Method and software for visualizing latent image of phase modulation pattern

Abstract

To provide a latent image visualization method of a phase modulation pattern capable of visualizing a latent image in the phase modulation pattern by using a multifunctional terminal, and software for the visualization.SOLUTION: Acquiring original image data of a phase modulation pattern divided into a latent image portion and a background portion by partially changing phases of some of a plurality of colored objects arranged at a predetermined pitch; acquiring an object arrangement pitch or object width from the acquired original image data; and dividing the original image data at an interval corresponding to 1 / 2 of the object arrangement pitch or the object width in an object arrangement direction; A method for visualizing a phase modulation pattern, comprising the steps of: obtaining odd-numbered-row image data and even-numbered-row image data; and performing color inversion processing on either the odd-numbered-row image data or the even-numbered-row image data.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method and software for visualizing a latent image pattern in a phase modulation pattern in which the phases of some of the lines arranged in a line pattern are different and the latent image pattern is revealed by dividing the image into a latent image portion and a background portion. [Background technology]

[0002] Anti-counterfeit printed matter is required to be difficult to counterfeit or tamper with by its nature. Phase modulation patterns are used as one of the techniques for implementing such anti-counterfeiting and anti-tampering measures. The applicant has proposed a technique for anti-counterfeit printed matter with a conventional phase modulation pattern, as shown in Patent Document 1 below.

[0003] The technology of Patent Document 1 allows a latent image to be visually recognized by placing a discriminator on a printed material having a phase modulation pattern in which density-modulated image lines are added to the image lines constituting the phase modulation pattern, thereby improving the concealment of the latent image under normal observation. The discriminator mainly takes the form of a transparent sheet printed with a parallel line screen (hereinafter referred to as a "line filter"), a lenticular lens, or a lens array. Patent Document 1 also discloses a latent image that can be visually recognized in color by configuring the latent image lines of the latent image portion with colors that are complementary to each other across the center. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7224588 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the phase modulation pattern used in the technology of Patent Document 1 requires a discriminating tool such as a lenticular lens or a line filter, which not everyone carries with them, so it is not possible for everyone to easily determine whether the pattern is genuine or counterfeit.

[0006] Therefore, the problem that the present invention aims to solve is to provide a method for easily visualizing a latent image using a commonly available multi-function terminal, without requiring a discriminator such as a line filter or lenticular lens, when visualizing a phase modulation pattern formed in black on a commonly used white substrate. [Means for solving the problem]

[0007] The method for visualizing a phase modulation pattern of the present invention is a method for visualizing a phase modulation pattern in which the phases of some of the colored images arranged at a constant pitch are partially different, thereby dividing the image into a latent image portion and a background portion, and the latent image portion and the background portion are visually perceived as being the same color, and is characterized by comprising the steps of: acquiring original image data of the phase modulation pattern; acquiring the pitch at which the images are arranged or the width of the images from the acquired original image data; dividing the original image data in the direction in which the images are arranged at intervals of 1 / 2 the pitch at which the images are arranged or the width of the images, and dividing the original image data into odd-numbered column image data and even-numbered column image data, respectively; and performing color inversion processing on either the odd-numbered column image data or the even-numbered column image data.

[0008] The step of dividing the odd-numbered column image data and the even-numbered column image data is characterized in that the configuration of the phase modulation pattern is as follows: i) if the image lines constituting the latent image portion are monochromatic, the original image data is divided based on the edges of the image lines; ii) if the phases of the image lines in the latent image portion and the background portion differ by less than half the pitch at which the image lines are arranged and the image lines constituting the latent image portion are composed of colors that are complementary to each other with the center as the boundary, the original image data is divided based on the edges of the image lines; and iii) if the phases of the image lines in the latent image portion and the background portion differ by half the pitch at which the image lines are arranged and the image lines constituting the latent image portion are composed of colors that are complementary to each other with the center as the boundary, the original image data is divided at a position shifted from the edge of the image line by 1 / 4 of the pitch at which the image lines are arranged or 1 / 2 the width of the image line.

[0009] The method further comprises a step of performing averaging processing on image data obtained by performing color inversion processing on either odd-numbered column image data or even-numbered column image data.

[0010] The step of acquiring the pitch at which the image lines are arranged or the width of the image lines is characterized in that: i) when acquiring the pitch at which the image lines are arranged, a process of counting the number of pixels between the edges of the image lines in the original image data is performed at multiple locations, and the most frequent number of pixels is acquired as the pitch at which the image lines are arranged; and ii) when acquiring the width of the image lines, a process of counting the number of pixels of the image lines in the width direction of the image lines in the original image data is performed at multiple locations, and the most frequent number of pixels is acquired as the width of the image lines.

[0011] The software for visualizing a phase modulation pattern of the present invention is characterized by causing a multifunction terminal to execute the above-described method for visualizing a phase modulation pattern. [Effects of the Invention]

