Latent image printed matter and method for making the same

Abstract

To provide a latent image printed matter which includes a printed pattern that achieves concealment of a latent image pattern without being affected by dot gain, and whose overall concentration is visible in balance with the naked eye.SOLUTION: The present invention is a latent image printed matter whose overall concentration is in balance so as to improve concealment of a latent image pattern by adding or deleting a line drawing that mitigates a concentration to or from a central region in a plurality of unit aggregates disposed so as to even out a line drawing area ratio of the unit aggregates which constitute a printed pattern included in a substrate and are disposed in a matrix shape.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a latent image print that can be output from any printing machine or printer, and a method for producing the same, in the field of security prints that require prevention of counterfeiting or alteration of banknotes, passports, securities, certificates, important documents, etc. [Background technology]

[0002] It is important to prevent counterfeiting and alteration in security printed matters such as banknotes, passports, securities, certificates, important documents, etc. One of the counterfeit prevention measures is printed matters with latent image patterns (hereinafter referred to as "latent image printed matters"), which are printed with patterns formed by the arrangement of halftone dots or lines or special materials, making characters, figures, etc. invisible to the naked eye.

[0003] As a representative example, Figure 1 is a schematic diagram showing an example of a conventional latent image print (1'). When the latent image print (1') shown in Figure 1(a) is copied using a copier, a latent image pattern (13') in the form of the word "copy" shown in Figure 1(b) appears on the copy, providing a copy deterrent effect. Such latent image prints (1') have long been used for certificates, important documents, etc., and are composed of a latent image portion (2) made of halftone dots of a size that is easy to reproduce using a copier, and a background portion (3) made of halftone dots of a size that is difficult to reproduce using a copier. By making the density of the latent image portion (2) and the background portion (3) uniform, the latent image pattern (13') in the form of the word "copy" is concealed (see, for example, Patent Document 1).

[0004] As described above, in the latent image print (1') intended to have a copy deterrent effect, the dots and lines that make up the latent image portion (2) and the background portion (3) are formed in different sizes. When the latent image print (1') is printed using a printing press, a phenomenon called dot gain occurs in the dots that make up the print pattern (8').

[0005] Figure 2 is a schematic diagram showing the mechanism of dot gain. According to Non-Patent Document 1, dot gain is a phenomenon in which the diameter of the ink dots (6b) printed on the substrate (5) during printing becomes larger than the diameter of the dots (6a) formed on the printing plate surface (4), as shown in Figure 2. This phenomenon is said to occur when the ink adhering to the dots (6a) on the printing plate surface (4) is crushed and spread by the pressure applied when it is transferred from the printing plate surface (4) to the substrate (5) or blanket.

[0006] This phenomenon occurs because the ink film thickness remains constant regardless of the size of the halftone dot (6b), so if the printing pressure is the same, the width of the halftone dot (6b) will also be the same. In other words, the smaller the halftone dot (6a), the greater the rate at which the diameter increases due to dot gain. Furthermore, dot gain is not a phenomenon limited to printing presses; it also occurs when printing masters using printers, although the mechanism is different. Printers, in particular, require a process known as calibration, in which the master design values ​​are adjusted to suit the printer's printing method, image quality, and other characteristics.

[0007] On the other hand, in recent years, due to the improvement in convenience, a service has been provided in which certificates and the like are printed from multi-copy machines installed in convenience stores nationwide. If the halftone dots and lines are different between the latent image portion (2) and the background portion (3), as in the latent image print (1') in Patent Document 1, it would be necessary to feed back the output results and perform calibration on all the printers owned by each convenience store.

[0008] Furthermore, the latent image print (1') intended to deter copying, as in Patent Document 1, reveals a latent image pattern (13') on the copy, making it easy to determine whether the copy is not the original. However, to verify the latent image pattern (13') to determine the authenticity of the original, it is necessary to copy the latent image print (1') using a copier and reveal the latent image pattern (13'). This method is dependent on the environment in which the copier is installed, such as at a city hall counter, and is inconvenient in that the latent image pattern (13') cannot be easily verified when traveling by public transportation, such as at a station or airport, or when entering a facility.

[0009] Therefore, in order to eliminate such inconveniences, the applicant has disclosed a latent image print (1'') that uses lines of the same shape and size for the latent image portion (2) and the background portion (3) to form a highly confidential latent image pattern (13''), while being unaffected by factors that affect the print result, such as dot gain, when output from any printing machine or printer (see, for example, Patent Document 2).

[0010] FIG. 3 is a diagram showing the state in which the latent image pattern of the latent image print (1'') of Patent Document 2 is visualized by a latent image reading device (11). The latent image print (1'') of Patent Document 2 can visualize and display the latent image pattern (13'') on a screen using a reading device (for example, a device with an application installed on a smartphone) that extracts singular points of the latent image pattern (13'') from a captured image (not shown) obtained by photographing the latent image print (1''). Therefore, when used on certificates, important documents, etc., it has become possible to easily determine the authenticity of the original by comparing the information written on the latent image print (1'') with the visualized information. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Special Publication No. 58-47708 [Patent Document 2] Patent No. 6976525 [Non-patent literature]

[0012] [Non-Patent Document 1] "Printing Terminology Handbook: Basic Edition" (2006) by the Printing Society of Japan Publishing Division Summary of the Invention [Problem to be solved by the invention]

[0013] FIG. 4 is a schematic diagram showing the latent image print (1'') of Patent Document 2, which has a printed pattern (8'') on a printable substrate (5) such as paper or card, in which a latent image pattern (13'') that becomes visible under specific conditions is applied. It is a schematic diagram showing the line configuration that makes up the printed pattern (8''). It shows a schematic diagram (8a) in which the printed pattern (8'') is enlarged so that the configuration in which multiple first units (9) and second units (10), which are the smallest units of the line representing the latent image portion (2) and the background portion (3), are arranged in a matrix can be seen, and a schematic diagram (8b) in which the divisions of the first units (9) or second units (10) are shifted by 0.5 units horizontally and 0.5 units vertically, and a central region (T) having the same area as the first units (9) and second units (10) can be seen.

[0014] The first unit (9) and the second unit (10) have image lines of the same shape but different orientations, and therefore the image area ratio in each unit (9, 10) is the same, so the density of the latent image portion (2) and the background portion (3) is observed uniformly, making the latent image pattern (13'') invisible.

[0015] However, in this state, the image area ratio per unit area of ​​each unit (9, 10) is constant, but the image area ratio per unit area in the central region (T) varies depending on the arrangement of the first unit (9) or the second unit (10) (2 units vertically by 2 units horizontally) (hereinafter referred to as the "unit assembly") present in the central region (T).

[0016] For example, as in the central region (T1) in the schematic diagram (8b) of Figure 4, when the shape consisting of four lines arranged in a unit assembly becomes a cross shape by switching between the first unit (9) and the second unit (10), the central region (T1) has a larger line area ratio per unit area and appears to be darker.

