JP2025105321A - Authenticity determination device, computer program, and authenticity determination method - Google Patents

Abstract

An authenticity determining device, a computer program, and an authenticity determining method are provided that are capable of determining the authenticity of a medium by estimating clear diffracted light.
[Solution] The authenticity determination device includes a control unit, which acquires a first image of the target medium by irradiating the target medium with light emitted from a light emitting unit, identifies a first hologram image based on the acquired first image, sharpens the identified first hologram image using a filter, and determines the authenticity of the target medium based on the sharpened first hologram image.
[Selected Figure] Figure 1

Description

The present invention relates to an authenticity determination device, a computer program, and an authenticity determination method.

Credit cards, paper money, stock certificates, gift certificates, luxury brand goods, etc. use media that contains information to prevent duplication and counterfeiting. Such media uses security technologies such as holograms, which are difficult to duplicate.

Patent Document 1 discloses an inspection device that irradiates light from a light source onto a hologram on a banknote, captures the light reflected from the hologram in two different directions into a reflective prism, and refracts it in approximately the same direction, making it possible to visually recognize two images of the hologram. However, operating an inspection device like that described in Patent Document 1 requires special skills and expertise.

On the other hand, mobile devices such as smartphones equipped with flashlights, high-performance cameras capable of taking high-quality photographs, and advanced image processing functions are widely in use, and it is reasonable to determine the authenticity of media by using the functions of such mobile devices without the need for special skills or expertise.

JP 2006-350995 A

However, the light-emitting elements used in flashlights installed in mobile devices such as smartphones are small surface light sources, and therefore have a larger light-emitting surface than an ideal point light source. Light emitted from a surface light source contains diffracted light. If diffracted light caused by this diffracted light is observed at the same time, there is a problem that the diffracted light cannot be obtained as clearly as in the case of a point light source.

The present invention has been made in consideration of the above circumstances, and aims to provide an authenticity determination device, computer program, and authenticity determination method that can estimate clear diffracted light and determine the authenticity of media.

The authenticity determination device of this embodiment includes a control unit, which irradiates a target medium with light emitted from a light emitting unit to obtain a first image of the target medium, identifies a first hologram image based on the obtained first image, sharpens the identified first hologram image using a filter, and determines the authenticity of the target medium based on the sharpened first hologram image.

The computer program of this embodiment causes a computer to execute the following process: irradiate a target medium with light emitted from a light-emitting unit to capture a first image of the target medium, identify a first hologram image based on the captured first image, sharpen the identified first hologram image using a filter, and determine the authenticity of the target medium based on the sharpened first hologram image.

The authenticity determination method of this embodiment involves irradiating a target medium with light emitted from a light-emitting unit to obtain a first image of the target medium, identifying a first hologram image based on the obtained first image, sharpening the identified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

According to the present invention, it is possible to estimate clear diffracted light and determine the authenticity of the medium.

FIG. 1 is a diagram illustrating an example of the configuration of an authenticity determining device. FIG. 2 is a plan view showing a schematic example of a hologram structure. 3 is a vertical cross-sectional view taken along line AA in FIG. 2. FIG. 11 is a diagram showing an example of diffracted light appearing around a zero-order diffracted light as a comparative example. 11A and 11B are diagrams illustrating an example of diffracted light appearing around the zeroth-order diffracted light in the present embodiment. 11A and 11B are diagrams illustrating an example of normal diffracted light due to ambient light in the present embodiment. FIG. 13 is a diagram showing an example of photographing a target medium that is a counterfeit. FIG. 2 is a diagram showing a first example of characteristics of a special diffracted light pattern according to the present embodiment. FIG. 13 is a diagram showing a second example of the characteristics of a special diffracted light pattern according to the present embodiment. 11A and 11B are diagrams illustrating an example of a method for detecting zero-order diffracted light. FIG. 13 is a diagram showing an example of a process for extracting a zero-order diffraction image. FIG. 13 is a diagram illustrating an example of a method for generating a kernel. FIG. 13 is a diagram illustrating an example of a method for generating a kernel. FIG. 13 is a diagram illustrating an example of a method for generating a kernel. FIG. 13 is a diagram showing an example of authenticity determination using a special diffracted light pattern. FIG. 13 is a diagram showing an example of a filter process for a first hologram image. FIG. 13 is a diagram showing an example of authenticity determination using a normal diffracted light pattern. FIG. 13 is a diagram showing an example of a display screen when authenticity is determined. 3 is a diagram showing an example of a procedure of an authenticity determining process performed by the authenticity determining device of the present embodiment. FIG. FIG. 1 is a diagram illustrating an example of a configuration of an authenticity determination system.

First Embodiment
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments. FIG. 1 is a diagram showing an example of the configuration of an authenticity determination device 50. The authenticity determination device 50 includes a control unit 51 that controls the entire device, a light emitting unit 52, an imaging unit 53, a display unit 54, an operation unit 55, a communication unit 56, a memory 57, and a storage unit 58. The authenticity determination device 50 is composed of a mobile device such as a smartphone, a tablet terminal, or a personal computer, and is carried by a user. In this embodiment, the authenticity determination device 50 will be described by taking a smartphone as an example.

The storage unit 58 can be configured with a semiconductor memory or the like, and can store a computer program 60, correct answer information 61, and required information. The computer program 60 is an authenticity determination application (also simply referred to as an "app"), and runs on the authenticity determination device 50. The correct answer information 61 includes a correct answer character string and a correct answer image, which will be described later.

