JP6523588B1 - Duplication detection device, duplicate detection method, and program - Google Patents

Abstract

The copy detection device (2) captures an image of a printed matter (1) on which a yellow gradation is printed, and generates a captured image represented by an RGB color gamut, and a control unit (24). Equipped with The control unit (24) converts the captured image represented by the RGB color gamut into a captured image represented by the Lab color system, and extracts the b channel representing the 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, when the portion corresponding to the yellow gradation in the binarized image does not have a predetermined shape, the control unit (24) determines the printed matter (1) as a duplicate.

Description

  The present invention relates to a duplicate detection apparatus, a duplicate detection method, and a program, and more particularly to a duplicate detection apparatus, a duplicate detection method, and a program that can easily detect duplicates.

  QR (Quick Response) code (registered trademark), which is a type of two-dimensional code, embeds machine-readable information in printed matter, and these days it has monetary value, as represented by airline tickets and tickets. The use of the QR code (registered trademark) is expanding (see, for example, Patent Document 1). For this reason, 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 problems, the original image of the two-dimensional code is separated into each color component of RGB, and then discrete wavelet transform is applied to each color of R, G, B to obtain LL component, LH component, HL component, and It is decomposed into frequency components such as HH component. Then, a technology was developed to generate watermark information-containing two-dimensional code by embedding watermark information only in the HH component in which the value (coefficient value) of the wavelet coefficient is smaller than the LH component and the HL component (see Patent Document 2, for example) ).

  The technique described in Patent Document 2 can prevent the loss of watermark information from the appearance of information other than the watermark information as noise from the HH component of the two-dimensional code with 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 including the illegal watermark information copied (illegal copy) by the copying machine having different gray scale expression methods, Watermark information is lost. This makes it possible to detect a duplicate of the two-dimensional code.

  In the present specification, the specifications of the patent documents 1 and 2, the claims, and the entire drawing are incorporated as references.

Unexamined-Japanese-Patent No. 2006-318328 WO 2010/140639

  However, as business transactions using two-dimensional codes such as QR code (registered trademark) have expanded and become active, a technology that can detect duplication more simply and reliably than the technology described in Patent Document 2 is now available. It is strongly required.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide 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 copy detection device (2) according to the first aspect of the present invention captures a printed material (1) on which a yellow gradation is printed and captures a captured image represented by an RGB color gamut An imaging unit (22) to be generated, an illuminance sensor (25) for detecting the illuminance of the printed matter (1), and a captured image represented by the RGB color gamut are displayed on the captured image represented by the Lab color system. According to the illuminance detected by the illuminance sensor (25), the b channel representing the b value of each pixel is extracted from the captured image represented by the Lab color system, and the pixels of the b channel are extracted . A threshold value to be compared with the b value is determined, and the b value of each pixel of the b channel is compared with the threshold value to binarize to generate a binarized image , and corresponding to the yellow gradation in the binarized image If portions does not have a predetermined shape, said indicia A control unit for determining object a (1) and replica (24), the.

In the replication sensing device (2), before Symbol controller (24), the portion corresponding to the yellow gradation in the binarized image, if a predetermined length of less than, having said predetermined shape Alternatively, the printed matter (1) may be determined as a duplicate.

In the above-mentioned duplication detection device (2), in addition to the control unit (24) having a portion corresponding to the yellow gradation having the predetermined shape, the control unit (24) satisfies the second condition. the printed matter (1) determines that the original, if not met the second condition while that have a predetermined shape, the printed material (1) there is a possibility of the replica It may be determined that

  In the above copy detecting device (2), when the printed matter (1) is determined to be the copied matter, the control unit (24) may instruct re-imaging of the printed matter (1). .

In order to achieve the above object, in the duplication detection method according to the second aspect of the present invention, the imaging unit (22) images a printed matter (1) on which a yellow gradation is printed and is represented by an RGB color gamut The illuminance sensor (25) detects the illuminance of the printed matter (1), and the control unit (24) displays the captured image represented by the RGB color gamut in the Lab color system. The control unit (24) extracts the b channel representing the b value of each pixel from the captured image represented by the Lab color system, and the control unit (24) According to the illuminance detected by the illuminance sensor (25), a threshold to be compared with the b value of each pixel of the b channel is determined, and the control unit (24) calculates the b value of each pixel of the b channel It generates a binary image by binarizing compared to threshold value, the control unit (24) Portion corresponding to the gradient of the yellow in the binarized image, if not have a predetermined shape, to determine the printed material (1) and replica.

