JP2011151533A - Electronic watermark printed matter, reading system of electronic watermark printed matter, reading method of electronic watermark printed matter, and manufacturing system of electronic watermark printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic watermark printed matter, along with a reading system and a reading method thereof, in which a relative rotational angle around an optical axis can be detected even in the case of a small electronic watermark. <P>SOLUTION: An electronic watermark (20) of an electronic watermark printed matter includes: a first pattern (22) which is acquired by inverse Fourier transform of the sum of a unique information pattern and a temporary rotational angle detection pattern for detecting a relative rotational angle as a temporary rotational angle of 0° to less than 180°; and a second pattern (24), which is provided by partially replacing the first pattern (22), to determine whether the relative rotational angle is the temporary rotational angle or a corrected rotational angle acquired by adding an offset angle of 180° to the temporary rotational angle. The shape itself in the real space of the second pattern (24) contains the information for determining whether the relative rotational angle is the temporary rotational angle or the corrected rotational angle. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a digital watermark printed matter, a reading system for the digital watermark printed matter, a method for reading the digital watermark printed matter, and a manufacturing system for the digital watermark printed matter.

  As the digital watermark printed material, for example, there is a trading card used for playing on a computer game machine. In this type of trading card, a digital watermark is drawn on one side together with a title character and a background, and a character and the like are drawn on the other side. In this case, the digital watermark is an image in which unique information related to the character is coded, and is printed in a title character or background in an identifiable or unidentifiable manner.

In order to read the unique information included in the digital watermark of the trading card placed on the stage, the game machine captures the digital watermark and executes image processing.
Some game machines detect the relative rotation angle of the trading card with respect to the stage in accordance with the play method. The electronic watermark of a trading card provided for such a game machine also includes information on the relative rotation angle.

  For example, the digital watermark described in Patent Document 1 includes a provisional rotation angle detection digital watermark and an offset angle detection digital watermark in order to detect a relative rotation angle of 0 to 360 degrees. According to this digital watermark, the provisional rotation angle is obtained based on the spatial frequency component obtained by Fourier transforming the provisional rotation angle detection digital watermark. The relative rotation angle is the provisional rotation angle itself or the provisional rotation angle plus an offset angle of 180 degrees.

Japanese Patent No. 2008-104061

According to the rotation angle detection method disclosed in Patent Literature 1, in order to determine the relative rotation angle of a trading card based on a digital watermark, almost the entire provisional angle detection digital watermark and offset angle detection digital watermark are photographed. There is a need.
The digital watermark disclosed in Patent Document 1 is large as a whole because the provisional angle detection digital watermark and the offset angle detection digital watermark are provided in separate areas.
Even if a large digital watermark is drawn with transparent ink, since human vision is sensitive, there is a possibility of affecting the design of the digital watermark printed matter. In order to prevent such an influence, it is desired to realize a smaller digital watermark.

  The present invention has been made in view of the above-described circumstances, and an object thereof is an electronic watermark printed matter in which a relative rotation angle around the optical axis is detected even for a small electronic watermark, and a reading system for the electronic watermark printed matter. Another object of the present invention is to provide a method for reading the digital watermark printed matter and a system for manufacturing the digital watermark.

  In order to achieve the above-described object, according to one aspect of the present invention, acquisition of unique information and detection of a relative rotation angle between 0 degrees and less than 360 degrees around the optical axis can be performed in an external image capturing processing apparatus. An electronic watermark printed matter on which an allowable electronic watermark is printed, wherein the electronic watermark is used to detect the unique information pattern and the relative rotation angle in a spatial frequency space as a temporary rotation angle of 0 to less than 180 degrees. A first pattern obtained by performing inverse Fourier transform on the sum of the provisional rotation angle detection patterns and a part of the first pattern are provided, and the relative rotation angle is 180 degrees to the provisional rotation angle and the provisional rotation angle. A second pattern for determining which one of the corrected rotation angles is obtained by adding the offset angle of the degree, and the relative rotation is added to the shape itself of the second pattern in real space. Watermarking prints corners characterized in that it contains information for determining which one of said provisional rotation angle and the corrected rotational angle is provided (claim 1).