[0017] Furthermore, when the shape of the four image lines arranged in the unit assembly becomes square by switching between the first unit (9) and the second unit (10), as in the central region (T2), the image area ratio per unit area of ​​the central region (T2) becomes smaller, and the density is perceived as light. As such, because the image area ratio per unit area of ​​the central region (T) differs, the density is perceived as uneven in parts to the naked eye, and therefore, embedding a latent image pattern (13") in a flat printed pattern (8") such as a tint block creates an unnatural feeling, and there is room for improvement.

[0018] The present invention aims to solve the above-mentioned problems, and provides a latent image print that can conceal a latent image pattern without being affected by dot gain when output from any printing machine or printer, and that has a balanced overall density that can be seen with the naked eye regardless of the location where the latent image pattern is embedded. [Means for solving the problem]

[0019] The present invention is a latent image print having a printed pattern with a latent image pattern on at least a part of a substrate, characterized in that the printed pattern is arranged in a matrix of multiple unit assemblies, each of which consists of four units arranged adjacently in a 2x2 pattern in the X and Y directions, and each of the multiple arranged units has either a first image line formed in correspondence with the latent image pattern or a second image line formed in correspondence with the background of the latent image pattern, the first image line and the second image line having the same image area ratio within the unit and differing in at least one of the angle and shape at which they are arranged, and the multiple arranged unit assemblies have the same image area ratio in the central region.

[0020] The present invention also provides a latent image print, characterized in that the central region has a third image line in a plurality of unit aggregates, the third image line having the same length, shape and color as the image line.

[0021] The present invention also provides a method for producing a latent image print, comprising: a basic latent image pattern data input step of inputting basic latent image pattern data that is the basis of a latent image pattern; converting the basic latent image pattern data input in the basic latent image pattern data input step into monochrome image data; then converting the monochrome image data into two-level gradation to generate two-level image data consisting of white pixels and black pixels; and then replacing one of the white pixels and the black pixels with a first unit having first basic image data that is the basis of a first image line, and the other with a second unit having second basic image data that is the basis of a second image line, thereby producing X This method for producing latent image prints comprises a base image data creation process for generating base image data in which a plurality of unit aggregates are arranged, each of which consists of four units arranged adjacently in a 2x2 pattern in the X and Y directions; a density adjustment process for generating print pattern data by adjusting the imbalance in density in the central area of ​​the base image data created in the base image data creation process by deleting or adding lines from the plurality of unit aggregates; and a formation process for forming a print pattern by printing or laser on a substrate using the print pattern data created in the density adjustment process. [Effects of the Invention]

[0022] The latent image print of the present invention balances the density of the entire latent image print observed with the naked eye by adding and deleting image lines that reduce the density in each unit so as to make the image area ratio in each unit constant, thereby improving the concealment of the latent image pattern compared to conventional latent image prints. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram showing an example of a conventional latent image print (1'). [Figure 2] Schematic diagram showing the mechanism of dot gain. [Figure 3]FIG. 1 is a diagram showing the state in which the latent image pattern of the latent image print (1'') of Patent Document 2 is visualized by a latent image reading device (11). [Figure 4] Schematic diagram showing the latent image print (1'') of Patent Document 2. [Figure 5] FIG. 1 is a diagram showing the state in which the latent image pattern (13) of the latent image print (1) of the present invention is visualized by a latent image reading device (11). [Figure 6] Schematic diagram showing an enlarged print pattern (8) of the present invention. [Figure 7] FIG. 2 is a schematic diagram showing an image configuration according to the first embodiment. [Figure 8] FIG. 2 is a schematic diagram showing an image configuration in pixels according to the first embodiment. [Figure 9] FIG. 1 is a schematic diagram showing a unit assembly (F) of the present invention in which the concentration imbalance is alleviated. [Figure 10] FIG. 3 is a flowchart showing a method for producing a latent image print (1) described in the first embodiment of the present invention. [Figure 11] FIG. 10 is a detailed flowchart of the base line data creation process in STEP 2 of the present invention. [Figure 12] FIG. 10 is a detailed flowchart of the density adjustment step of STEP 3 of the present invention. [Figure 13] Schematic diagram showing that the unit assembly (F) of the present invention is entirely composed of the second image line (S2). [Figure 14] FIG. 10 is a schematic diagram showing a unit assembly (F) on which the concentration relaxation treatment of the present invention has been performed. [Figure 15] FIG. 4 is a schematic diagram illustrating the image area ratio per unit area of ​​the central region (T). [Figure 16] FIG. 10 is a schematic diagram showing an example of basic print pattern data (D8) output from an inkjet printer (14). [Figure 17] FIG. 10 is a schematic diagram showing an example in which the first object (S1) and the second object (S2) of the basic printing pattern data (D8) are output from a printer (14) that is a laser printer. [Figure 18] 10 is a schematic diagram showing an example of a combination of angles (d) of a first object (S1) and a second object (S2) that does not depend on the output direction of a printer (14). FIG. [Figure 19] Schematic diagram showing the result of applying a differential filter (f1). [Figure 20] FIG. 2 is a schematic diagram showing the result of applying a differential filter (f2) to a first object (S1) and a second object (S2). [Figure 21] FIG. 10 is a schematic diagram showing the conversion from an output image (16-1) to an averaged image (20-1). [Figure 22] FIG. 1 is a schematic diagram showing the process of visualizing the latent image pattern (13) of the printed pattern (8) using a latent image reading device (11). [Figure 23] FIG. 10 is a schematic diagram showing a latent image print (1) according to a second embodiment. [Figure 24] FIG. 10 is a diagram showing the arrangement of a fourth object (S4) according to the second embodiment. [Figure 25] FIG. 10 is a schematic diagram showing an example of the arrangement of a fourth object (S4) according to the second embodiment. [Figure 26] FIG. 10 is a schematic diagram showing a latent image print (1) according to a third embodiment. [Figure 27] Schematic diagram showing a change from a first color (C1) to a second color (C2). [Figure 28] FIG. 11 is a diagram showing an example of a combination of multiple colors according to the third embodiment. [Figure 29] FIG. 10 is a diagram showing a combined use of the second and third embodiments. [Figure 30] FIG. 13 is a schematic diagram showing a change in color for forming a second latent image pattern (13-2) according to the third embodiment. [Figure 31] FIG. 13 is a schematic diagram showing a method for observing the second latent image pattern (13-2) according to the third embodiment. [Figure 32] FIG. 10 is a schematic diagram showing a method for verifying the unique information “A” possessed by the latent image pattern (13). [Figure 33] 1 is a schematic diagram showing a certificate-type latent image print (1) of this embodiment. [Figure 34] 10 is a schematic diagram showing the units (9, 10) and the fourth image line (S4) that form the print pattern (8) of this embodiment. FIG. [Figure 35] 35 is a schematic diagram showing a print pattern (8) consisting of the image configuration shown in FIG. 34. [Figure 36] FIG. 10 is a schematic diagram showing a collation result of the present embodiment. [Figure 37] FIG. 1 is a plan view comparing the latent image print (1'') of Patent Document 2 with the latent image print (1) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The form for implementing the present invention will be described with reference to the drawings, but the present invention is not limited to the form for implementing the present invention described below, and various other embodiments are included as long as they are within the scope of the technical idea described in the claims.