The control unit 51 is configured with a required number of CPUs (Central Processing Units), MPUs (Micro-Processing Units), GPUs (Graphics Processing Units), etc. The control unit 51 can execute processing defined by a computer program 60. In other words, processing by the control unit 51 is also processing by the computer program 60. A recording medium (a non-transitory recording medium that can be read by a computer) M on which the computer program 60 is recorded may be read by a recording medium reading device (such as a computer) 40, and the read computer program 60 may be downloaded via the communication unit 56 and stored in the memory unit 59.

The light-emitting unit 52 includes a light-emitting element such as an LED. The light-emitting element is a small surface light source. A white LED or the like can be used as the LED. The light-emitting unit 52 irradiates the target medium with reference light. The target medium is an object to be judged for authenticity, and is a medium on which information is recorded to prevent copying and counterfeiting, such as credit cards, banknotes, stock certificates, gift certificates, and luxury brand items. In this embodiment, holography (hologram) is used as the target medium.

Holography is a technology that records the amplitude and phase of the light wave to be recorded (object light) on a medium as interference fringes by causing it to interfere with a reference light, and then reconstructs the recorded light wave using the diffraction phenomenon. Recorded interference fringes are called holograms.

The imaging unit 53 includes a camera. The imaging unit 53 can acquire an image of the target medium. Specifically, the imaging unit 53 acquires an image (first image) of the target medium under conditions in which the light from the light-emitting unit 52 is irradiated onto the target medium (also referred to as "LED on"), and acquires an image (second image) of the target medium under conditions in which the light from the light-emitting unit 52 is not irradiated onto the target medium (also referred to as "LED off").

The display unit 54 is equipped with a liquid crystal display panel, an organic EL display panel, etc., and can display the results of the determination made by the authenticity determination device 50.

The operation unit 55 is configured with a touch panel or the like, and allows the user to input characters on the display unit 54, as well as to perform operations on icons, images, characters, etc. displayed on the display unit 54.

The communication unit 56 has a communication module and has the ability to communicate with external devices via a communication network.

The memory 57 can be composed of a semiconductor memory such as a static random access memory (SRAM), a dynamic random access memory (DRAM), or a flash memory. By expanding the computer program 60 in the memory 57, the control unit 51 can execute the computer program 60.

The control unit 51 (computer program 60, authenticity determination application) can control the on/off of the light emission unit 52, control the amount of light, and control the operation of the imaging unit 53. The control unit 51 also performs image processing on the acquired image and performs processes such as authenticity determination of the target medium.

Next, we will explain the hologram structure that is provided on the target medium that is the target of the authenticity determination device 50 of this embodiment.

Figure 2 is a plan view showing an example of a schematic of the hologram structure 10, and Figure 3 is a vertical cross-sectional view taken along line A-A in Figure 2. The hologram structure 10 has a hologram layer 1 having a hologram formation region 11. A phase-type Fourier transform hologram that converts light incident from a light-emitting unit 52 into a desired optical image is recorded in the hologram formation region 11. The hologram formation region 11 is a reflection-type Fourier transform hologram formation region, and the hologram structure 10 has a deposition layer 2 formed so as to be in contact with the uneven surface 12 of the hologram formation region 11. In the hologram structure 10, a transparent substrate 3 is laminated on the surface of the hologram layer 1 opposite the deposition layer 2. In Figure 3, the region surrounded by a dashed line is the hologram formation region 11.

Here, a phase-type Fourier transform hologram is recorded, which means that the phase information of the Fourier transform image obtained through the Fourier transform of the original image is multi-valued and recorded as depth. Therefore, an uneven surface 12 is formed in the hologram formation area 11 of the hologram layer 1 where the phase-type Fourier transform hologram is recorded.

As described above, since a phase-type Fourier transform hologram is recorded in the hologram formation region 11, the hologram structure 10 can reproduce a light image (also referred to as a "special diffraction light pattern" or "first hologram image") in the hologram formation region in a planar view by the light incident from the light emitting unit 52. That is, the light image can be reproduced only when light is irradiated from the light emitting unit 52, and the light image is not reproduced when light is not irradiated from the light emitting unit 52. The light image is an image that can be used to extract original digital information from a shape represented by a pattern or picture using the authenticity determination device 50, and includes two-dimensional codes such as barcodes, QR codes (registered trademarks), and two-dimensional barcodes (first hologram images). Details of the aforementioned hologram structure are disclosed in Japanese Patent Application No. 2020-68389 (Patent No. 6973550) filed by the applicant. In addition, details relating to matters related to phase-type Fourier transform holograms and the like are disclosed in the applicant's patent applications, Patent No. 4780319, Patent No. 6037103, Patent No. 6686322, Patent No. 6686323, Patent No. 6759600, Patent No. 6743465, Patent No. 6909438, Patent No. 6915346, and Patent No. 7190113.

Next, a method for determining the authenticity of the target medium will be described. The user can obtain the authenticity determination result of the target medium by simply performing a simple operation using the authenticity determination device 50, and no special skills or expertise are required. The user first starts the authenticity determination app (app). The user points the light-emitting unit 52 and the imaging unit 53 of the smartphone, which is the authenticity determination device 50, toward the target medium. The authenticity determination app obtains an image (first image) of the target medium by irradiating the target medium with light from the light-emitting unit 52, and obtains an image (second image) of the target medium without irradiating the target medium with light from the light-emitting unit 52. The authenticity determination app performs an authenticity determination of the target medium based on the acquired images (first image and second image) and outputs the determination result. In this way, the user can perform an authenticity determination by simply holding the smartphone toward the target medium. The authenticity determination app can repeat the process of acquiring images (first and second images) and the process of determining authenticity as necessary. Specific examples of authenticity determination are described below.