In the electronic watermark printed matter according to claim 1, the second pattern is formed by replacing a part of the first pattern. Here, since the shape of the second pattern itself contains information, there is no need to Fourier transform the second pattern. A pattern that is Fourier transformed to read information is required to have a considerable size in real space, but the second pattern may be small in real space because information is read out without Fourier transformation.
Therefore, the digital watermark of the digital watermark printed matter may be small as a whole, and even if a part of the first pattern is replaced with the second pattern, the information included in the first pattern is not impaired. For this reason, acquisition of specific information and detection of a relative rotation angle are also executed smoothly.

Preferably, the second pattern includes three or more figures arranged geometrically (claim 2).
According to the electronic watermark printed matter of claim 2, the relative rotation angle is corrected to the provisional rotation angle and the correction by previously determining the relationship between the geometric arrangement of three or more figures, the provisional rotation angle, and the relative rotation angle. It is reliably determined which of the rotation angles is.
In addition, since the plurality of figures are geometrically arranged, the second pattern is reliably detected and the determination is accurately performed.

Preferably, the second pattern includes three or more figures arranged on one shape selected from the group consisting of a semicircle and a polygon.
According to the electronic watermark printed matter of claim 3, the geometric arrangement of a plurality of figures can be easily and reliably grasped by arranging the figures on a semicircle or polygon.

Preferably, the second pattern includes only one figure recognizable as a set of three or more geometrically arranged blocks.
According to the electronic watermark printed matter of the fourth aspect, the second pattern is constituted by one graphic that can be identified as a set of three or more blocks. If one figure can be identified as a set of three or more blocks, the relationship between the set of these blocks, the provisional rotation angle, and the relative rotation angle is determined in advance, so that the relative rotation angle becomes the provisional rotation angle and It is reliably determined which of the corrected rotation angles is.
In addition, since the three or more blocks are geometrically arranged, the second pattern is reliably detected and the determination is accurately performed.

Preferably, one of the second pattern and the periphery of the first pattern does not have the same ink as that constituting the first pattern, and the other includes the ink.
According to the digital watermark printed matter of the fifth aspect, even if the photographed image includes the periphery of the digital watermark, the periphery of the digital watermark and the second pattern are reliably identified, and the determination is performed accurately.

Preferably, the ink constituting the electronic watermark includes an absorbent having an absorption peak of light in a wavelength region other than the visible light region.
According to the electronic watermark printed matter of claim 6, since it becomes easy to make the ink constituting the electronic watermark inconspicuous, the electronic watermark hardly affects the design of the electronic watermark printed matter, and the degree of freedom of the design is ensured. The

  According to another aspect of the present invention, a stage on which the digital watermark printed matter according to any one of claims 1 to 6 is placed, and at least a part of the digital watermark of the digital watermark printed matter placed on the stage A digital watermark printed matter comprising: a photographing device for photographing the image; and an image processing device that acquires the unique information based on an image photographed by the photographing device and detects a relative rotation angle of the digital watermark printed matter with respect to the stage. The image processing apparatus calculates the provisional rotation angle based on a pattern in the spatial frequency space of the first pattern obtained by Fourier transforming the image, and calculates the provisional rotation angle and the calculated Based on the second pattern in the image, the relative rotation angle of the digital watermark printed material is the temporary rotation angle and the corrected rotation. Watermarking prints reading system, characterized in that determination is provided which one of (Claim 7).

8. The electronic watermark printed material reading system according to claim 7, wherein the second pattern is formed by replacing a part of the first pattern and is small in the electronic watermark printed material to be applied. For this reason, it is not necessary to increase the photographing range of the digital watermark. In other words, the second pattern is photographed even if the photographing range of the digital watermark is narrow.
For this reason, in this digital watermark printed material reading system, the photographing magnification may be low, and the distance between the lens and the digital watermark may be short. As a result, an increase in the size and price of the electronic watermark printed material reading system can be prevented.

Preferably, the imaging apparatus is capable of detecting light in a wavelength region absorbed by the absorbent when the ink constituting the digital watermark includes an absorbent having an absorption peak in a wavelength region other than a visible light region. (Claim 8).
According to the electronic watermark printed material reading system of the eighth aspect, even when the electronic watermark is not visible, the electronic watermark is reliably photographed.