[0025] (Embodiment 1) 5 is a diagram showing the state in which the latent image pattern (13) of the latent image print (1) of the present invention is visualized by a latent image reading device (11), and the printed pattern (8) has a latent image pattern (13) that becomes visible under specific conditions, at least in a portion of a printable substrate (5) such as paper or card. This printed pattern (8) has a color different from that of the substrate (5) so that it can be recognized visually as a pattern. In addition, the printed pattern (8) is composed of a plurality of first units (9) and second units (10), which are the minimum units of the image configuration described below, arranged in the X and Y directions.

[0026] When the latent image print (1) of the present invention is observed using, for example, a reading and inspection device for latent image print (1'') shown in Patent Document 2 (here, a latent image reading device (11) on which an application for visualizing the latent image pattern (13) is installed on a smartphone), the printed pattern (8) is visualized as the latent image pattern (13), a "phoenix," by the camera function and application of the latent image reading device (11), and is displayed on the screen (12).

[0027] Figure 6(a) is an enlarged schematic diagram of the printed pattern (8) of the present invention. The printed pattern (8) is composed of a plurality of unit aggregates (F) arranged in a matrix, each of which consists of four units arranged adjacently in a 2x2 pattern in the X and Y directions, as shown in Figure 6(b). Note that in the present invention, each unit (9, 10) and unit aggregate (F) is shown as an image line, but these are virtual lines and are not actually formed as printed images in the latent image print (1). Furthermore, although one unit aggregate (F) is shown as a solid line, these are also virtual lines.

[0028] As shown in FIG. 6(b), among the multiple unit assemblies (F) that make up the print pattern (8), a third object (S3) is arranged in a central region (T) of the unit assembly (F), which appears light in density, in an area where the first object (S1) and / or the second object (S2) are not present. By arranging the third object (S3), the image area ratio per unit area in the central region (T) becomes larger than before the third object (S3) was arranged, and the image area ratios of the multiple arranged unit assemblies (F) become equal. Therefore, the imbalance in density seen with the naked eye is alleviated compared to conventional latent image prints (1''). The invention will be described in detail below.

[0029] 7 is a schematic diagram showing the image structure in embodiment 1. This image structure is the smallest unit called a unit, and the first unit (9) and the second unit (10) have the same shape and size, with the vertical and horizontal dimensions (u) ranging from 0.18 mm to 0.50 mm.

[0030] When the printing pattern data (8D) that forms the basis of the printing pattern (8) equipped with the first unit (9) and the second unit (10) is output from the printer (14), it is preferable that the data be composed of five or more pixels in both the vertical and horizontal directions, taking into consideration the drawing performance of the printer (14). Converting these five pixels, the dimension (u) is approximately 0.21 mm for a printer (14) with an output resolution of 600 dpi, and the dimension (u) is approximately 0.18 mm for a printer (14) with an output resolution of 720 dpi.

[0031] Because the latent image print (1) of the present invention is intended to form a highly confidential latent image pattern (13), it is preferable that the individual lines (S1, S2, S3) are not recognized as separate lines when viewed from a human's near vision. For example, if each unit (9, 10) is small, the lines (S1, S2, S3) are not recognized as lines when viewed from a human's near vision, but are observed as uniform density. However, if each unit (9, 10) is large, the lines (S1, S2, S3) are recognized as separate lines. Although this depends on the viewing conditions of the latent image print (1), if the dimension (u) shown in FIG. 7 exceeds 0.50 mm, the lines tend to be recognized as lines (S1, S2, S3) when viewed from a human's near vision. Therefore, it is preferable that the dimension (u) be 0.50 mm or less.

[0032] Furthermore, if it is smaller than 0.18 mm, it becomes difficult to form the first object line (S1) and the second object line (S2) using the printer (14) etc. However, the dimensions (u) of the first object line (S1) and the second object line (S2) formed in each unit (9, 10) are determined taking into consideration the current performance of the printer (14), and it goes without saying that this range will change appropriately as the performance of the printer (14) improves in the future, and will also vary depending on differences in conditions such as the checker's eyesight and viewing angle, but this is merely an example and does not limit the technical scope of the present invention.

[0033] Further, although the units (9, 10) are described as having a square shape as an example, the units (9, 10) of the present invention may have a rectangular or hexagonal shape.

[0034] The first unit (9) has a first object (S1), and the second unit (10) has a second object (S2). The object widths of the first object (S1) and the second object (S2) are preferably within a range of 1 / 5 to 1 / 10 of the dimension (u) of each unit (9, 10). For example, when the dimension (u) of each unit (9, 10) is 0.423 mm, the object widths of the first object (S1) and the second object (S2) are 0.40 to 0.85 mm. When the object widths of the first object (S1) and the second object (S2) are greater than 1 / 5 of the dimension (u) of each unit (9, 10), the latent image pattern (13) becomes more visible. If the image width of the first image line (S1) and the second image line (S2) is narrower than 1 / 10 of the dimension (u) of each unit (9, 10), it becomes difficult to read the first image line (S1) and the second image line (S2) and reproduce the latent image pattern (13).

[0035] Although the first object (S1) and the second object (S2) are shown as having the same shape and size, the shapes and sizes do not have to be equal as long as the image area ratios of the first object (S1) and the second object (S2) arranged within each unit (9, 10) are all equal. For example, the image area ratios can be made equal by making the length of the first object (S1) shorter than that of the second object (S2) and making the image width of the first object (S1) wider than that of the second object (S2). It is also preferable to use shapes with different aspect ratios so that the latent image pattern (13) can be visualized by the latent image reader (11). The aspect ratio of the objects (S1, S2) is preferably 1:2 or greater. FIG. 8 is a schematic diagram showing the image configuration in pixels according to the first embodiment. For example, in the case of FIG. 8, the aspect ratio is 1:4.

[0036] Furthermore, the first object line (S1) of the first unit (9) and the second object line (S2) of the second unit (10) are arranged at angles (d) within the range of 90 degrees ± 45 degrees within each unit (9, 10).

[0037] For example, in the case of Fig. 7 described above, the angle (d) of the second object line (S2) of the second unit (10) differs by 90 degrees from the first object line (S1) of the first unit (9). As described above, the first object line (S1) of the first unit (9) and the second object line (S2) of the second unit (10) may freely be determined in combination with each other as long as the angle (d) of the second object line (S2) relative to the first object line (S1) satisfies the requirement that the angle (d) of the second object line (S2) differs within the range of 90 degrees ± 45 degrees.

[0038] FIG. 9 is a schematic diagram showing a unit assembly (F) of the present invention in which density imbalance is alleviated. To alleviate the apparent density imbalance, in the present invention, as shown in FIG. 9(a), the image area of ​​the second object (S2) is made smaller than the image area of ​​the first object (S1) in the central region (T) where the density appears dark. As an example, in FIG. 9(a), the image area is made 10% smaller. Conversely, the image area of ​​the first object (S1) may be made smaller than the image area of ​​the second object (S2). This reduces the image area ratio per unit area in the central region (T), thereby alleviating the density imbalance as seen with the naked eye.

