Authenticity determination device, computer program, and authenticity determination method

Abstract

To provide an authenticity determination device, a computer program, and an authenticity determination method that can estimate sharp diffraction light to perform authenticity determination for a medium.SOLUTION: The authenticity determination device includes a control unit. The control unit acquires a first image obtained by radiating light emitted from a light emission unit to a target medium to capture an image of the target medium, specifies a first hologram image based on the acquired first image, sharpens the specified first hologram image using a filter, and determines authenticity of the target medium based on the sharpened first hologram image.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a genuine / fake determination device, a computer program, and a genuine / fake determination method.

Background Art

[0002] For credit cards, banknotes, stock certificates, gift certificates, luxury brand products, etc., media in which information for preventing duplication and forgery is recorded are used. For such media, security technologies such as holograms that are difficult to duplicate are utilized.

[0003] Patent Document 1 discloses an inspector that irradiates light from a light source onto a hologram of a banknote, captures reflected light in two different directions from the hologram by a reflection prism, refracts it in substantially the same direction, and enables viewing of two images of the hologram. However, handling an inspector such as that in Patent Document 1 requires special skills and expertise.

[0004] On the other hand, portable terminals such as flashlights, high-performance cameras capable of taking high-quality photos, and smartphones equipped with advanced image processing functions have become widely popular. It is reasonable to perform genuine / fake determination of media by utilizing the functions of such portable terminals without special skills or expertise.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the light-emitting element used in the flashlight mounted on a portable terminal such as a smartphone is a small area light source, the light-emitting surface is wider compared to an ideal point light source. The light emitted from the area light source includes wrap-around light. When diffracted light due to this wrap-around light is simultaneously observed, there is a problem that clear diffracted light cannot be obtained compared to the case of a point light source.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a authenticity determination device, a computer program, and an authenticity determination method capable of estimating clear diffracted light and performing authenticity determination of a medium.

Means for Solving the Problems

[0008] The authenticity determination device of the present embodiment includes a control unit. The control unit irradiates the target medium with the light emitted from the light-emitting unit to obtain a first image of photographing the target medium, specifies a first hologram image based on the obtained first image, sharpens the specified first hologram image using a filter, and determines the authenticity of the target medium based on the sharpened first hologram image.

[0009] The computer program of the present embodiment causes a computer to execute a process of irradiating a target medium with the light emitted from a light-emitting unit to obtain a first image of photographing the target medium, specifying a first hologram image based on the obtained first image, sharpening the specified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

[0010] The authenticity determination method of the present embodiment includes obtaining a first image of photographing a target medium by irradiating the target medium with the light emitted from a light-emitting unit, specifying a first hologram image based on the obtained first image, sharpening the specified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

Effects of the Invention

[0011] According to the present invention, it is possible to estimate clear diffracted light and determine the authenticity of a medium.

Brief Description of the Drawings

[0012]

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Mode for Carrying Out the Invention

[0013] (First Embodiment) Hereinafter, the present invention will be described based on the drawings showing its embodiments. FIG. 1 is a diagram showing an example of the configuration of the 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 portable device such as a smartphone, a tablet terminal, or a personal computer, and is carried by a user. In the present embodiment, a smartphone will be taken as an example to describe the authenticity determination device 50.

[0014] The storage unit 58 can be composed of a semiconductor memory or the like, and can store a computer program 60, correct information 61, and required information. The computer program 60 is an authenticity determination application (also simply referred to as an "app") that operates on the authenticity determination device 50. The correct information 61 includes a correct character string and a correct image, which will be described later.

[0015] The control unit 51 is configured by incorporating a required number of CPUs (Central Processing Units), MPUs (Micro-Processing Units), GPUs (Graphics Processing Units), etc. The control unit 51 can execute the processes defined by the computer program 60. That is, the processes by the control unit 51 are also the processes by the computer program 60. A recording medium M (a non-transitory recording medium readable by a computer) on which the computer program 60 is recorded may be read by a recording medium reader (such as a computer) 40, and the read computer program 60 may be downloaded via the communication unit 56 and stored in the storage unit 59.

[0016] The light emitting unit 52 includes a light emitting element such as an LED. The light emitting element is a small area light source. As the LED, a white LED or the like can be used. The light emitting unit 52 irradiates the target medium with reference light. The target medium is an object for authenticity determination, and is a medium on which information for preventing duplication, forgery, etc. is recorded, such as a credit card, banknote, stock certificate, gift certificate, or high-class brand product. In the present embodiment, the target medium uses holography (hologram).

[0017] Holography is a technique of recording the amplitude and phase (object light) of a light wave to be recorded as an interference fringe on a medium by interfering it with a reference light, and reproducing the recorded light wave using the diffraction phenomenon. An object on which the interference fringe is recorded is called a hologram.