In order to achieve the above object, a program according to a third aspect of the present invention captures on a computer a printed matter (1) on which yellow gradation is printed and generates a captured image represented by RGB color gamut The illuminance of the printed matter (1) is detected, and the captured image represented by the RGB color gamut is converted into the captured image represented by the Lab colorimetric system, and the captured image represented by the Lab colorimetric system The b channel representing the b value of each pixel is extracted from, and the threshold value to be compared with the b value of each pixel of the b channel is determined according to the detected illuminance, and the b value of each pixel of the b channel is determined generates a binary image by binarizing compared to a threshold, duplicate portion corresponding to the yellow gradation in the binarized image, if not have a predetermined shape, the printed matter (1) To make things happen A.

  According to the present invention, it is possible to provide a copy detection device, a copy detection method, and a program that can easily detect a copy.

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 showing an example of composition of a duplication detection device concerning this embodiment. It is explanatory drawing which shows the color space of Lab colorimetric 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 copy of printed matter. It is a flowchart which shows the detail of a duplication detection process. (A) is a table showing the optimal threshold for each illuminance in the duplicate detection device according to the present embodiment, and (b) is a table showing the optimal threshold for each illuminance in the duplicate detection device according to the modification . It is a block diagram which shows the structural example of the duplication detection apparatus which concerns on a modification.

  The best mode for carrying out the present invention will be described below.

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

  The copy detection device is configured of, for example, a general-purpose smartphone or a tablet computer. In the present embodiment, a copy detection application program for detecting whether the printed matter according to the present embodiment is an original or a copy is installed on an iPhone (registered trademark) 6s manufactured by Apple Incorporated and copied. It constitutes a detection device. The copy detection device may be an Android (registered trademark) smartphone, a tablet computer, or the like, or may be a general-purpose mobile phone, a personal computer, or the like.

  FIG. 1 is a diagram illustrating a printed matter according to the present embodiment.

  As shown in FIG. 1, the printed matter 1 is a two-dimensional code 11 with a logo obtained by superimposing a two-dimensional code such as a QR code (registered trademark) on a visible logo image on a printing medium such as printing paper on white. It forms by printing the substantially square frame-like yellow gradation 12 which encloses the outer periphery of the two-dimensional code 11 with a logo. Here, the gradation 12 is yellow because yellow is the most susceptible to duplication among various colors. For this reason, a yellow gradation 12 is printed on the printed matter 1 in order to detect whether it is an original or a duplicate.

  The two-dimensional code with logo 11 is generally used for the portion of the logo image that is less than the first lightness recognized as black by the general-purpose two-dimensional code reader (such as the background portion and the keyhole portion in the example shown in FIG. 1). Only the first type of lightness cells (white cells in the example shown in FIG. 1) recognized as white by the two-dimensional code reader are superimposed. On the other hand, in the part of the logo image that has the first lightness or more (the key body portion etc. in the example shown in FIG. 1), cells of the first kind lightness (white cells in the example shown in FIG. 1) Both the second type of lightness cells (black cells in the example shown in FIG. 1) recognized as black by the two-dimensional code reader are superimposed.

  The logo-added two-dimensional code 11 is recognized as black by the general-purpose two-dimensional code reader and the general-purpose two-dimensional code reader as cells of the first type of lightness recognized as white by the general-purpose two-dimensional code reader Distribution of cells of the second type of lightness (black cells in the example shown in FIG. 1) and portions of the logo image having less than the first lightness (background part and keyhole parts in the example shown in FIG. 1) The pattern expresses predetermined information such as a URL (Uniform Resource Locator).

  The gradation 12 is a printing medium such as printing paper on a white background, and each vertex of a substantially square having a side length of about 23 mm using only Y (yellow) ink among the four color inks in the CMYK color gamut. From the center to the center of each side.

  FIG. 2 (a) is a view showing a yellow gradation in the original of the printed matter. FIG. 2 (b) is a diagram showing a yellow gradation in a copy of a printed matter.