[0012] The phase modulation pattern visualization method and visualization software of the present invention makes it possible to easily visualize latent images using a multi-function terminal, without the need for a discriminator that was previously required to visualize latent images. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing an example of the configuration of an apparatus capable of implementing a method for visualizing a phase modulation pattern according to a first embodiment of the present invention. [Figure 2] FIG. 3 is an explanatory diagram showing the configuration of the phase modulation pattern in an enlarged manner. [Figure 3] 10A and 10B are explanatory diagrams showing an example of the configuration of latent image lines and background image lines included in a phase modulation pattern to which the above-described phase modulation pattern visualization method can be applied. [Figure 4] 4 is a flowchart showing a processing procedure of a method for visualizing a phase modulation pattern according to the first embodiment. [Figure 5] 10 is an explanatory diagram showing division of the phase modulation pattern into odd-numbered column image data and even-numbered column image data based on the edges of the image lines; FIG. [Figure 6] 6 is an explanatory diagram showing a case where color inversion processing is performed on only odd-numbered column image data out of the odd-numbered column image data and even-numbered column image data shown in FIG. 5; FIG. [Figure 7] An explanatory diagram showing image data of a phase modulation pattern captured by a multifunction terminal and a black (K) latent image visualized by performing color inversion processing on only the odd-numbered column image data of this phase modulation pattern. [Figure 8] FIG. 10 is an explanatory diagram showing a white (W) latent image visualized by performing color inversion processing on only the even-numbered column image data. [Figure 9] 10 is an explanatory diagram showing an example of the configuration of a latent image line and a background image line included in a phase modulation pattern to which a phase modulation pattern visualization method according to a second embodiment can be applied. FIG. [Figure 10] 10 is a flowchart showing a processing procedure of a method for visualizing a phase modulation pattern according to a second embodiment of the present invention. [Figure 11] 11 is an explanatory diagram showing a state in which image data is divided into odd-numbered column image data and even-numbered column image data based on edges of image lines in the configuration shown in FIG. 10; [Figure 12] 12 is an explanatory diagram showing a state in which color inversion processing is performed on only odd-numbered column image data out of the odd-numbered column image data and even-numbered column image data shown in FIG. 11; FIG. [Figure 13] FIG. 13 is an explanatory diagram showing a red (R) latent image visualized by performing color inversion processing on only odd-numbered column image data as shown in FIG. 12; [Figure 14] FIG. 10 is an explanatory diagram showing a cyan (C) latent image visualized by performing color inversion processing on only the even-numbered column image data. [Figure 15] 10A and 10B are explanatory diagrams showing an example of the configuration of a latent image line and a background image line included in a phase modulation pattern to which a phase modulation pattern visualization method according to a third embodiment can be applied. [Figure 16] 10 is a flowchart showing a processing procedure of a method for visualizing a phase modulation pattern according to a third embodiment of the present invention. [Figure 17] FIG. 17 is an explanatory diagram showing that image data is cut out and divided at a cutout position CP that is shifted 1 / 4 of the pitch P1 from the edge of the image line in the configuration shown in FIG. 16. [Figure 18] FIG. 18 is an explanatory diagram showing the state in which the configuration shown in FIG. 17 is divided into odd-numbered column image data and even-numbered column image data based on a cutout position CP that is shifted 1 / 4 of the pitch P1 from the edge of the image line. [Figure 19] 19 is an explanatory diagram showing a state in which color inversion processing is performed on only odd-numbered column image data out of the odd-numbered column image data and even-numbered column image data shown in FIG. 18. [Figure 20] FIG. 20 is an explanatory diagram showing a cyan (C) latent image visualized by performing color inversion processing on only odd-numbered column image data as shown in FIG. 19; [Figure 21] FIG. 10 is an explanatory diagram showing a red (R) latent image visualized by performing color inversion processing on only the even-numbered column image data. [Figure 22] 1 is a flowchart showing an integrated processing procedure of the phase modulation pattern visualization methods according to the first, second, and third embodiments. [Figure 23] FIG. 10 is an explanatory diagram showing a process of cutting out an arbitrary range from original image data. [Figure 24] 10A and 10B are explanatory diagrams showing a process of obtaining the pitch of a phase modulation pattern using cut-out image data. [Figure 25]10A and 10B are explanatory diagrams showing a process of dividing image data into odd-numbered column image data and even-numbered column image data along the line direction based on the acquired pitch. [Figure 26] FIG. 10 is an explanatory diagram showing a state in which color inversion processing is performed on either odd-numbered column image data or even-numbered column image data. [Figure 27] FIG. 10 is an explanatory diagram showing a latent image visualized by processing the original image data according to the above procedure. [Figure 28] 10A and 10B are explanatory diagrams showing that averaging processing corresponding to the pitch in the vertical direction of the image line is performed on image data that has undergone color inversion processing; [Figure 29] FIG. 29 is an explanatory diagram showing the averaging process shown in FIG. 28. [Figure 30] FIG. 3 is an explanatory diagram showing an example of a processing procedure for acquiring the pitch between images in the method for visualizing a phase modulation pattern according to the first, second, and third embodiments. [Figure 31] 10A and 10B are explanatory diagrams showing a method of displaying imaging assist lines on an imaging screen as an optimization of capturing a captured image. [Figure 32] FIG. 10 is an explanatory diagram showing a technique for optimizing the capture of a captured image by displaying imaging assistance lines on the imaging screen to obtain the optimal distance, angle, and tilt. [Figure 33] FIG. 10 is an explanatory diagram showing a technique for optimizing the capture of captured images by automatically capturing images at a timing when optimal imaging conditions are met. [Figure 34] FIG. 10 is an explanatory diagram showing a method of angle correction as a correction to captured original image data. [Figure 35] FIG. 35 is an explanatory diagram showing the state after angle correction using the method shown in FIG. 34. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the following embodiments and includes various other embodiments within the scope of the technical concept set forth in the claims.

[0015] (First embodiment) The configuration of a multifunction terminal (300) capable of implementing a method for visualizing a phase modulation pattern according to a first embodiment will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the device configuration of the multifunction terminal (300), which has at least an image processing unit (M11), a memory unit (M12), and a display unit (M13). The multifunction terminal (300) also has an imaging unit (M1) and an external connection unit (M2) as appropriate, depending on the form of acquiring an image of a phase modulation pattern in a method for visualizing a phase modulation pattern, which will be described later. Examples of the multifunction terminal (300) that can be used include a smartphone, a mobile phone, a tablet terminal, and a personal computer. Details of each unit constituting the multifunction terminal (300) will be described below.

[0016] The imaging unit (M1) includes a camera, a scanner, or the like having an imaging function, and captures an image of the phase modulation pattern and captures the image data.

[0017] The external connection unit (M2) has a function as a network interface and an interface for connecting with various external devices.

[0018] The storage unit (M12) includes a ROM, a RAM, a hard disk, etc., and stores image data of the phase modulation pattern as well as programs required for image processing.

[0019] The image processing unit (M11) performs image processing on the input image data to visualize a phase modulation pattern as described below, and stores the results in the storage unit (M12).

