JP6668538B2 - Information detection apparatus, method, and program - Google Patents

Description

  The present invention relates to an information detection device, a method, and a program for adding and detecting information to an input medium.

  As a technology to easily prevent the forgery of valuable media (for example, concert tickets) and media for which forgery prevention is important (for example, resident's card and family register), the original is not visible in the copy. There is a technique in which a ground pattern is pre-printed on the original so that characters and characters are generated. This technique utilizes the fact that moire is generated during reading by a copying machine, and a pattern (for example, a character or pattern indicating that the image is a copy) is generated in the image after reading due to the moire. When this technique is used, information that does not exist in the original copy appears on the copy, so that the original copy and the copy can be easily distinguished visually.

  However, this technique is premised on visual confirmation by a person, and cannot be used for the purpose of reading a medium and automatically determining whether the copy is an original or a copy. This is because if the “reading” process is performed even on the original, a pattern similar to that of a copy will be generated in the data of the reading result. That is, the data obtained by reading the original is the same as the data obtained by reading a copy in which the pattern generated by moire can be visually confirmed.

  Rather than assuming visual confirmation, one of the approaches to reading media using a reader such as a camera and preventing counterfeiting by the copier at a low cost is as follows. By utilizing the fact that small irregularities on the surface of a medium are hardly reflected on a copying machine, information may be embedded in the surface of the medium with irregularities (eg, emboss). When reading information embedded by embossing, for example, a plurality of images obtained by photographing a medium under illumination conditions in a plurality of directions (for example, two directions of obliquely upward and right above) in which unevenness is easily detected are used ( According to Patent Literature 1), information embedded with unevenness can be extracted.

JP 2000-037797 A

  However, embedding information in the form of letters and numbers on the surface of a medium due to unevenness causes a problem that reading of information becomes difficult when there are scratches, breaks, clogging, etc. at the local portion where the letters or numbers are carved. . This means that the robustness is low.

  The present invention has been made to solve the above problems, and provides an information detection device, method, and program capable of detecting ID information with high accuracy from a pattern of concavities and convexities formed on a medium. With the goal.

  In order to achieve the above object, a pattern generation device according to a first aspect of the present invention includes a digital watermark pattern generation unit that generates a linear digital watermark pattern represented by multi-valued pixel values based on information to be embedded, On the basis of each pixel value of the linear digital watermark pattern generated in the digital watermark pattern generation unit, using the intermediate value between the maximum pixel value and the minimum pixel value of the linear digital watermark pattern as a threshold value, And a binarization processing unit that generates a binarized linear digital watermark pattern by binarizing each pixel value of the digital watermark pattern.

  According to the first aspect, the digital watermark pattern generation unit generates a linear digital watermark pattern represented by multi-valued pixel values based on the information to be embedded, and the line generated by the binarization processing unit. Based on each pixel value of the linear digital watermark pattern, using the intermediate value between the maximum pixel value and the minimum pixel value of the linear digital watermark pattern as a threshold, each pixel value of the linear digital watermark pattern is binary. A binarized linear digital watermark pattern is generated.

  As described above, a linear digital watermark pattern is generated based on the information to be embedded, and a binarized linear digital watermark pattern is generated based on each pixel value of the generated linear digital watermark pattern. By doing so, information can be embedded in the medium in an uneven pattern.

  An information embedding device according to a second aspect of the present invention provides an emboss ID for processing a medium so as to form irregularities of a binarized linear digital watermark pattern generated by the pattern generation device according to the first aspect on the surface. It is configured to include an embedded portion.

  Further, an information embedding method according to a third invention is an information embedding method in an information embedding device including an emboss ID embedding section, wherein the emboss ID embedding section is a multi-valued embedding section generated based on information to be embedded. Using a median value between the maximum pixel value and the minimum pixel value of the linear digital watermark pattern generated based on each pixel value of the linear digital watermark pattern represented by the pixel value of The medium is processed so that the unevenness of the binarized linear digital watermark pattern obtained by binarizing each pixel value of the linear digital watermark pattern is formed on the surface.

  According to the second and third aspects, the emboss ID embedding unit uses each pixel of the linear digital watermark pattern by using an intermediate value between the maximum pixel value and the minimum pixel value of the linear digital watermark pattern as a threshold value. The medium is processed so that the unevenness of the binarized linear digital watermark pattern obtained by binarizing the value is formed on the surface.