  The inventor determined the length of the yellow gradation 12 in the original and the copy of the printed matter 1 respectively. Here, the length of the gradation 12 refers to the length of a portion of the sides of the gradation 12 where the adhesion of Y (yellow) ink can be confirmed visually. The length of the yellow gradation 12 in the original was about 21.5 mm to about 23 mm as shown in FIG. 2 (a). On the other hand, the length of the yellow gradation 12 in the duplicate was shorter than the original, as shown in FIG. 2B, and was about 14 mm to about 19.5 mm.

  Thus, the yellow gradation 12 is attenuated by replication, and the length of the yellow gradation 12 in the replication is shorter than the original. The reason is that the color gamut (color space), the reproduction method, and the like are different between the CMYK color gamut used for printing and the RGB color gamut used for copying. Specifically, the CMYK color gamut is expressed as a subtractive color which becomes white when the color is reduced (and is black when added), and the RGB color gamut is white when the color is added (decreased to black) Express colors by additive color mixture.

  The yellow gradation 12 is converted into a mixed color of the RGB gamut at the time of scanning, and the CMYK 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 portions with low density (lighter) become lighter. The reason is that the mechanism for expressing colors by printing. That is, in printing, a dot (point) of ink is placed or not placed on a printing medium such as paper, that is, a color is represented by binary values of dot on / off, and dot shape (for example, size of dot) or dot Color shading is expressed in a distributed manner. Light colors naturally make the dot shape smaller. In order to obtain an image sensor when scanning such a small dot, sufficient resolution is required, but the resolution of a general-purpose copying machine. There is only about 400ppi. For this reason, light color tends to be easily lost, and as a result, light color tends to be lighter. In particular, the yellow gradation 12 is more likely to change to a lighter color due to duplication using a scanner, a camera or the like.

  The copy detection apparatus according to the present embodiment detects whether the printed matter 1 is an original or a copy, using the nature of the yellow gradation 12 as described above.

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

  As shown in FIG. 3, the duplication 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 configured of, for example, a general-purpose touch panel in which a liquid crystal display device and a pointing device are combined. The touch panel 21 displays various screens and receives various operations by the user. In the present embodiment, the touch panel 21 displays a reading icon or the like for instructing reading of the two-dimensional code 11 with logo.

  The imaging unit 22 is configured by, for example, a solid-state imaging device such as a CCD (Charge Coupled Device). The imaging unit 22 captures an image of the printed matter 1 and generates a captured image represented by the RGB color gamut.

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

  The control unit 24 includes, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). The CPU uses the RAM as a work memory and controls various operations of the copy detection apparatus 2 by appropriately executing programs stored in the ROM, the storage unit 23 and the like.

  In the present embodiment, the control unit 24 displays the read icon on the touch panel 21 in response to the user operating the touch panel 21 and activating the copy detection application program stored in the storage unit 23. In response to the user pointing the imaging unit 22 to the printed matter 1 and tapping the reading icon, the control unit 24 images the printed matter 1 with the imaging unit 22 and generates a captured image represented by the RGB color gamut . When the tilt of the captured image is equal to or greater than a predetermined angle (for example, 2 °) or when the size of the captured image is less than a predetermined size (for example, 300 pixels in width) You may do so.

  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 view showing a 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 in which colors are expressed by three values such as L value indicating lightness and 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 larger the value, the higher the lightness. When L value is "0", it becomes black, and when it is "100", it becomes white. The a value is a value indicating the chromaticity between red and green, and in the present embodiment, has a value in the range of “−255” to “255”. When the value of a is a positive value, it becomes red, and the larger the positive value, the higher the density of red. On the other hand, when the value of a is a negative value, it becomes green, and as the negative value becomes smaller, the density of green becomes higher. The b value is a value indicating the chromaticity between yellow and blue, and in the present embodiment, has a value in the range of “−255” to “255”. When the b value is a positive value, it becomes yellow, and as the positive value becomes larger, the yellow density becomes higher. On the other hand, when the b value is a negative value, it becomes blue, and as the negative value becomes smaller, the blue density becomes higher. When both the a value and the b value are "0", the color becomes achromatic.

  The control unit 24 illustrated in FIG. 3 extracts the 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), and sets the b value less than the threshold value to "0" and the b value greater than or equal to the threshold value. Binarize to 1 ′ ′ to generate a binarized image.

  FIG. 5A is a view showing a binarized image when the original of the printed matter is imaged. FIG. 5B is a view showing a binarized image in the case of imaging a copy of a printed matter.