[0039] 9(a), the central region (T) in the unit assembly (F) is a region having the same area as the first unit (9) and the second unit (10), with the center (J) of the unit assembly (F) as the center of the central region (T). Specifically, it is a region having the same area as the first unit (9) and the second unit (10), shifted by half the predetermined interval (Z1) at which the first unit (9) or the second unit (10) is arranged, that is, by 0.5 units (Z2) in the X direction and 0.5 units (Z3) in the Y direction.

[0040] Furthermore, as shown in Figure 9(b), in the central region (T) where the density is perceived as light, a third object (S3) is additionally placed in an area where the first object (S1) and / or the second object (S2) present in the central region (T) are absent. As an example, in Figure 9(b), when the image area ratio of the first object (S1) or the second object (S2) is taken as 100%, the third object (S3) is formed at 0.5 to 20%. This increases the image area ratio per unit area in the central region (T), thereby alleviating the imbalance in density as seen with the naked eye.

[0041] (Method for creating latent image prints) Next, a method for creating the latent image print (1) described in the first embodiment of the present invention will be described with reference to Fig. 10. The method includes a base latent image pattern data input process as STEP 1, a latent image pattern unit creation process as STEP 2, a density adjustment process as STEP 3, and a printing process as STEP 4. Each step will be described below.

[0042] First, in STEP 1, a base latent image pattern data input process, base latent image pattern data (D1) that will be the basis for the latent image pattern (13) in the latent image print (1) is input to a personal computer, etc. The base latent image pattern data (D1) may be any of characters, numbers, symbols, marks, facial patterns, landscapes, etc., and is not particularly limited.

[0043] Next, in the basic image data creation step of STEP 2, the basic latent image pattern data (D1) is converted into basic image data (D4) consisting of a first image (S1) and a second image (S2).

[0044] FIG. 11 is a flowchart showing in detail the basic image data creation process in STEP 2.

[0045] First, as shown in STEP 2-1, the basic latent image pattern data (D1) obtained in the basic latent image pattern data input process of STEP 1 is converted into monochrome image data (D2). The basic latent image pattern data (D1) can be converted into monochrome image data (D2) using commercially available design software such as Adobe Illustrator (registered trademark).

[0046] Next, as shown in STEP 2-2, the monochrome image data (D2) is converted to a resolution of 60 dpi and then converted to two gradations using error diffusion dithering, resulting in the generation of monochrome two-gradation image data (D3) with a coarse pixel density, known as a mosaic. Note that although the resolution is set to 60 dpi as an example here, it is not limited to 60 dpi as long as it can be converted to a relatively coarse resolution.

[0047] This binarization process can be performed using simple binarization or halftoning, and halftoning can be further divided into dot-concentrated halftoning and dot-dispersed halftoning. Dot-concentrated halftoning can be performed using AM screens or specially shaped screens, while dot-dispersed halftoning can be performed using pattern dithering or the error diffusion dithering used in the present invention. With recent technological advances, it is now possible to use neural networks (machine learning) for dot-concentrated halftoning and dot-dispersed halftoning. The method to be used can be selected appropriately based on the creator's intended use.

[0048] Next, as shown in STEP 2-3, basic image data (D4) consisting of a first object (S1) and a second object (S2) is generated from the two-tone image data (D3). The basic image data (D4) is generated by replacing one of the two-tone image data (D3) consisting of white pixels and black pixels with a first unit (9) having the first object (S1) and the other with a second unit (10) having the second object (S2).

[0049] As described as the prior art using FIG. 3, the base line data (D4) generated in STEP2 has an uneven density. The latent image print (1) of the present invention can also be formed by arranging the third line (S3) shown in FIG. 9 in accordance with the uneven density visible to the naked eye. However, as described next, in the density adjustment step of STEP3, it is also possible to form by executing deletion and addition of lines for each unit U[x,y] which is the minimum unit by an algorithm. Here, [x] is the number of steps counted from the left in the horizontal direction for the unit, and [y] is the number of steps counted from the top in the vertical direction for the unit.

[0050] FIG. 12 is a flowchart diagram detailing the density adjustment step of STEP3. First, in STEP3-1, for the base line data (D4) generated in STEP2, the first line (S1) and the second line (S2) are sequentially detected for each unit U[x,y] arranged in a matrix in columns.

[0051] Next, in STEP3-2, the process of Loop 1 is executed. Loop 1 is an iterative process that starts from y = 0 and adds 1 to y while y < N in the unit U[x,y]. Here, N is the maximum number of steps in the vertical direction. For example, in the case of the unit U[100,80], the iterative process is performed 80 times.

[0052] In STEP3-3, the process of Loop 2 is executed. Loop 2 is an iterative process that starts from x = 0 and adds 1 to x while x < M in the unit U[x,y]. Here, M is the maximum number of steps in the horizontal direction. For example, in the case of the unit U[100,80], the iterative process is performed 100 times. After the end of Loop 2, it returns to Loop 1.

[0053] In STEP 3-4, if the 2×2 units of unit U[x,y], unit U[x+1,y], unit U[x,y+1], and unit U[x+1,y+1] are all first units (9) or second units (10), that is, if the condition that all 2×2 units have the same object (first object (S1) or second object (S2)) is met, then the object coverage rate per unit area in the central region (T) is constant, and no density adjustment such as deletion or addition of object (S1) from each unit (9, 10) is performed, and the process returns to loop 2 in STEP 3-3. If the condition is not met, the process proceeds to STEP 3-5.

[0054] Fig. 13 is a schematic diagram showing a case where a unit group (F) is entirely composed of the second object (S2). For example, as shown in Fig. 13, when the 2 × 2 units of unit U[x, y], unit U[x+1, y], unit U[x, y+1], and unit U[x+1, y+1] that make up the unit group (F) are all second units (10), that is, when the condition that all of the 2 × 2 units that make up the unit group (F) have the same object, the second object (S2), is met, the object area ratio per unit area in the central region (T2) is constant, and therefore the process returns to loop 2 in STEP 3-3 without adjusting the density, such as by deleting or adding the objects (S1, S2) of each unit (9, 10).

[0055] In STEP 3-5, the total image area AT of the first image (S1) and second image (S2) of each of the 2x2 units constituting the unit group (F) in the central region (T) is compared with the image area S of the first image (S1) or second image (S2) of the unit U[x,y].

[0056] Fig. 14 is a schematic diagram showing a unit assembly (F) that has undergone the density relaxation process of the present invention, which will be described later. For example, in Fig. 14, the density imbalance in the central region (T) has already been alleviated by the density relaxation process, which will be described later.

[0057] If the total image area AT of the first image (S1) and the second image (S2) in the central region (T) is equal to the image area AU[x,y] of the first image (S1) or the second image (S2) in the unit U[h,v], the image area ratio per unit area in the central region (T) is constant, and therefore the process returns to the loop processing of STEP 3-3 without adjusting the density by deleting or adding each image (S1, S2) in each unit (9, 10). If the condition is not met, the process proceeds to STEP 3-6.