  As described above, by processing the medium so that the unevenness of the binarized linear digital watermark pattern obtained by binarizing each pixel value of the linear digital watermark pattern is formed on the surface, the information can be converted to the unevenness. It can be embedded in the medium in a pattern.

  Further, in the information embedding device according to the second invention, the information embedding device further includes a medium input unit for physically inputting the medium, wherein the information to be embedded is ID information, and the emboss ID embedding unit includes the medium input unit. The above-described processing may be performed on an arbitrary area on the surface of the medium by using an embosser, which is an embossing mold, so as to form irregularities of the binarized linear digital watermark pattern. Good.

  An information detection device according to a fourth aspect of the present invention is an information detection device that detects ID information previously embedded in the medium by photographing a target medium, and includes an imaging device for photographing the medium. Using at least one or more illumination light sources, taking an image of the medium for each illumination environment, obtaining a digital input with a camera input unit with auxiliary illumination, and based on each of the acquired images, An image pair is created for the combination, a difference image is calculated for each of the image pairs by calculating a difference value of a pixel value for each image included in the image pair, and the difference image is calculated for each of the difference images. A difference image calculation unit that calculates a sum of absolute values of the pixel values of the difference image and selects the difference image having the largest calculated sum, and a sum of the selected difference images. Based on a value and a predetermined threshold value, the unevenness degree determination unit that determines whether a shadow caused by unevenness has been detected, and when it is determined that the shadow has been detected, from the selected difference image And an emboss ID detection unit for detecting ID information embedded as an uneven pattern.

  The information detection method according to the fifth aspect of the present invention includes capturing an image of a target medium including an auxiliary illumination-equipped camera input unit, a difference image calculation unit, an unevenness determination unit, and an emboss ID detection unit. An information detection method in an information detection device that detects ID information embedded in the medium in advance, wherein the auxiliary illumination-equipped camera input unit includes: a shooting device for shooting the medium; Using an illumination light source, the medium is photographed for each illumination environment and acquired as digital data, and the difference image calculation unit creates an image pair for all image combinations based on each of the acquired images. Then, for each of the image pairs, a difference image is calculated by calculating a difference value of a pixel value for each image included in the image pair, and for each of the difference images, The sum of the absolute values of the pixel values of the minute image is calculated, the difference image having the largest calculated sum is selected, and the unevenness degree determination unit calculates the sum of the selected difference images. Based on a predetermined threshold value, it is determined whether or not a shadow caused by unevenness has been detected.If the emboss ID detection unit is determined to have detected the shadow, the emboss ID detection unit determines whether or not the shadow has been detected. The ID information embedded as an uneven pattern is detected.

  According to the fourth and fifth aspects of the present invention, the medium is photographed for each lighting environment using the photographing device for photographing the medium and at least one or more illumination light sources by the camera input unit with auxiliary illumination, and Acquired as data, the difference image calculation unit creates an image pair for all image combinations based on each of the acquired images, and for each of the image pairs, calculates the pixel value of each image included in the image pair. The difference image is calculated by calculating the difference value, and for each of the difference images, the sum of the absolute values of the pixel values of the difference image is calculated, and the difference image having the largest calculated sum is selected. The unevenness degree determination unit determines whether or not a shadow caused by the unevenness has been detected based on the total value of the selected difference images and a predetermined threshold, and the emboss ID detection unit can detect the shadow. And If it is constant, to detect the ID information embedded as a concavo-convex pattern from the difference image selected.

  In this manner, the medium is photographed for each lighting environment, acquired as digital data, an image pair is created based on each of the acquired images, a difference image is calculated for each of the image pairs, and a difference image of the difference image is calculated. For each, calculate the sum of the absolute values of the pixel values of the difference image, select the difference image having the largest calculated sum, and calculate the sum of the selected difference image and a predetermined threshold. Based on this, it is determined whether or not the shadow caused by the unevenness has been detected.If it is determined that the shadow has been successfully detected, the ID information embedded as the unevenness pattern is detected from the selected difference image, so that the medium can be detected. ID information can be detected with high accuracy from the formed pattern of irregularities.

  The medium according to the sixth invention is a medium in which a linear pattern is embedded with irregularities, and the linear pattern is a linear digital watermark pattern in which each pixel value is represented by a binary value. is there.

  Further, a program of the present invention is a program for causing a computer to function as each unit of the above-described pattern generation device, information embedding device, or information detection device.

