Printed matter inspection device, printed matter inspection method, and program

Abstract

The present disclosure pertains to a printed matter inspection device (20) that inspects printed matter to which an OVD has been pasted. The printed matter inspection device (20) comprises: a matching template generation unit (21) that generates a matching template image for specifying a pasting position of an OVD through template matching; and a defect detection unit (22) that specifies the pasting position of the OVD in an image to be inspected which has been captured by photographing printed matter by using the matching template image, masks the specified pasting position of the OVD, and detects a defect in the image to be inspected on the basis of a difference image between the image to be inspected in which the pasting position of the OVD has been masked and an inspection template image.

Description

[Technical Field]

[0001] The present disclosure relates to a printed matter inspection device, a printed matter inspection method, and a computer-readable medium, and in particular to a printed matter inspection device, a printed matter inspection method, and a computer-readable medium that inspect printed matter having an OVD (Optical Variable Device) attached to a substrate. [Background technology]

[0002] Inspection of printed matter is carried out taking into consideration various factors that can cause variations in the printing process of the object being inspected and when capturing an image of the object. For example, such factors can include misalignment during printing and changes in brightness due to the reflection of illumination light during capture. In the inspection of printed matter, areas where these variations may occur are masked (set outside the inspection area), making it possible to perform the inspection without affecting inspection accuracy.

[0003] Furthermore, OVDs are sometimes affixed to printed materials such as banknotes, securities, gift certificates, coupons, and cards to prevent counterfeiting. OVDs come in various shapes, including circular and rectangular, as shown in FIG. 1. However, regardless of their shape, OVDs have significant variations in brightness due to the reflection of illumination light during photography due to their optical properties. Therefore, as shown in FIG. 1, OVDs are masked in print inspection methods according to related technologies. Furthermore, as shown in FIG. 2, there is variation in the placement of OVDs. Therefore, in print inspection methods according to related technologies, areas where OVDs may be present are masked, taking into account misalignment of the OVDs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4753181 Summary of the Invention [Problem to be solved by the invention]

[0005] However, defects may occur in areas of the mask area that are not OVDs (hereinafter referred to as dead zone areas). In the print inspection method according to the related art described above, areas where OVDs may exist are also masked. Therefore, as shown in FIG. 3, defects in the dead zone areas are also masked, and it may not be possible to detect defects in the dead zone areas. Although methods for inspecting OVDs have been disclosed (for example, Patent Document 1), methods for inspecting dead zone areas of the mask area that are not OVDs have not been disclosed.

[0006] Therefore, in consideration of the above-mentioned problems, the object of the present disclosure is to provide a printed matter inspection device, a printed matter inspection method, and a computer-readable medium that are capable of inspecting dead zone areas of a mask area that are not OVDs during printed matter inspection. [Means for solving the problem]

[0007] A print inspection device according to one aspect includes: A print inspection device that inspects prints to which an OVD (Optical Variable Device) is attached, a matching template creation unit that creates a matching template image for identifying the OVD attachment position by template matching; a defect detection unit that uses the matching template image to identify an OVD attachment position in an inspection target image obtained by photographing the printed matter, masks the identified OVD attachment position, and detects defects in the inspection target image based on a difference image between the inspection target image in which the OVD attachment position has been masked and the inspection template image; Equipped with.

[0008] A print inspection method according to one aspect includes: A print inspection method performed by a print inspection device that inspects a print to which an OVD (Optical Variable Device) is attached, comprising: a matching template creation step of creating a matching template image for identifying the OVD attachment position by template matching; a defect detection step of using the matching template image to identify an OVD attachment position in an inspection target image obtained by photographing the printed matter, masking the identified OVD attachment position, and detecting defects in the inspection target image based on a difference image between the inspection target image in which the OVD attachment position has been masked and the inspection template image; Includes.

