern L in addition to the graphic region 5. The printed matter capable of authenticating authenticity of the present invention forms a dummy area or a line drawing pattern, so that the forger cannot determine that information is embedded in the image, and thus has an excellent anti-counterfeit effect. However, when forming a line drawing pattern in an image, it is necessary to use a line drawing pattern having a spatial frequency component different from the spatial frequency component of a region formed by lines including a curve.

  It is preferable that the pattern formed on the printed matter capable of authenticity determination is a pastel color. Pastel color is a term that commonly refers to colors with low saturation and high brightness, and there is no clear standard in various color marking systems, but securities such as banknotes, stock certificates, bonds, various certificates and important Pastel patterns have been used for a long time because of the effect of being difficult to reproduce in the background pattern used for precious printed matter such as documents. By forming a pattern with such pastel colors, design harmony can be achieved even for products that conventionally require anti-counterfeiting, and at the same time, it is effective as an anti-counterfeiting measure. It works.

  Further, the image lines constituting the pattern of the present invention are preferably curves and concentric circles forming an arithmetic progression. Of course, the same effect can be obtained with a straight line. However, when obtaining the inverse spatial distance from the spatial frequency coordinates, for example, when viewed from the FFT pattern, the display from the low frequency to the high frequency is from the center of the two-dimensional coordinate axis (0 point) It is displayed to spread. In such a spatial frequency calculation method, curves and concentric circles forming an arithmetic progression are likely to appear as strong signals all around, for example, FIGS. 3B to 8B. This is because a clear intensity peak as seen in the frequency intensity graph displayed in the fourth quadrant on the FFT pattern shown can be known. It should be noted that the intensity peak of the spatial frequency is also affected by the brightness of the printing color. Generally, the intensity peak becomes clear as the brightness is low, but a sufficient intensity peak can be obtained even in the pastel color as described above. . Therefore, it is advantageous to identify the information embedded in the printed matter by constructing the pattern with curves and concentric circles forming an arithmetic progression.

  As mentioned above, although the embodiment of the present invention has been described based on examples, the present invention is not limited to such examples, and is effective not only in monochrome printing but also in the case of using a plurality of colors. Will never change. Therefore, it goes without saying that there are various embodiments within the scope of the technical matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Printed matter 1a Graphic area group 1b Graphic area group 1c Graphic area group 2a Graphic area group 2b Graphic area group 2c Graphic area group 3a Graphic area group 3b Graphic area group 3c Graphic area group 4a Graphic area group 4b Graphic area group 4c Graphic area group 5 graphic region group d1 interval d2 interval d3 interval L line drawing pattern P1-10 vertex q1 inverse space distance q2 inverse space distance q3 inverse space distance R circle r radius α line group α1-3 line segment

Claims (4)

Provided with an image having an arbitrary shape on the substrate,
The image has a plurality of regions;
The plurality of regions are formed by lines including a curve,
The line including the curve has an image line selected from an image line width of 30 μm to 80 μm and a non-image line selected from a non-image line width of 30 μm to 80 μm alternately arranged, A relationship between the selected image line width and the selected non-image line width is formed in a range of 2: 1 to 1: 2.
At least one area of the plurality of areas is such that both the selected image line width and the selected non-image line width are the same as the selected image line width and the selected non-image line of another area. Unlike width,
The plurality of regions have substantially the same line area ratio per unit area for each region,
The area formed by the line including the curve is visually recognized at a constant density by the naked eye, and a predetermined frequency component is extracted when frequency analysis is performed on the area formed by the line including the curve. A printed matter capable of authenticating authenticity. The printed matter capable of authenticating authenticity according to claim 1, wherein the line including the curve is a concentric circle or a curved line obtained by extracting a part of the concentric circle. The printed matter according to claim 1, wherein the image further includes a chromatic pattern line. A method for authenticating printed matter according to any one of claims 1 to 3, comprising:
The processor unit obtains image data including an area formed by lines including the curve,
The image processing unit performs frequency analysis on the image data to generate a frequency component,
An authentication method for a printed matter capable of authenticating authenticity, wherein the authenticating of the printed matter capable of determining authenticity is performed by comparing and collating the frequency component with a predetermined frequency component by a determination unit.

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