  According to still another aspect of the present invention, a photographing step of photographing at least a part of the digital watermark of the digital watermark printed matter according to any one of claims 1 to 6 placed on a stage, and the photographing step An image processing step of acquiring the unique information based on the image photographed in step S1 and detecting a relative rotation angle of the digital watermark printed matter with respect to the stage, wherein the image processing step includes: A calculation process for calculating the temporary rotation angle based on a pattern in the spatial frequency space of the first pattern obtained by Fourier transform of the image, the temporary rotation angle calculated by the calculation process, and the image Based on the second pattern, a relative rotation angle of the digital watermark printed material is any of the temporary rotation angle and the corrected rotation angle. Reading method for an electronic watermark printed matter characterized in that it comprises a determination process whether there is provided (claim 9).

In the digital watermark printed matter reading method according to claim 9, in the digital watermark printed matter to be applied, the second pattern is formed by replacing a part of the first pattern and is small, so the second pattern is photographed. For this reason, it is not necessary to increase the photographing range of the digital watermark. In other words, the second pattern is photographed even if the photographing range of the digital watermark is narrow.
For this reason, in this digital watermark printed matter reading method, the photographing magnification may be low, and the distance between the lens and the digital watermark may be short. As a result, an increase in the size and price of the apparatus used in the digital watermark printed material reading method can be prevented.

  According to still another aspect of the present invention, a digital watermark that allows an external image capturing processing device to acquire unique information and detect a relative rotation angle of 0 degree or more and less than 360 degrees around the optical axis is printed. A digital watermark printed matter manufacturing system, comprising: an image processing device that creates master data corresponding to the digital watermark; and a printing device that prints the digital watermark based on the master data, the image processing The apparatus obtains a first obtained by performing an inverse Fourier transform on the sum of the unique information pattern in the spatial frequency space and the provisional rotation angle detection pattern for detecting the relative rotation angle as a provisional rotation angle of 0 ° to less than 180 °. A first data generation unit that generates first data corresponding to a pattern, and the relative rotation angle is calculated by adding an offset angle of 180 degrees to the temporary rotation angle and the temporary rotation angle. A second data generation unit corresponding to a second pattern for determining which of the correction rotation angles is to be performed, and the first pattern so that a part of the first pattern is replaced with the second pattern. A master data generation unit that processes the data and the second data, and generates master data corresponding to the digital watermark, and the relative rotation angle is the temporary rotation angle and the shape itself in the real space of the second pattern. Information for determining which of the corrected rotation angles is included is provided, and a digital watermark printed matter manufacturing system is provided (claim 10).

In the electronic watermark printed matter manufactured by the electronic watermark printed matter manufacturing system according to claim 10, the second pattern is formed by replacing a part of the first pattern. Here, since the shape of the second pattern itself contains information, there is no need to Fourier transform the second pattern. A pattern that is Fourier transformed to read information is required to have a considerable size in real space, but the second pattern may be small in real space because information is read out without Fourier transformation.
Therefore, the digital watermark of the digital watermark printed matter may be small as a whole, and even if a part of the first pattern is replaced with the second pattern, the information included in the first pattern is not impaired. For this reason, acquisition of specific information and detection of a relative rotation angle are also executed smoothly.

  According to the present invention, even with a small digital watermark, a digital watermark printed matter whose relative rotation angle around the optical axis is detected, a reading system for the digital watermark printed matter, a method for reading the digital watermark printed matter, and the A system for producing a digital watermark print is provided.

It is a schematic perspective view of the computer game machine with which the trading card of 1st Embodiment is applied. It is a schematic plan view of the trading card of the first embodiment. FIG. 3 is a schematic enlarged view of a digital watermark in FIG. 2. FIG. 4 is a diagram schematically showing unique information and provisional rotation angle information obtained by performing Fourier transform on the first pattern in FIG. 3. It is a flowchart which shows the method for detecting the relative rotation angle with respect to the stage of a trading card. It is a block diagram which shows the schematic structure of a digital watermark printing system. FIG. 4 is an enlarged view of a second pattern in FIG. 3. It is an enlarged view of the 2nd pattern concerning a 2nd embodiment. It is an enlarged view of the 2nd pattern concerning a 3rd embodiment. It is a schematic plan view of the digital watermark which concerns on 4th Embodiment. It is a figure which shows the outline in the edge image of the 2nd pattern in FIG. It is a schematic enlarged view which shows the digital watermark and its periphery which concern on the modification of 1st thru | or 4th Embodiment.