[0058] In STEP 3-6, if the condition that the total image area AT of the first image (S1) and the second image (S2) in the central region (T) is greater than the image area AU[x,y] of the first image (S1) or the second image (S2) in the unit U[h,v] is met, the process proceeds to STEP 3-7, and if the condition is not met, the process proceeds to STEP 3-8.

[0059] In STEP 3-7, in order to prevent the central region (T) from having an increased image area ratio per unit area and visually perceiving the density as unbalanced (dark), the first image line (S1) and / or the second image line (S2) in the central region (T) are partially deleted. In this case, the image area by which the first image line (S1) and / or the second image line (S2) existing in the central region (T) are deleted is 0 to 20%, preferably 8 to 13%, when the image area of ​​the first image line (S1) or the second image line (S2) is taken as 100%.

[0060] When a latent image print (1) of the present invention output at 600 to 720 dpi, the mainstream resolution of digital output devices, is to be read on a smartphone, a screen ruling of 60 to 75 lpi is preferred. While a screen ruling of as high resolution (high ruling) as possible is desirable, a ruling finer than 75 lpi makes reading difficult due to the lens installed in the smartphone. Furthermore, a ruling coarser than 60 lpi results in larger halftone dots, resulting in a coarse latent image pattern (13). For these reasons, when a latent image print (1) of the present invention with a screen ruling of 60 to 75 lpi is produced on a digital output device outputting at a resolution of 600 to 720 dpi, a size of 8 x 8 pixels to 12 x 12 pixels is suitable for each unit (9, 10).

[0061] To prevent a large change in the shape of the object by deleting a part of the first object (S1) and / or the second object (S2), in the case of 8×8 pixels, deleting one pixel from the first object (S1) or the second object (S2) consisting of 8 pixels reduces the object area by 12.5%, and in the case of 12×12 pixels, deleting one pixel from the first object (S1) or the second object (S2) consisting of 12 pixels reduces the object area by 8.3%. For these reasons, the object area from which the first object (S1) and / or the second object (S2) are deleted is preferably 8 to 13% when the object area of ​​the first object (S1) or the second object (S2) is taken as 100%.

[0062] In addition, if 20% or more of the image area of ​​the first image line (S1) or the second image line (S2) is removed, the image areas of the latent image portion (2) which is the latent image pattern (13) and the first image line (S1) and the second image line (S2) which constitute the background portion (3) which is the background surrounding the latent image portion (2) will differ, which is undesirable as it will affect the print results, including dot gain, in the output from any printing machine or printer (14).

[0063] 14(a), for example, the second object (S2) of the second unit (10) in the unit U[x,y] and unit U[x+1,y+1] constituting the unit aggregate (F) has its object area reduced by 10% compared to the first object (S1) of the first unit (9) in the other units U[x+1,y] and unit U[x,y+1]. This reduces the object area ratio per unit area in the central region (T), and alleviates the unevenness of density as seen with the naked eye.

[0064] After the completion of STEP3-7 and STEP3-8 described below, return to loop 2 of STEP3-3. As described above, loop 2 in STEP3-3 starts from x = 0 and, while x < M, is an iterative process of adding 1 to x. Therefore, after the completion of STEP3-3, 1 is added to x. Similarly, loop 1 in STEP3-2 also starts from y = 0 and, while y < N, is an iterative process of adding 1 to y. Therefore, after the completion of STEP3-7 and STEP3-8 described below, 1 is added to y.

[0065] In STEP3-8, in order to prevent the line drawing area ratio per unit area of the central region (T) from becoming small and the density from being visually recognized as unbalanced (thin), a third line (S3) is added to the region where the first line (S1) and / or the second line (S2) possessed by each unit of the 2×2 unit existing in the central region (T) do not exist. At this time, the total line drawing area ratio of the third line (S3) added to the central region (T) is set to 0.5 to 20% when the line drawing area ratio of the first line (S1) or the second line (S2) is 100%.

[0066] As an example of the resolution of a general digital printer, when it is 720 dpi, the maximum size of one unit is 14 pixels × 14 pixels. In that case, when replacing one pixel of the outputable third line (S3) with the line drawing area ratio, it is an increase of 0.5%. Therefore, it is set to 0.5% or more. Also, when adding a third line (S3) having a line drawing area ratio exceeding 20%, the edge of the third line (S3) is emphasized by the differential filter used for visualizing the latent image pattern (13) by the latent image reading device (11) described below, which becomes a factor affecting the reading of the latent image pattern (13).

[0067] 14(b), when the 2x2 units constituting the unit aggregate (F) are such that the unit U[x,y] and the unit U[x+1,y+1] are composed of the first unit (9), and the other units U[x+1,y] and the unit U[x,y+1] are composed of the second unit (10), a third object (S3) is added to the central region (T) and the region where the first object (S1) or the second object (S2) does not exist. This increases the object area ratio per unit area in the central region (T), and alleviates the unevenness of density as seen with the naked eye.

[0068] The image area ratio for deleting the first object (S1) and / or the second object (S2) or adding the third object (S3) differs depending on the image area ratio of the central region (T).

[0069] For example, Figure 15 is a schematic diagram illustrating the image area ratio per unit area of ​​a central region (T), and Figures 15(a) to 15(d) show 2x2 units that make up a unit group (F), each of which is composed of 10x10 pixels. In the 2x2 units that make up the unit group (F) shown in Figures 15(a) to 15(d), a first image (S1) and a second image (S2) are arranged, each with an image area ratio of 10% relative to the unit area of ​​the 10x10 pixel unit. Note that while central regions (T1 to T4) are shown in Figures 15(a) to 15(d), this is added for the purpose of separate explanation; all of these refer to the aforementioned central region (T), each composed of 10x10 pixels.

[0070] For example, the image area ratio per unit area in each unit (9, 10) consisting of 10 x 10 pixels in the central region (T1) shown in Figure 15(a) is 20%, the image area ratio in the central region (T2) shown in Figure 15(b) is 0%, the image area ratio in the central region (T3) shown in Figure 15(c) is 15%, and the image area ratio in the central region (T4) shown in Figure 15(d) is 5%.

[0071] To prevent the density from being perceived as uneven, it is preferable to make the image area ratio of the central region (T1 to T4) close to the image area ratio per unit area of ​​each unit (9, 10) consisting of 10 x 10 pixels of the first image line (S1) or the second image line (S2). For example, in Figure 15, it is preferable to make the image area ratio per unit area close to 10%. Therefore, the image area ratio for deleting the first image line (S1) and / or the second image line (S2) or adding the third image line (S3) varies depending on the image area ratio per unit area of ​​the central region (T). After STEP 3-8 is completed, the process returns to loop 2 of STEP 3-3.

[0072] By performing the processing in STEP 3 on all units U[x, y] in the basic image data (D4) generated in STEP 2, basic printing pattern data (D8) is obtained in which the density imbalance has been corrected.