[0020] The display unit (M13) is given the result of the image processing and displays the latent image visualized from the phase modulation pattern (3).

[0021] The image data input to the image processing unit (M11) may be image data of the phase modulation pattern (3) to be visualized captured by the imaging unit (M1), or image data of the phase modulation pattern (3) acquired from various external devices by the external connection unit (M2).

[0022] FIG. 2 shows the appearance of a phase modulation pattern (3) to which the visualization method according to the first embodiment can be applied. As shown in the enlarged view of FIG. 2, the phase modulation pattern (3) in this embodiment has an image width (W1), and colored images (41) formed in a first direction (S1) are arranged at a constant pitch (P1) in a second direction (S2). In FIG. 2, the direction in which the images (41) are arranged (hereinafter referred to as the "second direction (S2)") is the upward direction in FIG. 2, but the same configuration applies even if the images (41) are arranged in the downward direction. Note that the "colored" of the colored images (41) is not particularly limited as long as they are a color different from the base material, such as paper or card, on which the phase modulation pattern (3) is formed.

[0023] Figure 3 is a diagram showing the latent image portion (10) and background portion (30) of the phase modulation pattern (3). As shown in the enlarged view of Figure 3, the phase of a portion of the image line (41) differs, thereby dividing the image into the latent image portion (10) and the background portion (30). In the following explanation, of the images (41) that make up the phase modulation pattern (3), the image line (41) in the latent image portion (10) will be referred to as the "latent image image (11)," and the image line (41) in the background portion (30) will be referred to as the "background image (31)." The latent image image (11) and the background image (31) have the same element width (W1), and the latent image images (11) and the background images (31) are arranged at the same pitch (P1), respectively. In the present invention, "the phases of the images are different" means that the latent image image (11) and the background image (31) are arranged with a shift in a second direction (S2) perpendicular to the first direction (S1). The phase modulation pattern (3) shown in Fig. 3 shows an example in which the latent image image (11) is arranged with a shift in the second direction (S2), but it may also be arranged with a shift in the direction opposite to the second direction (S2) (downward in Fig. 3). In the first embodiment, the phases of the latent image image (11) and the background image (31) differ by 1 / 2 of the pitch (P1).

[0024] Specific processing steps of a method for visualizing the phase modulation pattern (3) having such a configuration will be described in detail with reference to FIGS.

[0025] 4 shows a flowchart of a method for visualizing a phase modulation pattern (3) in the first embodiment. In step S11, image data of the phase modulation pattern (3) is acquired by the multifunction terminal (300). Methods for acquiring image data include capturing an image of the phase modulation pattern (3) by the imaging unit (M1) and acquiring it as image data, acquiring image data from the outside (for example, a cloud or an external server) by the external connection unit (M2), and acquiring image data stored in the storage unit (M12). In the following description, the image data of the phase modulation pattern (3) acquired in step S11 will be described as "original image data (1)."

[0026] In step S12, the pitch (P1) or width (W1) of the object lines (41) constituting the phase modulation pattern (3) is acquired based on the original image data (1) acquired in step S11. As a specific example of step S12, as shown in FIG. 5, in order to acquire the pitch (P1) of the object lines (41), an arbitrary range of the original image data (1) is cut out to acquire a cut-out image (1A), and edges (E) of the object lines (41) are extracted, thereby acquiring the distance between the edges (E) as the pitch (P1). While FIG. 5 shows an example in which the edge (E) of the object line (41) located at the top of the cut-out image (1A) is extracted, the position of the extracted edge (E) is not particularly limited in the present invention, and it is sufficient to extract the edge (E) of a predetermined object line (41). To acquire the width (W1) of the object line (41), it is sufficient to acquire the number of pixels (not shown) adjacent to the object line (41) in the second direction (S2). 5, the direction (second direction (S2)) for obtaining the number of adjacent pixels in the object line (41) is the downward direction, but the number of adjacent pixels in the upward direction may also be obtained. Note that the arbitrary range for obtaining the cropped image (1A) in step S12 is not particularly limited as long as it includes two or more objects (41).

[0027] 5, edge (E) is set as the cut-out position (CP), and image data included in a range obtained by dividing the image data in the second direction (S2) from the cut-out position (CP) by a width (W1) that is half the pitch (P1) is divided into odd-numbered column image data (51A), and image data included in a range obtained by dividing the image data in the second direction (S2) from the edge (Ea) at the bottom of the odd-numbered column image data (51A) by a width (W1) that is half the pitch (P1) is divided into even-numbered column image data (51B). Therefore, the pitch (P1) is the sum of the width (W1) of the odd-numbered column image data (51A) in the second direction (S2) and the width (W1) of the even-numbered column image data (51B) in the second direction (S2). In FIG. 5, the object (41) is divided in the second direction (downward) based on the upper edge (E), but it may be divided based on the lower edge (E), or it may be divided in the upward direction, which is the opposite of the second direction (S2), which is downward. This process is performed on the entire phase modulation pattern (3). Furthermore, if the width (W1) of the object (41) is acquired in step S12, it is also possible to divide the object (41) by the width (W1) of the object (41) from the cut-out position (CP), and to designate the image data in the odd-numbered columns as odd-numbered column image data (51A) and the image data in the even-numbered columns as even-numbered column image data (51B). In the present invention, either the pitch (P1) or the width (W1) of the object (41) may be acquired in step S12, but the following description will be given assuming that the pitch (P1) of the object (41) is acquired.

[0028] In step S14, color inversion processing is performed on only one of the odd-numbered column image data (51A) and the even-numbered column image data (51B).