Hereinafter, a trading card 10 will be described as a digital watermark printed matter according to a first embodiment of the present invention with reference to the drawings.
In FIG. 1, the trading card 10 is placed on the stage 14 of the computer game machine 12. The trading card 10 is used for play on the computer game machine 12.

FIG. 2 is a plan view showing one surface (front surface) of the trading card 10. On the surface of the trading card 10, for example, “AB” as the title character 16 and a circle surrounding the title character as the background 18 are drawn.
A digital watermark 20 is drawn at the center of the surface of the trading card 10. For example, the title characters 16 and the background 18 are printed with different color inks. The digital watermark 20 is printed so as to overlap the title character 16 and the background 18, and is preferably printed with a nearly transparent ink containing an infrared absorber (infrared absorbing pigment).

As the infrared absorber, for example, ITO (tin-doped indium oxide) or antimony-doped tin oxide can be used, and antimony-doped tin oxide is preferably used. In the case of an ink using antimony-doped tin oxide, for example, 30 parts by mass of antimony-doped tin oxide is included with respect to 100 parts by mass of a polyester resin as a vehicle.
In consideration of printability, the infrared absorber preferably has an average particle size in the range of 0.01 μm to 100 μm, and more preferably has an average particle size in the range of 0.1 μm to 3.0 μm. .
And the infrared absorber using an antimony dope tin oxide is a single-piece | unit, and the thing which shows L value of 50 or more as a brightness is preferable. Since ink containing such an infrared absorber is easy to camouflage, it is more difficult to recognize that it is a uniform pattern such as the digital watermark 20, and it is possible to make visual recognition impossible.
The ink of the digital watermark 20 may include an absorbent other than the infrared absorbent as long as it has an absorption peak of light in a specific wavelength region other than the visible light region.

FIG. 3 is a schematic plan view showing the digital watermark 20 in an enlarged manner. The digital watermark 20 can be photographed independently from the title characters 16 and the background 18 by using a photographing device capable of detecting light in the wavelength region absorbed by the absorbent, for example, a photographing device having sensitivity to infrared rays. .
In FIG. 3, the ink-applied portion, that is, the digital watermark is shown in black, and the ink-free portion, that is, the background portion is shown in white.

The digital watermark 20 includes a first pattern 22 and a second pattern 24. The digital watermark 20 is formed at the center of the surface so that the second pattern 24 is included in the shooting range when the trading card 10 rotates relative to the stage 14.
The first pattern 22 is a pattern in real space obtained by inverse Fourier transform of two pieces of information. The first pattern 22 has a complicated spotted pattern or striped pattern, and extends over a certain area of the digital watermark 20.

One of the two pieces of information included in the first pattern 22 is information unique to the trading card 10, specifically, information on the character drawn on the other side (back side) of the trading card 10. is there.
One of the two pieces of information included in the first pattern 22 is provisional rotation angle information for detecting the relative rotation angle of the trading card 10 with respect to the stage 14. The provisional rotation angle is an angle between 0 degrees and less than 180 degrees, and is equal to a relative rotation angle or an angle obtained by adding an offset angle of 180 degrees to the relative rotation angle (hereinafter referred to as a corrected rotation angle).
Note that the relative rotation angle of the trading card 10 with respect to the stage 14 can be said to be the relative rotation angle of the trading card 10 about the optical axis of shooting.

FIG. 3 schematically shows unique information and provisional rotation angle information included in the first pattern 22 in a spatial frequency space.
The unique information is represented, for example, as a set of points on three ID circles having different radii, that is, spatial frequencies. The provisional rotation angle information is represented as a set of points on one rotation angle circle having a spatial frequency different from that of the ID circle.
Therefore, the unique information can be acquired based on the unique information pattern in the spatial frequency space.

In addition, the directions of the coordinate axes are the same between the spatial frequency space and the real space, and the temporary rotation angle can be calculated based on the temporary rotation angle information pattern in the spatial frequency space.
In FIG. 3, only half of the spatial frequency space is drawn, and half is omitted. This is because the pattern in the spatial frequency space obtained by Fourier transform of the first pattern 22 has a 180 degree point symmetry. Due to this point symmetry, the provisional rotation angle is limited to a range of 0 degrees or more and less than 180 degrees.