[0018] 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 the condition that the target medium is irradiated with light from the light emitting unit 52 (also referred to as "LED on"), and an image (second image) of the target medium under the condition that the target medium is not irradiated with light from the light emitting unit 52 (also referred to as "LED off").

[0019] The display unit 54 includes a liquid crystal display panel, an organic EL display panel, etc., and can display the determination result by the authenticity determination device 50 and the like.

[0020] The operation unit 55 is composed of a touch panel or the like, can perform a character input operation on the display unit 54, and can also perform an operation on an icon, an image, a character, etc. displayed on the display unit 54.

[0021] The communication unit 56 includes a communication module and has a communication function with an external device via a communication network.

[0022] The memory 57 can be composed of a semiconductor memory such as SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), or flash memory. By expanding the computer program 60 in the memory 57, the control unit 51 can execute the computer program 60.

[0023] The control unit 51 (computer program 60, authenticity determination application) can control the on / off of the light emission of the light emitting unit 52, control the light amount, and control the operation of the imaging unit 53. Further, the control unit 51 performs processing such as image processing on the acquired image and authenticity determination of the target medium.

[0024] Next, the hologram structure provided on the target medium targeted by the authenticity determination device 50 of the present embodiment will be described.

[0025] FIG. 2 is a plan view showing an example of the outline of the hologram structure 10, and FIG. 3 is a longitudinal sectional view taken along line A-A of FIG. 2. The hologram structure 10 has a hologram layer 1 having a hologram forming region 11. In the hologram forming region 11, a phase type Fourier transform hologram that converts the light incident from the light emitting unit 52 into a desired optical image is recorded. The hologram forming region 11 is a reflective Fourier transform hologram forming region, and the hologram structure 10 has a vapor deposition layer 2 formed so as to be in contact with the uneven surface 12 of the hologram forming region 11. The hologram structure 10 has a transparent substrate 3 laminated on the surface opposite to the vapor deposition layer 2 of the hologram layer 1. In FIG. 3, the region surrounded by the broken line is the hologram forming region 11.

[0026] Here, the recording of the phase type Fourier transform hologram 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 the depth. Therefore, an uneven surface 12 is formed in the hologram forming region 11 of the hologram layer 1 on which the phase type Fourier transform hologram is recorded.

[0027] As described above, since the phase-type Fourier transform hologram is recorded in the hologram formation region 11, the hologram structure 10 can reproduce an optical image (also referred to as a "special diffraction light pattern" or a "first hologram image") within the hologram formation region in a plan view by the light incident from the light emitting unit 52. That is, the optical image can be reproduced only when irradiated with the light from the light emitting unit 52, and the optical image is not reproduced when not irradiated with the light from the light emitting unit 52. The optical image can extract the original digital information from the shape represented by a pattern, a picture, etc. using the authenticity determination device 50, and includes two-dimensional codes such as barcodes, QR codes (registered trademarks), two-dimensional barcodes (first hologram images), and the like. The details of the above-described hologram structure are disclosed in Japanese Patent Application No. 2020-68389 (Patent No. 6973550) filed by the applicant. Further, the details of matters related to the phase-type Fourier transform hologram and the like are disclosed in 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 related to the applicant's patent application.

[0028] 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 an operation using the authenticity determination device 50, without requiring special skills or expertise. The user first activates the authenticity determination application (app). The user points the light emitting unit 52 and the imaging unit 53 of the smartphone, which is the authenticity determination device 50, at the target medium. The authenticity determination application irradiates the target medium with the light from the light emitting unit 52 to obtain an image (first image) of the target medium taken, and also obtains an image (second image) of the target medium taken without irradiating the target medium with the light from the light emitting unit 52. The authenticity determination application performs 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 authenticity determination simply by holding the smartphone pointing at the target medium. Note that the authenticity determination application can repeat the acquisition process of the images (first image and second image) and the authenticity determination process as necessary. Hereinafter, a specific example of authenticity determination will be described.

[0029] FIG. 4 is a diagram showing an example of diffracted light that appears centered on the zero-order diffracted light as a comparative example. In the example of FIG. 4, it is assumed that the target medium is real and is irradiated with light from an LED light source (LED on). Since the LED is in the on state, in addition to the ambient light, the light from the LED light source is irradiated onto the target medium as reference light. When the real target medium is irradiated with light from the LED light source as reference light, a special diffracted light pattern (unique bright spot pattern) is reproduced around the zero-order diffracted light (total reflection). In the determination region, the first hologram is recorded so that a 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 regarded as a point light source, the spot of the zero-order diffracted light (reflected light) is large and the degree of blurring of the special diffracted light pattern is strong. For this reason, there is a risk of hindering the reading of the special diffracted light pattern.