[0009] According to one aspect, a computer-readable medium includes: A non-transitory computer-readable medium storing a program to be executed by a print inspection device that inspects printed matter to which an OVD (Optical Variable Device) is attached, The program a matching template creation step of creating a matching template image for identifying the OVD attachment position by template matching; a defect detection step of using the matching template image to identify an OVD attachment position in an inspection target image obtained by photographing the printed matter, masking the identified OVD attachment position, and detecting defects in the inspection target image based on a difference image between the inspection target image in which the OVD attachment position has been masked and the inspection template image; Includes. [Effects of the Invention]

[0010] According to the above-described aspects, it is possible to provide a print inspection device, a print inspection method, and a computer-readable medium that are capable of inspecting a dead zone area that is not an OVD in a mask area during print inspection. [Brief explanation of the drawings]

[0011] [Figure 1] 10A and 10B are diagrams showing examples of OVD attachment positions, mask areas, and dead zone areas on printed matter. [Figure 2] FIG. 10 is a diagram showing an example of an image of misalignment of an OVD. [Figure 3] 10A and 10B are diagrams showing an example in which defects in a dead zone cannot be detected by a print inspection method according to the related art; [Figure 4] 1 is a diagram illustrating an example of the configuration of a printed matter inspection device according to a first embodiment. [Figure 5] FIG. 4 is a diagram showing an example of a method for creating a matching template image according to the first embodiment. [Figure 6] FIG. 1 is a diagram illustrating an example of a print inspection method according to a related art. [Figure 7] 10A and 10B are diagrams illustrating an example of a method for creating a detection template image according to the related art. [Figure 8] FIG. 4 is a diagram showing an example of a method for creating a detection template image according to the first embodiment. [Figure 9] 1 is a diagram illustrating an example of a printed matter inspection method according to a first embodiment. [Figure 10] 5 is a flowchart showing an example of the flow of a process for creating a matching template image, a process for creating an inspection template image, and an inspection process in the print inspection device according to the first embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of the configuration of a printed matter inspection device according to a second embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of the hardware configuration of a print inspection device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. In addition, in the following drawings, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0013] <First Embodiment> As shown in Figure 1, the printed matter inspection device 10 of this embodiment 1 is also capable of inspecting dead zone areas that are not OVDs among the mask areas related to related technologies on the printed matter to be inspected.

[0014] First, an example configuration of a printed matter inspection device 10 according to the first embodiment will be described with reference to Fig. 4. As shown in Fig. 4, the printed matter inspection device 10 according to the first embodiment includes a matching template creation device 11, an inspection template creation device 12, a defect detection device 13, an image input device 14, and a storage device 15.

[0015] The matching template creation device 11 is connected to the inspection template creation device 12, the defect detection device 13, and the storage device 15, and includes a calculation unit 111 and an image output unit 112. The matching template creation device 11 creates a matching template image for identifying the OVD attachment position by template matching. As shown in FIG. 5 , the matching template creation device 11 calculates the brightness value variance of each pixel in multiple training OVD images, and uses an image of an area (pattern) where pixels with a relatively low brightness value variance compared to other areas are concentrated as the matching template image. The calculation unit 111 reads multiple training OVD images stored in the storage device 15 in advance and calculates the brightness value variance of each pixel in the multiple training OVD images. After the calculation unit 111 calculates the brightness value variance of each pixel, the image output unit 112 extracts an area where pixels with a relatively low brightness value variance compared to other areas are concentrated, and outputs the image of the extracted area as the matching template image. Here, the matching template image has the shape of a portion of a pattern drawn on an OVD, and cannot be represented in a specific shape, but for simplicity it is shown as a star in Fig. 5. The matching template image output from the matching template creation device 11 is input to the inspection template creation device 12 and the defect detection device 13.

[0016] The inspection template creation device 12 is connected to the matching template creation device 11, the defect detection device 13, and the storage device 15, and includes an OVD position detection unit 121, a calculation unit 122, and an image output unit 123. The inspection template creation device 12 creates an inspection template image for detecting defects in an inspection target image.

[0017] As shown in Figure 6, the inspection of a printed matter is performed using a difference image between the image to be inspected and the inspection template image. If a defect exists on the printed matter, only the defective portion will appear in the difference image, allowing the defect to be detected. Although the OVD within the mask area does not actually appear in the difference image, the mask area and OVD are illustrated in Figure 6, the above-mentioned Figure 3, and Figure 9 described below to show the positional relationship between the mask area, the OVD, and the defect.

[0018] The inspection template creation device 12 creates an inspection template image from a plurality of learning normal paper images stored in advance in the storage device 15. The learning normal paper image is a defect-free image that has been confirmed in advance to have no defects on the substrate of the printed matter except for the OVD and its surroundings. For example, the learning normal paper image may be a defect-free image in which no defects exist on the substrate of the printed matter except for a mask area according to related technology.

