JP2019133711A - Duplication detection device, duplication detection method and program - Google Patents

Abstract

To simply detect duplication.SOLUTION: A duplication detection device (2) includes an image pickup unit (22) that captures an image of a printed matter (1) on which yellow gradation is printed to generate a captured image expressed by an RGB color gamut, and a control unit (24). The control unit (24) converts the captured image expressed by the RGB color gamut into a captured image expressed by a Lab color system to extract a b channel expressing a b value of each pixel from the captured image. The control unit (24) binarizes the b value of each pixel of the b channel to generate a binarized image. Then, the control unit (24) determines the printed matter (1) as a duplicated matter when a portion corresponding to the yellow gradation in the binarized image has no predetermined shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a copy detection device, a copy detection method, and a program, and more particularly, to a copy detection device, a copy detection method, and a program that can easily detect a copy.

  QR (Quick Response) code (registered trademark), which is a kind of two-dimensional code, embeds machine-readable information in printed materials. Recently, it has a monetary value as represented by airline tickets and tickets. The use of QR codes (registered trademark) is expanding (see, for example, Patent Document 1). For this reason, the development of a method for detecting forgery or duplication of a two-dimensional code represented by QR code (registered trademark) is an urgent issue.

  In order to solve the above problem, after separating the original image of the two-dimensional code into RGB color components, discrete wavelet transform is performed for each of R, G, and B colors to obtain an LL component, an LH component, an HL component, and Decompose into frequency components such as HH components. Then, a technology has been developed that embeds watermark information only in the HH component whose wavelet coefficient value (coefficient value) is smaller than the LH component and the HL component to generate a two-dimensional code with watermark information (see, for example, Patent Document 2). ).

  In the technique described in Patent Document 2, it is possible to prevent the watermark information from being lost due to information other than the watermark information appearing as noise from the HH component of the two-dimensional code containing the regular watermark information that has not been copied. On the other hand, since information other than the watermark information appears very strongly in the HH component of the two-dimensional code containing the non-regular watermark information copied (illegally copied) by a copier having a different density expression method, Watermark information is lost. Thereby, it becomes possible to detect the duplication of the two-dimensional code.

  In addition, the specification of patent documents 1 and 2, a claim, and the whole drawing shall be taken in this specification for reference.

JP 2006-318328 A WO2010 / 140639

  However, at present, when commercial transactions using two-dimensional codes represented by QR Code (registered trademark) have expanded and become active, there is a technology that can detect a copy more easily and reliably than the technology described in Patent Document 2. There is a strong demand.

  SUMMARY An advantage of some aspects of the invention is that it provides a copy detection device, a copy detection method, and a program that can easily detect a copy.

  In order to achieve the above object, the duplication detection device (2) according to the first aspect of the present invention images the printed matter (1) on which a predetermined pattern is printed, and generates an imaged image (22). When a chromaticity channel representing the chromaticity of each pixel is extracted from the captured image, and the portion corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition, the printed matter (1) is A control unit (24) for determining a duplicate.

  In the copy detection device (2), the predetermined pattern is gradation, and the control unit (24) does not have a predetermined shape in a portion corresponding to the gradation in the chromaticity channel. In this case, the printed matter (1) may be determined as a duplicate, assuming that the first condition is not satisfied.

  In the copy detection device (2), when the predetermined pattern is gradation and the control unit (24) has a portion corresponding to the gradation in the chromaticity channel shorter than a predetermined length, The printed matter (1) may be determined as a duplicate, assuming that it does not have the predetermined shape.

  In the copy detection device (2), the gradation is preferably a yellow gradation.

  In the copy detection device (2), the imaging unit (22) generates the captured image represented by the RGB color gamut, and the control unit (24) captures the captured image represented by the RGB color gamut. Is converted into the captured image represented in the Lab color system, and a b channel representing the b value of each pixel is extracted from the captured image represented in the Lab color system, and the yellow gradation is extracted in the b channel. If the portion corresponding to the item does not have the predetermined shape, the printed matter (1) may be determined as a duplicate, assuming that the first condition is not satisfied.

  In the copy detection device (2), the control unit (24) binarizes the b value of each pixel of the b channel to generate a binarized image, and the yellow gradation in the binarized image If the portion corresponding to the item does not have the predetermined shape, the printed matter (1) may be determined as a duplicate, assuming that the first condition is not satisfied.

  The copy detection device (2) further includes an illuminance sensor (25) for detecting the illuminance of the printed matter (1), and the control unit (24) responds to the illuminance detected by the illuminance sensor (25). Then, a threshold value to be compared with the b value of each pixel of the b channel may be determined, and the b value of each pixel of the b channel may be compared with the threshold value and binarized.

  In the copy detection device (2), the control unit (24) generates the printed matter (1) when the portion corresponding to the predetermined pattern satisfies the first condition and the second condition. When the first condition is satisfied but the second condition is not satisfied, it may be determined that the printed matter (1) is likely to be the duplicate. .