[0030] FIG. 5 is a diagram showing an example of diffracted light that appears centered on the zero-order diffracted light in the case of the present embodiment. In the example of FIG. 5, it is assumed that the target medium is genuine and that light from the light emitting unit 52 is being irradiated (LED on). Since the LED is in the on state, in addition to the ambient light, the light from the light emitting unit 52 is irradiated onto the target medium as reference light. When the genuine target medium is irradiated with light from the light emitting unit 52 as reference light, it reproduces a special diffracted light pattern (unique bright spot pattern) around the zero-order diffracted light (total reflection). In this specification, the zero-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 it is also referred to as total reflection or reflected light. Note that in the present embodiment, the light emitting unit 52 and the imaging unit 53 are arranged within 2 to 3 cm. Thereby, a clear light image can be obtained. A first hologram is recorded in the determination region 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 will be described later, for the specified first hologram image, a sharpening process is performed using a filter (kernel), and the first hologram image reproduced when the target medium is irradiated with light from a light source that can be regarded as a point light source as reference light is estimated. Therefore, the spot of the zero-order diffracted light (reflected light) is small and the special diffracted light pattern becomes clear. For this reason, it becomes easy to read the special diffracted light pattern.

[0031] FIG. 6 is a diagram showing an example of normal diffracted light due to ambient light in the case of the present embodiment. In the example of FIG. 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). Since the LED is in the off state, only the ambient light is irradiated onto the target medium as reference light. When the genuine target medium is irradiated with ambient light as reference light, it reproduces a normal diffracted light pattern (in the example of the figure, the pattern of a tiara). A second hologram is recorded in the determination region so that normal diffracted light is reproduced by the ambient light. The normal diffracted light pattern is the diffracted light of the second hologram.

[0032] FIG. 7 is a diagram showing an example of photographing when the target medium is a fake. When the target medium is a fake (such as printed forgery), there is no hologram in the determination area of the target medium. FIG. 7A shows the case where the target medium is photographed with the light emitting unit 52 of the smartphone, which is the genuine / fake determination device 50, not irradiating light (LED off). Since the LED is in the off state, only the ambient light is irradiated onto the target medium as the reference light, and the reflected light returns to the imaging unit 53 (camera). Since there is no hologram in the determination area, the above-mentioned normal diffraction light pattern cannot be seen.

[0033] FIG. 7B shows the case where the target medium is photographed with the light emitting unit 52 of the smartphone irradiating light (LED on). Since the LED is in the on state, in addition to the ambient light, the light from the light emitting unit 52 is irradiated onto the target medium as the reference light. In this case, bright spots due to the light from the light emitting unit 52 are detected in the determination area, and the direct reflected light of the light returns to the imaging unit 53 (camera). Since there is no hologram in the determination area, the above-mentioned special diffraction light pattern cannot be seen.

[0034] As described above, in the case of a genuine target medium, depending on the photographing conditions (LED on / off), a special diffraction light pattern and a normal diffraction light pattern are reproduced, while in the case of a fake target medium, neither the special diffraction light pattern nor the normal diffraction light pattern is reproduced, so the genuine / fake determination of the target medium can be easily performed.

[0035] On the other hand, it is also assumed that there may be an illegal third party who illegally obtains a copy of the special diffraction light pattern (the first hologram image, specifically, a two-dimensional barcode, etc.) exemplified in FIG. 5 and passes off the fake as the genuine. Hereinafter, countermeasures against such illegal acts will be described.

[0036] FIG. 8 is a diagram showing a first example of the characteristics of the special diffraction pattern of this embodiment. FIGS. 8A and 8B show the case where the light emitting unit 52 is not emitting light, that is, the case where the LED is off. As shown in FIG. 8A, a normal diffraction pattern (in the example of the figure, a tiara pattern) is reproduced in the determination area. As shown in FIG. 8B, even when the smartphone is moved in the direction of the arrow (horizontal direction) with respect to the determination area, the position of the normal diffraction pattern reproduced in the determination area does not change. The normal diffraction pattern has such characteristics.

[0037] On the other hand, FIGS. 8C and 8D show the case where the light emitting unit 52 is emitting light, that is, the case where the LED is on. As shown in FIG. 8C, a special diffraction pattern (code information such as a two-dimensional code or a two-dimensional bar code around the zero-order diffracted light as shown in the figure) is reproduced in the determination area. As shown in FIG. 8D, when the smartphone is moved in the direction of the arrow with respect to the determination area, the position of the special diffraction pattern in the determination area moves following the positions of the light emitting unit 52 and the imaging unit 53 together with the zero-order diffracted light. This is because the incident point of the light incident on the determination area moves.

[0038] The control unit 51 (genuine / fake determination application) can guide (such as output by voice or display of a guidance text) the user to move the smartphone in the horizontal direction with respect to the target medium when the user aims the light emitting unit 52 and the imaging unit 53 of the smartphone, which is the genuine / fake determination device 50, at the target medium. The control unit 51 (genuine / fake determination application) can photograph the target medium with the light emitting unit 52 emitting light while the user moves the smartphone and perform a genuine / fake determination of the target medium.