[0029] Here, color inversion and complementary colors will be described. Color inversion refers to the process of converting the object (41) into a color that is the exact opposite on the color wheel, if the object (41) has a color such as red, blue, or yellow. While it is preferable to invert the color into a color that is the exact opposite on the color wheel, the effects of the present invention can also be achieved with colors that are similar to the exact opposite color. If the object (41) does not have a color, such as white, black, or gray, the process involves converting black to white and white to black. Gray is inverted according to the gray's brightness. For example, dark gray is inverted into light gray. Complementary colors are a combination of colors that are the exact opposite on the color wheel. In the present invention, colors that are the exact opposite on the color wheel are also considered to have a complementary relationship. There are various combinations of two colors that have a complementary relationship, and the present invention is not limited to these. Examples include red and cyan, green and magenta, and blue and yellow. For example, a combination of red and cyan may be used to represent human skin, a combination of blue and yellow to represent a blue sky, and a combination of green and magenta to represent forests or grass.

[0030] Returning to step S14, as shown in FIG. 6, a case will be described where color inversion processing is performed only on the odd-numbered column image data (51A). By this processing, the first color (e.g., black) of the odd-numbered column image data (51A) in the background portion (30) is inverted and becomes the same as the second color (e.g., white) of the even-numbered column image data (51B). Furthermore, the second color (e.g., white) of the odd-numbered column image data (51A) in the latent image portion (10) is inverted and becomes the same as the first color (e.g., black) of the even-numbered column image data (51B). As a result, the odd-numbered column image data (51A) and even-numbered column image data (51B) in the background portion (30) all become the second color (e.g., white), and the odd-numbered column image data (51A) and even-numbered column image data (51B) in the latent image portion (10) all become the second color (e.g., white).

[0031] In step S15, the image data that has been subjected to the inversion process in step S14 is displayed on the display of the multi-function terminal (300).

[0032] As shown in Figure 7(a), original image data (1) of a phase modulation pattern (3) is acquired by a multifunction terminal (300) and visualized using the above-mentioned method for visualizing a phase modulation pattern (3), and a latent image (2) is displayed on the display of the multifunction terminal (300) as shown in Figure 7(b).

[0033] In Fig. 7(b), the latent image (2) is displayed as a positive image in a first color (e.g., black). When color inversion processing is performed only on the even-numbered column image data (51B), the latent image (2) in a second color (e.g., white) is displayed as a negative image against a background of the first color (e.g., black), as shown in Fig. 8. Whether the latent image (2) is a positive image or a negative image is determined by which color of the odd-numbered column image data (51A) or the even-numbered column image data (51B) is inverted.

[0034] (Second embodiment) The method for visualizing a phase modulation pattern (3) according to the second embodiment is directed to a phase modulation pattern (3) formed by latent image lines of two complementary colors.

[0035] 9 is a diagram showing an example of a phase modulation pattern (3) used in the second embodiment. As shown in the enlarged view of FIG. 9, the phase modulation pattern (3) in this embodiment is similar to the first embodiment in that the latent image image (11) of the latent image portion (10) differs in phase from the background image (31) by ¼ of the pitch (P1) relative to the background image (31), and is divided into a first latent image image (11A) on one side and a second latent image image (11B) on the other side, with the center of the latent image image (11) in the second direction (S2) as the boundary, and the first latent image image (11A) and the second latent image image (11B) being configured in a complementary color relationship.

[0036] In this way, the first latent image line (11A) and the second latent image line (11B) form the latent image portion (10) in a complementary color relationship, so that the latent image portion (10) as a whole is visually recognized as gray. On the other hand, by forming the background image line (31) in a single color, the same gray color as the latent image portion (10), it is possible to conceal the latent image (2) when the latent image portion (10) and the background portion (30) are observed visually as a whole.

[0037] In the second embodiment, the relationship between the complementary colors of the first latent image line (11A) and the second latent image line (11B) is a combination of colors that are located exactly opposite each other on the color wheel described above.

[0038] Specific processing steps of the method for visualizing a phase modulation pattern having such a configuration will be described in detail with reference to FIGS.

[0039] FIG. 10 shows a flowchart of a method for visualizing a phase modulation pattern in the second embodiment, and in step S11, original image data (1) of a phase modulation pattern (3) is acquired by a multifunction terminal (300).

[0040] In step S12, the pitch (P1) of the image lines (41) constituting the phase modulation pattern (3) is obtained based on the original image data (1) obtained in step S11. As a specific example of step S12, as shown in Fig. 11, in order to obtain the pitch (P1) of the image lines (41), an arbitrary range of the original image data (1) is cut out to obtain a cut-out image (1A), and edges (E) of the image lines (41) are extracted, thereby obtaining the distance between the edges (E) as the pitch (P1).

[0041] In step S13, as shown in Fig. 11, the edge (E) is set as the cutout position (CP), and image data included in a range obtained by dividing the image data from the cutout position (CP) in the second direction (S2) by a width (W1) that is half the pitch (P1) is divided into odd-numbered column image data (51A), and image data included in a range obtained by dividing the image data from the edge (Ea) at the bottom side of the odd-numbered column image data (51A) in the second direction (S2) by a width (W1) that is half the pitch (P1) is divided into even-numbered column image data (51B). This process is performed for the entire phase modulation pattern (3). Here, the latent image line (11) consisting of the first latent image line (11A) and the second latent image line (11B) is shifted by ¼ of the pitch P1 with respect to the background image line (31). In this case, as with the phase modulation pattern that is the target of visualization in the phase modulation pattern visualization method according to the first embodiment, the edge (E) is used as the cutout position (CP) to divide the image data into odd-numbered column image data (51A) and even-numbered column image data (51B).

[0042] In step S14, color inversion processing is performed on only one of the odd-numbered column image data (51A) and the even-numbered column image data (51B). Here, as shown in FIG. 12, a case will be described in which color inversion processing is performed on only the odd-numbered column image data (51A) to generate color-inverted odd-numbered column image data (51AR). By this processing, in the odd-numbered column image data (51A), the first color (e.g., black) of the background image (31) is inverted to a complementary second color (e.g., white), the third color (e.g., cyan) of the second latent image (11B) is inverted to a complementary fourth color (e.g., red), and areas where no image is present and the second color (e.g., white) are inverted to the first color (e.g., black). Strictly speaking, the background image (31) is formed in gray, but when the gray is inverted, it becomes a color close to white. Therefore, for the sake of convenience, the relationship is described as a first color (e.g., black) and a second color (e.g., white).