  As described above, according to the pattern generation device of the present invention, a linear digital watermark pattern is generated based on the information to be embedded, and a 2D digital watermark pattern is generated based on each pixel value of the generated linear digital watermark pattern. By generating a digitized linear digital watermark pattern, information can be embedded in the medium in an uneven pattern.

  Further, according to the information embedding apparatus, method, and program, a medium is formed such that unevenness of a binarized linear digital watermark pattern obtained by binarizing each pixel value of the linear digital watermark pattern is formed on the surface. By processing the information, it is possible to embed information in a medium in an uneven pattern.

  According to the information detecting apparatus, method, and program, the medium is photographed for each lighting environment, acquired as digital data, and based on each of the acquired images, an image pair is created. Calculating the difference image, for each of the difference images, calculating the sum of the absolute values of the pixel values of the difference image, selecting the difference image having the largest calculated sum, and selecting the difference image of the selected difference image. Based on the total value and a predetermined threshold value, it is determined whether or not a shadow caused by the unevenness has been detected, and when it is determined that the shadow has been detected, it is embedded as an unevenness pattern from the selected difference image. By detecting the ID information, it is possible to accurately detect the ID information from the pattern of the irregularities formed on the medium.

FIG. 11 is a diagram illustrating an example of an image obtained by copying a medium in which an emboss ID is embedded by a copying machine. FIG. 4 is a diagram illustrating an example of imaging a medium on which emboss processing has been performed as viewed from a specific angle. FIG. 4 is a diagram illustrating an example of imaging a medium on which emboss processing has been performed as viewed from a specific angle. FIG. 1 is a diagram illustrating a configuration of an information embedding system according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a functional configuration of the pattern generation device according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a functional configuration of the information detection device according to the first embodiment of the present invention. It is a figure showing an example of a lighting environment. 5 is a flowchart illustrating a pattern generation processing routine in the pattern generation device according to the first embodiment of the present invention. 5 is a flowchart illustrating a detection processing routine in the information detection device according to the first embodiment of the present invention. It is a figure showing the composition of the information embedding system concerning a 2nd embodiment of the present invention. FIG. 6 is a block diagram illustrating a functional configuration of a pattern generation device according to a second embodiment of the present invention. FIG. 7 is a block diagram illustrating a functional configuration of an information detection device according to a second embodiment of the present invention. 9 is a flowchart illustrating a pattern generation processing routine in the pattern generation device according to the second embodiment of the present invention. It is a flow chart which shows a detection processing routine in an information detecting device concerning a 2nd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Overview of Embodiment of the Present Invention>
First, an outline of an embodiment of the present invention will be described. The apparatus according to the present embodiment can assign individual ID information to a paper medium on which an arbitrary pattern or image or the like is printed or a medium similar thereto without visually affecting the underlying pattern or image. The present invention relates to a device and method for detecting embedded ID information, which can be performed and difficult to copy by a general copying machine or the like.

  As a technique for embedding information in a large area by increasing resistance to partial information loss, there is a digital watermarking technique. When the digital watermarking technique is used, information can be embedded in a large area on the surface of the medium so as to maintain robustness, and therefore, it is possible to restore information even if it is difficult to locally read a part.

  For this reason, in the present embodiment, the printing medium is subjected to fine (thin, difficult to read by frontal illumination by a copier, but shaded by diagonal illumination) three-dimensional unevenness (hereinafter referred to as embossing). By embedding the ID information (hereinafter, referred to as emboss ID) by recording the watermark pattern, the emboss ID is detected by using a camera having a plurality of illumination light sources.

  FIG. 1 shows an example of an image when a medium created by embedding an emboss ID and embedding an emboss ID is copied by a copying machine. As shown in FIG. 1, the unevenness embedded by embossing is not reflected in copying.

  FIG. 2 and FIG. 3 are diagrams illustrating an example of a medium created by embossing and embedding an emboss ID, and are examples of image diagrams viewed from different angles. Here, the information embedded by embossing is not visible at the angle of FIG. 2, but the pattern is clearly visible at the angle of FIG. Therefore, when the authenticity of the medium is determined, the medium is read with the emboss by reading the medium at an angle corresponding to FIG. 3 (a predetermined angle corresponding to the depth and width of the embossed unevenness) and the lighting conditions. Information can be read.