[0039] As described above, when the position of the smartphone (the positions of the light-emitting unit 52 and the imaging unit 53) is moved horizontally with respect to the target medium, the position of the zero-order diffracted light coincides with the position of the special diffracted light pattern and moves. On the other hand, when simply displaying a copy of the special diffracted light pattern, the displayed copy of the special diffracted light pattern does not move. Thus, according to the present embodiment, the authenticity of the target medium can be accurately determined.

[0040] FIG. 9 is a diagram showing a second example of the characteristics of the special diffracted light pattern of the present embodiment. FIG. 9 shows a case where imaging is performed with the light-emitting unit 52 emitting light, that is, in a state where the LED is on. As shown in FIG. 9, the distance between the target medium and the smartphone is changed as H1, H2 (>H1), H3 (>H2). As the distance between the target medium and the smartphone increases, the size of the special diffracted light pattern around the zero-order diffracted light increases.

[0041] The control unit 51 (the authenticity determination application) can guide (such as output by voice or display of a guidance text) the user so that the distance between the smartphone, which is the authenticity determination device 50, and the target medium becomes longer or shorter when the user aims the light-emitting unit 52 and the imaging unit 53 of the smartphone at the target medium. The control unit 51 (the authenticity determination application) can photograph the target medium with the light-emitting unit 52 emitting light while the user moves the smartphone, and determine the authenticity of the target medium.

[0042] As described above, 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 becomes longer or shorter, the size of the special diffracted light pattern around the zero-order diffracted light changes. On the other hand, when simply displaying a copy of the special diffracted light pattern, the size of the displayed copy of the special diffracted light pattern does not change. Thus, according to the present embodiment, the authenticity of the target medium can be accurately determined.

[0043] As described above, the light emitting unit 52 includes an LED light source, and is a small surface light source. As described with reference to FIG. 4, the spot of the zero-order diffracted light (reflected light) is large, and the blurring degree of the special diffracted light pattern is strong. Therefore, a method for making the special diffracted light pattern obtained when the light emitted from the light emitting unit 52 irradiates the target medium equivalent to the special diffracted light (see FIG. 5) obtained when irradiating the target medium with light from a light source that can be regarded as an ideal point light source will be described.

[0044] FIG. 10 is a diagram showing an example of a method for detecting zero-order diffracted light. The zero-order diffracted light is a strong white bright spot in which all of the RGB color components are saturated or nearly saturated, and has a circular or square shape. Also, the zero-order diffracted light is a set of bright spots having an area within a certain range. Here, "saturated" means, for example, a state in which light having a light intensity equal to or higher than the detection upper limit of the camera sensor is incident. Note that the hologram diffracted light (special diffracted light) is different from the zero-order diffracted light in that the RGB color components are non-uniform, is not a white bright spot, and has a lower luminance than the zero-order diffracted light.

[0045] As shown in FIG. 10, the control unit 51 irradiates the target medium with the light from the light emitting unit 52 to obtain a captured image (first image) of the target medium, and performs a bright spot region specifying process on the obtained captured image to specify a region having a predetermined light intensity or higher as a bright spot region. In the example of FIG. 10, the white bright spots (saturated bright spots) are left.

[0046] Next, the control unit 51 performs a zero-order diffracted light detection process. In the zero-order diffracted light detection process, condition discrimination of the zero-order diffracted light, calculation of the shape, area, and center point of the zero-order diffracted light, etc. are performed. The condition discrimination of the zero-order diffracted light discriminates (1) that all of the RGB color components are saturated or nearly saturated, (2) that the shape is circular or square, (3) that it is a set of bright spots having an area within a certain range, etc., which are the conditions of the zero-order diffracted light. The center of the set of bright spots becomes the zero-order diffracted light detection coordinates. The area is the number of pixels in a region where pixels of bright spots that are saturated or nearly saturated are continuous.

[0047] The control unit 51 cuts out a zero-order diffracted light image, which is a set of bright spots, centered on the zero-order diffracted light detection coordinates by performing a zero-order diffracted light image cutting-out process.

[0048] Figure 11 is a diagram showing an example of the extraction process of the zero-order diffraction image. The control unit 51 obtains the distance D that is the farthest from the zero-order diffraction light coordinates among the distances D1, D2, D3, and D4 in four directions (x-, y-, x+, y+) where strong white bright spots continue continuously in four directions centered on the detected zero-order diffraction light coordinates. The strong white bright spot can be, for example, the average luminance in the RGB grayscale conversion in a pixel being (230 / 256) or more. The control unit 51 cuts out a rectangle that inscribes a circle with a radius of the distance D + the blur width of the zero-order diffraction light (for example, the distance D × α, α = 0.3). The cut-out rectangle can be used as the zero-order diffraction light image. Note that α is not limited to 0.3.