[0019] In order to take into account the printing process of the print to be inspected and the various variations in normal paper that occur when capturing images of the print, an inspection template image is created by calculating the average brightness value of each pixel in multiple learning normal paper images, as shown in Figure 7. In other words, an average value image of the learning normal paper images is used as the inspection template image.

[0020] In the print inspection method according to the related art, the pixels in the area where the OVD may exist (the mask area according to the related art) are not added to the inspection template image, including the dead zone area, in consideration of the positional deviation of the OVD. In contrast, in the first embodiment, the OVD attachment position can be identified by template matching using a matching template image. Therefore, in the first embodiment, as shown in FIG. 8, the pixels in the dead zone area of ​​the mask area according to the related art can be added to the inspection template image (i.e., the mask area of ​​the inspection template image can be narrowed).

[0021] The OVD position detection unit 121 identifies the OVD attachment position for each of the multiple normal learning sheets using the matching template created by the matching template creation device 11. The calculation unit 122 adds each pixel in the area excluding the OVD attachment position identified by the OVD position detection unit 121 for each of the multiple normal learning sheets to the inspection template image. The calculation unit 122 then calculates the average luminance value of each pixel in the area excluding the OVD attachment position on the multiple normal learning sheets. The image output unit 123 outputs an image in which the average luminance value of each pixel calculated by the calculation unit 122 is overwritten on each pixel of the inspection template image as the inspection template image. The inspection template image output from the inspection template creation device 12 is input to the defect detection device 13.

[0022] The image input device 14 is connected to the defect detection device 13 and includes an imaging unit 141 and an image output unit 142. The imaging unit 141 captures an image of a printed matter to be inspected. The image output unit 142 outputs the image obtained by the imaging unit 141 as an image to be inspected. The image to be inspected output from the image input device 14 is input to the defect detection device 13.

[0023] The defect detection device 13 is connected to the matching template creation device 11, the inspection template creation device 12, and the image input device 14, and includes an OVD position detection unit 131, an OVD mask setting unit 132, a defect difference calculation unit 133, and a judgment unit 134. The defect detection device 13 detects defects in an inspection target image. As shown in FIG. 9 , the OVD position detection unit 131 identifies an OVD attachment position in the inspection target image using the matching template image created by the matching template creation device 11. The OVD mask setting unit 132 performs masking processing limited to the OVD based on the position information of the OVD attachment position identified by the OVD position detection unit 131. The defect difference calculation unit 133 calculates a difference image between the inspection template image created by the inspection template creation device 12 and the inspection target image in which the OVD attachment position is masked by the OVD mask setting unit 132. The determination unit 134 determines whether or not a defect exists in the inspection target image based on the difference image calculated by the defect difference calculation unit 133 .

[0024] In the print inspection method according to the related art, the area where the OVD may exist (the mask area according to the related art) is masked, taking into account the positional deviation of the OVD. In contrast, in the first embodiment, the OVD attachment position in the image to be inspected can be identified. Therefore, in the first embodiment, it is possible to limit the masking to the OVD, eliminating the need for a wide-area mask that takes into account the positional deviation of the OVD. As a result, it becomes possible to inspect the dead zone area of ​​the mask area according to the related art.

[0025] Hereinafter, with reference to FIG. 10, an example of the flow of the matching template image creation process S10, the inspection template image creation process S11, and the inspection process S12 in the print inspection device 10 according to the first embodiment will be described.

[0026] First, in the matching template creation process S10, the matching template creation device 11 inputs multiple training OVD images read from the storage device 15 and expands them in memory (not shown) (S101). As shown in FIG. 5, the training OVD images read here must have the OVD and its surrounding area cropped out, and the OVD positions must be aligned in advance across the multiple training OVD images. Next, the matching template creation device 11 calculates the luminance value of each pixel in each of the multiple training OVD images input in S101 and adds the calculated luminance value of each pixel to an array in memory corresponding to each pixel in the training OVD image (S102). In other words, the luminance values ​​of pixels at the same position are added across the multiple training OVD images. The process of S102 is performed for the number of training OVD images input, i (i is an integer greater than or equal to 2). The matching template creation device 11 repeats the brightness value addition process for the number of input images, and then calculates the brightness value variance of each pixel based on the brightness values ​​of each pixel stored in the array in memory (S103). Next, the matching template creation device 11 extracts, from the areas on the learning OVD image, areas with relatively small brightness value variance compared to other areas (S104). Next, the matching template creation device 11 outputs the image of the area with small brightness value variance extracted in S104 as a matching template image to the inspection template creation device 12 and the defect detection device 13 (S105).