  Also, a digital watermark of a pattern composed of a “linear pattern” suitable for embossed expression can be created from the information to be embedded (Non-Patent Document 1: Takao Nakamura, Jun Katayama, Masashi Yamamuro, Sonehara Noboru, "High-speed digital watermark detection method from analog image using mobile phone with camera" Transactions of IEICE, D-II Vol.J87-D-II, No.12, pp.2145-2155, 2004). When embedding information by embossing, linear patterns are suitable for embedding information, and spatially low-frequency patterns reduce the amount of information that can be embedded and reduce the amount of information that can be embedded in flat areas such as scratches and dents. It is not suitable for embossing information because it is easily affected and the robustness decreases.

  However, the linear pattern created by the technique of Non-Patent Document 1 described above is a pattern having multiple values, and only a binary pattern can be expressed by embossing. Therefore, the technique described in Non-Patent Document 1 is used as it is. Does not become an embossed pattern. Therefore, in the present embodiment, a binary pattern is created as described later, and the binary pattern is used as an emboss pattern.

  In the present embodiment, an ID information embedding portion for embedding ID information and an ID information detecting portion for detecting ID information are configured separately.

  In the ID information embedding part, a frame edge is added to the already printed object, and emboss processing expressing a digital watermark pattern is performed. The embossed printed matter has such a property that the shading pattern due to the embossing is not copied even by a general copying machine.

  This is because the scanner of the copier irradiates light evenly from the front to the surface of the printing medium, so that no shading due to minute unevenness occurs. Therefore, it is difficult to copy the watermarked print medium obtained by the present embodiment, for example, by copying a shadow pattern by a copying machine.

  As a condition that the emboss pattern is not reflected as a shadow pattern, it is important that the depth of the unevenness is not too deep. In the present embodiment, for example, the depth of the unevenness is about 0.01 mm to 0.1 mm. However, it is not limited to this range. Also, in order to increase the number of bits of the ID information, the line width should be as narrow as possible. However, the line width that can be embossed is generally up to about 1 pt = 0.35 mm, so it is necessary to keep the width larger than that. Further, as a medium to be printed, a solid material such as thick paper or a plastic sheet is preferably used so that the pattern of the unevenness can be stored for a long period of time.

  On the other hand, in the ID information detection portion, a plurality of illumination light sources are blinked in a predetermined order, and a plurality of camera captured images are obtained in synchronization with the blinking. Then, a frame edge of the print medium is detected from the image, projection transformation is performed, the image is normalized to an image viewed from the front, and a difference image is calculated from a plurality of camera capture images. As a result of the calculation, if the sum of the difference values is larger than the threshold value, it is determined that the input image is a print medium including fine irregularities.

  Also, the digital watermark information is detected from the difference image determined to be a print medium including fine irregularities, and the result is output. This makes it possible to identify whether or not the detected digital watermark information is a shading pattern generated by embossing, and to determine whether or not the detected digital watermark information is a forgery based on a two-dimensional shading pattern printed by a general printer. Can be determined.

  As described above, in the present embodiment, since the ID information is embedded by embossing the print medium and recording the watermark pattern, the watermark pattern cannot be copied even with a general copying machine. In addition, since the ID information is detected using a camera having a plurality of illumination light sources, only the embossed shadow pattern can be extracted, and a two-dimensionally forged watermark pattern can be eliminated. Therefore, as a result, it is possible to create a watermarked print medium that is difficult to copy.

<Configuration of Information Embedding System According to First Embodiment>
Next, the configuration of the information embedding system according to the first embodiment will be described. As shown in FIG. 4, the information embedding system 100 according to the first embodiment includes a print medium input unit 101, a frame border providing device 102, an emboss ID embedding device 103, a print medium output unit 104, a pattern generation unit The apparatus includes a device 105, a control unit 106, and a transport unit 107.

  The print medium input unit 101 physically receives the target print medium, and transports the print medium to the frame edge applying device 102 via the transport unit 107. In the first embodiment, the print medium is a paper medium. In the first embodiment, it is assumed that an arbitrary pattern or image is printed on a print medium. The print medium may be a medium similar to a paper medium, such as a plastic sheet, in addition to the paper medium. Also, the print medium does not have to be printed at all. Further, any necessary printing may be performed on the print medium received by the print medium input unit 101 in the process of sending the print medium to the frame edge applying apparatus 102 via the transport unit 107.