[0049] Figures 12, 13, and 14 are diagrams showing an example of the method for generating a kernel. The kernel (also referred to as a filter) is for sharpening a special diffraction light pattern (the first hologram image) specified based on a first image obtained by irradiating a target medium with light emitted from the light emitting unit 52 and photographing the target medium.

[0050] The generation of the kernel can be performed according to the following procedure. As shown in Figure 12, the control unit 51 divides the cut-out zero-order diffraction light image into, for example, 7×7 regions and calculates the average luminance value of each region (x, y). In the example of Figure 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 other regions are as shown in Figure 12. Note that the average luminance value is an example and is not limited to the example of Figure 12.

[0051] Next, as shown in FIG. 13, the control unit 51 calculates the number of regions including the 0th-order diffracted light with an average luminance of 250.00 or more and the blur of the 0th-order diffracted light with an average luminance of the threshold value (for example, 230.00) or more based on the calculated average luminance value. 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 for regions with an average luminance of 230.00 or more, the weighting coefficient is calculated as (average luminance - threshold value). In the example of FIG. 13, for the region (0, 2), the average luminance is 222.34 and the weighting coefficient is 0. For the region (2, 2), the average luminance is 243.79 and the weighting coefficient is 13.79. The same applies to other regions.

[0052] Next, as shown in FIG. 14, the control unit 51 normalizes the calculated weighting coefficient and calculates the kernel coefficient of each region (x, y) using the formula: kernel coefficient (x, y) = {weighting coefficient of the region / (total of the weighting coefficients of each region) × (-1 / (kernel size))}. As shown in FIG. 14, the kernel coefficient of the region (3, 3) is -0.002. The same applies to other regions (x, y).

[0053] The absolute value of the kernel coefficient at the center of the kernel is larger than the absolute value of the kernel coefficient at the periphery. As a result, the special diffracted light pattern (first hologram image) identified based on the first image obtained by irradiating the target medium with the light emitted from the light emitting unit 52 and photographing the target medium can be sharpened. Sharpening is a conversion process that increases the pixel value change (shading change) of the original image. Therefore, if the change in luminance values between a plurality of pixels in the first hologram image after the filtering process is larger than the change in luminance values between the plurality of pixels in the first hologram image before the filtering process, it can be said that the sharpening process by the filter has been performed.

[0054] The kernel coefficient of the kernel for sharpening is not limited to a fixed value. When photographing the target medium in a state where the light from the light emitting unit 52 irradiates the target medium (LED on state), the luminance distribution of the zero-order diffracted light image may vary depending on the photographing state and the state of the target medium. Therefore, the kernel coefficient of the kernel can be made different according to the difference in the luminance distribution of the zero-order diffracted light image. It can be made like this.

[0055] As described above, the control unit 51 can extract a zero-order diffracted light image including a bright point region based on the acquired first image, and generate a filter for sharpening based on the extracted zero-order diffracted light image. Further, the control unit 51 can generate a filter having different filter coefficients according to the luminance distribution of the extracted zero-order diffracted light image.

[0056] Next, the details of authenticity determination using a special diffracted light pattern (LED on state) and a normal diffracted light pattern will be described.

[0057] FIG. 15 is a diagram showing an example of authenticity determination using a special diffracted light pattern. Each process shown in FIG. 15 is performed by the control unit 51 (authenticity determination application). The control unit 51 acquires a captured image (first image) obtained by irradiating the target medium with the light from the light emitting unit 52 and photographing the target medium, and performs a bright point region specifying process on the acquired captured image to specify a region having a predetermined light intensity or higher as the bright point region. In the filter process shown in FIG. 15, among the bright points in the captured image, a process of leaving only strong white bright points that are saturated or nearly saturated can be performed to specify the white bright point region.

[0058] The control unit 51 performs a zero-order diffracted light detection process on the white bright point region to detect the zero-order diffracted light coordinates. The zero-order diffracted light detection process includes (1) a determination process for strong white bright points where all RGB color components are saturated or nearly saturated, (2) a process for calculating the shape and area of the zero-order diffracted light based on the number of pixels in a region where pixels of saturated bright points or bright points close to saturation are continuous, (3) a process for calculating the coordinates of the center point, and the like.

[0059] The control unit 51 performs a bright spot pattern detection process. Specifically, the control unit 51 detects the bright spot pattern in the peripheral region of the zero-order diffracted light. Although the luminance of the bright spot pattern is lower than that of the zero-order diffracted light, it is stronger than the normal diffracted light pattern. Therefore, it is only necessary to detect the bright spots within a predetermined luminance 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 bar code is detected (identified). That is, the control unit 51 can identify the first hologram image based on the acquired first image.