[0043] In the even-numbered column image data (51B), areas where there is no image and the second color (e.g., white) is maintained, and the fourth color (e.g., red) of the first latent image (11A) is maintained. As a result, the first latent image (11A) and the second latent image (11B) of the latent image portion (10) are both displayed in the fourth color (e.g., red). Note that the latent image portion (10) also contains a first color (e.g., black) that is the inverse of the second color (e.g., white), but because the area of ​​the first color (e.g., black) is small, it has little effect on the visibility of the latent image (2).

[0044] In step S15, the image data that has been subjected to the inversion process in step S14 is displayed on the display of the multi-function terminal (300).

[0045] FIG. 13 is a diagram showing a state in which the latent image (2) is displayed on the display of the multifunction terminal (300) by the visualization method described above. When the color of only the odd-numbered column image data (51A) is inverted, the latent image (2) is displayed as a positive image in a fourth color (e.g., red). On the other hand, when the color of only the even-numbered column image data (51B) is inverted, the latent image (2) is displayed as a negative image in a third color (e.g., cyan), as shown in FIG. 14. Whether the latent image (2) is a positive image or a negative image is determined by which color of the odd-numbered column image data (51A) or the even-numbered column image data (51B) is inverted.

[0046] (Third embodiment) The method for visualizing a phase modulation pattern (3) according to the third embodiment is similar to the second embodiment in that the phase modulation pattern (3) formed of latent image lines of two complementary colors is the object of visualization, but differs in that in the phase modulation pattern (3), the latent image line (11) consisting of the first latent image line (11A) and the second latent image line (11B) is out of phase with the background image (31) by 1 / 2 the pitch (P1).

[0047] Fig. 15 is a diagram showing an example of a phase modulation pattern (3) used in the third embodiment. As shown in the enlarged view of Fig. 15, the phase modulation pattern (3) in this embodiment is divided into a latent image portion (10) and a background portion (30) by changing the phase of a portion of the image (41). The latent image portion (10) has a latent image portion (11) consisting of a first latent image portion (11A) and a second latent image portion (11B), the background portion (30) has a background image portion (31), and the first latent image portion (11A) and the second latent image portion (11B) are configured in a complementary color relationship. However, this embodiment differs from the second embodiment in that the latent image portion (11) has a phase difference of 1 / 2 the pitch (P1) from the background image portion (31).

[0048] Specific processing content of the method for visualizing a phase modulation pattern having such a configuration will be described in detail with reference to FIGS.

[0049] 16 is a flowchart showing a method for visualizing a phase modulation pattern (3) in the third embodiment. In step S11, the original image data (1) of the phase modulation pattern (3) is acquired by the multifunction terminal (300).

[0050] In step S12, the pitch (P1) of the image lines (41) constituting the phase modulation pattern (3) is acquired based on the original image data (1) acquired in step S11. As a specific example of step S12, as shown in Fig. 17, in order to acquire the pitch (P1) of the image lines (41), an arbitrary range of the original image data (1) is cut out to acquire a cut-out image (1A), and edges (E) of the image lines (41) are extracted, thereby acquiring the distance between the edges (E) as the pitch (P1).

[0051] In step S13, as shown in Fig. 17, a position shifted by 1 / 4 of the pitch (P1) from the edge (E) is set as the cut-out position (CP), and as shown in Fig. 18, the image data included in the range obtained by dividing the cut-out position (CP) in the second direction (S2) by a width (W1) that is half the pitch (P1) is divided into odd-numbered column image data (51A), and the image data included in the range obtained by dividing the odd-numbered column image data (51A) in the second direction (S2) by a width (W1) that is half the pitch (P1) from the edge (Ea) on the lower side of the odd-numbered column image data (51A) is divided into even-numbered column image data (51B). This process is performed for the entire phase modulation pattern (3).

[0052] 18, the odd-numbered column image data (51A) contains the first latent image image (11A) and the background image image (31), but does not contain the second latent image image (11B), and the even-numbered column image data (51B) contains the second latent image image (11B) and the background image image (31), but does not contain the first latent image image (11A). Thus, the first latent image image (11A) exists only in the odd-numbered column image data (51A), and the second latent image image (11B) exists only in the even-numbered column image data (51B).

[0053] In step S14, color inversion processing is performed on only one of the odd-numbered column image data (51A) and the even-numbered column image data (51B). Here, as shown in FIG. 19, a case will be described in which color inversion processing is performed on only the odd-numbered column image data (51A) to generate color-inverted odd-numbered column image data (51AR). By this processing, in the odd-numbered column image data (51A), the first color (e.g., black) of the background image (31) is inverted to a complementary second color (e.g., white), the fourth color (e.g., red) of the first latent image (11A) is inverted to a complementary third color (e.g., cyan), and areas where no image is present and the second color (e.g., white) are inverted to the first color (e.g., black). Strictly speaking, the background image (31) is formed in gray, but when the gray is inverted, it becomes a color close to white. Therefore, for the sake of convenience, the relationship is described as a first color (e.g., black) and a second color (e.g., white).

[0054] In the even-numbered column image data (51B), the areas where there is no image and the second color (e.g., white) are maintained, the first color (e.g., black) of the background image (31) is maintained, and the third color (e.g., cyan) of the second latent image (11B) is maintained. As a result, the latent image portion (10) has only the third color (e.g., cyan) in both the first latent image (11A) and the second latent image (11B).

[0055] In step S15, the image data that has been subjected to the inversion process in step S14 is displayed on the display of the multi-function terminal (300).

[0056] FIG. 20 is a diagram showing a state in which the latent image (2) is displayed on the display of the multifunction terminal (300) by the visualization method described above. When the color of only the odd-numbered column image data (51A) is inverted, the latent image (2) is displayed as a positive image in a third color (e.g., cyan). On the other hand, when the color of only the even-numbered column image data (51B) is inverted, the latent image (2) is displayed as a negative image in a fourth color (e.g., red), as shown in FIG. 21. Whether the latent image (2) is a positive image or a negative image is determined by which color of the odd-numbered column image data (51A) or the even-numbered column image data (51B) is inverted.