  The frame edge applying device 102 recognizes the entire print medium received by the print medium input unit 101 via the transport unit 107 by a camera or the like built in the frame edge applying device 102 by an arbitrary method. In addition, when the frame border applying apparatus 102 recognizes the entire print medium, the print medium detected by an arbitrary method using a printing device such as a printer built in the frame border applying apparatus 102 with respect to the print medium. Overwrites the rectangular border on the edge of. Note that the thickness and color of the rectangular frame line are predetermined, and for example, white, black, or a combination thereof can be set as the color. Further, the frame edge providing device 102 transports the print medium on which the rectangular frame line has been overwritten by printing to the emboss ID embedding device 103 via the transport unit 107. The printed rectangular frame line is added to identify the position of the digital watermark pattern from the camera captured image when detecting the digital watermark.

  When the emboss ID embedding device 103 recognizes, by a camera or the like built in the emboss ID embedding device 103, the entire print medium conveyed via the conveyance unit 107 and overwritten by the frame edge applying device 102, the print medium The whole is photographed and output to the pattern generation device 105. When receiving the binarized linear digital watermark pattern from the pattern generation device 105, the emboss ID embedding device 103 receives an embossing mold called an embosser, which is a part of the emboss ID embedding device 103. To match the digital watermark pattern. Here, adapting to a digital watermark pattern means changing to an embosser that forms irregularities of the digital watermark pattern on the surface.

  Further, the emboss ID embedding device 103 sands the target print medium from both sides of the print medium using the embosser embedded in the emboss ID embedding device 103 using the changed embosser. Then, emboss processing is performed so as to form irregularities of the digital watermark pattern on the surface, and the digital watermark pattern is embedded. Further, the emboss ID embedding device 103 transports the print medium in which the digital watermark pattern is embedded to the print medium output unit 104 via the transport unit 107. In the first embodiment, the emboss ID embedding device 103 embeds the digital watermark pattern so as to fit exactly into the frame rectangle printed on the print medium.

  As described above, embossing in the first embodiment is realized by taking a mold called an embosser and sanding the target print medium from both sides with a stamping machine or the like. In the first embodiment, an embosser made of acrylic resin or the like is used, but the embosser is not limited to this. In addition, a 3D printer may be used to create the mold.

  The print medium output unit 104 physically outputs the print medium with the digital watermark embedded therein, which is transported via the transport unit 107.

  The control unit 106 controls the print medium input unit 101, the frame edge providing device 102, the emboss ID embedding device 103, the print medium output unit 104, the pattern generation device 105, and the transport unit 107.

  The pattern generation device 105 can be configured by a computer including a CPU, a RAM, and a ROM that stores a program for executing a pattern generation routine described later and various data. The pattern generation device 105 functionally includes an input unit 200, a calculation unit 202, and an output unit 210 as shown in FIG.

  The input unit 200 receives, from the emboss ID embedding device 103, image data of the entire print taken by the emboss ID embedding device 103.

  The calculation unit 202 includes a digital watermark pattern generation unit 204 and a binarization processing unit 206.

  The digital watermark pattern generation unit 204 determines the image size (at least the W × H pixel size of the entire print medium) representing the entire print medium captured by the emboss ID embedding device 103 received by the input unit 200, and And generates a digital watermark pattern based on the k-bit digital watermark information ID, which is information to be embedded, stored in a memory (not shown) and outputs the digital watermark pattern to the binarization processing unit 206. In the first embodiment, as a method of generating a digital watermark pattern to be a pattern, for example, a method disclosed in Non-Patent Document 1 is used. Information to be embedded in the first embodiment is ID information. The information to be embedded corresponding to the photographed print medium can be obtained by an arbitrary method.

Specifically, first, error correction and error detection coding are performed on the obtained k-bit digital watermark information ID, and an n-bit coded code is obtained. Next, using a predetermined integer value N, a sequence of length N ² obtained by repeating each bit value c _j of the post-code by l = N ² / n times is represented by the following equation (1). I do.

  Also, a pseudo-random number sequence of length l

J = 0. . . prepared for n-1, the length N ² of series by arranging them to the following equation (2).

  Next, direct spreading modulation is performed according to the following equation (3).

However, the value of b _i is 0 for the bit value "0", "- 1", when the bit value "1" to calculate read as "+1". Next, there is prepared a pseudorandomly determined replacement represented by the following equation (4).

Further, by scrambling the sequence of {s _i} with substitution of equation (4), calculates the embedding sequence {t _i} according to the following equation (5).

  Here, scrambling has an effect as interleave coding, and contributes to preventing imbalance in tolerance between bits.