[0060] The control unit 51 sharpens the identified special diffracted light pattern (first hologram image) using a filter and generates a sharpened special diffracted light pattern (first hologram image). Note that the control unit 51 can sharpen the special diffracted light pattern (first hologram image) using the generated filter or the selected filter. Specific examples of the filtering process will be described later.

[0061] The control unit 51 performs a character reading process 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 the character string, but the character string is not limited to the URL.

[0062] The control unit 51 performs a character string matching process to determine whether the converted character string matches any of the plurality of correct character strings included in the correct information 61, and outputs a character string matching result. If a predetermined threshold (such as 90%) or more of the characters in the converted character string match the characters of the correct character string, it can be determined that the character strings match.

[0063] 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, compares the converted character string with the correct character string, and determines the authenticity of the target medium. In addition, the control unit 51 can determine the authenticity of the target medium according to whether the number of matching characters between the character string and the correct character string is equal to or greater than a predetermined threshold.

[0064] The control unit 51 performs authenticity determination processing and outputs a first authenticity determination result based on the character string matching result. The first authenticity determination result can determine that it is "genuine" when the character string matching result is "matched", and determine that it is "fake" when the character string matching result is "unmatched".

[0065] 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, since the first hologram image identified based on the first image is sharpened using a filter and the authenticity of the target medium is determined based on the sharpened first hologram image, clear diffracted light can be estimated (generated) to determine the authenticity of the medium.

[0066] FIG. 16 is a diagram showing an example of filter processing for the first hologram image. As shown in FIG. 16, for convenience, the filter is set to 3×3 pixels, and the filter coefficients are k1, k2, k3, …, k9 from the upper left to the lower right of the filter. Let the pixel values of the pixel region corresponding to the filter be a1, a2, a3, …, a9. The center of the pixel region is the pixel of interest.

[0067] In the filter processing for the first hologram image before sharpening, the filter coefficients are multiplied by the pixel values of the pixel region and all are added (sum-of-products operation) so that the operation result 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 by the formula a5′ = a1·k1 + a2·k2 + a3·k3 + a4·k4 + a5·k5 + a6·k6 + a7·k7 + a8·k8 + a9·k9. By operating the filter for each pixel of interest while performing the operation on the first hologram image before sharpening, the first hologram image after sharpening can be generated.

[0068] FIG. 17 is a diagram showing an example of authenticity determination using a normal diffraction pattern. Each process shown in FIG. 17 is performed by a control unit 51 (authenticity determination application). The control unit 51 acquires a captured image (second image) obtained by photographing the target medium without irradiating the target medium with the light from the light emitting unit 52, and performs a diffraction pattern detection process on the acquired captured image to detect (specify) a normal diffraction pattern.

[0069] The control unit 51 calculates the similarity between the detected normal diffraction pattern and one or more correct images included in the correct information 61 by performing a similarity calculation process. For calculating the similarity, the following template matching method can be used. That is, the mean square error of the luminance values for each corresponding pixel is calculated between the detected normal diffraction pattern and the correct image, the mean square errors calculated for each pixel are added, and the reciprocal of the added value can be used as the similarity. In this case, since the similarity is a value corresponding to the reciprocal of the value calculated based on the mean square error, the greater the similarity, the more similar the normal diffraction pattern and the correct image are. Note that the calculation of the similarity is not limited to the template matching method.

[0070] 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 can be determined as "genuine" when the calculated similarity is equal to or greater than a predetermined similarity threshold, and determined as "fake" when the calculated similarity is less than the similarity threshold.

[0071] As described above, the control unit 51 can acquire the second image obtained by photographing the target medium without irradiating the target medium with the light from the light emitting unit 52, specify the second hologram image (normal diffraction pattern) based on the acquired second image, and determine the authenticity of the target medium based on the specified second hologram image. Further, the control unit 51 can calculate the similarity between the specified second hologram image and the correct image, and determine the authenticity of the target medium based on the calculated similarity and the similarity threshold.

[0072] When the control unit 51 determines that the target medium is genuine in each of the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image, it can determine that the target medium is genuine. Thereby, even if either the first hologram image or the second hologram image is illegally obtained by a third party, by adopting 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 situation where a counterfeit is determined to be genuine.

[0073] FIG. 18 is a diagram showing an example of a display screen at the time of authenticity determination. The display screen shown in FIG. 18 is displayed on the display unit 54. FIG. 18A shows a display screen when the target medium is determined to be genuine in the authenticity determination, and FIG. 18B shows a display screen when it is determined to be a counterfeit. When the user activates the authenticity determination application, the control unit 51 acquires a first image obtained by photographing the target medium with the LED in the on state, identifies a first hologram image (special diffraction light pattern) based on the acquired first image, performs a sharpening process on the identified first hologram image, performs a first authenticity determination process based on the sharpened first hologram image, acquires a second image obtained by photographing the target medium with the LED in the off state, and based on the acquired second image, identifies a second hologram image (normal diffraction light pattern) 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 the first hologram image by the first authenticity determination process, it displays the first hologram image on the display unit 54, and then, when the second hologram image is identified by the second authenticity determination process, it displays the second hologram image on the display unit 54. When the control unit 51 determines that the target object is genuine in each of the first authenticity determination based on the first hologram image and the second authenticity determination based on the second hologram image, it can display a statement such as "The hologram has been recognized" to notify the user that the target object is genuine.