[0057] The processing steps in the visualization methods for the phase modulation pattern (3) according to the first, second and third embodiments are shown in an integrated form in the flowchart of FIG.

[0058] In step S11, the original image data (1) of the phase modulation pattern (3) is acquired by the multifunction terminal (300).

[0059] In step S12, an arbitrary range of the original image data (1) is cut out, the edges (E) of the image line (41) are extracted, and the distance between the edges (E) is obtained as the pitch (P1).

[0060] In step S21, it is determined whether the latent image image (11) is composed of a first latent image image (11A) and a second latent image image (11B) of two complementary colors, and whether the phase difference between the latent image image (11) and the background image (31) is 1 / 2 the pitch (P1). If the latent image image (11) is composed of a first latent image image (11A) and a second latent image image (11B) of two complementary colors, and the phase difference between the latent image image (11) and the background image (31) is 1 / 2 the pitch (P1), the process proceeds to step S22; otherwise, the process proceeds to step S13.

[0061] If the process proceeds to step S22, the image data is divided into odd-numbered column image data (51A) and even-numbered column image data (51B) at a position shifted by 1 / 4 of the pitch (P1) from the edge (E) of the image line (41) as the cut-out position (CP).

[0062] If the process proceeds to step S13, the position of the edge (E) of the image line (41) is set as the cutout position (CP) and the image data is divided into odd-numbered column image data (51A) and even-numbered column image data (51B).

[0063] In step S21, an example of a method for determining whether the latent image image (11) is configured by the first latent image image (11A) and the second latent image image (11B) being in a complementary color relationship, and whether the phase difference between the latent image image (11) and the background image (31) is 1 / 2 the pitch (P1), is to store in advance in a memory unit (M12) the configurations of the phase modulation patterns (3) imparted to a plurality of products (information relating to the phase difference between the latent image image (11) and the background image (31) and information as to whether the latent image image (11) is configured in a single color or in a complementary color relationship), and when a user selects a product to be visualized in the app, a process is automatically performed in accordance with the configuration of the phase modulation pattern (3) imparted to the product.

[0064] In step S14, color inversion processing is performed on only one of the odd-numbered column image data (51A) and the even-numbered column image data (51B), for example, the odd-numbered column image data (51A). Here, if the latent image (11) is composed of two complementary colors, a first latent image (11A) and a second latent image (11B), and the odd-numbered column image data (51A) includes only the first latent image (11A), the even-numbered column image data (51B) includes only the second latent image (11B). Therefore, when color inversion processing is performed only on the odd-numbered column image data (51A), the color of the first latent image (11A) in the odd-numbered column image data (51A) is inverted and becomes the same color as the second latent image (11B) in the even-numbered column image data (51B). Conversely, if the odd-numbered column image data (51A) includes only the second latent image line (11B), the even-numbered column image data (51B) includes only the first latent image line (11A). Therefore, when color inversion processing is performed on only the odd-numbered column image data (51A), the color of the second latent image line (11B) in the odd-numbered column image data (51A) is inverted and becomes the same color as the first latent image line (11A) in the even-numbered column image data (51B). This allows the first latent image line (11A) and the second latent image line (11B), which are unified in one of the two colors, to be clearly distinguished from the background image line (31).

[0065] In step S15, the image data that has been subjected to the inversion process in step S14 is displayed on the display of the multi-function terminal (300).

[0066] Furthermore, in step S16, an averaging process may be performed on the image data after the color inversion process. The details of the averaging process will be described later, but by performing the averaging process, it is possible to obtain image data from which noise has been removed.

[0067] Next, an example will be described in which the visualization method for the phase modulation pattern (3) according to the first to third embodiments is applied to a specific phase modulation pattern (3).

[0068] FIG. 23 shows original image data (1) obtained by capturing a phase modulation pattern (3), and in step S11, the original image data (1) of the phase modulation pattern (3) is acquired by the multifunction terminal (300).

[0069] Fig. 24 shows an arbitrary range cut out from the original image data (1) shown in Fig. 23. In step S12, an arbitrary range from the original image data (1) is cut out to obtain a cut-out image (1A), and edges (E) of the image line (41) are extracted from the cut-out image (1A) to obtain the distance between the edges (E) as a pitch (P1).

[0070] In step S13, the original image data (1) of the phase modulation pattern (3) is divided into odd-numbered column image data (51A) and even-numbered column image data (51B) based on the acquired pitch (P1). FIG. 25 is a diagram schematically illustrating the process of step S13, where FIG. 25(a) shows the original image data (1) before division, FIG. 25(b) shows the divided odd-numbered column image data (51A), and FIG. 25(c) shows the divided even-numbered column image data (51B). Note that the diagram in FIG. 25(c) is the even-numbered column image data (data 51B), which is technically white and therefore invisible, but is depicted with diagonal lines to make it easier to understand as a drawing. The dotted lines surrounding each image data indicate the range of the cropped image (1A).

[0071] In Figure 25, for ease of explanation, the image data is shown divided into odd-numbered column image data (51A) in Figure 25(b) and even-numbered column image data (51B) in Figure 25(c), but in reality, it is sufficient to divide it on a single original image data (1).

[0072] In step S14, color inversion processing is performed on either the odd column image data (51A) or the even column image data (51B) shown in FIG. 26(a) (for example, the odd column image data (51A)). FIG. 26(b) shows image data obtained by performing color inversion processing on the gray odd column image data (51A) of FIG. 26(a). If the even column image data (51B) is a color close to white, the gray odd column image data (51A) is inverted to a color close to white, and both the odd column image data (51A) and the even column image data (51B) will be a color close to white; however, for ease of explanation, only the even column image data (51B) is shown with diagonal lines.