Returning to FIG. 2 again, the second pattern 24 is provided by replacing a part of the first pattern 22, and is formed from five quadrilaterals 26 arranged at equal intervals of 45 degrees on a virtual semicircle. Become. In other words, the five quadrilaterals 26 are geometrically arranged so as not to have 180 degree point symmetry in the plane on which the digital watermark 20 is printed.
The square 26 is formed by not applying ink to the square area. The square 26 is a square having a side length of, for example, 1 mm, and the radius of the semicircle is, for example, 2 mm. Each of the plurality of figures constituting the second pattern 24 may be a circle or the like instead of a rectangle.

Hereinafter, a method for detecting the relative rotation angle of the trading card 10 with respect to the stage 14 will be described.
FIG. 5 is a flowchart showing the procedure of the detection method.
In the detection method, first, an image of the digital watermark 20 as shown in FIG. 2 is taken (step S10). Note that the size of the imaging region is, for example, 1.2 cm × 1.6 cm. Shooting is performed so that the first pattern 22 occupies a certain ratio or more, for example, 50% or more of the shooting area, and the second pattern 24 is included in the shooting area.

The captured image is subjected to Fourier transform (step S12), and unique information and provisional rotation angle information are acquired based on a pattern in a spatial frequency space obtained by Fourier transforming the digital watermark 20. (Step S14). Based on the acquired provisional angle information, a provisional rotation angle is calculated (step S16).
On the other hand, the captured image itself, that is, the image in the real space is subjected to image processing, and the square 26 of the second pattern 24 is detected (step S18). Then, based on the detected shape of the second pattern 24, it is determined whether the temporary rotation angle is a relative rotation angle or a corrected rotation angle, and the relative rotation angle is determined (S20). As a matter of course, the relationship among the second pattern 24, the provisional rotation angle, and the relative rotation angle is predetermined.

Hereinafter, a detection method (calculation method) of the second pattern 24 will be described.
An edge detection operator such as a Laplacian operator (Laplacian filter) is applied to the captured image, and an image (edge image) representing an edge is obtained.
The edge image is divided into a plurality of blocks. Each block includes a plurality of pixels, for example, 12 × 12 pixels, and each pixel has a gray value of, for example, 256 gradations.

  In each block, the number of pixels (high density pixels) whose gray value is equal to or greater than a threshold value is counted. Since a block including a certain number or more of high density pixels includes many edges, the block is determined to be a block (first pattern block) corresponding to a complex striped first pattern. On the other hand, a block including less than a certain number of high density pixels is determined to be a block (non-first pattern block) corresponding to the periphery of the second pattern 24 or the digital watermark 20 having a simple shape other than the first pattern 22. The

A flag is set for the non-first pattern block, and a set of adjacent non-first pattern blocks is formed using the flag. A label is assigned to each set of non-first pattern blocks.
Whether or not the set of non-first pattern blocks is a set corresponding to the quadrangle 26 of the second pattern 24 is determined based on the size and shape thereof. For example, when determining whether one of the sets of non-first pattern blocks is a rectangle 26, the shape of the set is vertically long considering that the shape of the set does not exactly match the shape of the rectangle 26. Or it is determined based on whether it is not horizontally long. As a result of the determination, a set corresponding to the square 26 of the second pattern 24 is detected.
In the present embodiment, it is possible to increase the determination accuracy of the set corresponding to the rectangle 26 by checking whether or not a plurality of sets are arranged on a semicircle.

The digital watermark printing system 100 (digital watermark printed matter manufacturing system) will be described below.
As shown in FIG. 6, the digital watermark printing system 100 includes an image processing apparatus 102 and a printing apparatus 104. The image processing apparatus 102 is configured by a computer, for example, and includes a CPU (Central Processing Unit), a memory, a storage device, and the like.
The image forming processing apparatus 102 includes a first data generation unit 106, a second data generation unit 108, and a master data generation unit 110 when viewed in terms of functions.

The first data generation unit 106 generates first data as image data corresponding to the first pattern 22 based on the unique information of the trading card 10 and predetermined provisional rotation angle detection information.
The second data generation unit 108 creates second data as image data corresponding to the second pattern 24.
The master data generation unit 110 creates master data as image data corresponding to the digital watermark 20 based on the first data and the second data. Specifically, the master data generation unit 110 processes the first data and the second data so that a part of the first pattern is replaced with the second pattern, and creates master data.
The printing apparatus 104 prints the digital watermark 20 on the trading card 10 based on the master data created by the image processing apparatus 102.