[0074] On the other hand, as shown in FIG. 18B, when it is determined that the target medium is a fake 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 "Timed out" can be displayed to notify the user that the target object is a fake.

[0075] FIG. 19 is a diagram showing an example of the procedure of the authenticity determination process by the authenticity determination device 50 of the present embodiment. The control unit 51 activates an application (authenticity determination application) (S11), acquires an image (first image) of the target medium taken under the condition of LED on (S12), and extracts a zero-order diffracted light image based on the acquired image (S13). The control unit 51 generates a filter for sharpening based on the extracted zero-order diffracted light image (S14).

[0076] The control unit 51 detects the position of the zero-order diffracted light based on the acquired image (first image) (S15). The control unit 51 identifies the first hologram image in the peripheral region of the zero-order diffracted light (special diffracted light pattern) (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 collates the converted character string with the correct character string to perform the first authenticity determination (S19).

[0077] The control unit 51 acquires an image (second image) of the target medium taken under the condition of LED off (S20), identifies the 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 the second authenticity determination based on the calculated similarity (S23).

[0078] The control unit 51 can repeat the processes of steps S13 to S19 the required number of times until the first authenticity determination result is obtained. Further, the control unit 51 can repeat the processes of steps S20 to S23 the required number of times until the 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 determination result of the authenticity determination (S25) and ends the process.

[0079] (Second Embodiment) In the above-described first embodiment, the configuration was such that a smartphone or the like, which is the authenticity determination device 50, performs authenticity determination alone, but the present invention is not limited to this. In the second embodiment, a case where the terminal device that captures the target medium and the authenticity determination device that performs authenticity determination are separate devices will be described.

[0080] FIG. 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.

[0081] The terminal device 100 can be configured by 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 imaging unit 103, a display unit 104, an operation unit 105, a communication unit 106, a memory 107, and a storage unit 108. Since the control unit 101, the light emitting unit 102, the imaging unit 103, the display unit 104, the operation unit 105, the communication unit 106, the memory 107, and the storage unit 108 have the same functions as the control unit 51, the light emitting unit 52, the imaging 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, the description thereof is omitted.

[0082] The computer program 110 is obtained by removing the processes related to authenticity determination from the computer program 60 illustrated in FIG. 1. Further, it is different from the configuration of FIG. 1 in that the storage unit 108 does not store the correct answer information 61.

[0083] The authenticity determination device 150 can be implemented on a server or in the 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. Since 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, the description thereof is omitted.

[0084] The computer program 160 includes processing related to authenticity determination among the computer programs 60 illustrated in FIG. 1. The correct answer information 161 is the same as the correct answer information 61 illustrated in FIG. 1.

[0085] In the first embodiment and the second embodiment, the points of difference are as follows: the terminal device 100 transmits the first image and the second image captured by the terminal device 100 to the authenticity determination device 150; the authenticity determination device 150 acquires the first image and the second image 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. Since the authenticity determination by the authenticity determination device 150 is the same as that in the case of the first embodiment, the description thereof is omitted.

[0086] According to each of the above-described embodiments, by using a widespread device such as a smartphone, it is possible to easily perform authenticity determination of a target medium by estimating (generating) clear diffracted light from a light source that can be regarded as a point light source without requiring special skills.

[0087] (Appendix 1) The authenticity determination device includes a control unit, and the control unit irradiates a target medium with light emitted from a light emitting unit to obtain a first image of the photographed target medium, specifies a first hologram image based on the obtained first image, sharpens the specified first hologram image using a filter, and determines the authenticity of the target medium based on the sharpened first hologram image.

[0088] (Appendix 2) In Appendix 1, the authenticity determination device is such that 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 specified first hologram image using the generated filter.

[0089] (Appendix 3) In Appendix 1 or Appendix 2, the authenticity determination device stores filter information associating each of a plurality of different zero-order diffracted light images with a sharpening filter. The control unit extracts a zero-order diffracted light image including a bright spot region based on the acquired first image, selects a sharpening filter corresponding to the extracted zero-order diffracted light image from the filter information, and sharpens the specified first hologram image using the selected filter.

[0090] (Appendix 4) In any one of Appendices 1 to 3, the filter coefficient at the center of the filter is larger than the filter coefficient at the peripheral portion.

[0091] (Appendix 5) In any one of Appendices 1 to 4, the control unit converts the sharpened first hologram image into a character string, compares the converted character string with the correct character string, and determines the authenticity of the target medium.