  In the copy detection device (2), when the control unit (24) determines that the printed material (1) is the copied material, the control unit (24) may instruct imaging of the printed material (1) again. .

  In order to achieve the above object, in the duplicate detection method according to the second aspect of the present invention, the imaging unit (22) captures a printed matter (1) on which a predetermined pattern is printed, generates a captured image, The control unit (24) extracts a chromaticity channel representing the chromaticity of each pixel from the captured image, and the control unit (24) has a portion corresponding to the predetermined pattern in the first chromaticity channel. If the condition is not satisfied, the printed matter (1) is determined as a duplicate.

  In order to achieve the above object, a program according to a third aspect of the present invention generates a captured image by capturing an image of a printed matter (1) on which a predetermined pattern is printed on a computer, and generates each pixel from the captured image. A chromaticity channel representing the chromaticity of the image is extracted, and when the portion corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition, the printed matter (1) is determined as a duplicate. It is for execution.

  ADVANTAGE OF THE INVENTION According to this invention, the replication detection apparatus, the replication detection method, and program which can detect a replication simply can be provided.

It is a figure which illustrates the printed matter concerning this embodiment. (A) is a figure which shows the yellow gradation in the original of printed matter, (b) is a figure which shows the yellow gradation in the reproduction of printed matter. It is a block diagram which shows the structural example of the duplication detection apparatus which concerns on this embodiment. It is explanatory drawing which shows the color space of a Lab color system. (A) is a figure which shows the binarized image at the time of imaging the original of printed matter, (b) is a figure which shows the binarized image at the time of imaging the duplicate of printed matter. It is a flowchart which shows the detail of a replication detection process. (A) is a table | surface which shows the optimal threshold value for every illumination intensity in the replication detection apparatus which concerns on this embodiment, (b) is a table | surface which shows the optimal threshold value for every illumination intensity in the replication detection apparatus which concerns on a modification. . It is a block diagram which shows the structural example of the duplication detection apparatus which concerns on a modification.

  Hereinafter, the best mode for carrying out the present invention will be described.

  First, the configuration of the copy detection apparatus according to the present embodiment will be described with reference to the drawings.

  The duplication detection device is composed of, for example, a general-purpose smartphone or tablet computer. In this embodiment, a copy detection application program for detecting whether a printed material according to this embodiment is an original or a copy is installed in iPhone (registered trademark) 6s manufactured by Apple Inc. It constitutes a detection device. The duplicate detection device may be an Android (registered trademark) smartphone or tablet computer, or may be a general-purpose mobile phone or personal computer.

  FIG. 1 is a diagram illustrating a printed material according to this embodiment.

  As shown in FIG. 1, the printed matter 1 includes a two-dimensional code 11 with a logo in which a two-dimensional code such as a QR code (registered trademark) is superimposed on a visible logo image on a printing medium such as a white background printing paper, It is formed by printing a substantially square frame-shaped yellow gradation 12 surrounding the outer periphery of the logo-attached two-dimensional code 11. Here, the gradation 12 is yellow because yellow is the most susceptible to reproduction among various colors. Therefore, a yellow gradation 12 is printed on the printed material 1 in order to detect whether the printed material is an original or a duplicate.

  The logo-added two-dimensional code 11 has a general-purpose two-dimensional code reader that recognizes black as a black color by a general-purpose two-dimensional code reader (such as a background portion and a keyhole portion in the example shown in FIG. 1). Only the cells of the first type of brightness that are recognized as white by the two-dimensional code reader (white cells in the example shown in FIG. 1) are superimposed. On the other hand, in the portion of the logo image that is higher than the first brightness (the key body portion in the example shown in FIG. 1), a first type brightness cell (white cell in the example shown in FIG. 1) and a general-purpose Both of the second type lightness cells (black cells in the example shown in FIG. 1) recognized as black by the two-dimensional code reader are superimposed.

  The two-dimensional code 11 with a logo is recognized as a first type of lightness cell (white cell in the example shown in FIG. 1) recognized as white by a general-purpose two-dimensional code reader and black as a general-purpose two-dimensional code reader. Distribution of the second type lightness cells (black cells in the example shown in FIG. 1) and a portion of the logo image that is less than the first lightness (background portion, keyhole portion, etc. in the example shown in FIG. 1) Predetermined information such as a URL (Uniform Resource Locator) is expressed by a pattern.

  The gradation 12 is obtained by using only Y (yellow) ink among four colors of CMYK color gamut on a printing medium such as white printing paper, and each vertex of a substantially square having a side length of approximately 23 mm. To the center of each side, printing is performed so that the yellow color gradually becomes lighter.

  FIG. 2A is a diagram showing a yellow gradation in an original printed matter. FIG. 2B is a diagram showing a yellow gradation in a reproduction of a printed material.