[0073] Finally, in STEP 4, the base print pattern data (D8) obtained in STEP 3 is formed on the substrate (5). When forming the pattern on the substrate (5) by printing, various printing machines, various printers (14), and laser printing using laser irradiation can be used, and the printed pattern (8) may also be formed by laser marks by irradiating the substrate (5) with a laser. There are no particular limitations on this laser irradiation as long as it is possible to form laser marks on the substrate (5), and for example, a general YAG laser can be used.

[0074] Figure 16 is a schematic diagram showing an example of the base printing pattern data (D8) output from an inkjet printer, which is a printer (14). Some printer (14) models tend to have different ink bleeding widths depending on the head stroke direction and the feed direction of the substrate (5). This is due to the principle that ink bleeding is more likely to occur in the head stroke direction, but in such cases, it is preferable to use a combination of angles (d) for the first object line (S1) and the second object line (S2) that is independent of the output direction of the printer (14).

[0075] For example, as shown in Figure 16, the amount of dot gain is the same for a printed image (p1) obtained by outputting a first image (S1) in the base printing pattern data (D8) from a printer (14) to a substrate (5), and a printed image (p2) obtained by outputting a second image (S2) in the base printing pattern data (D8) from the same printer (14) to a substrate (5).

[0076] FIG. 17 is a schematic diagram showing an example in which a first object (S1) and a second object (S2) in the base printing pattern data (D8) are output from a laser printer (14). Some printer (14) models tend to produce different dot sizes in the horizontal and vertical directions due to the characteristics of the laser or LED. Even in such cases, a combination of angles (d) of the first object (S1) and the second object (S2) that is independent of the output direction of the printer (14) is preferable. For example, as shown in FIG. 17, the printed object (p3) obtained by outputting the first object (S1) from the printer (14) to the substrate (5) and the printed object (p4) obtained by outputting the second object (S2) from the printer (14) to the substrate (5) have the same image area ratio.

[0077] Figure 18 is a schematic diagram showing an example of a combination of angles (d) of the first object (S1) and the second object (S2) that does not depend on the output direction of the printer (14). As shown in Figure 18(a), the angle (d) of the second object (S2) is determined by inverting the image at the horizontal central axis (r1) of the first unit (9), or as shown in Figure 18(b), the angle (d) of the second object (S2) is determined by inverting the image at the vertical central axis (r2) of the first unit (9). Any combination of angles (d) of the first object (S1) and the second object (S2) that results in the same amount of dot gain and image area ratio when output by the printer (14) is within the scope of the present invention.

[0078] (visualization of latent image patterns) Next, a mechanism for visualizing the latent image pattern (13) contained in the print pattern (8) of the latent image print (1) of the present invention using the latent image reading device (11) will be described.

[0079] The latent image pattern (13) is visualized by extracting specific points of the latent image pattern (13) from the captured image of the latent image print (1). Specifically, a differential filter (f1) that emphasizes local features (hereinafter referred to as "edges") of the captured image is used to extract the specific points.

[0080] 19 is a schematic diagram showing the result of applying a differential filter (f1). For example, when a Prewitt filter with a kernel size of 3x3, which emphasizes horizontal edges, is applied as a differential filter (f1) to a captured image (18) of 8 vertical pixels by 8 horizontal pixels, an output image (16) is generated. By applying the differential filter (f1), pixels located in a specific direction become white, and other pixels become black in the output image (16).

[0081] In the present invention, the latent image pattern (13) is formed by varying the directions of the first object line (S1) and the second object line (S2). Therefore, in the captured image (18), the pixels of one of the first object line (S1) and the second object line (S2) are white and the pixels of the other are black, thereby causing the latent image pattern (13) to appear in the output image (16). Note that, since the focus of the present invention is the latent image print (1), an explanation of the principle of the differential filter (f1), which is a known image processing operator, will be omitted.

[0082] 20 is a schematic diagram showing the results of applying a differential filter (f2) to a first object (S1) and a second object (S2). When a differential filter (f2) with a 5×5 kernel size that emphasizes diagonal edges is applied to the first object (S1) of a first unit (9) of 12 vertical pixels by 12 horizontal pixels, an output image (16-1) with 24 white pixels is output.

[0083] Furthermore, when the same differential filter (f2) is applied to the second object (S2) of the second unit (10) having the same number of pixels, an output image (16-2) with 43 white pixels is output. In this way, by applying differential filters (f1, f2) according to the angles (d) of the first object (S1) and second object (S2) of each unit (9, 10), a difference occurs in the number of white pixels in the output image. In other words, the first object (S1) has a shape whose edges are not easily emphasized by the differential filter (f1), while the second object (S2) has a shape whose edges are easily emphasized by the differential filter (f2).

[0084] The differential filters (f1, f2) may be, for example, Prewitt filters or Sobel filters. The appropriate kernel size is determined based on the number of vertical and horizontal pixels of each unit (9, 10), the performance of the camera of the latent image reader (11), and other factors.

[0085] Next, the output image (16-1) output by the differential filters (f1, f2) is averaged per unit area and converted into a density value. FIG. 21 is a schematic diagram showing the conversion from the output image (16-1) to an averaged image (20-1). As shown in FIG. 21, for example, when an output image (16-1) with 24 white pixels is averaged over 12 vertical pixels by 12 horizontal pixels, it is converted into an averaged image (20-1) with a density value of 43 (8 bits). Similarly, when an output image (16-2) with 43 white pixels is averaged over 12 vertical pixels by 12 horizontal pixels, it is converted into an averaged image (20-2) with a density value of 76 (8 bits). The difference between these two density values ​​becomes the image contrast for visualizing the latent image pattern (13) using the latent image reader (11).

[0086] Fig. 22 is a schematic diagram showing the flow of visualizing the latent image pattern (13) of the printed pattern (8) by the latent image reading device (11). As shown in Fig. 22, the printed pattern (8) is photographed by a camera function controlled by an application (17) installed in the latent image reading device (11), and is acquired as a captured image (18) in the memory of the device body.

[0087] In step 5-1, the differential filters (f1, f2) are applied to the captured image (18) to obtain a differential image (19). Next, in step 5-2, the differential image (19) is subjected to the averaging process to obtain an averaged image (20). Note that a smoothing filter such as a Gaussian filter may be used for this averaging.

[0088] The averaged image (20) may not have the desired contrast and may be insufficient to clearly visualize the latent image pattern (13). The contrast of the averaged image (20) obtained here is related to the aspect ratio and angle (d) of each of the objects (S1, S2) of each unit (9, 10). As mentioned above, the first object (S1) and the second object (S2) generally have shapes with different aspect ratios and angles (d). When differential filters (f1, f2) that emphasize horizontal edges are applied to objects (S1, S2) that are short in the vertical direction, the number of white pixels decreases.

[0089] Conversely, if a differential filter that emphasizes horizontal edges is applied to vertically long lines (S1, S2), the number of white pixels will increase. Since this is averaged to obtain the density value, the greater the difference between the number of white pixels in the former and latter, the easier it is to obtain contrast.

[0090] Therefore, in order to obtain sufficient contrast to clearly visualize the latent image pattern (13), it is preferable that the aspect ratio of the first object (S1) and the second object (S2) is as large as possible. If the contrast is still insufficient, in STEPS 5-3, the contrast of the averaged image (20) is adjusted (for example, by adjusting highlight points and shadow points) to obtain the output image (16).