  In the binarized images shown in FIGS. 5A and 5B, the pixel set to “0” is black, and the pixel set to “1” is white. In the binarized image in the case of imaging the original of the printed matter, as shown in FIG. 5A, the portion corresponding to the yellow gradation 12 is almost connected while the image of the printed matter is imaged In the binarized image of, only the four corner portions of the gradation 12 remain as shown in FIG. 5 (b).

  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 can not detect a line segment of a predetermined length or more in the portion corresponding to the yellow gradation 12, it determines that the printed matter 1 is a duplicate, and reads the touch icon 21 along with the determination result. indicate.

  Even when the control unit 24 can detect a line segment having a predetermined length or more in a portion corresponding to the yellow gradation 12, a line segment having a predetermined length or more in any of the four sides of the portion corresponding to the yellow gradation 12 If it can not be detected, it is determined that the printed matter 1 is likely to be a copy, and the read 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, it determines that the printed matter 1 is an original, and the determination result is a touch panel Display on 21. Then, the control unit 24 reads predetermined information from the logo-added two-dimensional code 11 included in the captured image.

  Next, copy detection processing performed by the copy detection device having the above configuration will be described with reference to the drawings.

  After activating the copy detection application program, the control unit 24 of the copy detection device 2 starts copy detection processing in response to the user pointing the imaging unit 22 at the printed material 1 and tapping the reading icon.

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

  As shown in FIG. 6, in the commodity ordering process, first, the control unit 24 picks up the printed matter 1 including the logo-added two-dimensional code 11 by the imaging unit 22 and generates a picked-up image represented by the RGB color gamut (Step S1).

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

  Subsequently, the control unit 24 extracts the 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 sets the b value less than the threshold value to “0” and the b value more than the threshold value to “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 can not detect a line segment of a predetermined length or more in the portion corresponding to the yellow gradation 12 (step S6; No), the control unit 24 determines that the printed matter 1 is a copy, and After displaying the read icon on the touch panel 21 (step S7), the copy detection process is ended.

  On the other hand, even when the control unit 24 can detect a line segment having a predetermined length or more in the portion corresponding to the yellow gradation 12 (step S6; Yes), the four sides of the portion corresponding to the yellow gradation 12 When a line segment of a predetermined length or more can not be detected in any of the above (step S8; No), it is determined that the printed matter 1 is a copy possibility, and the read icon is displayed on the touch panel 21 together with the determination result. After that (step S9), the copy detection process is ended.

  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), it determines that the printed matter 1 is an original. Then, the determination result is displayed on the touch panel 21 (step S10).

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

  As described above, the duplication detection device 2 according to the present embodiment captures an image of the printed material 1 on which a predetermined pattern is printed to generate a captured image, and represents the chromaticity of each pixel from the captured image. And a control unit that extracts the chromaticity channel and determines that the printed matter 1 is a copy 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 also 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 the b channel representing the b value of each pixel as the chromaticity channel from the captured image represented by 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, when the portion corresponding to the yellow gradation in the binarized image does not have a predetermined shape, that is, the control unit 24 does not have a line segment of a predetermined length or more in the portion corresponding to the yellow gradation. And the printed matter 1 is determined as a copy, assuming that the first condition is not satisfied.

  On the other hand, when there is a line segment of a predetermined length or more in any of the four sides of the portion corresponding to the yellow gradation, the control unit 24 determines that the first condition and the second condition are satisfied, Determine the original. On the other hand, when there is a line segment of a predetermined length or more in the portion corresponding to the yellow gradation, the control unit 24 sets the first condition if there is no line segment of a predetermined length or more in any of the four sides. It is determined that the printed matter 1 has the possibility of a copy, on the assumption that the second condition is not satisfied while the second condition is not satisfied.

  Then, when it is determined that the printed matter 1 is a copy, the control unit 24 displays a read icon on the touch panel 21 and instructs the imaging of the printed matter 1 again.