  The inventor obtained the lengths of the yellow gradation 12 in the original and the duplicate of the printed material 1 respectively. Here, the length of the gradation 12 refers to the length of the portion of each side of the gradation 12 where Y (yellow) ink can be visually confirmed. The length of the yellow gradation 12 in the original was about 21.5 mm to about 23 mm as shown in FIG. On the other hand, the length of the yellow gradation 12 in the duplicate was about 14 mm to about 19.5 mm shorter than the original, as shown in FIG.

  Thus, the yellow gradation 12 is attenuated by duplication, and the length of the yellow gradation 12 in the reproduction is shorter than that of the original. This is because the color gamut (color space), reproduction method, and the like differ between the CMYK color gamut used for printing and the RGB color gamut used for copying. Specifically, the CMYK color gamut represents a color by subtractive color mixing when the color is reduced (added to black), and the RGB color gamut becomes white (added to black when reduced). The color is expressed by additive color mixture.

  The yellow gradation 12 is converted into a mixed color of the RGB color gamut at the time of scanning, and the CMYK color gamut is used again at the time of printing. At this time, the gradation 12 is printed in a mixed color of the CMYK color gamut, and the portion having a low density (light) is further lightened. The reason is the mechanism for expressing colors by printing. In other words, in printing, the color is expressed by whether the ink dots (dots) are placed on a printing medium such as paper or not, that is, the binary value of dot on / off, and the dot shape (for example, dot size) or dot Color shades are expressed in a distributed manner. Naturally, the light color has a smaller dot shape. In order to acquire such an image when scanning such a small dot, sufficient resolution is required, but the resolution of a general-purpose copying machine is. There is only about 400ppi. For this reason, light colors are apt to be lost, and as a result, light colors tend to become lighter. In particular, the yellow gradation 12 tends to change to a lighter color by copying using a scanner, a camera, or the like.

  The copy detection apparatus according to the present embodiment detects whether the printed material 1 is an original or a copy using the property of the yellow gradation 12.

  FIG. 3 is a block diagram illustrating a configuration example of the copy detection apparatus according to the present embodiment.

  As illustrated in FIG. 3, the copy detection device 2 includes a touch panel 21, an imaging unit 22, a storage unit 23, and a control unit 24, which are connected via a bus or the like.

  The touch panel 21 is composed of, for example, a general-purpose touch panel that combines a liquid crystal display device and a pointing device. The touch panel 21 displays various screens and accepts various operations by the user. In the present embodiment, a reading icon or the like for instructing reading of the logo-added two-dimensional code 11 is displayed on the touch panel 21.

  The imaging unit 22 includes a solid-state imaging device such as a CCD (Charge Coupled Device). The imaging unit 22 captures the printed material 1 and generates a captured image represented in the RGB color gamut.

  The storage unit 23 is configured by a non-volatile memory such as a general-purpose flash memory, for example. The storage unit 23 stores a copy detection application program for detecting whether the printed material 1 is an original or a copy.

  The control unit 24 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU controls various operations of the copy detection device 2 by appropriately executing programs stored in the ROM and the storage unit 23 using the RAM as a work memory.

  In the present embodiment, the control unit 24 displays a reading icon on the touch panel 21 in response to the user operating the touch panel 21 and starting the copy detection application program stored in the storage unit 23. In response to the user pointing the imaging unit 22 toward the printed material 1 and tapping the reading icon, the control unit 24 captures the printed material 1 with the imaging unit 22 and generates a captured image represented by the RGB color gamut. . In addition, when the inclination of the captured image is a predetermined angle (for example, 2 °) or more, or when the size of the captured image is less than the predetermined size (for example, the width is 300 pixels), the control unit 24 captures the print 1 again. You may make it perform.

  The control unit 24 converts the captured image represented by the RGB color gamut generated by the imaging unit 22 into a captured image represented by the CIE L * a * b * (hereinafter referred to as “Lab”) color system. .

  FIG. 4 is an explanatory diagram showing the color space of the Lab color system.

  As shown in FIG. 4, the color space of the Lab color system is a complementary color space that expresses a color with three values such as an L value indicating lightness and an a value and b value indicating chromaticity (hue and saturation). is there. The L value takes a value in the range of “0” to “100”, and the brightness increases as the L value increases. When the L value is “0”, the color is black, and when it is “100”, the color is white. The a value is a value indicating chromaticity between red and green, and takes a value in the range of “−255” to “255” in the present embodiment. When the a value is a positive value, the color is red, and as the positive value increases, the density of red increases. On the other hand, when the a value is a negative value, the color becomes green, and the green value increases as the negative value decreases. The b value is a value indicating chromaticity between yellow and blue, and takes a value in the range of “−255” to “255” in the present embodiment. When the b value is a positive value, the color is yellow, and the higher the positive value, the higher the yellow density. On the other hand, when the b value is a negative value, it becomes blue, and the blue value increases as the negative value decreases. When both the a value and the b value are “0”, an achromatic color is obtained.