  In the trading card 10 of the first embodiment described above, the second pattern 24 is formed by replacing a part of the first pattern 22. Here, since the shape of the second pattern 24 itself contains information, it is not necessary to Fourier transform the second pattern 24. A pattern that is Fourier transformed to read information requires a considerable size in real space, but the second pattern 24 may be small in real space because information is read out without Fourier transformation. .

  Therefore, the electronic watermark 20 of the trading card 10 may be small as a whole, and even if a part of the first pattern 22 is replaced with the second pattern 24, the information included in the first pattern 22 is not impaired. For this reason, acquisition of specific information and detection of a relative rotation angle are also executed smoothly.

  Then, according to the trading card 10 of the first embodiment described above, the relative rotation angle is corrected to the provisional rotation angle and the correction by predetermining the relationship between the arrangement of the plurality of squares 26, the provisional rotation angle, and the relative rotation angle. It is reliably determined which of the rotation angles is.

Further, since the three or more quadrangles 26 are arranged on the semicircle, the second pattern 24 and the periphery of the digital watermark 20 are surely distinguished. For this reason, the detection accuracy of the 2nd pattern 24 becomes high, and determination is performed accurately.
Specifically, as shown in FIG. 7, first, the position of the center C of the semicircle is obtained from the intersection of two lines orthogonal to the line connecting the detected rectangles 26. Then, all the quadrilaterals 26 are inspected to determine whether or not they are located at a predetermined distance from the center C. If the distance is long or short, one of the detected quadrilaterals 26 is erroneously detected. It can be seen that it is included.

Furthermore, in the first embodiment, the relative rotation angle can be determined based on only a part of the shape of the second pattern 24.
Specifically, if three quadrilaterals 26 are detected among the five quadrilaterals 26, the position of the center C of the semicircle can be obtained by calculation as shown in FIG. The relative rotation angle can be detected from the detected positions of the three quadrangles 26, the position of the center C of the semicircle, and the provisional rotation angle. That is, the relative rotation angle can be determined even when a part of the second pattern 24 deviates from the shooting range as the trading card 10 rotates.
Note that the virtual semicircle includes not only half of a perfect circle but also half of an ellipse as long as the same effect can be obtained.

  Furthermore, according to the trading card 10 of the first embodiment, it becomes easy to make the ink constituting the digital watermark 20 inconspicuous, so that the digital watermark 20 hardly affects the design of the trading card 10 and the design of the design. A degree of freedom is secured.

On the other hand, in the computer game machine 12, since the second pattern 24 is formed by replacing a part of the first pattern 22 and is small in the trading card 10 to be applied, the second pattern 24 is photographed. In addition, it is not necessary to increase the shooting range of the digital watermark 20. In other words, even if the shooting range of the digital watermark 20 is narrow, the second pattern 24 is shot.
For this reason, in the computer game device 12, the shooting magnification may be low, and the distance between the lens and the digital watermark 20 may be short. As a result, an increase in size and price of the computer game device 12 is prevented.

In the method of reading the trading card 10 executed by the computer game device 12, the second pattern 24 is formed by replacing a part of the first pattern 22 and is small in the trading card 10 to be applied. In order to photograph the second pattern 24, it is not necessary to increase the photographing range of the digital watermark 20. In other words, even if the shooting range of the digital watermark 20 is narrow, the second pattern 24 is shot.
For this reason, in the method for reading the trading card 10, the photographing magnification may be low, and the distance between the lens and the digital watermark 20 may be short. As a result, an increase in the size and price of the computer game machine 12 used in the method for reading the trading card 10 is prevented.

[Second Embodiment]
FIG. 8 shows a second pattern 30 according to the second embodiment. Similar to the second pattern 24, the second pattern 30 is also provided by replacing a part of the first pattern 22.
The second pattern 30 includes three quadrangles 32 arranged at the vertices of a triangle. The second pattern 30 also determines whether the temporary rotation angle is a relative rotation angle or a corrected rotation angle by determining the relationship between the second pattern 30 and the temporary rotation angle and the relative rotation angle in advance. Is done.
Further, the accuracy of detection of the quadrangle 32 can be increased by inspecting the size of the triangle in which the quadrangle 32 is arranged.