[0073] By applying the visualization method described above to the original image data (1) shown in Figure 27(a), it is possible to visualize the latent image (2) from the original image data (1) of the phase modulation pattern (3), as shown in Figure 27(b).

[0074] (averaging process) Figure 28 is a diagram illustrating the averaging process for improving the visibility of the latent image (2) inverted in step S14. As shown in the overall view of Figure 28(a) and the partially enlarged view of Figure 28(b), averaging process corresponding to the pitch (P1) is performed on the image data (1R) that has undergone color inversion process in the vertical direction of the image line (41), i.e., in the second direction (S2), thereby making it possible to visualize the latent image (2) in which the differences in pixel values ​​between pixels adjacent in the second direction (S2) are averaged. Note that while the diagram in Figure 28 uses simple figures to explain the averaging process, in reality, the averaging process is performed on the latent image (2) shown in Figure 27(b).

[0075] The averaging process shown in FIG. 28 will be described in detail with reference to FIG. 29. First, original image data (1) of the phase modulation pattern (3) is shown in FIG. 29(a). The above-described method for visualizing the phase modulation pattern (3) is applied to this original image data (1). FIG. 29(b) shows a state in which color inversion processing is performed on only one of the odd-numbered column image data (51A) and the even-numbered column image data (51B) (here, the odd-numbered column image data (51A)) as image data prior to the averaging process. If there is a difference in the image line width or pitch (P1) between the image lines (41) in the phase modulation pattern (3), or if the phase modulation pattern (3) is tilted due to the orientation of the camera during imaging, linear noise along the first direction (S1) will appear in the image data after image processing, as shown in FIG. 29(b).

[0076] In contrast, by performing averaging processing in a second direction (S2) perpendicular to the linear noise, the difference in pixel values ​​between pixels adjacent in the second direction (S2) is reduced, and a noise-removed latent image (2) is obtained as shown in Figure 29(c). As an example of the averaging processing, a known image processing method using filter processing may be used. Furthermore, since performing averaging processing blurs the contours of the latent image (2), various corrections may be performed after the averaging processing, as necessary, to enhance the contrast of the image data. As an example of various corrections, known image processing methods such as a method of changing the tone curve of the image data and level correction may be used.

[0077] (An example of how to obtain the line pitch) Here, an example of a method for obtaining the pitch (P1) of the image lines (41) by a statistical method in step S12 will be described.

[0078] FIG. 30(a) shows a cut-out image (1A) obtained by cutting out and enlarging an arbitrary range of the original image data (1).

[0079] FIG. 30(b) shows the image obtained by performing binarization processing on the cut-out image (1A) shown in FIG. 30(a) to clarify the image lines (41).

[0080] Figure 30(c) shows an extracted image of only the upper boundary of each object (41) shown in Figure 30(b). As shown in the enlarged view of Figure 30(c), starting from the upper left pixel of the cut-out image (1A), scanning is performed along the second direction (S2) to count the number of pixels up to the upper boundary of the next object (41). In other words, the number of pixels between the edges of the object (41) in the second direction is counted.

[0081] This process is repeated along the first direction (S1), counting the number of pixels between edges of the image line (41) in the second direction (S2). When the first stage is completed, the process moves to the second stage, where the number of pixels is counted in the same manner.

[0082] 30(d) is a graph showing the values ​​of the number of pixels counted by the above-mentioned process. The most frequent value among the counted number of pixels is estimated to be the pitch of the image line (41) and is obtained as the pitch (P1).

[0083] Furthermore, in step S12, when the width (W1) of the object line (41) is obtained by a statistical method, the number of pixels in the width direction of the object line (41) is counted at multiple locations in a manner similar to the method for obtaining the pitch of the object line (41) by a statistical method, and the most frequent value is obtained as the width (W1) of the object line (41).

[0084] The method of obtaining the pitch (P1) of the image lines (41) using a statistical method is not limited to the above, and other methods such as checking the periodicity of the image lines (41) using spatial frequency conversion, or filtering to extract a specific period may also be used.

[0085] When the phase modulation pattern (3) is captured by a camera to obtain the original image data (1), various corrections can be performed. For example, a method for optimizing the capture of image data during capture or a method for correcting the captured original image data (1) can be considered.

[0086] As a first method for optimizing the capture of image data during imaging, imaging assistance lines (SAL1, SAL2) are displayed on the imaging screen of the multifunction terminal (300) as shown in FIG.

[0087] By adjusting the edges of the captured image (1B) displayed while capturing the phase modulation pattern (3) so that they are parallel to the capture assist lines (SAL1, SAL2), tilt, etc. can be reduced. Note that the form of the capture assist lines is not limited to this, and for example, the capture assist lines may be displayed so as to surround the image in a square, or only the four corners may be displayed as capture assist lines.

[0088] As a second technique, as shown in Fig. 32, the captured image (1B) is adjusted to obtain the optimum distance, angle, and tilt with respect to the shooting assistance line (SAL3) displayed as a square, for example. Here, for example, the multifunction terminal (300) may display an announcement on the display or notify by voice, such as "Please come closer" or "Please move the camera to the right."

[0089] As a third technique, as shown in FIG. 33, an image is automatically captured under optimal imaging conditions, for example, at a timing when the captured image (1B) matches a shooting assistance line (SAL3).

[0090] As a method for correcting the captured original image data (1), as shown in FIG. 34, the tilt angle θ1 of the virtual line (VL1) that coincides with the upper end of the captured image (1B) before correction and the virtual line (VL2) that coincides with the lower end of the captured image (1B) relative to the reference line (RL) for angle correction on the imaging screen of the multifunction terminal (300) is compared with a specified value. If the specified value is, for example, 0 degrees, the image is tilted by the tilt angle θ1 from this specified value, and angle correction is performed. If the tilt angle θ1 coincides with the specified value, angle correction is not performed. A known technique may be used for the angle correction, for example, an affine transformation. Alternatively, angle correction may be performed based on the calculated tilt by performing spatial frequency transformation on the original image data (1), as disclosed in Patent Document (JP 2022-150301).