  The control unit 24 illustrated in FIG. 3 extracts a b channel representing the b value of each pixel of the captured image from the captured image represented in the color space of the Lab color system. Then, the control unit 24 compares the b value of each pixel of the b channel with a predetermined threshold value (“123” in this embodiment), sets the b value less than the threshold value to “0”, and sets the b value greater than the threshold value to “ A binarized image is generated by binarizing to 1 ″.

  FIG. 5A is a diagram illustrating a binarized image when an original image of a printed material is imaged. FIG. 5B is a diagram illustrating a binarized image when a copy of a printed material is imaged.

  In the binarized images shown in FIGS. 5A and 5B, the pixels set to “0” are shown in black, and the pixels set to “1” are shown in white. In the binarized image when the original image of the printed material is imaged, as shown in FIG. 5A, the portion corresponding to the yellow gradation 12 is almost connected, whereas the reproduced image of the printed material is imaged. In the binarized image, only the four corner portions of the gradation 12 remain as shown in FIG.

  The control unit 24 illustrated in FIG. 3 detects a line segment having a predetermined length or more in a portion corresponding to the yellow gradation 12 of the binarized image. When the control unit 24 cannot detect a line segment of a predetermined length or longer in the portion corresponding to the yellow gradation 12, the control unit 24 determines that the printed material 1 is a duplicate, and displays the reading icon on the touch panel 21 together with the determination result. indicate.

  Even when the control unit 24 can detect a line segment having a predetermined length or longer in the portion corresponding to the yellow gradation 12, the control unit 24 selects a line segment having a predetermined length or longer in any of the four sides of the portion corresponding to the yellow gradation 12. If it cannot be detected, it is determined that there is a possibility that the printed material 1 is a duplicate, and a reading icon is displayed on the touch panel 21 together with the determination result.

  When the control unit 24 can detect a line segment having a predetermined length or more on any of the four sides of the portion corresponding to the yellow gradation 12, the control unit 24 determines that the printed product 1 is the original and displays the determination result on the touch panel. 21. Then, the control unit 24 reads predetermined information from the logo-added two-dimensional code 11 included in the captured image.

  Next, a copy detection process executed by the copy detection apparatus having the above configuration will be described with reference to the drawings.

  The control unit 24 of the copy detection device 2 starts the copy detection process in response to the user pointing the image pickup unit 22 toward the printed matter 1 and tapping the read icon after the copy detection application program is started.

  FIG. 6 is a flowchart showing details of the copy detection process.

  As shown in FIG. 6, in the product ordering process, first, the control unit 24 images the printed matter 1 including the logo-added two-dimensional code 11 with the imaging unit 22 to generate a captured image represented by the RGB color gamut. (Step S1).

  Next, the control unit 24 converts the captured image expressed in the RGB color gamut generated in step S1 into a captured image expressed in the Lab color system (step S2).

  Subsequently, the control unit 24 extracts a b channel representing the b value of each pixel of the captured image from the captured image represented by the Lab color system converted in step S2 (step S3).

  Then, the control unit 24 compares the b value of each pixel of the b channel extracted in step S3 with a predetermined threshold value, and the b value less than the threshold value is “0”, and the b value greater than the threshold value is “1”. Thus, binarization is performed to generate a binarized image (step S4).

  Subsequently, the control unit 24 detects a line segment having a predetermined length or more in a portion corresponding to the yellow gradation 12 of the binarized image generated in step S4 (step S5).

  When the control unit 24 cannot detect a line segment of a predetermined length or longer in the portion corresponding to the yellow gradation 12 (step S6; No), the control unit 24 determines that the printed product 1 is a duplicate, and along with the determination result, After the reading icon is displayed on the touch panel 21 (step S7), the copy detection process is terminated.

  On the other hand, even when the control unit 24 can detect a line segment having a predetermined length or longer in the portion corresponding to the yellow gradation 12 (step S6; Yes), the four sides of the portion corresponding to the yellow gradation 12 are detected. If a line segment of a predetermined length or longer cannot be detected in any of the above (Step S8; No), it is determined that the printed material 1 may be a duplicate, and a reading icon is displayed on the touch panel 21 together with the determination result. After that (step S9), the copy detection process is terminated.

  On the other hand, when the control unit 24 can detect a line segment having a predetermined length or more on any of the four sides of the portion corresponding to the yellow gradation 12 (step S8; Yes), the control unit 24 determines that the printed product 1 is the original. Then, the determination result is displayed on the touch panel 21 (step S10).

  The control unit 24 reads predetermined information from the logo-added two-dimensional code 11 included in the captured image (step S11), and ends the copy detection process.