[0027] Next, in the test template creation process S11, the test template creation device 12 first inputs multiple learning normal paper images read from the storage device 15 and expands them in memory (not shown) (S111). The learning normal paper images read here must be images that have been confirmed in advance to be free of defects on the base material of the printed material except for the OVD and its surroundings. Next, the test template creation device 12 reads the matching template image created by the matching template creation device 11 (S112). Next, for each of the multiple learning normal paper images input in S111, the test template creation device 12 identifies the attachment position of the OVD attached to the learning normal paper image by template matching using the matching template image read in S112 (S113). Next, the test template creation device 12 calculates the luminance value of each pixel in the area of ​​the learning normal paper image, excluding the OVD attachment position identified in S113, and adds the calculated luminance value of each pixel to the array in memory corresponding to each pixel in the learning normal paper image (S114). That is, the luminance values ​​of pixels at the same position are added together across multiple learning normal paper images. The processes of S113 and S114 are performed for the number of input learning normal paper images, j (j is an integer greater than or equal to 2). After repeating the process of identifying the OVD attachment position and the process of adding luminance values ​​for the number of input learning normal paper images, the test template creation device 12 calculates the average luminance value of each pixel by dividing the luminance value of each pixel stored in the array in memory by the number of input learning normal paper images (S115). However, typically, the number of learning normal paper images (number of input images) added together differs for each pixel. Therefore, it should be noted that the divisor also differs for each pixel. Thereafter, the inspection template creation device 12 overwrites each pixel of the inspection template image with the average brightness value of each pixel stored in the array on the memory (S116), and outputs the inspection template image to the defect detection device 13 (S117).

[0028] Next, in the inspection process S12, first, the defect detection device 13 expands the inspection target image input from the image input device 14 in memory (S121). Next, the defect detection device 13 reads the matching template image created by the matching template creation device 11 (S122). Next, the defect detection device 13 uses the matching template image read in S122 to identify the attachment position of the OVD attached to the inspection target image by template matching (S123).

[0029] Here, if the matching score of the template matching is less than 95% of the matching score for the preset reference image, the defect detection device 13 does not perform subsequent processing. Possible reasons for a low matching score include the OVD not being attached to the printed material, a part of the OVD being missing, or the OVD being misaligned beyond the amount of misalignment that would normally occur, all of which are caused by defects in the OVD itself. Inspection target images in which there is a defect in the OVD itself are not subject to inspection in this first embodiment. It should be noted that the above-mentioned matching score of 95% is just an example and is not limited to this value.

[0030] Next, the defect detection device 13 places a mask on the OVD attachment position identified in S123 and sets the area where the mask is placed as an area not to be inspected (S124). Next, the defect detection device 13 reads the inspection template image created by the inspection template creation device 12 (S125) and calculates a difference image between the inspection target image on which the mask is placed in S124 and the inspection template image (S126). If a defect exists in the inspection target image, only the defect will appear in the difference image. Therefore, the defect detection device 13 inspects the difference image including the dead zone area (S127). If there is an area in the difference image where a difference exceeding a predetermined shape or size is detected, that area becomes a defect candidate.

[0031] As described above, according to the first embodiment, the matching template creation device 11 creates a matching template image for identifying the OVD attachment position by template matching. The defect detection device 13 uses the matching template image to identify the OVD attachment position in the inspection target image, masks the identified OVD attachment position, and detects defects in the inspection target image based on a difference image between the inspection target image in which the OVD attachment position has been masked and the inspection template image.

[0032] In this way, in the first embodiment, the defect detection device 13 can identify the OVD attachment position in the inspection target image using the matching template image. Therefore, it is possible to limit the masking to the OVD, eliminating the need for a wide-area mask that takes into account OVD positional deviation. As a result, it is possible to inspect even the dead zone area of ​​the mask area according to the related art.

[0033] The matching template creation device 11 calculates the brightness value variance of each pixel in multiple learning OVD images, and creates an image of an area with a relatively small brightness value variance compared to other areas as a matching template image.