Figure 4 is a diagram showing an example of diffracted light appearing around the zeroth-order diffracted light as a comparative example. In the example of Figure 4, it is assumed that the target medium is genuine and is irradiated with light from an LED light source (LED on). Since the LED is on, in addition to ambient light, light from the LED light source is irradiated as reference light onto the target medium. When light from the LED light source is irradiated as reference light onto a genuine target medium, a special diffracted light pattern (unique bright spot pattern) is reproduced around the zeroth-order diffracted light (total reflection). In the judgment area, a first hologram is recorded so that the special diffracted light pattern (unique bright spot pattern) is reproduced by the light from the LED light source. The special diffracted light pattern is the diffracted light of the first hologram. However, since the light from the LED light source is not light from a light source that can be considered as a point light source, the spot of the zeroth-order diffracted light (reflected light) is large and the special diffracted light pattern is highly blurred. For this reason, there is a risk that reading of the special diffracted light pattern will be hindered.

Figure 5 is a diagram showing an example of diffracted light appearing around the zeroth-order diffracted light in the present embodiment. In the example of Figure 5, the target medium is assumed to be genuine, and light from the light-emitting unit 52 is irradiated (LED on). Since the LED is on, the target medium is irradiated with light from the light-emitting unit 52 as reference light in addition to ambient light. When light is irradiated from the light-emitting unit 52 as reference light, the genuine target medium reproduces a special diffracted light pattern (unique bright spot pattern) around the zeroth-order diffracted light (total reflection). In this specification, the zeroth-order diffracted light is the reflected light when the light from the light-emitting unit 52 is reflected, and an image is formed by the reflected light, and is also referred to as total reflection or reflected light. In this embodiment, the light-emitting unit 52 and the imaging unit 53 are arranged within 2 to 3 cm. This allows a clear light image to be obtained. In the judgment area, a first hologram is recorded so that a special diffracted light pattern (unique bright spot pattern) is reproduced by the light from the light-emitting unit 52. In the example of FIG. 5, as described below, a filter (kernel) is used to sharpen the identified first hologram image, and the first hologram image that is reproduced when the target medium is irradiated with light from a light source that can be considered a point light source as reference light is estimated. This makes the spot of the zeroth-order diffracted light (reflected light) small and the special diffracted light pattern clear. This makes it easier to read the special diffracted light pattern.

Figure 6 is a diagram showing an example of normal diffracted light due to ambient light in the case of this embodiment. In the example of Figure 6, it is assumed that the target medium is genuine and that light from the light-emitting unit 52 is not being irradiated (LED off). Because the LED is off, only ambient light is irradiated onto the target medium as reference light. When ambient light is irradiated onto a genuine target medium as reference light, it reproduces a normal diffracted light pattern (a tiara pattern in the example shown). A second hologram is recorded in the judgment area so that normal diffracted light is reproduced by ambient light. The normal diffracted light pattern is the diffracted light of the second hologram.

Figure 7 shows an example of photographing a target medium when it is a counterfeit. When the target medium is a counterfeit (such as a forged print), no hologram is present in the judgment area of the target medium. Figure 7A shows a case where the target medium is photographed with no light emitted from the light-emitting unit 52 of the smartphone, which is the authenticity determination device 50 (the LED is off). Because the LED is off, only ambient light is irradiated onto the target medium as reference light, and the reflected light returns to the imaging unit 53 (camera). Because no hologram is present in the judgment area, the usual diffracted light pattern described above is not seen.

Figure 7B shows the case where the target medium is photographed with light irradiated from the light-emitting unit 52 of the smartphone (LED is on). Because the LED is on, the target medium is irradiated with light from the light-emitting unit 52 as reference light in addition to ambient light. In this case, a bright spot caused by the light from the light-emitting unit 52 is detected in the determination area, and the specularly reflected light of that light is returned to the imaging unit 53 (camera). Because no hologram is present in the determination area, the special diffracted light pattern described above is not seen.

As described above, in a genuine target medium, a special diffracted light pattern and a normal diffracted light pattern are reproduced depending on the shooting conditions (LED on/off), whereas in a counterfeit target medium, neither the special diffracted light pattern nor the normal diffracted light pattern is reproduced, making it easy to determine the authenticity of the target medium.

On the other hand, it is also conceivable that there may be an unauthorized third party who obtains an unauthorized copy of the special diffracted light pattern (first hologram image, specifically, a two-dimensional barcode, etc.) illustrated in FIG. 5 and disguises a counterfeit as the genuine article. The following describes how to deal with such fraud.

Figure 8 is a diagram showing a first example of the characteristics of the special diffracted light pattern of this embodiment. Figures 8A and 8B show the case where an image is captured when the light-emitting unit 52 is not emitting light, i.e., the LED is off. As shown in Figure 8A, a normal diffracted light pattern (in the example shown), is reproduced in the judgment area. As shown in Figure 8B, even if the smartphone is moved in the direction of the arrow (horizontally) relative to the judgment area, the position of the normal diffracted light pattern reproduced in the judgment area does not change. A normal diffracted light pattern has such characteristics.