  As described above, the copy detection device 2 according to the present embodiment captures the printed material 1 on which a predetermined pattern is printed, generates the captured image, and represents the chromaticity of each pixel from the captured image. A control unit that extracts a chromaticity channel and discriminates that the printed product is a duplicate if the portion corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition;

  In the present embodiment, a yellow gradation is printed on the printed matter 1 as a predetermined pattern. The imaging unit 22 generates a captured image represented by the RGB color gamut. The control unit 24 converts the captured image represented by the RGB color gamut into a captured image represented by the Lab color system. Next, the control unit 24 extracts a b channel representing the b value of each pixel as a chromaticity channel from the captured image represented in the Lab color system. Subsequently, the control unit 24 binarizes the b value of each pixel of the b channel to generate a binarized image.

  Then, the control unit 24, when the portion corresponding to the yellow gradation in the binarized image does not have a predetermined shape, that is, when the portion corresponding to the yellow gradation does not have a line segment longer than the predetermined length Assuming that the first condition is not satisfied, the printed matter 1 is determined as a duplicate.

  On the other hand, the control unit 24 determines that the first condition and the second condition are satisfied and the printed matter 1 is satisfied if there is a line segment having a predetermined length or more in any of the four sides of the portion corresponding to the yellow gradation. Distinguish from the original. On the other hand, if there is a line segment having a predetermined length or longer in the portion corresponding to the yellow gradation, but the control unit 24 does not have a line segment having a predetermined length or longer in any of the four sides, the first condition is satisfied. However, it is determined that the printed material 1 may be a duplicate, assuming that the second condition is not satisfied.

  Then, the control unit 24 displays a reading icon on the touch panel 21 when the printed material 1 is determined as a duplicate, and instructs the imaging of the printed material 1 again.

  As described above, the control unit 24 has a color model in which the captured image represented by the RGB color gamut has an L value indicating brightness and two values (a value and b value) indicating chromaticity and does not depend on a device. To a captured image represented by the Lab color system. Then, the control unit 24 extracts only the b channel that is easily affected by the duplication from the captured image represented by the Lab color system, and the L channel that represents the L value that is easily affected by the ambient light and the duplication After removing the a channel representing the a value which is not easily affected, the captured image is binarized. As a result, the control unit 24 can generate a binarized image that is not easily affected by ambient light and has a distinct yellow component necessary for the detection of replication. In the binarized image generated in this way, the attenuation amount of the portion corresponding to the yellow gradation 12 is clarified depending on whether the printed material 1 is an original or a duplicate. Can be easily and reliably determined whether it is a duplicate or a copy

  In addition, this invention is not limited to said embodiment, A various deformation | transformation and application are possible. Hereinafter, modifications of the above-described embodiment applicable to the present invention will be described.

  In the above embodiment, the predetermined threshold value compared with the b value of each pixel of the captured image has been described as being “123”. However, the present invention is not limited to this, and the predetermined threshold value may be varied according to the model of the smartphone or tablet computer constituting the duplication detection device 2, the illuminance of the printed material 1, and the like.

  The inventor of the present invention uses a copy detection device 2 configured by iPhone (registered trademark) 6s manufactured by Apple Inc. according to the above-described embodiment and a copy detection configured by P9 lite manufactured by Huawei according to a modification. The optimum threshold value for each illuminance in each of the devices 20 (FIG. 8) was obtained. Specifically, the inventor images the original and the duplicate of the printed material 1 at various threshold values for each illuminance (300 lx to 1000 lx) in a general living space, and detects the duplicate shown in FIG. The process was executed. Then, in the copy detection process, the printed material 1 is not determined to be a copy, and is not correctly determined to be duplicated twice, and is correctly determined continuously 50 times. The threshold value was determined as the optimum threshold value.

  FIG. 7A is a table showing the optimum threshold value for each illuminance in the copy detection apparatus according to the present embodiment. FIG. 7B is a table showing the optimum threshold value for each illuminance in the duplicate detection device according to the modification.

  In FIGS. 7A and 7B, “◯” indicates an optimum threshold value at each illuminance. As shown in FIG. 7A, in the copy detection device 2 according to the present embodiment, “123” is included in the optimum threshold value for any illuminance. Therefore, in this embodiment, “123” is set as a predetermined threshold value to be compared with the b value of each pixel of the captured image. On the other hand, as shown in FIG. 7B, in the copy detection device 20 (FIG. 8) according to the modified example, the optimum threshold varies depending on the illuminance of the printed matter 1.

  FIG. 8 is a block diagram illustrating a configuration example of a copy detection apparatus according to a modification.

  As illustrated in FIG. 8, the copy detection device 20 further includes an illuminance sensor 25 that detects the illuminance of the printed matter 1 in addition to the touch panel 21, the imaging unit 22, the storage unit 23, and the control unit 24 included in the copy detection device 2. These are connected via a bus or the like.