[0091] The captured image (1B) obtained by performing angle correction in this manner is shown in Figure 35. The inclination angle θ1 of the virtual line (VL1) coinciding with the upper end of the captured image (1B) and the virtual line (VL2) coinciding with the lower end with respect to the reference line (RL) becomes 0 degrees, and angle correction is completed.

[0092] Note that angle correction may increase the size of the image data displayed on the display depending on the angle, but this does not cause any problems. However, trimming or other processing may be performed as necessary. Alternatively, processing to adjust the contrast may be performed to improve the visibility of the image data displayed on the display.

[0093] So far, we have explained an example of performing angle correction on captured image data, but it is also possible to visualize the latent image (2) without performing angle correction by performing image processing from step S12 to step S14 shown in the flowchart of FIG. 22 in a direction perpendicular to the virtual line (VL1) that coincides with the upper end of the captured image (1B) shown in FIG. 34 or the virtual line (VL2) that coincides with the lower end.

[0094] The phase modulation pattern to be visualized by the method for visualizing a phase modulation pattern according to the above embodiment can be applied in various forms to anti-counterfeit printed materials such as various certificates, product packages, and the like.

[0095] For example, information such as the certificate holder's facial image, address, date of birth, etc. can be formed as a phase modulation pattern on various certificates such as passes, resident registration cards, identification cards, resident registration cards, passports, and cards, and this phase modulation pattern can be read and visualized using a multi-function terminal to determine authenticity.

[0096] Alternatively, information such as a certification mark can be embedded in the product packaging of a branded product as a phase modulation pattern, and this phase modulation pattern can be read and visualized using a multi-function terminal, making it possible to determine whether the product is genuine or not.

[0097] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the technical scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the technical scope and spirit of the invention, and are also included in the scope of the inventions and their equivalents as set forth in the claims.

[0098] The above-described method for visualizing a phase modulation pattern can be implemented by hardware in a multifunction terminal such as a smartphone, mobile phone, tablet terminal, or personal computer, or by software executed by the multifunction terminal. When implemented by software, the method can be implemented by a processing unit or the like of the hardware, stored as one or more instructions or codes on a computer-readable medium of the multifunction terminal or transmitted via the computer-readable medium of the multifunction terminal or computer, for example. The computer-readable medium may include a computer-readable medium corresponding to a tangible medium such as a data storage medium or a communication medium, including, for example, any medium that enables the transfer of a computer program from one place to another according to a communication protocol. In this way, the computer-readable medium may correspond to a non-transitory readable medium or a communication medium such as a signal, carrier wave, or the like. [Explanation of symbols]

[0099] 1. Original image data 1A Cutout image 1B Captured image 1R Image data with inverted colors 1RA Image data with color inverted and averaged 2 Latent Image 3 Phase modulation pattern 10 Latent Image Section 11 Latent Image Line 11A First latent image 11B Second latent image 11AR Color-reversed latent image 30 Background section 31 Background lines 31R Color-reversed background image 41 Lines 51A odd-numbered column image data 51AR Color-inverted odd-numbered column image data 51B Even column image data 300 Multi-function Terminals M1 imaging unit M2 external connection M11 Image Processing Unit M12 storage section M13 Display section E, Ea edge CP Cutout Position S1, S2 direction SAL1, SAL2 photography auxiliary lines VL1, VL2 virtual lines RL reference line θ1 tilt angle

Claims

1. A method for visualizing a phase modulation pattern in which a plurality of image lines having a color different from the color of a substrate formed in a first direction are arranged at a constant pitch in a second direction, and the image lines are divided into a latent image portion and a background portion by partially varying the phases of some of the image lines in the second direction, acquiring original image data of the phase modulation pattern; acquiring a pitch at which the image lines are arranged or a width of the image lines from the acquired original image data; dividing the original image data in the second direction into odd-numbered column image data and even-numbered column image data at intervals of 1 / 2 the pitch at which the image lines are arranged or at intervals of the width of the image lines; performing color inversion processing on either the odd-numbered column image data or the even-numbered column image data; A method for visualizing a phase modulation pattern, comprising a step of displaying the image data that has undergone the color inversion processing on a display.

2. The step of dividing the image data into odd-numbered column image data and even-numbered column image data includes: The configuration of the phase modulation pattern is i) when the image lines constituting the latent image portion are monochromatic, dividing the original image data based on the edges of a predetermined image line; ii) when the phases of the image lines of the latent image portion and the background portion differ by less than half the pitch at which the image lines are arranged, and the image lines constituting the latent image portion are composed of colors that are complementary to each other with respect to the center in the second direction, dividing the original image data based on the edges of the image lines; iii) When the phases of the image lines of the latent image portion and the background portion differ by half the pitch at which the image lines are arranged, and the image lines constituting the latent image portion are composed of colors that are complementary to each other with respect to the center in the second direction, the original image data is divided at a position shifted from the edge of the image line by either one-quarter of the pitch at which the image lines are arranged or one-half the width of the image line.

3. The method for visualizing a phase modulation pattern according to claim 1 or 2, further comprising a step of performing an averaging process on image data in which color inversion processing has been performed on either the odd-numbered column image data or the even-numbered column image data.

4. The step of acquiring the pitch at which the image lines are arranged or the width of the image lines includes: i) When obtaining the pitch at which the image lines are arranged, performing a process of counting the number of pixels between edges of the image lines in the original image data at a plurality of locations, and acquiring the most frequently occurring number of pixels as the pitch at which the image lines are arranged; ii) When obtaining the width of the image line, 4. The method for visualizing a phase modulation pattern according to claim 3, wherein a process of counting the number of pixels of the image line in the width direction of the image line is performed at a plurality of locations in the original image data, and the most frequently occurring number of pixels is obtained as the width of the image line.

5. 10. Software for visualizing a phase modulation pattern, which causes a multi-function terminal to execute the method for visualizing a phase modulation pattern according to claim 1.

Images