On the other hand, Figures 8C and 8D show images captured when the light-emitting unit 52 is illuminated, i.e., when the LED is on. As shown in Figure 8C, a special diffracted light pattern (code information such as a two-dimensional code or a two-dimensional barcode around the zeroth-order diffracted light as shown in the figure) is reproduced in the judgment area. As shown in Figure 8D, when the smartphone is moved in the direction of the arrow relative to the judgment area, the position of the special diffracted light pattern in the judgment area moves in conjunction with the positions of the light-emitting unit 52 and the imaging unit 53 together with the zeroth-order diffracted light. This is because the point of incidence of the light entering the judgment area moves.

When the user points the light-emitting unit 52 and image-capturing unit 53 of the smartphone, which is the authenticity determining device 50, at the target medium, the control unit 51 (authenticity determination application) can guide (by outputting audio or displaying a guide message, etc.) the smartphone to move horizontally relative to the target medium. While the user moves the smartphone, the control unit 51 (authenticity determination application) can photograph the target medium with the light-emitting unit 52 illuminated, and determine the authenticity of the target medium.

As described above, the special diffracted light pattern according to this embodiment moves so that the position of the zeroth order diffracted light coincides with the position of the special diffracted light pattern when the position of the smartphone (the positions of the light emitting unit 52 and the imaging unit 53) is moved horizontally relative to the target medium. On the other hand, when a copy of the special diffracted light pattern is simply displayed, the displayed copy of the special diffracted light pattern does not move. As a result, according to this embodiment, the authenticity of the target medium can be determined with high accuracy.

Figure 9 is a diagram showing a second example of the characteristics of the special diffracted light pattern of this embodiment. Figure 9 shows a case where an image is captured with the light-emitting unit 52 emitting light, i.e., the LED on. As shown in Figure 9, the distance between the target medium and the smartphone is changed to H1, H2 (> H1), and H3 (> H2). The larger the distance between the target medium and the smartphone, the larger the size of the special diffracted light pattern around the zeroth-order diffracted light.

When the user points the light-emitting unit 52 and the image capturing unit 53 of the smartphone, which is the authenticity determination device 50, at the target medium, the control unit 51 (authenticity determination application) can provide guidance (such as audio output or display of guidance) to increase or decrease the distance of the smartphone from the target medium. The control unit 51 (authenticity determination application) can determine the authenticity of the target medium by photographing the target medium with the light-emitting unit 52 illuminated while the user moves the smartphone.

As described above, the special diffracted light pattern according to this embodiment changes in size around the zeroth-order diffracted light when the position of the smartphone (the positions of the light-emitting unit 52 and the imaging unit 53) is moved so that the distance from the target medium is longer or shorter. On the other hand, when a copy of the special diffracted light pattern is simply displayed, the size of the displayed copy of the special diffracted light pattern does not change. As a result, according to this embodiment, the authenticity of the target medium can be determined with high accuracy.

As mentioned above, the light-emitting unit 52 is equipped with an LED light source, but it is a small surface light source, and as explained in FIG. 4, the spot of the zero-order diffracted light (reflected light) is large and the special diffracted light pattern is highly blurred. Therefore, a method is described for making the special diffracted light pattern obtained when the target medium is irradiated with light emitted from the light-emitting unit 52 equivalent to the special diffracted light obtained when the target medium is irradiated with light from a light source that can be considered an ideal point light source (see FIG. 5).

Figure 10 shows an example of a method for detecting zeroth-order diffracted light. Zeroth-order diffracted light is a strong white spot where all RGB color components are saturated or close to being saturated, and has a circular or rectangular shape. Zeroth-order diffracted light is also a collection of bright spots with a certain area. Here, "saturation" refers to, for example, a state in which light with a luminous intensity equal to or greater than the upper detection limit of a camera sensor is incident. Note that hologram diffracted light (special diffracted light) differs from zeroth-order diffracted light in that the RGB color components are non-uniform, it is not a white spot, and has a lower brightness than zeroth-order diffracted light.

As shown in FIG. 10, the control unit 51 obtains a captured image (first image) of the target medium by irradiating the target medium with light from the light emitting unit 52, and performs a bright spot region identification process on the obtained captured image to identify regions with a predetermined luminous intensity or higher as bright spot regions. In the example of FIG. 10, white bright spots (saturated bright spots) are left.

Next, the control unit 51 performs a zeroth-order diffracted light detection process. In the zeroth-order diffracted light detection process, the condition of the zeroth-order diffracted light is determined, and the shape, area, and center point of the zeroth-order diffracted light are calculated. The condition determination of the zeroth-order diffracted light determines the conditions of the zeroth-order diffracted light, such as (1) that all RGB color components are saturated or close to being saturated, (2) that the shape is circular or square, and (3) that the light is a collection of bright spots having an area within a certain range. The center of the collection of bright spots becomes the zeroth-order diffracted light detection coordinates. The area is the number of pixels in the area where the pixels of the bright spots that are saturated or close to being saturated are consecutive.

The control unit 51 performs a zeroth-order diffracted light image extraction process to extract a zeroth-order diffracted light image, which is a collection of bright spots centered on the zeroth-order diffracted light detection coordinates.

Figure 11 is a diagram showing an example of the process of cutting out a zeroth-order diffraction image. The control unit 51 finds the farthest distance D from the zeroth-order diffraction light coordinate among the distances D1, D2, D3, and D4 in each of the four directions (x-, y-, x+, y+) at which strong white light spots continue in succession around the detected zeroth-order diffraction light coordinate. A strong white light spot can be, for example, one in which the average brightness of the RGB in the pixel converted to grayscale is (230/256) or more. The control unit 51 cuts out a rectangle inscribed in a circle with a radius equal to the distance D + the blur width of the zeroth-order diffraction light (for example, distance D x α, α = 0.3). The cut-out rectangle can be used as the zeroth-order diffraction light image. Note that α is not limited to 0.3.