[0034] In addition, in this embodiment 1, the inspection template creation device 12 uses a matching template image to identify the OVD attachment position for each of the multiple learning normal paper images, calculates the average brightness value of each pixel in the areas other than the OVD attachment positions in the multiple learning normal paper images, and creates an inspection template image by overwriting each pixel in the inspection template image with the calculated average brightness value of each pixel.

[0035] As described above, in the first embodiment, the inspection template creation device 12 can identify the OVD attachment position in each of the multiple learning normal paper images using the matching template image. Therefore, pixels in the dead zone area of ​​the mask area according to the related art can be added to the inspection template image. This makes it possible to create an inspection template image that can be used for inspection by the defect detection device 13.

[0036] <Embodiment 2> Next, a configuration example of a printed matter inspection device 20 according to a second embodiment will be described with reference to Fig. 11. The second embodiment corresponds to an embodiment that is a higher-level concept of the first embodiment described above.

[0037] 11, the printed matter inspection device 20 according to the second embodiment includes a matching template creation unit 21 and a defect detection unit 22. The printed matter inspection device 20 according to the second embodiment is a device that inspects printed matter to which an OVD is attached.

[0038] The matching template creation unit 21 creates a matching template image for identifying the OVD attachment position by template matching. The defect detection unit 22 uses a matching template image to identify the OVD attachment position in the inspection target image obtained by photographing the printed matter to be inspected, masks the identified OVD attachment position, and detects defects in the inspection target image based on the difference image between the inspection target image in which the OVD attachment position has been masked and the inspection template image.

[0039] This allows the defect detection unit 22 to identify the OVD attachment position in the inspection target image using the matching template image. Therefore, it is possible to limit the masking to the OVD, eliminating the need for a wide-area mask that takes into account OVD positional deviation. As a result, it is possible to inspect even the dead zone area of ​​the mask area in the related art.

[0040] The matching template creation unit 21 may calculate the brightness value of each pixel in each of the multiple training OVD images, calculate the brightness value variance of each pixel based on the brightness value of each pixel in each of the multiple training OVD images, extract an area with a relatively small brightness value variance compared to other areas, and create an image of the extracted area as a matching template image. Also, each of the multiple training OVD images may be an image in which an area including the OVD and its surroundings has been cut out, and the positions of the OVDs may be aligned between the multiple training OVD images.

[0041] Furthermore, the print inspection device 20 according to the second embodiment may further include an inspection template creation unit that creates an inspection template image. The inspection template creation unit may use a matching template image to identify the OVD attachment position in each of the multiple learning normal paper images, calculate the luminance value of each pixel in the area other than the identified OVD attachment position, calculate the average luminance value of each pixel based on the luminance value of each pixel in the area other than the OVD attachment position in each of the multiple learning normal paper images, and create the inspection template image by overwriting each pixel in the inspection template image with the calculated average luminance value of each pixel.

[0042] This allows the inspection template creation unit to identify the OVD attachment position in each of the multiple learning normal paper images using the matching template image. Therefore, pixels in the dead zone area of ​​the mask area according to the related art can be added to the inspection template image. This makes it possible to create an inspection template image that can be used for inspection by the defect detection unit 22. Each of the multiple learning normal paper images may be an image that has been confirmed to have no defects in areas other than the OVD and its surroundings.

[0043] <Third Embodiment> Next, an example of the hardware configuration of the printed matter inspection device 30 according to the third embodiment will be described with reference to FIG. As shown in FIG. 12, a printed matter inspection device 30 according to the third embodiment includes a processor 31 and a memory 32.

[0044] The processor 31 may be, for example, a microprocessor, a microprocessing unit (MPU), or a central processing unit (CPU). The processor 31 may include multiple processors.

[0045] The memory 32 is configured by a combination of volatile memory and non-volatile memory. The memory 32 may include storage located remotely from the processor 31. In this case, the processor 31 may access the memory 32 via an I (Input) / O (Output) interface (not shown).

[0046] The printed matter inspection devices 10 and 20 according to the first and second embodiments described above may have the hardware configuration shown in FIG. 12. A program is stored in the memory 32. This program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more of the functions described in the first and second embodiments described above. The components of the printed matter inspection devices 10 and 20 described above may be realized by the processor 31 reading and executing the program stored in the memory 32. Furthermore, the storage functions of the components of the printed matter inspection devices 10 and 20 described above may be realized by the memory 32.