Next, two 90-degree rotationally symmetric two-dimensional sine curves P ⁻ = {P ⁻ _{x, y} } and P ⁺ = {} whose relative frequencies to the image size are (Freq, Freq) and (Freq, −Freq). P ⁺ _{x, y} } is generated, divided into N × N blocks, and a block image group

To get. Then, for each block position in the block division (h, v), along the raster scan order of blocks selecting the section embedded sequence _{t i (i = h + vN} ), the electronic watermark pattern in accordance with the value of t _i The block image P ^{(h, v)} _{x, y} is selected as in the following equation (6).

By performing this processing for all block positions (h, v), a linear digital watermark pattern P = {P _{x, y} } of W × H pixels represented by multi-valued pixel values is generated.

  The binarization processing unit 206 performs binarization processing on the obtained linear digital watermark pattern to convert the obtained linear digital watermark pattern into an embossable shape, and outputs the binarized linear digital watermark pattern to the output unit 210. Via the output unit 210, the data is output to the emboss ID embedding device 103.

  Here, the reason for performing the binarization processing will be described. Since digital watermark patterns represented by Non-Patent Document 1 are all represented by multi-valued patterns, they cannot be used when a print medium is directly processed as an emboss as in the first embodiment. . Therefore, in the first embodiment, the digital watermark pattern generated by the multi-value pattern is subjected to a binarization process, and is converted into a digital watermark pattern of an embossable binary pattern.

  Specifically, a fixed threshold value is provided for the digital watermark pattern, and pixel values larger than the threshold value are converted to 1 and other pixel values are converted to 0. By doing so, it is possible to convert to a binary pattern. However, by converting a multi-value pattern into a binary pattern, the portion where the pixel value changes smoothly is crushed, and the amount of information as image data is lost. Therefore, even if the threshold value for binarization is set arbitrarily, there is a high possibility that the pattern cannot be converted into a detectable pattern.

  Therefore, in the first embodiment, the maximum value (maximum pixel value) and the minimum value (minimum pixel value) of all the pixel values constituting the digital watermark pattern are obtained, and the intermediate value ((maximum value + minimum value)) is obtained. The binarization is performed using (value) / 2) as a threshold value. In the digital watermarking method as in Non-patent Document 1, the shading of the pattern is represented by a smoothly varying sine wave such that the spatial frequency of the striped pattern is constant so that the pattern is more difficult to recognize. The indicated ID information is represented by the pattern shape itself (specifically, the frequency of the wave represented by the pattern).

  Further, in the detection of the digital watermark pattern, the digital watermark pattern is extracted based on the frequency, so that the ID information itself is not lost if the shape of the pattern is stored. When a method using the intermediate value of all the pixel values of the digital watermark pattern as a threshold value can be converted into a rectangular wave having the same frequency as the sine wave, binarization can be performed while retaining ID information indicated by the pattern.

<Configuration of Information Detection Device According to First Embodiment>
Next, the configuration of the information detection device according to the first embodiment will be described. As shown in FIG. 6, an information detection device 300 according to the first embodiment is a computer including a CPU, a RAM, and a ROM storing a program for executing a detection processing routine described later and various data. Can be configured. The information detection device 300 functionally includes an auxiliary illumination-equipped camera input unit 310, a calculation unit 320, and a result output unit 390, as shown in FIG.

  The auxiliary-illuminated camera input unit 310 uses a digital camera or the like as a photographing device to photograph a target printed matter and receives each digital data image. In the first embodiment, a light source provided in the camera input unit with auxiliary illumination 310 and a digital camera are used to sequentially irradiate light at different angles from a plurality of locations (any number of locations is possible if there are two or more locations). An image is taken each time the irradiation angle is changed (for each lighting environment). For example, if the configuration is as shown in FIG. 7, first, the light source 1 is turned on and the light source 2 is turned off, and the image is shot once. Next, the light source 1 is turned off and the light source 2 is turned on, and one image is taken. Then, the light source 1 is turned off and the light source 2 is turned off, and the image is shot once. Thus, a plurality of images having different light irradiation angles can be obtained. Alternatively, a single light source may be used, and the photographing angle of the camera may be changed a plurality of times to take a picture one by one. May be adopted.

  The calculation unit 320 includes a frame edge detection geometric correction unit 322, a difference image calculation unit 324, an unevenness degree determination unit 326, and an emboss ID detection unit 328.

  The frame edge detection geometric correction unit 322 obtains the position of a rectangular frame line included in the image received by the camera input unit with auxiliary illumination 310, and defines a front view based on the rectangular frame line. To an image of size. Thereby, the projection transformation distortion can be corrected and normalized to an image of a predetermined size regardless of the shooting angle of the camera. As a specific method used in the frame edge detection in the first embodiment, a frame edge detection method described in Non-Patent Document 1 is used.