[Third Embodiment]
FIG. 9 shows a second pattern 40 according to the third embodiment. Similarly to the second patterns 24 and 30, the second pattern 40 is also provided by replacing a part of the first pattern 22.
The second pattern 40 includes six quadrilaterals 42 arranged on a rectangle. Also with this second pattern 40, it is determined whether the temporary rotation angle is a relative rotation angle or a corrected rotation angle by determining the relationship between the second pattern 40, the temporary rotation angle, and the relative rotation angle in advance. Is done.

Alternatively, by determining the relationship between the position of the vertex P of the rectangle in which the quadrangle 42 is arranged, the provisional rotation angle, and the relative rotation angle, whether the provisional rotation angle is a relative rotation angle or a corrected rotation angle. Determined.
Further, the accuracy of detection of the quadrangle 32 can be increased by inspecting the size of the rectangle in which the quadrangle 42 is arranged.
That is, when the second pattern is composed of three or more figures, it is preferable that a plurality of three or more figures are arranged geometrically in order to increase the figure detection accuracy. In addition, the 3 or more some figure may be arranged on polygons other than a triangle and a quadrangle | tetragon.

[Fourth Embodiment]
FIG. 10 is a plan view of the digital watermark 20 according to the fourth embodiment. In the digital watermark 20, a second pattern 50 is provided by replacing a part of the first pattern 22 instead of the second pattern 24. The second pattern 50 is composed of, for example, one right triangle, and is arranged so that the bottom of the triangle is along the bottom of the trading card 10.

  FIG. 11 shows a part of the edge image, and the triangle 52 shows the outline of the second pattern 50. As can be seen from the size of the triangle 52, the second pattern 50 has a size extending over three or more blocks 54. If at least three geometrically arranged blocks 54 are detected, the second pattern 50 can be detected with high accuracy, and the relative rotation angle is accurately determined.

  If the geometric figure has a size including at least three or more blocks 54 arranged so as not to have 180 degree point symmetry and can determine the relative rotation angle, the second figure is used. The pattern is not limited to a triangle.

The present invention is not limited to the first to fourth embodiments described above, and includes embodiments in which various modifications are made to these embodiments. The present invention also includes an embodiment in which the above-described embodiment is combined with a known technique.
For example, in the first to fourth embodiments, as shown in FIG. 12, a region 55 that is filled with the ink constituting the digital watermark 20 may be provided around the digital watermark 20. In this case, the presence of the solid area 55 makes it easy to distinguish between the periphery of the digital watermark 20 and the second patterns 24, 30, 40, 50, and detection of the second patterns 24, 30, 40, 50 is possible. Performed with high accuracy.

  In the first to fourth embodiments, the ink constituting the electronic watermark 20 is not applied to the regions of the second patterns 24, 30, 40, and 50. However, ink may be applied. In this case, it is preferable that the ink constituting the digital watermark 20 is not solidly painted around the digital watermark 20.

Furthermore, as shown in FIG. 12, the digital watermark 20 is included in a part of the shooting area within a range that does not hinder acquisition of unique information based on the first pattern 22, for example, up to 50% of the entire shooting area. A region 56 where no ink is applied may be provided so as to enter. This area 56 overlaps the title character 16, and the title character 16 has an excellent gloss by not applying the ink of the digital watermark 20 to this area 56.
In order to discriminate between the region 56 and the second patterns 24, 30, 40, and 50, it is preferable that ink is applied on one side and ink is not applied on the other side.

In addition, the ink used for drawing the digital watermark 20 is preferably transparent, but is not necessarily transparent.
Furthermore, the title characters 16 and the background 18 corresponding to the background of the digital watermark 20 are not limited in particular to the presence or absence of the design.
The digital watermark printed matter of the present invention can be applied to uses other than playing with a computer game machine, and is not limited to a trading card, and may be a cash card or a credit card. .
The digital watermark printed material photographing device can be selected as appropriate according to the intended use. The digital watermark printed material is photographed by a Web camera attached to the computer or a built-in camera of the cellular phone, and the unique information is read by the computer or cellular phone. May be. Note that the imaging device may be fixed or movable depending on the application.