Figures 12, 13, and 14 are diagrams showing an example of a method for generating a kernel. The kernel (also called a filter) is used to sharpen a special diffracted light pattern (first hologram image) identified based on a first image captured by irradiating the target medium with light emitted from the light-emitting unit 52.

The kernel can be generated by the following procedure. As shown in FIG. 12, the control unit 51 divides the cut-out zero-order diffracted light image into, for example, 7×7 regions, and calculates the average luminance value of each region (x, y). In the example of FIG. 12, it is divided into 49 regions, from region (0, 0) to region (6, 6). Note that the number of divisions is not limited to 7×7. The average luminance value of region (0, 0) is 214.08, the average luminance value of region (1, 0) is 213.76, and the average luminance values of the other regions are as shown in FIG. 12. Note that the average luminance values are merely examples, and are not limited to the example of FIG. 12.

Next, as shown in FIG. 13, the control unit 51 calculates the number of regions including zero-order diffracted light with an average luminance of 250.00 or more and blurred zero-order diffracted light with an average luminance of a threshold value (e.g., 230.00) or more based on the calculated average luminance. The control unit 51 weights each region (x, y). The weighting coefficient is set to 0 for regions with an average luminance less than 230.00, and is calculated as weighting coefficient = (average luminance - threshold value) for regions with an average luminance of 230.00 or more. In the example of FIG. 13, the average luminance is 222.34 for region (0, 2) and the weighting coefficient is 0. The average luminance is 243.79 for region (2, 2) and the weighting coefficient is 13.79. The same applies to the other regions.

Next, as shown in FIG. 14, the control unit 51 normalizes the calculated weighting coefficients and calculates the kernel coefficient for each region (x, y) using the formula Kernel coefficient (x, y) = {Weighting coefficient of region/(Total weighting coefficients of each region) x (-1/(Kernel size))}. As shown in FIG. 14, the kernel coefficient for region (3, 3) is -0.002. The same applies to the other regions (x, y).

The absolute value of the kernel coefficient in the center of the kernel is greater than the absolute value of the kernel coefficient in the peripheral portion. This makes it possible to sharpen a special diffracted light pattern (first hologram image) identified based on a first image captured of the target medium by irradiating the target medium with light emitted from the light-emitting unit 52. Sharpening is a conversion process that increases the change in pixel value (change in shading) of the original image. Therefore, if the change in luminance value between certain pixels of the first hologram image after filter processing is greater than the change in luminance value between the same pixels of the first hologram image before filter processing, it can be said that sharpening processing has been performed by the filter.

The kernel coefficients of the kernel for sharpening are not limited to fixed values. When photographing a target medium with light from the light emitting unit 52 irradiated onto the target medium (LED on), the luminance distribution of the zeroth-order diffracted light image may differ depending on the photographing state and the state of the target medium. Therefore, the kernel coefficients of the kernel may be made different according to the difference in the luminance distribution of the zeroth-order diffracted light image.

As described above, the control unit 51 can extract a zero-order diffracted light image including a bright spot region based on the acquired first image, and generate a sharpening filter based on the extracted zero-order diffracted light image. The control unit 51 can also generate a filter having different filter coefficients according to the luminance distribution of the extracted zero-order diffracted light image.

Next, we will explain the details of authenticity determination using a special diffracted light pattern (LED on) and a normal diffracted light pattern.

Figure 15 is a diagram showing an example of authenticity determination using a special diffracted light pattern. Each process shown in Figure 15 is performed by the control unit 51 (authenticity determination application). The control unit 51 acquires a captured image (first image) of the target medium by irradiating the target medium with light from the light emitting unit 52, and can perform a bright spot region identification process on the acquired captured image to identify areas with a predetermined luminous intensity or higher as bright spot regions. The filter process shown in Figure 15 can identify white bright spot regions by performing a process that leaves only strong white bright spots that are saturated or close to saturation among the bright spots in the captured image.

The control unit 51 performs a zeroth-order diffracted light detection process on the white bright spot area to detect the zeroth-order diffracted light coordinates. The zeroth-order diffracted light detection process includes (1) a process for determining whether there is a strong white bright spot where all of the RGB color components are saturated or close to being saturated, (2) a process for calculating the shape and area of the zeroth-order diffracted light based on the number of pixels in the area where pixels of saturated bright spots or close to being saturated are consecutive, and (3) a process for calculating the coordinates of the center point.

The control unit 51 performs a process of detecting the bright spot pattern. Specifically, the control unit 51 detects the bright spot pattern in the peripheral area of the zeroth-order diffracted light. The brightness of the bright spot pattern is lower than that of the zeroth-order diffracted light, but is stronger than a normal diffracted light pattern, so it is sufficient to detect bright spots within a predetermined brightness value range. In the example of FIG. 15, a special diffracted light pattern including an image such as a two-dimensional code or a two-dimensional barcode is detected (identified). That is, the control unit 51 can identify the first hologram image based on the acquired first image.

The control unit 51 sharpens the identified special diffracted light pattern (first hologram image) using a filter to generate a sharpened special diffracted light pattern (first hologram image). The control unit 51 can sharpen the special diffracted light pattern (first hologram image) using the generated filter or a selected filter. Specific examples of filter processing will be described later.