  As described above, the control unit 24 has a device-independent color model that has an L value indicating lightness and two values (a value and b value) indicating chromaticity, for the captured image represented in the RGB color gamut. The captured image is represented by the Lab color system. Then, the control unit 24 extracts only the b channel that is easily affected by 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 ambient light, and After removing the a channel representing the insensitive a value, the captured image is binarized. As a result, the control unit 24 can generate a binarized image which is not easily affected by ambient light and in which the yellow component necessary for detecting a duplicate is remarkable. In the binarized image generated in this manner, the amount of attenuation of the portion corresponding to the yellow gradation 12 becomes clear depending on whether the printed matter 1 is an original or a duplicate, so that the control unit 24 determines that the printed matter 1 is an original Whether it is a copy or a copy can be easily and reliably determined

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

  The inventor of the present invention is a duplicate detection apparatus comprising the duplicate detection device 2 comprising the iPhone (registered trademark) 6s manufactured by Apple Incorporated, according to the above-described embodiment, and the P9 lite manufactured by Huawei according to the modification. The optimal threshold for each illuminance in each of the devices 20 (FIG. 8) was determined. Specifically, the inventor images each of the original and the copy of the printed matter 1 with various threshold values for each illuminance (300 lx to 1000 lx) in a general living space, and detects the copy shown in FIG. Executed processing. Then, in the copy detection process, the printed material 1 is not determined to be a copy once, and it is not determined that there is a possibility of copying twice in a row, so that it is correctly determined 50 times in a row. Threshold was determined as the optimal threshold.

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

  In FIG. 7 (a) and (b), "(circle)" shows the optimal threshold value in each illumination intensity. As shown to Fig.7 (a), in the duplication detection apparatus 2 which concerns on this embodiment, "123" was contained in the optimal threshold value also in any illumination intensity. Therefore, in the present embodiment, “123” is set as the 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 modification, the optimum threshold value differs according to the illuminance of the printed matter 1.

  FIG. 8 is a block diagram showing a configuration example of a duplicate detection apparatus according to a modification.

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

  The control unit 24 of the duplicate detection apparatus 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 set to 500lx to 699lx, the predetermined threshold is set to "135". When the illuminance is set to 700lx to 899lx, the predetermined threshold is set to "132" and the illuminance is set to 900lx to 1000lx. In this case, the predetermined threshold may be set to “128”.

  In the above-described embodiment, the control unit 24 of the duplication detection device 2 detects a line segment of a predetermined length or more on any of the four sides of the portion corresponding to the yellow gradation 12, and the printed matter 1 is It demonstrated as what discriminate | determined as an original. However, the present invention is not limited to this, and the conditions for determining that the printed matter 1 is the original are the model of the smartphone or tablet computer constituting the copy detection device 2, the illuminance at the time of imaging, etc. It can be suitably changed according to.

  For example, in addition to the fact that the control unit 24 of the duplication detection device 2 can detect a line segment of a predetermined length or more on any of the four sides of the portion corresponding to the yellow gradation 12, a line segment of a predetermined length or more is predetermined It may be determined that the printed matter 1 is the original on condition that the number (for example, five or more) has been detected. Furthermore, in addition to these conditions, the control unit 24 of the copy detection device 2 determines the number of white pixels on the outer periphery of the logo-added two-dimensional code 11 to perform noise determination, and the noise is 10% or more. It is determined that the printed matter 1 is a copy, and when the noise is 0.8% or more and less than 10%, the printed matter 1 is determined to be a copyable, and the noise is less than 0.8%. In this case, it may be determined that the printed matter 1 is an original.

  In addition, the control unit 24 of the duplication detection device 2 can detect a line segment having a predetermined length or more on 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 matter 1 is an original on condition that Furthermore, the control unit 24 of the duplication detection device 2 can detect a line segment having a predetermined length or more on 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 to the above, it may be determined that the printed matter 1 is an original on 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, for example, linear. In this case, the control unit 24 of the duplication 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. In the case of short, it may be determined that the printed matter 1 is a duplicate, not having 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 a 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 can be used. For example, the control unit 24 may convert the captured image represented by the RGB color gamut into a captured image represented by the YUV color system, the YCbCr color system, the YPbPr color system, or the like.