10 Electronic watermark printed matter 12 Computer game machine (reading system)
14 Stage 16 Title character 18 Background 20 Digital watermark 22 First pattern 24, 30, 40, 50 Second pattern 100 Digital watermark printing system (manufacturing system)

Claims (10)

An electronic watermark printed matter on which an electronic watermark that allows acquisition of specific information and detection of a relative rotation angle between 0 degrees and less than 360 degrees around an optical axis is permitted to an external image capturing processing apparatus,
The watermark is
A first pattern obtained by performing an inverse Fourier transform on the sum of the unique information pattern in the spatial frequency space and the provisional rotation angle detection pattern for detecting the relative rotation angle as a provisional rotation angle of 0 degree to less than 180 degrees;
Whether the relative rotation angle is one of the provisional rotation angle and a corrected rotation angle obtained by adding an offset angle of 180 degrees to the provisional rotation angle. A second pattern for determining
The shape itself in the real space of the second pattern includes information for determining whether the relative rotation angle is the temporary rotation angle or the corrected rotation angle. Watermark print.   The digital watermark printed matter according to claim 1, wherein the second pattern includes three or more geometrically arranged figures.   The digital watermark printed matter according to claim 2, wherein the second pattern includes three or more figures arranged on one shape selected from the group consisting of a semicircle and a polygon.   The digital watermark printed matter according to claim 1, wherein the second pattern includes only one figure that can be recognized as a set of three or more geometrically arranged blocks.   The one of the second pattern and the periphery of the first pattern does not have the same ink as that constituting the first pattern, and the other includes the ink. 5. The digital watermark printed material according to any one of 4 above.   The digital watermark printed matter according to claim 1, wherein the ink constituting the digital watermark includes an absorbent having an absorption peak of light in a wavelength region other than a visible light region. A stage on which the digital watermark printed matter according to any one of claims 1 to 6 is placed;
A photographing device for photographing at least a part of the digital watermark of the digital watermark printed matter placed on the stage;
An electronic watermark printed matter reading system comprising: an image processing device that acquires the unique information based on an image photographed by the photographing device and detects a relative rotation angle of the digital watermark printed matter with respect to the stage,
The image processing apparatus includes:
Calculating the provisional rotation angle based on a pattern in the spatial frequency space of the first pattern obtained by Fourier transforming the image;
Based on the calculated temporary rotation angle and the second pattern in the image, it is determined whether the relative rotation angle of the digital watermark printed material is the temporary rotation angle or the corrected rotation angle. A digital watermark printed material reading system. The imaging apparatus is capable of detecting light in a wavelength region absorbed by the absorbent when the ink constituting the digital watermark includes an absorbent having an absorption peak in a wavelength region other than a visible light region. The electronic watermark printed material reading system according to claim 7, wherein: A photographing step of photographing at least a part of the digital watermark of the digital watermark printed matter according to any one of claims 1 to 6 placed on a stage;
An electronic watermark printed matter reading method comprising: an image processing step of acquiring the unique information based on an image photographed in the photographing step and detecting a relative rotation angle of the digital watermark printed matter with respect to the stage,
The image processing step includes
An arithmetic process for calculating the provisional rotation angle based on a pattern in a spatial frequency space of the first pattern obtained by Fourier transforming the image;
Based on the temporary rotation angle calculated in the calculation process and the second pattern in the image, whether the relative rotation angle of the digital watermark printed material is the temporary rotation angle or the corrected rotation angle. And a determination process for determining the electronic watermark printed matter. An electronic watermark printed material manufacturing system on which a digital watermark is printed that allows an external image photographing processing device to acquire unique information and detect a relative rotation angle between 0 degrees and less than 360 degrees around an optical axis. ,
An image processing device for creating master data corresponding to the electronic watermark;
A printing device that prints the digital watermark based on the master data,
The image processing apparatus includes:
Corresponds to the first pattern obtained by inverse Fourier transform of the sum of the unique information pattern in the spatial frequency space and the provisional rotation angle detection pattern for detecting the relative rotation angle as a temporary rotation angle of 0 degree to less than 180 degrees A first data generation unit for generating first data to be
Second data corresponding to the second pattern for determining whether the relative rotation angle is one of the temporary rotation angle and the corrected rotation angle obtained by adding an offset angle of 180 degrees to the temporary rotation angle. A generator,
A master data generating unit that processes the first data and the second data so that a part of the first pattern is replaced with the second pattern, and creates master data corresponding to the digital watermark;
The shape itself in the real space of the second pattern includes information for determining whether the relative rotation angle is the temporary rotation angle or the corrected rotation angle. Watermark print production system.

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