The control unit 51 performs character reading processing on the sharpened special diffracted light pattern to convert the special diffracted light pattern into a character string. In the example of FIG. 15, a URL is given as an example of a character string, but the character string is not limited to a URL.

The control unit 51 performs a string matching process to determine whether the converted string matches any of the multiple correct strings included in the correct answer information 61, and outputs the string matching result. If a predetermined threshold value (e.g., 90%) or more of the characters in the converted string match the characters in the correct answer string, the strings can be determined to match.

That is, the control unit 51 determines the authenticity of the target medium based on the sharpened first hologram image. More specifically, the control unit 51 converts the sharpened first hologram image into a character string, and compares the converted character string with the correct answer character string to determine the authenticity of the target medium. The control unit 51 can also determine the authenticity of the target medium based on whether the number of characters that match between the character string and the correct answer character string is equal to or greater than a predetermined threshold.

The control unit 51 performs an authenticity determination process and outputs a first authenticity determination result based on the string matching result. The first authenticity determination result is a determination that the item is "genuine" if the string matching result is "match", and a determination that the item is "fake" if the string matching result is "mismatch".

As described above, the control unit 51 can identify the first hologram image based on the acquired first image, sharpen the identified first hologram image using a filter, and determine the authenticity of the target medium based on the sharpened first hologram image. As described above, the control unit 51 can sharpen the first hologram image identified based on the first image using a filter, and determine the authenticity of the target medium based on the sharpened first hologram image, so that clear diffracted light can be estimated (generated) to determine the authenticity of the medium.

Figure 16 is a diagram showing an example of filter processing on a first hologram image. As shown in Figure 16, for convenience, the filter is assumed to be 3 x 3 pixels, and the filter coefficients are k1, k2, k3, ..., k9 from the upper left to the lower right of the filter. The pixel values of the pixel area corresponding to the filter are assumed to be a1, a2, a3, ..., a9. The center of the pixel area is the pixel of interest.

In the filter processing of the first hologram image before sharpening, the filter coefficient is multiplied by the pixel value of the pixel area, and the result of the calculation (product-sum calculation) that is added together becomes the pixel value of the corresponding pixel of interest in the first hologram image after sharpening. The pixel value a5' of the corresponding pixel of interest in the first hologram image after sharpening can be calculated using the formula a5' = a1.k1 + a2.k2 + a3.k3 + a4.k4 + a5.k5 + a6.k6 + a7.k7 + a8.k8 + a9.k9. The first hologram image after sharpening can be generated by calculating each pixel of interest on the first hologram image before sharpening while operating the filter.

Figure 17 is a diagram showing an example of authenticity determination using a normal diffracted light pattern. Each process shown in Figure 17 is performed by the control unit 51 (authenticity determination application). The control unit 51 acquires a captured image (second image) of the target medium without irradiating the target medium with light from the light emitting unit 52, and performs a diffracted light pattern detection process on the acquired captured image to detect (identify) a normal diffracted light pattern.

The control unit 51 performs a similarity calculation process to calculate the similarity between the detected normal diffraction light pattern and one or more correct images included in the correct answer information 61. The calculation of the similarity can use the following template matching method. That is, the mean square error of the luminance values for each corresponding pixel between the detected normal diffraction light pattern and the correct answer image is calculated, the mean square errors calculated for each pixel are added, and the reciprocal of the sum is taken as the similarity. In this case, the similarity is a value equivalent to the reciprocal of the value calculated based on the mean square error, so the larger the similarity, the more similar the normal diffraction light pattern and the correct answer image are. Note that the calculation of the similarity is not limited to the template matching method.

The control unit 51 performs an authenticity determination process and outputs a second authenticity determination result based on the calculated similarity. The second authenticity determination result is determined to be "genuine" if the calculated similarity is equal to or greater than a predetermined similarity threshold, and is determined to be "fake" if the calculated similarity is less than the similarity threshold.

As described above, the control unit 51 can acquire a second image of the target medium without irradiating the target medium with light from the light emitting unit 52, identify a second hologram image (normal diffracted light pattern) based on the acquired second image, and determine the authenticity of the target medium based on the identified second hologram image. The control unit 51 can also calculate the similarity between the identified second hologram image and a correct image, and determine the authenticity of the target medium based on the calculated similarity and a similarity threshold.

The control unit 51 can determine the target medium as genuine when the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image are both determined to be genuine. As a result, even if either the first hologram image or the second hologram image is illegally obtained by a third party, by employing both the first authenticity determination based on the first hologram image and the second authenticity determination based on the second hologram image, it is possible to prevent a counterfeit from being determined to be genuine.

Figure 18 is a diagram showing an example of a display screen during authenticity determination. The display screen shown in Figure 18 is displayed on the display unit 54. Figure 18A shows a display screen when the target medium is determined to be genuine in the authenticity determination, and Figure 18B shows a display screen when the target medium is determined to be a counterfeit. When a user starts the authenticity determination application, the control unit 51 acquires a first image obtained by photographing the target medium with the LED turned on, identifies a first hologram image (special diffracted light pattern) based on the acquired first image, performs a sharpening process on the identified first hologram image, and performs a first authenticity determination process based on the sharpened first hologram image, while acquiring a second image obtained by photographing the target medium with the LED turned off, identifies a second hologram image (normal diffracted light pattern) based on the acquired second image, and performs a second authenticity determination process. The first authenticity determination process and the second authenticity determination process can be repeated a predetermined number of times until an authenticity determination result is obtained. As shown in FIG. 18A , when the control unit 51 identifies a first hologram image through the first authenticity determination process, the control unit 51 displays the first hologram image on the display unit 54, and thereafter, when the control unit 51 identifies a second hologram image through the second authenticity determination process, the control unit 51 displays the second hologram image on the display unit 54. When the control unit 51 determines that the first authenticity determination based on the first hologram image and the second authenticity determination based on the second hologram image are both true, the control unit 51 can display a message such as "Hologram recognized" to notify the user that the target object is real.