[0091] Next, the output image (16) is displayed on the screen (12) of the latent image reading device (11). Note that the image captured by the latent image reading device (11) is not limited to a still image, but may also be a moving image. In the case of a moving image, the processing from STEPS 5-1 to S5-3 is repeated for each frame. The latent image reading device (11) may also be configured to acquire an image using, for example, a scanner connected to a computer, and display the visualized image on a display screen through processing by software installed on the computer.

[0092] The latent image reading device (11) described here is one means for visualizing the latent image pattern (13) contained in the printed pattern (8), and does not limit the form of the latent image print (1) of the present invention. Furthermore, the latent image reading device (11) is not limited to embodiment 1, but can also be used in embodiments 2 and 3 described below.

[0093] (Embodiment 2) Next, the second embodiment will be described with reference to the drawings. However, the description of the formation of the printed pattern (8) by the arrangement of the first unit (9) and the second unit (10), which is the same as in the first embodiment, and the visualization of the latent image pattern (13) by the latent image reading device (11) will be omitted, and the fourth image line (S4) for forming the visible pattern (8v), which is a feature of the second embodiment, will be described.

[0094] Fig. 23 is a schematic diagram showing a latent image print (1) in embodiment 2. As shown in Fig. 23, by arranging a fourth image line (S4) described later on the printed pattern (8) on the latent image print (1) of the present invention, a visible pattern (8v) that can be recognized visually is formed.

[0095] Figure 24 shows the arrangement of the fourth object (S4) in embodiment 2. As shown in Figure 24(a), the printed pattern (8) in embodiment 2 has first units (9) and second units (10) regularly arranged, similar to embodiment 1. As shown in Figure 24(b), in the area where the visible pattern (8v) is formed, the fourth object (S4) is arranged in an area where the first object (S1) and the second object (S2) are not present, thereby forming the visible pattern (8v) shown in Figure 24(c).

[0096] The fourth object (S4) may be located in an area where the third object (S3) is present, as long as the first object (S1) and the second object (S2) are not present. Similarly to the third object (S3), the fourth object (S4) preferably has a shape and size such that the edges are not easily emphasized by a differential filter used in visualizing the latent image pattern (13) by the latent image reading device (11).

[0097] FIG. 25 is a schematic diagram showing an example of the arrangement of the fourth object (S4) in the second embodiment. As shown in FIG. 25(a), the position of the fourth object (S4) may be determined in accordance with the non-image areas of the first unit (9) and the second unit (10). As shown in FIG. 25(b), the fourth object (S4) may be arranged in the non-image areas adjacent to the first object (S1) and the second object (S2), so that the thickness and length of the object appear to be partially expanded. As shown in FIG. 25(c), the fourth object (S4) may have a halftone dot shape, for example, using the FM (Frequency Modulation) screening method, if it is in the non-image areas of the first unit (9) and the second unit (10).

[0098] (Embodiment 3) Next, the third embodiment will be described with reference to the drawings. However, the description of the formation of the printed pattern (8) by the arrangement of the first unit (9) and the second unit (10), which is the same as in the first embodiment, and the visualization of the latent image pattern (13) by the latent image reading device (11) will be omitted, and the second color (C2) for forming the visible pattern (8v), which is a feature of the third embodiment, will be described.

[0099] Fig. 26 is a schematic diagram showing a latent image print (1) of embodiment 3. In embodiment 3, as shown in Fig. 26, a visible pattern (8v) that can be recognized visually is formed by changing a part of a first object (S1) and a part of a second object (S2) formed in a first color (C1) to a second color (C2).

[0100] FIG. 27 is a schematic diagram showing a change from a first color (C1) to a second color (C2). As shown in FIG. 27(a), the printed pattern (8) in the third embodiment has first units (9) and second units (10) regularly arranged, as in the first embodiment. Furthermore, the first object (S1), the second object (S2), and the third object (S3) formed in the first color (C1) in the area forming the visible pattern (8v) are changed to the second color (C2) as shown in FIG. 27(b), thereby forming the visible pattern (8v). Note that the color to be changed is not limited to one color. For example, as shown in FIG. 28, a combination of multiple colors may be used, such as using a third color (C3) in addition to the second color (C2).

[0101] Furthermore, the third embodiment may also use a fourth object (S4) as shown in FIG. 29, as long as it satisfies the requirements of the second embodiment.

[0102] Furthermore, in the third embodiment, the second latent image pattern (13-2) may be formed instead of the visible pattern (8v) by using an ink that is the same color or a color equivalent to the first color (C1) but has different functionality as the second color (C2). Figure 30 is a schematic diagram showing a color change for forming the second latent image pattern (13-2) in the third embodiment. For example, as shown in Figure 30(a), the first color (C1) of the image line included in the area forming the second latent image pattern (13-2), which is the letter "B," is changed to the second color (C2) as shown in Figure 30(b), thereby forming the second latent image pattern (13-2) shown in Figure 30(c).

[0103] Here, for example, ink that is the same color as the first color (C1) and does not absorb infrared rays is used as the first color (C1), and ink that absorbs infrared rays is used as the second color (C2). Alternatively, the first color (C1) may be 100% cyan, 100% magenta, and 100% yellow, and the second color (C2) may be 100% black containing carbon that has the property of absorbing infrared rays.

[0104] FIG. 31 is a schematic diagram showing a method for observing the second latent image pattern (13-2) in the third embodiment. As shown in FIG. 31(a), the latent image patterns (13, 13-2) of the printed pattern (8) are not visually recognizable. By using a latent image reading device (11), the letter "A" of the latent image pattern (13) can be observed as shown in FIG. 31(b). Furthermore, by using a device that visualizes infrared wavelengths (approximately 800 nm to 1500 nm), such as an infrared camera, as another latent image reading device (11), the second color (C2), which is an ink that absorbs infrared light, is detected, and the letter "B" of the second latent image pattern (13-2) can be observed as shown in FIG. 31(c).

[0105] Although the second latent image pattern (13-2) has been described above using an ink with infrared absorbing properties, it is within the scope of the present invention to use ink with other functionality, such as ink that emits light when exposed to ultraviolet light.

[0106] (Information verification) Next, as an example of how to use the latent image print (1) of the present invention, a means for detecting falsification (such as tampering with the written information (26a, 26b)) by verifying the information will be described.

[0107] Figure 32 is a schematic diagram showing a method for verifying the unique information "A" possessed by the latent image pattern (13). Specifically, it is a schematic diagram showing an environment in which the unique information "A", which is the latent image pattern (13) to be certified, is recorded in a cloud computing server system (23), and a certificate (25a) is output from a printer (14) via network communication (27) in which the unique information "A", which is part of the written information (26a), is the latent image pattern (13).