  The control unit 24 of the duplicate detection device 20 may set a predetermined threshold value to be compared with the b value of each pixel of the captured image in accordance with the illuminance detected by the illuminance sensor 25. In the example illustrated in FIG. 7B, when the illuminance detected by the illuminance sensor 25 is 300 lx to 499 lx, the control unit 24 sets the predetermined threshold to be compared with the b value of each pixel of the captured image to “139”. When the illuminance is 500 lx to 699 lx, the predetermined threshold is set to “135”, and when the illuminance is 700 lx to 899 lx, the predetermined threshold is set to “132” and the illuminance is 900 lx to 1000 lx. In this case, the predetermined threshold value may be set to “128”.

  In the above embodiment, the control unit 24 of the copy detection device 2 can detect the printed matter 1 on the condition that a line segment having a predetermined length or more can be detected in any of the four sides of the portion corresponding to the yellow gradation 12. It was explained that it was determined to be the original. However, the present invention is not limited to this, and the conditions for determining that the printed material 1 is the original are the model of the smartphone or tablet computer that constitutes the copy detection device 2, the illuminance at the time of imaging, etc. It can be changed as appropriate.

  For example, the control unit 24 of the copy detection apparatus 2 can detect a line segment having a predetermined length or longer on any of the four sides of the portion corresponding to the yellow gradation 12, and a line segment having a predetermined length or longer is predetermined. You may discriminate | determine that the printed matter 1 is an original on condition that the number (for example, 5 etc.) or more was detected. Furthermore, in addition to these conditions, the control unit 24 of the duplicate detection device 2 determines the number of white pixels on the outer periphery of the logo-added two-dimensional code 11 and performs noise determination. When the noise is 10% or more, When it is determined that the printed matter 1 is a duplicate, and the noise is 0.8% or more and less than 10%, it is determined that the printed matter 1 may be a duplicate, and the noise is less than 0.8%. In this case, it may be determined that the printed material 1 is the original.

  Further, the control unit 24 of the duplicate detection device 2 was able to detect a line segment having a predetermined length or more in at least a predetermined number of sides (for example, two sides) among the four sides of the portion corresponding to the yellow gradation 12. It may be determined that the printed material 1 is the original on the condition of the above. Further, the control unit 24 of the copy detection device 2 was able to detect a line segment having a predetermined length or more in at least a predetermined number of sides (for example, two sides) among the four sides of the portion corresponding to the yellow gradation 12. In addition, it may be determined that the printed material 1 is the original, on the condition that a predetermined number (for example, five or more) of line segments having a predetermined length or more can be detected.

  In the above embodiment, the gradation 12 has been described as having a substantially square frame shape. However, the present invention is not limited to this, and the shape of the gradation 12 is arbitrary, and may be linear, for example. In this case, the control unit 24 of the copy detection device 2 obtains the length of the portion corresponding to the yellow gradation 12 in the binarized image, and the length of the portion corresponding to the yellow gradation 12 is longer than a predetermined length. If it is short, the printed matter 1 may be determined as a duplicate, assuming that it does not have a predetermined shape.

  In the above embodiment, the control unit 24 has been described as converting the captured image represented by the RGB color gamut into the captured image represented by the Lab color system. However, the present invention is not limited to this, and any color system that can be divided into lightness and chromaticity is arbitrary. For example, the control unit 24 may convert a captured image represented by the RGB color gamut into a captured image represented by a YUV color system, a YCbCr color system, a YPbPr color system, or the like.

  Further, the control unit 24 may convert the captured image represented by the RGB color gamut into a captured image represented by the CMYK color gamut. The control unit 24 extracts a Y channel representing the Y (yellow) value of each pixel of the captured image from the captured image represented by the CMYK color gamut, and compares the Y value of each pixel of the Y channel with a predetermined threshold value. The binarized image is generated by binarizing so that the Y value less than the threshold value is “0” and the Y value equal to or greater than the threshold value is “1”. Then, the control unit 24 detects a line segment having a predetermined length or more in a portion corresponding to the yellow gradation 12 of the binarized image, and determines whether the printed product 1 is an original or a duplicate. May be.

  However, when converting to a captured image expressed in the CMYK color gamut, the quality of the light source at the time of imaging (whether it is close to white light or high brightness, etc.), the paper quality of the printed matter 1 (coating paper or matte paper) Depending on the distance and the angle between the printed matter 1 and the copy detection device 2 at the time of imaging, subtle light and darkness of the light is generated on the printed matter 1 at the time of imaging. For this reason, if the printed material 1 is made of paper having a stable smoothness and the light source state and the distance and angle between the printed material 1 and the copy detection device 2 at the time of imaging are not stable, During binarization, it is difficult to detect only the portion corresponding to the yellow gradation 12 due to the influence of subtle light brightness and darkness that occurs during imaging. Therefore, it is expressed in the Lab color system rather than converting to a captured image expressed in the CMYK color gamut so as to cut off the information on the extra lightness and extract only the portion corresponding to the yellow gradation 12 composed of the yellow component. It is preferable to convert to a captured image.