  In addition, 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 the 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. Then, the binarized image is generated by binarizing the Y value less than the threshold value to "0" and the Y value greater than or equal to the threshold value to "1". Then, the control unit 24 detects a line segment of a predetermined length or more in a portion corresponding to the yellow gradation 12 of the binarized image, and determines whether the printed matter 1 is an original or a duplicate. May be

  However, when converting into a captured image represented in the CMYK color gamut, the quality of the light source at the time of imaging (close to white light, high lightness, etc.), the paper quality of the printed matter 1 (coated paper or matte paper) Depending on the presence of paper thickness and the like, and the distance and angle between the printed matter 1 at the time of imaging and the copy detection device 2, subtle light and dark of light and the like are generated in the printed matter 1 at the time of imaging. For this reason, unless the printed matter 1 is made of paper having stable smoothness, and the light source state and the distance and angle between the printed matter 1 and the duplicate detection device 2 at the time of imaging are stable, At the time of binarization, it is difficult to detect only the portion corresponding to the yellow gradation 12 due to the influence of subtle light and dark and the like generated at the time of imaging. Therefore, it is represented by the Lab color system rather than converting it into a captured image represented by the CMYK color gamut, in order to discard the information related to the extra lightness and extract only the part corresponding to the yellow gradation 12 composed of the yellow component. It is preferable to convert into a captured image.

  In the above embodiment, although the gradation is described as being yellow, the present invention is not limited to this. The gradation may be a color other than yellow. Although the gradation of colors other than yellow is not as great as yellow gradation, the light color is attenuated by copying and discolored to white (paper color), and the gradation length becomes shorter than the original. Then, 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 matter 1 is an original It may be determined whether it is a copy or a copy.

  In the above embodiment, the pattern printed on the printed matter 1 is described as gradation, but the present invention is not limited to this. The pattern printed on the printed matter 1 is arbitrary as long as the shape changes due to copying, and for example, the density of 20% to 30% using only the K (black) ink in the CMYK color gamut It may be a gray (black one-dimensional) pattern printed on the printed matter 1 in the above.

  Such a gray (black one-dimensional) pattern is converted to a mixed color (red, green, and blue three-dimensional) of the RGB gamut during scanning, and the CMYK gamut is used again during printing. At this time, the pattern is printed in a mixed color (four-dimensional of cyan, magenta, yellow and black) and turns cloudy and bluish gray. Although mixed color printing can represent black with 100% purity in the RGB gamut, CMY ink alone in the CMYK color gamut can not physically create black with 100% purity. Black ink must be used.

  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 the pattern is black based on the a value and / or b value of the portion corresponding to the pattern. It is determined whether the color other than the color is mixed with the predetermined reference value or more. Then, when it is determined that the color other than black is mixed with the pattern at a predetermined reference value or more, the control unit 24 may determine that the printed matter 1 is a copy, 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 logo. However, the present invention is not limited to this. The printed matter 1 may include something other than the logo-added two-dimensional code 11 such as a bar code or a document, or nothing other than the gradation 12 may be included.

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

  In the above embodiment, the logo attached two-dimensional code 11 is a part of the logo image which is less than the first lightness, while only the cells of the first kind of lightness are superimposed, while the first one of the logo images is It has been described that in the portion above the lightness, both the cells of the first kind of lightness and the cells of the second kind of lightness are superimposed. However, the present invention is not limited to this.

  For example, in the logo image with the two-dimensional code 11, only cells of the first type are superimposed on portions less than the first lightness in the logo image, and portions less than the second lightness in portions higher than the first lightness. The second type of lightness is applied to a portion of the second lightness or higher in which both a cell of the first kind of lightness and a cell of the second kind of lightness are superimposed and which is recognized as white by a general-purpose two-dimensional code reader. Only the cells of may be superimposed. In this case, the logo-added two-dimensional code 11 is formed by the first-type cell of lightness recognized as white by the general-purpose two-dimensional code reader and the portion of the second or higher brightness of the logo image and the general-purpose two-dimensional code reader Predetermined information is expressed by the distribution pattern of the second type of lightness cells recognized as black and the portion of the logo image with less than the first lightness (see, for example, WO 2011/118540).

  Further, in the logo-added two-dimensional code 11, a cell having a predetermined lightness or more recognized as white by the general two-dimensional code reader is superimposed on a logo image less than the predetermined lightness recognized as black by the general 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 more recognized as white by a general-purpose two-dimensional code reader, and a logo image having a brightness less than a predetermined brightness recognized as black by the general-purpose two-dimensional code reader. Prescribed information is expressed by the distribution pattern of (see, for example, Japanese Patent Application Laid-Open No. 2007-287004).