On the other hand, as shown in FIG. 18B, if the target medium is determined to be a counterfeit by either the first authenticity determination based on the first hologram image or the second authenticity determination based on the second hologram image, a message such as "Timeout has occurred" can be displayed to notify the user that the target medium is a counterfeit.

Figure 19 is a diagram showing an example of the procedure for authenticity determination processing by the authenticity determination device 50 of this embodiment. The control unit 51 starts an app (authenticity determination application) (S11), acquires an image (first image) of the target medium taken with the LED on (S12), and extracts a zeroth-order diffracted light image based on the acquired image (S13). The control unit 51 generates a sharpening filter based on the extracted zeroth-order diffracted light image (S14).

The control unit 51 detects the position of the zeroth-order diffracted light based on the acquired image (first image) (S15). The control unit 51 identifies a first hologram image (special diffracted light pattern) in the peripheral area of the zeroth-order diffracted light (S16), and sharpens the identified first hologram image using the filter generated in step S14 (S17). The control unit 51 converts the sharpened first hologram image into a character string (S18). The control unit 51 compares the converted character string with the correct character string to perform a first authenticity determination (S19).

The control unit 51 acquires an image (second image) of the target medium captured with the LED off (S20), identifies a second hologram image (normal diffracted light pattern) based on the acquired image (S21), and calculates the similarity between the identified second hologram image and the correct image (S22). The control unit 51 performs a second authenticity determination based on the calculated similarity (S23).

The control unit 51 can repeat the processes of steps S13 to S19 a required number of times until a first authenticity determination result is obtained. The control unit 51 can also repeat the processes of steps S20 to S23 a required number of times until a second authenticity determination result is obtained. The control unit 51 determines the authenticity of the target medium based on the first and second authenticity determination results (S24). The control unit 51 outputs the authenticity determination result (S25) and ends the process.

Second Embodiment
In the first embodiment described above, the authenticity determination device 50 is a smartphone or the like that performs the authenticity determination by itself, but the present invention is not limited to this. In the second embodiment, a case will be described in which the terminal device that photographs the target medium and the authenticity determination device that performs the authenticity determination are separate devices.

Figure 20 is a diagram showing an example of the configuration of an authenticity determination system. The authenticity determination system includes a terminal device 100 and an authenticity determination device 150. The terminal device 100 and the authenticity determination device 150 are connected via a communication network N.

The terminal device 100 can be configured as a smartphone, a tablet terminal, a PC, or the like. The terminal device 100 includes a control unit 101 that controls the entire device, a light emitting unit 102, an image capturing unit 103, a display unit 104, an operation unit 105, a communication unit 106, a memory 107, and a storage unit 108. The control unit 101, the light emitting unit 102, the image capturing unit 103, the display unit 104, the operation unit 105, the communication unit 106, the memory 107, and the storage unit 108 each have the same functions as the control unit 51, the light emitting unit 52, the image capturing unit 53, the display unit 54, the operation unit 55, the communication unit 56, the memory 57, and the storage unit 58 illustrated in FIG. 1, respectively, and therefore description thereof will be omitted.

Computer program 110 is computer program 60 illustrated in FIG. 1 with the processing related to authenticity determination removed. Also, computer program 110 differs from the configuration in FIG. 1 in that memory unit 108 does not store correct answer information 61.

The authenticity determination device 150 can be realized by a server or a cloud. The authenticity determination device 150 includes a control unit 151 that controls the entire device, a communication unit 152, a memory 153, and a storage unit 154. The control unit 151, the communication unit 152, the memory 153, and the storage unit 154 have the same functions as the control unit 51, the communication unit 56, the memory 57, and the storage unit 58 illustrated in FIG. 1, respectively, and therefore will not be described.

Computer program 160 includes the process related to authenticity determination among computer program 60 illustrated in FIG. 1. Correct answer information 161 is the same as correct answer information 61 illustrated in FIG. 1.

The first and second embodiments differ in that the first and second images captured by the terminal device 100 are transmitted to the authenticity determination device 150, the authenticity determination device 150 acquires the first and second images captured by the terminal device 100 from the terminal device 100, and the authenticity determination device 150 transmits the authenticity determination result to the terminal device 100. The authenticity determination by the authenticity determination device 150 is the same as in the first embodiment, so a description thereof will be omitted.

According to each of the above-mentioned embodiments, by using a common device (equipment) such as a smartphone, it is possible to easily determine the authenticity of the target medium by estimating (generating) clear diffracted light from a light source that can be considered a point light source, without requiring any special skills.

(Supplementary Note 1) The authenticity determination device includes a control unit, which obtains a first image of the target medium by irradiating the target medium with light emitted from a light-emitting unit, identifies a first hologram image based on the obtained first image, sharpens the identified first hologram image using a filter, and determines the authenticity of the target medium based on the sharpened first hologram image.

(Appendix 2) In the authenticity determination device of Appendix 1, the control unit extracts a zero-order diffracted light image including a bright spot region based on the acquired first image, generates a sharpening filter based on the extracted zero-order diffracted light image, and sharpens the identified first hologram image using the generated filter.