  In the above embodiment, the gradation has been described as being yellow, but the present invention is not limited to this. The gradation may be a color other than yellow. Even if it is a gradation of a color other than yellow, the light color is attenuated by duplication and becomes white (paper color) due to duplication, and the length of the gradation becomes shorter than the original. When the gradation is red or green, the control unit 24 extracts the a channel representing the a value of each pixel of the captured image from the captured image represented by the Lab color system, and the printed material 1 is the original. Or a duplicate.

  In the above embodiment, the pattern printed on the printed matter 1 has been described as a gradation, but the present invention is not limited to this. The pattern printed on the printed material 1 is arbitrary as long as the shape changes by duplication. For example, the density of 20% to 30% using only K (black) ink in the CMYK color gamut. A gray (black one-dimensional) pattern printed on the printed material 1 may be used.

  Such a gray (black one-dimensional) pattern is converted into a mixed color (three-dimensional red, green, and blue) of the RGB color gamut at the time of scanning, and the CMYK color gamut is used again at the time of printing. At this time, the pattern is printed in a mixed color (four dimensions of cyan, magenta, yellow, and black), and turns turbid and bluish gray. In the RGB color gamut, 100% purity black can be expressed in the RGB color gamut, but only CMY ink in the CMYK color gamut cannot physically create 100% purity black, and K ( This is because it is necessary to use black ink.

  Therefore, the control unit 24 extracts the a channel and / or the b channel from the captured image represented by the Lab color system, and blacks the pattern based on the a value and / or b value of the portion corresponding to the pattern. It is determined whether or not colors other than are mixed with a predetermined reference value or more. Then, when the control unit 24 determines that the color other than black is mixed with a predetermined reference value or more, the control unit 24 may determine that the printed material 1 is a duplicate, assuming that the first condition is not satisfied.

  In the above embodiment, the printed matter 1 has been described as including the two-dimensional code 11 with a logo. However, the present invention is not limited to this. The printed matter 1 may include items other than the logo-added two-dimensional code 11 such as a barcode or a document, or may include nothing other than the gradation 12.

  In the above-described embodiment, the printed matter 1 has been described by taking the logo-attached two-dimensional code 11 in which the two-dimensional code is superimposed on the visible logo image as an example. However, the present invention is not limited to this, and may be a general-purpose two-dimensional code that expresses predetermined information by a distribution pattern of white cells and black cells.

  In the above embodiment, the logo-added two-dimensional code 11 is such that only the first type of lightness cells are superimposed on the portion of the logo image that is less than the first lightness, while the first of the logo images. In the above description, it is assumed that both the first-type lightness cell and the second-type lightness cell are overlapped in the portion above the lightness. However, the present invention is not limited to this.

  For example, in the two-dimensional code 11 with a logo, only cells of the first type of brightness are superimposed on the portion of the logo image that is less than the first brightness, and the portion that is greater than or equal to the first brightness and less than the second brightness. The first type lightness cell and the second type lightness cell are overlapped, and a portion of the second lightness or higher recognized as white by a general-purpose two-dimensional code reader has a second type lightness. These cells may be superposed. In this case, the logo-added two-dimensional code 11 is obtained by a first-type lightness cell recognized as white by a general-purpose two-dimensional code reader and a portion of the logo image having a second lightness or higher and a general-purpose two-dimensional code reader. Predetermined information is expressed by a distribution pattern of cells of the second type brightness that are recognized as black and a portion of the logo image that is less than the first brightness (see, for example, WO2011 / 118540).

  Further, in the logo-added two-dimensional code 11, a logo image less than a predetermined brightness recognized as black by a general-purpose two-dimensional code reader is overlaid with cells having a predetermined brightness or higher recognized as white by a general-purpose two-dimensional code reader. It may be. In this case, the logo-added two-dimensional code 11 includes a cell having a predetermined brightness or higher that is recognized as white by a general-purpose two-dimensional code reader, a logo image having a predetermined brightness that is recognized as black by a general-purpose two-dimensional code reader, The predetermined information is expressed by the distribution pattern (see, for example, JP-A-2007-287004).

  Furthermore, the logo-added two-dimensional code 11 is equal to or higher than a predetermined lightness recognized as white by a general-purpose two-dimensional code reader in a portion of the logo image less than the predetermined lightness recognized as black by a general-purpose two-dimensional code reader. The cells of a predetermined brightness or higher that are recognized as white by a general-purpose two-dimensional code reader are overlapped with cells of less than the predetermined brightness that are recognized as black by a general-purpose two-dimensional code reader. (For example, refer to JP 2008-15642 A).

  In this specification, the specifications, claims, and entire drawings of JP-A-2007-287004, JP-A-2008-15642, and WO2011-118540 are incorporated by reference.