[0092] (Appendix 6) In Appendix 5, the control unit determines the authenticity of the target medium according to whether the number of matching characters between the character string and the correct character string is equal to or greater than a predetermined threshold.

[0093] (Appendix 7) In any one of Appendices 1 to 6, the control unit acquires a second image obtained by photographing the target medium without irradiating the target medium with light from the light emitting unit, specifies a second hologram image based on the acquired second image, and determines the authenticity of the target medium based on the specified second hologram image.

[0094] (Appendix 8) In the authenticity determination device, in Appendix 7, the control unit calculates the similarity between the specified second hologram image and the correct image, and determines the authenticity of the target medium based on the calculated similarity and the similarity threshold.

[0095] (Appendix 9) In the authenticity determination device, in Appendix 7 or Appendix 8, when the control unit determines that the target medium is genuine in both the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image, the control unit determines that the target medium is genuine.

[0096] (Appendix 10) The computer program causes the computer to execute a process of obtaining a first image obtained by irradiating the target medium with light emitted from a light emitting unit and photographing the target medium, specifying a first hologram image based on the obtained first image, sharpening the specified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

[0097] (Appendix 11) The authenticity determination method includes obtaining a first image obtained by irradiating the target medium with light emitted from a light emitting unit and photographing the target medium, specifying a first hologram image based on the obtained first image, sharpening the specified first hologram image using a filter, and determining the authenticity of the target medium based on the sharpened first hologram image.

[0098] The matters described in each embodiment can be combined with each other. Also, the independent claims and dependent claims described in the claims can be combined with each other in all possible combinations regardless of the citation format. Furthermore, although the claims use a format (multi-claim format) of describing a claim that cites two or more other claims, it is not limited to this. A format of describing a multi-claim (multi-multi-claim) that cites at least one multi-claim may be used.

Description of Reference Numerals

[0099] 1 Hologram layer 2 Deposition layer 3 Transparent Substrate 10 Hologram Structure 11 Hologram Formation Region 12 Concave-Convex Surface 30 Cover 40 Recording Medium Reading Device 50, 150 Authenticity Judgment 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

1. Comprising a control unit, The control unit, Obtains a first image by irradiating a target medium with light emitted from a light emitting unit and photographing the target medium, Identifies a first hologram image based on the obtained first image, Sharpens the identified first hologram image using a filter, Determines the authenticity of the target medium based on the sharpened first hologram image, An authenticity determination device.

2. The control unit, Extracts a zero-order diffracted light image including a bright point region based on the obtained first image, Generates a filter for sharpening based on the extracted zero-order diffracted light image, Sharpens the identified first hologram image using the generated filter, The authenticity determination device according to claim 1.

3. Stores filter information associating each of a plurality of different zero-order diffracted light images with a filter for sharpening, The control unit, Extracts a zero-order diffracted light image including a bright point region based on the obtained first image, Selects a filter for sharpening corresponding to the extracted zero-order diffracted light image from the filter information, Sharpens the identified first hologram image using the selected filter, The authenticity determination device according to claim 1.

4. The filter coefficient at the central part of the filter is larger than the filter coefficient at the peripheral part, The authenticity determination device according to any one of claims 1 to 3.

5. The control unit, Converts the sharpened first hologram image into a character string, Compares the converted character string with a correct character string to determine the authenticity of the target medium, The authenticity determination device according to any one of claims 1 to 3.

6. The control unit, Determines the authenticity of the target medium according to whether the number of matching characters between the character string and the correct character string is equal to or greater than a predetermined threshold value, The authenticity determination device according to claim 5.

7. The control unit, Obtains a second image by photographing 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, Determines the authenticity of the target medium based on the identified second hologram image, The authenticity determination device according to any one of claims 1 to 3.

8. The control unit, Calculates the similarity between the identified second hologram image and a correct image, Determines the authenticity of the target medium based on the calculated similarity and a similarity threshold value, The authenticity determination device according to claim 7.

9. The control unit, When it is determined to be genuine in each of the authenticity determination based on the first hologram image and the authenticity determination based on the second hologram image, determining that the target medium is genuine. The authenticity determination device according to claim 7.

10. Obtaining a first image obtained by irradiating the target medium with light emitted from a light emitting unit and photographing the target medium. Identifying a first hologram image based on the obtained first image. Sharpening the identified first hologram image using a filter. Determining the authenticity of the target medium based on the sharpened first hologram image. A computer program for causing a computer to execute a process.

11. Obtaining a first image obtained by irradiating the target medium with light emitted from a light emitting unit and photographing the target medium. Identifying a first hologram image based on the obtained first image. Sharpening the identified first hologram image using a filter. Determining the authenticity of the target medium based on the sharpened first hologram image. An authenticity determination method.

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