  The difference image calculation unit 324 creates an image pair for all combinations of images based on each of the images normalized by the frame edge detection geometric correction unit 322. Further, the difference image calculation unit 324 calculates a difference image by calculating a difference between pixel values of each image included in the image pair for each of the created image pairs.

  When the number of times of shooting at the time of camera input is N, N × (N−1) / 2 kinds of image pairs are created, so that N × (N−1) / 2 kinds of difference images can be obtained. it can. Further, when calculating the difference, since it is necessary to make the overall brightness uniform, it is necessary to make adjustments so that the average value of the pixel values becomes a predetermined numerical value.

  Further, the difference image calculation unit 324 selects, from each of the calculated difference images, a difference image in which the sum of the absolute values of the pixel values of the difference image is the largest, and determines the selected difference image as the unevenness degree determination unit. 326.

  If the total value of the absolute values of the pixel values of the difference image obtained by the difference image calculation unit 324 is larger than a predetermined threshold, the unevenness degree determination unit 326 determines that the shadow caused by the unevenness has been detected, The determination result is output to the emboss ID detection unit 328.

  When the sum of the absolute values of the pixel values of the difference image obtained by the difference image calculation unit 324 is smaller than a predetermined threshold, the unevenness degree determination unit 326 determines that the shadow caused by the unevenness has not been detected. The result is output from the result output unit 390.

  In addition to the above-described determination method, emboss ID detection is directly performed from each of the plurality of images normalized by the frame edge detection geometric correction unit 322. As a result, when the illumination is applied from the front of the print medium, the detection is performed. If it is not possible, and if it can be detected when the illumination is applied from an oblique direction, it may be determined that the shadow caused by the unevenness has been detected.

  The emboss ID detection unit 328 detects an emboss ID embedded as a digital watermark from the difference image acquired by the difference image calculation unit 324. As the digital watermark detection method, for example, the method disclosed in Non-Patent Document 1 can be used. This utilizes the fact that only a shadow pattern generated by embossing can be filtered by the difference image. By using this method, only the concave / convex pattern expressed by the concave / convex can be a target of the watermark detection, so that an effect of improving the detection accuracy can be expected. However, the emboss ID may be detected using the image normalized by the frame edge detection geometric correction unit 322 without using the difference image.

  The result output unit 390 outputs the determination result of the unevenness determination unit 326 or the emboss ID detected by the emboss ID detection unit 328 as a final result. In the output, it is displayed on a display or the like, or output as data to a memory or the like.

<Operation of Pattern Generation Apparatus According to First Embodiment>
Next, the operation of the pattern generation device 105 according to the first embodiment will be described. When the pattern generation device 105 receives the image data of the entire print medium from the emboss ID embedding device 103, the CPU executes the program stored in the ROM of the pattern generation device 105 to execute the pattern generation processing routine shown in FIG. Execute

  First, in step S100, k-bit digital watermark information ID corresponding to the acquired image data stored in the memory is read.

  Next, in step S102, a digital watermark pattern is generated based on the k-bit digital watermark information ID acquired in step S100 and the received image size representing the entire print medium.

  Next, in step S104, binarization processing is performed on the digital watermark pattern acquired in step S102.

  Next, in step S106, the digital watermark pattern subjected to the binarization processing acquired in step S104 is output via the output unit 210, and the pattern generation processing routine ends.

<Operation of Information Detection Device According to First Embodiment>
Next, the operation of the information detection device 300 according to the first embodiment will be described. When the information detection device 300 accepts each of the digital data images of the target printed matter each time the imaging environment is changed, the information is stored in the ROM of the information detection device 300. When the CPU executes the program, the detection processing routine shown in FIG. 9 is executed.

  First, in step S200, for each of the acquired images, the position of a rectangular frame included in the image is determined, and the image is projected and transformed into an image of a specified size viewed from the front based on the rectangular frame.

  Next, in step S202, an image pair is created for all combinations of images based on each of the projection-converted images acquired in step S200.

  Next, in step S204, a difference image is calculated for each of the image pairs acquired in step S202.

  Next, in step S206, based on each of the difference images acquired in step S204, a difference image having the largest sum of the absolute values of the pixel values of the difference image is selected.