  In the above embodiment, the two-dimensional code has been described as being a QR code (registered trademark). However, the present invention is not limited to this. Two-dimensional codes are other matrix type two-dimensional codes such as data matrix, aztec code, code one, array tag, box graphic code, maxi code, pericode, soft strip, CP code, carla code, ultra code, etc. There may be. Alternatively, a stack type two-dimensional code in which one-dimensional barcodes such as PDF417, code 49, code 16k, and coder block are vertically stacked may be used.

  In the above embodiment, the program executed by the CPU of the control unit 24 has been described as being stored in advance in the ROM, the storage unit 23, etc., but the present invention is not limited to this, and the above-described program is executed. You may make it function as the duplication detection apparatus 2 which concerns on said embodiment by applying the program for performing a process to the existing general purpose computer.

  A method for providing such a program is arbitrary. For example, the program may be stored and distributed on a computer-readable recording medium (flexible disk, CD (Compact Disc) -ROM, DVD (Digital Versatile Disc) -ROM, etc.). Alternatively, the program may be stored in a storage on a network such as the Internet and provided by downloading it.

  Furthermore, when the above processing is executed by sharing an OS (Operating System) and an application program, or by cooperation between the OS and the application program, only the application program may be stored in a recording medium or storage. It is also possible to superimpose a program on a carrier wave and distribute it via a network. For example, the program may be posted on a bulletin board (BBS: Bulletin Board System) on the network, and the program may be distributed via the network. Then, this program may be activated and executed in the same manner as other application programs under the control of the OS, so that the above processing can be executed.

  It should be noted that the present invention can be variously modified and modified without departing from the broad spirit and scope of the present invention. The above-described embodiment is for explaining an example of the present invention and does not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Printed matter 2 Duplication detection apparatus 11 Two-dimensional code with logo 12 Gradation 20 Duplication detection apparatus 21 Touch panel 22 Imaging part 23 Storage part 24 Control part 25 Illuminance sensor

Claims (11)

An imaging unit (22) for imaging a printed matter (1) on which a predetermined pattern is printed, and generating a captured image;
When a chromaticity channel representing the chromaticity of each pixel is extracted from the captured image, and the portion corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition, the printed material (1) is copied. A control unit (24) for determining
A duplication detection device (2). The predetermined pattern is gradation,
When the portion corresponding to the gradation in the chromaticity channel does not have a predetermined shape, the control unit (24) determines that the first condition is not satisfied and determines that the printed material (1) is a duplicate. To determine,
The duplication detection device (2) according to claim 1. The predetermined pattern is gradation,
When the portion corresponding to the gradation in the chromaticity channel is shorter than a predetermined length, the control unit (24) determines that the printed material (1) is not a copy and does not have the predetermined shape. To
The duplication detection device (2) according to claim 2. The gradation is a yellow gradation,
The duplication detection device (2) according to claim 2 or 3. The imaging unit (22) generates the captured image represented by an RGB color gamut,
The control unit (24) converts the captured image represented by the RGB color gamut into the captured image represented by the Lab color system,
B channel representing the b value of each pixel is extracted from the captured image represented by the Lab color system;
If the portion corresponding to the yellow gradation in the b channel does not have the predetermined shape, the printed matter (1) is determined as a duplicate, assuming that the first condition is not satisfied.
The duplication detection device (2) according to claim 4. The control unit (24) binarizes the b value of each pixel of the b channel to generate a binarized image,
When the portion corresponding to the yellow gradation in the binarized image does not have the predetermined shape, the printed matter (1) is determined as a duplicate, assuming that the first condition is not satisfied.
The duplication detection device (2) according to claim 5. An illuminance sensor (25) for detecting the illuminance of the printed matter (1);
The control unit (24) determines a threshold value to be compared with the b value of each pixel of the b channel according to the illuminance detected by the illuminance sensor (25).
The b value of each pixel of the b channel is binarized by comparing with the threshold value.
The duplication detection device (20) according to claim 6. The control unit (24) determines the printed matter (1) as an original when a portion corresponding to the predetermined pattern satisfies the first condition and the second condition,
When the first condition is satisfied but the second condition is not satisfied, it is determined that the printed matter (1) is likely to be the duplicate,
The duplication detection device (2) according to any one of claims 1 to 7. When the control unit (24) determines that the printed matter (1) is the duplicate, the control unit (24) instructs the imaging of the printed matter (1) again.
The duplication detection device (2) according to any one of claims 1 to 8. The imaging unit (22) captures the printed matter (1) on which a predetermined pattern is printed, generates a captured image,
The control unit (24) extracts a chromaticity channel representing the chromaticity of each pixel from the captured image,
When the part corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition, the control unit (24) determines the printed matter (1) as a duplicate.
Copy detection method. On the computer,
Capture a printed matter (1) printed with a predetermined pattern to generate a captured image,
Extracting a chromaticity channel representing the chromaticity of each pixel from the captured image;
When the portion corresponding to the predetermined pattern in the chromaticity channel does not satisfy the first condition, the printed matter (1) is determined as a duplicate.
A program to make things happen.