[0108] For example, in such an environment, the authenticity of the certificate (25a) can be confirmed by visualizing the latent image pattern (13) contained in the printed pattern (8) of the certificate (25a) using the latent image reader (11) and comparing it with the latent image pattern (13) recorded in the server system (23). On the other hand, if the latent image pattern (13) contained in the printed pattern (8) of the certificate (25b) is visualized using the latent image reader (11) and compared with the latent image pattern (13) recorded in the server system (23) and they do not match, for example, if a star-shaped tampered pattern (22) appears in the latent image pattern (13) that is different from the unique information "A" recorded in the server system (23) as shown in Figure 32, or if the latent image pattern (13) itself is not visualized, then the certificate (25b) is suspected to have been forged.

[0109] Furthermore, in addition to the method of visually checking whether the displayed latent image pattern (13) matches as described above, another verification method may be to use the network communication (27) of the latent image reading device (11) to perform electronic data verification with the latent image pattern (13) recorded in the server system (23).

[0110] (Example) Below, we will explain an example of a latent image print (1) that was specifically produced in accordance with the above-mentioned form for implementing the invention, with reference to the drawings, but the present invention is not limited to this example.

[0111] Figure 33 is a schematic diagram showing the certificate-type latent image print (1) of this embodiment, in which the printed pattern (8) on the substrate (5) has a visible pattern (8v) and a two-dimensional code formed as a latent image pattern (13), not shown.

[0112] Figure 34 is a schematic diagram showing the first unit (9), second unit (10), and fourth object (S4) that form the printed pattern (8) of this embodiment. The first object (S1) of the first unit (9) and the second object (S2) of the second unit (10) were designed with a combination of object angles (d) (S1, S2, S3, S4) that are independent of the output direction of the printer (14), taking into consideration the camera performance of the latent image reader (11) and the image quality of the printer (14) that outputs the latent image print (1). Furthermore, the fourth object (S4) for forming the visible pattern (8v) was designed to be positioned in a non-image area common to both the first unit (9) and the second unit (10).

[0113] Figure 35 is a schematic diagram showing a printed pattern (8) consisting of the image configuration shown in Figure 34. In this example, the latent image pattern (13) was a two-dimensional code. The dimensions of the first unit (9) and the second unit (10) were squares measuring 0.38 mm in both length and width, and they were arranged so that the horizontal and vertical directions were aligned on the same axis, as shown in Figure 15(a) in embodiment 1, in accordance with the module of the two-dimensional code. Furthermore, the visible pattern (8v) was formed by arranging the aforementioned fourth image (S4) in the area where the visible pattern (8v) was to be formed.

[0114] The output conditions for the latent image print (1) in this example were as follows: An image with an image resolution of 600 dpi and a color depth of 1 bpp was created as the print pattern (8), and a PDF file with this image embedded in a graphic object was created as the base print pattern data (D8). The printer (14) used was a monochrome laser printer, Canon Satera LPB221 (hereinafter referred to as the "target printer").

[0115] The effect of the latent image print (1) of this example will be explained. The latent image pattern (13) in the print pattern (8) was concealed to the extent that it was not recognizable to the naked eye, and only the "phoenix" was observed as the visible pattern (8v).

[0116] Next, the results of visualizing the latent image pattern (13) of this example using the latent image reading device (11) will be described. Fig. 36 is a schematic diagram showing the collation results of this example. As shown in Fig. 36, the latent image reading device (11) on which an application (17) for visualizing the latent image pattern (13) as a display image was installed on a smartphone was able to clearly visualize the two-dimensional code that is the latent image pattern (13).

[0117] Furthermore, the information embedded in the visualized latent image pattern (13) can also be read from the two-dimensional code. The latent image reading device (11) of this embodiment uses a device with Google PIXEL 4a and an application (17) developed with Android Studio 4.1 installed, and it was confirmed that the latent image pattern (13) can be clearly visualized within a range of observation distances of 50 mm to 140 mm from the latent image print (1) in a captured image of 640 pixels vertical x 480 pixels horizontal.

[0118] Figure 37 is a plan view comparing the latent image print (1'') of Patent Document 2 with the latent image print (1) of the present invention. Figure 37(a1) is a plan view and a partial enlarged view (a2) of the latent image print (1'') of Patent Document 2, and Figure 37(b1) is a plan view and a partial enlarged view (b2) of the latent image print (1) of the present invention. As shown in each enlarged view (a2, b2), the latent image print (1) of the present invention has a more constant image coverage per unit area, improving the concealment of the latent image pattern (13). [Explanation of symbols]

[0119] 1, 1', 1'' latent image print 2 Latent image section 3 Background part 4 Printing plate 5 Base material 6a, 6b halftone dots 8, 8a, 8b, 8' Printing pattern 8v visible pattern 9. First Unit 10 Second Unit 11 Latent image reader 12 screens 13 Latent Image Pattern 13-2 Second latent image pattern 14 Printer 16 Output images 17 Applications 18 Captured images 19 Differential Images 20 Averaged images 22 Tampering Pattern 23 Server System 25a, 25b certificate 26a, 26b Information 27 Network Communications S1 First stroke S2 Second stroke S3 Third stroke S4 Fourth stroke F unit assembly D1 Base latent image pattern data D2 monochrome image data D3 2-tone image data D4 base line data T, T1, T2, T3, T4 central region J center u, h, v dimensions d angle r1, r2 center axis x, y, N, M number of steps A Stroke Area p1, p2, p3, p4, p5, p6 print lines f1, f2, f3 derivative filters e1, e2, e3, e4, ex1, ex2 images C1 First color C2 Second Color C3 Third Color

Claims

1. A latent image printed matter having a printed pattern with a latent image pattern on at least a part of a substrate, The print pattern is formed by arranging a plurality of unit assemblies in a matrix, each unit assemblies being made up of four units arranged adjacently in a 2×2 pattern in the X and Y directions, each of the plurality of units has either a first image line formed corresponding to the latent image pattern or a second image line formed corresponding to a background of the latent image pattern; the first image line and the second image line have the same image area ratio within the unit, and are different in at least one of the angle at which they are arranged and the shape; A latent image print, wherein a plurality of the unit assemblies arranged have the same image area ratio in the central region.

2. 2. The latent image print according to claim 1, wherein the central region has a third image line in a plurality of the unit aggregates, the third image line having the same length, shape and color.

3. 3. A method for producing a latent image print according to claim 1 or 2, a base latent image pattern data input step of inputting base latent image pattern data that is the basis of the latent image pattern; a basic image data creating step of converting the basic latent image pattern data input in the basic latent image pattern data input step into monochrome image data, then converting the monochrome image data into two gradations to generate two-gradation image data composed of white pixels and black pixels, and then replacing one of the white pixels and the black pixels with a first unit having first basic image data that will be the basis of the first image line, and the other with a second unit having second basic image data that will be the basis of the second image line, thereby generating basic image data in which a plurality of unit aggregates are arranged, each of which is made up of four units arranged adjacently in a 2×2 matrix in the X direction and the Y direction; a density adjustment step of adjusting the density imbalance in the central region of the basic image data created in the basic image data creation step by deleting or adding images from the multiple unit aggregates, thereby generating print pattern data; a forming step of forming a print pattern on the substrate by printing or laser using the print pattern data created in the density adjusting step.

Images