  Furthermore, the logo attached two-dimensional code 11 is a logo image having a predetermined brightness which is recognized as white by the general-purpose two-dimensional code reader in a portion having a brightness less than the predetermined black recognized by the general-purpose two-dimensional code reader. The cells of the above are superimposed, and the cells of less than the predetermined brightness recognized as black by the general-purpose two-dimensional code reader are superimposed on the portions of the predetermined lightness or more recognized as white by the general-purpose two-dimensional code reader. (See, for example, JP-A-2008-15642).

  In this specification, the specifications, claims, and whole drawings of Japanese Patent Application Laid-Open Nos. 2007-287004, 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. The two-dimensional code is, for example, another matrix-type two-dimensional code such as data matrix, Aztec code, code one, array tag, box graphic code, maxi code, peri code, soft strip, CP code, Carla code, and ultra code. It may be. Alternatively, it may be a stack-type two-dimensional code in which one-dimensional barcodes such as PDF417, code 49, code 16k, coder block, etc. are vertically stacked.

  In the above embodiment, the program executed by the CPU of the control unit 24 is described as being stored in advance in the ROM, the storage unit 23 or the like, but the present invention is not limited to this, and the above-described The program for executing the process may be applied to an existing general-purpose computer to function as the copy detection device 2 according to the above embodiment.

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

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

  It is to be understood that various embodiments and modifications can be made without departing from the broad spirit and scope of the present invention. In addition, the embodiment described above is for describing one example of the present invention, and does not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 printed matter 2 duplicate detection apparatus 11 two-dimensional code with logo 12 gradation 20 duplicate detection apparatus 21 touch panel 22 imaging unit 23 storage unit 24 control unit 25 illuminance sensor

Claims (6)

An imaging unit (22) for imaging a printed matter (1) on which a yellow gradation is printed and generating a captured image represented by an RGB color gamut ;
An illuminance sensor (25) for detecting the illuminance of the printed matter (1);
The captured image represented by the RGB color gamut is converted to the captured image represented by the Lab color system, and b channels representing the b value of each pixel are extracted from the captured image represented by the Lab color system And the threshold value to be compared with the b value of each pixel of the b channel is determined according to the illuminance detected by the illuminance sensor (25), and the b value of each pixel of the b channel is compared with the threshold value. by binarizing generates binarized image, the portion corresponding to the yellow gradation in the binarized image, if not have a predetermined shape, control of determining the printed matter (1) and replica Part (24),
A duplicate detection device (2) comprising: Before SL controller (24), the portion corresponding to the yellow gradation in the binarized image, if a predetermined length of less than, as not having the predetermined shape, the printed matter (1) Discrimination as a duplicate,
A duplicate detection apparatus (2) according to claim 1 . The control unit (24) uses the printed matter (1) as the original when the portion corresponding to the yellow gradation satisfies the second condition in addition to the predetermined shape To determine
If you do not meet the second condition while that have a predetermined shape, wherein the printed matter (1) is determined that there is a possibility of the replica,
The duplicate detection device (2) according to claim 1 or 2 . When the control unit (24) determines that the printed matter (1) is the duplicate, it instructs the imaging of the printed matter (1) again.
A duplicate detection apparatus (2) according to claim 1 , 2 or 3 . An imaging unit (22) captures a printed material (1) on which a yellow gradation is printed, and generates a captured image represented by an RGB color space ;
An illuminance sensor (25) detects the illuminance of the printed matter (1),
The control unit (24) converts the captured image represented by the RGB color gamut into the captured image represented by the Lab colorimetric system,
The control unit (24) extracts the b channel representing the b value of each pixel from the captured image represented by the Lab color system ,
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 control unit (24) compares the b value of each pixel of the b channel with the threshold and binarizes to generate a binarized image.
The control section (24), a portion corresponding to the gradient of the yellow in the binarized image, if not have a predetermined shape, to determine the printed material (1) and replica,
Replication detection method. On the computer
Imaging a printed matter (1) on which a yellow gradation is printed to generate an imaged image represented by an RGB gamut ;
Detecting the illuminance of the printed matter (1);
Converting the captured image represented by the RGB color gamut into the captured image represented by the Lab color system;
The b channel representing the b value of each pixel is extracted from the captured image represented by the Lab color system ,
According to the detected illuminance, a threshold to be compared with the b value of each pixel of the b channel is determined;
The b value of each pixel of the b channel is compared with the threshold value and binarized to generate a binarized image,
Portion corresponding to the gradient of the yellow in the binarized image, if not have a predetermined shape, to determine the printed material (1) and replica,
Program to make things happen.