[0047] The above-described programs may also be stored on non-transitory computer-readable media or tangible storage media. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The programs may also be transmitted on transitory computer-readable media or communication media. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0048] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. [Explanation of symbols]

[0049] 10 Print inspection equipment 11. Matching template creation device 111 Arithmetic section 112 Image output unit 12 Inspection template creation device 121 OVD position detection unit 122 Arithmetic section 123 Image output unit 13 Defect detection equipment 131 OVD position detection unit 132 OVD mask setting section 133 Defect difference calculation unit 134 Judgment section 14 Image input device 141 Imaging unit 142 Image output unit 15 Storage device 20 Print inspection equipment 21 Matching template creation section 22 Defect detection section 30 Print inspection equipment 31 processors 32 memory

Claims

1. A print inspection device that inspects a print to which an OVD (Optical Variable Device) is attached, a matching template creation unit that creates a matching template image for identifying the attachment position of the OVD by template matching; a defect detection unit that uses the matching template image to identify an OVD attachment position in an inspection object image obtained by photographing the printed matter, masks the identified OVD attachment position, and detects defects in the inspection object image based on a difference image between the inspection object image in which the OVD attachment position has been masked and the inspection template image; Equipped with The matching template creation unit For each of the plurality of learning OVD images, a luminance value of each common pixel in the learning OVD image is calculated; calculating a variance of brightness values ​​of each pixel based on brightness values ​​of the pixels common to each of the plurality of learning OVD images; Extracting areas with relatively small variance of brightness values ​​compared to other areas, creating an image of the extracted region as the matching template image; Print inspection equipment.

2. Each of the plurality of training OVD images is an image obtained by cutting out an area including the OVD and its surroundings, and the positions of the OVDs are aligned among the plurality of training OVD images. The print inspection device according to claim 1 .

3. an inspection template creation unit that creates the inspection template image, The inspection template creation unit For each of a plurality of learning normal paper images, the matching template image is used to identify an OVD attachment position in the learning normal paper image, and a luminance value of each pixel in an area other than the identified OVD attachment position is calculated; calculating an average brightness value of each pixel based on the brightness value of each pixel in an area other than the OVD attachment position in each of the plurality of learning normal paper images; creating the inspection template image by overwriting each pixel in the inspection template image with the calculated average luminance value of each pixel; The print inspection device according to claim 1 or 2.

4. Each of the plurality of learning normal paper images is an image that has been confirmed to have no defects in areas other than the OVD and its surroundings. The print inspection device according to claim 3 .

5. A print inspection method performed by a print inspection device that inspects a print to which an OVD (Optical Variable Device) is attached, comprising: a matching template creation step of creating a matching template image for identifying the attachment position of the OVD by template matching; a defect detection step of using the matching template image to identify an OVD attachment position in an inspection object image obtained by photographing the printed matter, masking the identified OVD attachment position, and detecting defects in the inspection object image based on a difference image between the inspection object image in which the OVD attachment position has been masked and the inspection template image; Including, In the matching template creation step, For each of the plurality of learning OVD images, a luminance value of each common pixel in the learning OVD image is calculated; calculating a variance of brightness values ​​of each pixel based on brightness values ​​of the pixels common to each of the plurality of learning OVD images; Extracting areas with relatively small variance of brightness values ​​compared to other areas, creating an image of the extracted region as the matching template image; Print inspection methods.

6. A program to be executed by a print inspection device that inspects a print to which an OVD (Optical Variable Device) is attached, a matching template creation step of creating a matching template image for identifying the attachment position of the OVD by template matching; a defect detection step of using the matching template image to identify an OVD attachment position in an inspection object image obtained by photographing the printed matter, masking the identified OVD attachment position, and detecting defects in the inspection object image based on a difference image between the inspection object image in which the OVD attachment position has been masked and the inspection template image; Including, In the matching template creation step, For each of the plurality of learning OVD images, a luminance value of each common pixel in the learning OVD image is calculated; calculating a variance of brightness values ​​of each pixel based on brightness values ​​of the pixels common to each of the plurality of learning OVD images; Extracting areas with relatively small variance of brightness values ​​compared to other areas, creating an image of the extracted region as the matching template image; program.

Images