(Appendix 3) In appendix 1 or appendix 2, the authenticity determination device stores filter information that associates each of a plurality of different zeroth-order diffracted light images with a sharpening filter, and the control unit extracts a zeroth-order diffracted light image including a bright spot region based on the acquired first image, selects a sharpening filter that corresponds to the extracted zeroth-order diffracted light image from the filter information, and sharpens the identified first hologram image using the selected filter.

(Appendix 4) In the authenticity determination device according to any one of appendices 1 to 3, the filter coefficient of the central part of the filter is greater than the filter coefficient of the peripheral part.

(Appendix 5) In the authenticity determination device according to any one of appendices 1 to 4, the control unit converts the sharpened first hologram image into a character string, and compares the converted character string with a correct answer character string to determine the authenticity of the target medium.

(Appendix 6) In the authenticity determination device of Appendix 5, the control unit determines the authenticity of the target medium based on whether the number of characters that match between the character string and the correct answer character string is equal to or greater than a predetermined threshold.

(Appendix 7) In the authenticity determination device according to any one of appendices 1 to 6, the control unit obtains a second image of the target medium without irradiating the target medium with light from the light emitting unit, identifies a second hologram image based on the obtained second image, and determines the authenticity of the target medium based on the identified second hologram image.

(Appendix 8) In the authenticity determination device of appendix 7, the control unit calculates the similarity between the identified second hologram image and a correct image, and determines the authenticity of the target medium based on the calculated similarity and a similarity threshold.

(Supplementary Note 9) In the authenticity determination device of Supplementary Note 7 or Supplementary Note 8, the control unit determines the target medium to be authentic when the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image are both determined to be authentic.

(Appendix 10) The computer program causes a computer to execute a process of acquiring a first image of a target medium by irradiating the target medium with light emitted from a light emitting unit, identifying a first hologram image based on the acquired first image, sharpening the identified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

(Appendix 11) The authenticity determination method involves irradiating a target medium with light emitted from a light-emitting unit to obtain a first image of the target medium, identifying a first hologram image based on the obtained first image, sharpening the identified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

The matters described in each embodiment can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations regardless of the citation format. Furthermore, the claims use a format in which a claim cites two or more other claims (multi-claim format), but this is not limited to this. They may also be written in a format in which multiple claims cite at least one other claim (multi-multi-claim).

REFERENCE SIGNS LIST 1 hologram layer 2 deposition layer 3 transparent substrate 10 hologram structure 11 hologram formation area 12 uneven surface 30 cover 40 recording medium reading device 50, 150 authenticity determination device 51, 101, 151 control unit 52, 102 light emitting unit 53, 103 imaging unit 54, 104 display unit 55, 105 operation unit 56, 106, 152 communication unit 57, 107, 153 memory 58, 108, 154 storage unit 60, 110, 160 computer program 61, 161 correct answer information 100 terminal device

Claims (11)

A control unit is provided,
The control unit is
acquiring a first image by irradiating the target medium with light emitted from a light emitting unit and capturing the target medium;
Identifying a first hologram image based on the acquired first image;
The identified first hologram image is sharpened using a filter;
determining the authenticity of the target medium based on the sharpened first hologram image;
Authenticity determination device. The control unit is
Extracting a zero-order diffracted light image including a bright spot region based on the acquired first image;
generating a sharpening filter based on the extracted zero-order diffracted light image;
sharpening the identified first hologram image using the generated filter;
The authenticity determining device according to claim 1 . storing filter information in which each of a plurality of different zero-order diffracted light images is associated with a sharpening filter;
The control unit is
Extracting a zero-order diffracted light image including a bright spot region based on the acquired first image;
selecting a sharpening filter corresponding to the extracted zeroth-order diffracted light image from the filter information;
sharpening the identified first hologram image with a selected filter;
The authenticity determining device according to claim 1. The filter coefficients of the center portion of the filter are greater than the filter coefficients of the peripheral portions.
The authenticity determining device according to any one of claims 1 to 3. The control unit is
converting the sharpened first hologram image into a character string;
comparing the converted character string with a correct character string to determine the authenticity of the target medium;
The authenticity determining device according to any one of claims 1 to 3. The control unit is
determining the authenticity of the target medium based on whether the number of characters that match between the character string and the correct character string is equal to or greater than a predetermined threshold;
The authenticity determining device according to claim 5. The control unit is
acquiring a second image of the target medium without irradiating the target medium with light from the light emitting unit;
Identifying a second hologram image based on the acquired second image;
determining the authenticity of the target medium based on the identified second hologram image;
The authenticity determining device according to any one of claims 1 to 3. The control unit is
Calculating a similarity between the specified second hologram image and a correct image;
determining the authenticity of the target medium based on the calculated similarity and a similarity threshold;
The authenticity determining device according to claim 7. The control unit is
determining the target medium as genuine when both the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image are determined to be genuine;
The authenticity determining device according to claim 7. acquiring a first image by irradiating the target medium with light emitted from a light emitting unit and capturing the target medium;
Identifying a first hologram image based on the acquired first image;
The identified first hologram image is sharpened using a filter;
determining the authenticity of the target medium based on the sharpened first hologram image;
A computer program that causes a computer to carry out processing. acquiring a first image by irradiating the target medium with light emitted from a light emitting unit and capturing the target medium;
Identifying a first hologram image based on the acquired first image;
The identified first hologram image is sharpened using a filter;
determining the authenticity of the target medium based on the sharpened first hologram image;
Authenticity determination method.

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