  Next, in step S208, based on the difference image selected in step S206, it is determined whether or not the sum of the absolute values of the pixel values of the difference image is larger than a predetermined threshold. If the sum is greater than the predetermined threshold, the detection processing routine proceeds to step S210. On the other hand, when the total value is equal to or smaller than the predetermined threshold, the detection processing routine proceeds to step S300.

  Next, in step S210, an emboss ID embedded as a digital watermark is detected from the difference image obtained in step S206.

  Next, in step S212, the emboss ID acquired in step S210 is output as a final result, and the detection processing routine ends.

  In step S300, the result of the determination that the shadow caused by the unevenness has not been detected is output as the final result, and the detection processing routine ends.

  As described above, according to the information detection device according to the first embodiment, a medium is photographed for each lighting environment, acquired as digital data, and an image pair is created based on each of the acquired images. For each of the image pairs, calculate the difference image, for each of the difference images, calculate the sum of the absolute values of the pixel values of the difference image, and select the difference image having the largest calculated sum. Based on the total value of the selected difference images and a predetermined threshold, it is determined whether or not the shadow caused by the unevenness has been detected, and when it is determined that the shadow has been detected, from the selected difference image By detecting the ID information embedded as the concave / convex pattern, the ID information can be accurately detected from the concave / convex pattern formed on the medium.

  Also, since the ID information is embedded by embossing the print medium and recording the digital watermark pattern, the digital watermark pattern cannot be copied even with a general copying machine. In addition, since the ID information is detected using a camera having a plurality of illumination light sources, only the embossed shadow pattern can be extracted, and a two-dimensionally forged digital watermark pattern can be eliminated. As a result, it is possible to provide a method for producing a watermarked print medium that is difficult to copy.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made without departing from the gist of the present invention.

  Next, an information embedding system and an information detection device according to a second embodiment will be described.

  The second embodiment is different from the first embodiment in that the emboss ID is embedded in a print medium on which a two-dimensional code is printed, and the two-dimensional code and the emboss ID are detected by a camera to determine whether the two-dimensional code is authentic. Different from the first embodiment. Note that the same configurations and operations as those of the information embedding system 100 and the information detection device 300 according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

<Configuration of Information Embedding System According to Second Embodiment>
First, the configuration of the information embedding system according to the second embodiment will be described. As shown in FIG. 10, the information embedding system 400 according to the second embodiment includes a print medium input unit 101, a frame edge providing device 102, an emboss ID embedding device 403, a print medium output unit 104, a pattern generation unit The apparatus includes a device 405, a control unit 406, and a transport unit 107. It is assumed that a print medium received in the second embodiment has a two-dimensional code printed thereon.

  When the emboss ID embedding device 403 recognizes, by a camera or the like built in the emboss ID embedding device 403, the entire print medium conveyed via the conveyance unit 107 and overwritten by the frame edge applying device 102, the print medium The whole is photographed and output to the pattern generation device 405. In the second embodiment, the two-dimensional code printed on the print medium is read at the same time as the entire print medium is photographed, and the ID information represented by the two-dimensional code is also output to the pattern generation device 405.

  When the emboss ID embedding device 403 receives the binarized linear digital watermark pattern from the pattern generation device 405, the embosser that is a part of the emboss ID embedding device 403 adapts to the received digital watermark pattern. To change.

  Further, the emboss ID embedding device 403 sands the target print medium from both sides of the print medium using the embosser embedded in the emboss ID embedding device 403 using the changed embosser. Then, emboss processing is performed so as to form irregularities of the digital watermark pattern on the surface, and the digital watermark pattern is embedded. In addition, the emboss ID embedding device 403 conveys the print medium in which the digital watermark pattern is embedded to the print medium output unit 104 via the conveyance unit 107. In the second embodiment, the emboss ID embedding device 403 embeds a digital watermark pattern so as to overlap a two-dimensional code printed on a print medium.

  The control unit 406 controls the print medium input unit 101, the frame edge providing device 102, the emboss ID embedding device 403, the print medium output unit 104, the pattern generation device 405, and the transport unit 107.

  The pattern generation device 405 can be configured by a computer including a CPU, a RAM, and a ROM that stores a program for executing a pattern generation routine described later and various data. The pattern generation device 405 functionally includes an input unit 500, a calculation unit 502, and an output unit 510 as shown in FIG.

  The input unit 500 receives, from the emboss ID embedding device 403, the image size of the entire printed matter photographed by the emboss ID embedding device 403 and the ID information represented by the two-dimensional code printed on the print medium.

  The calculation unit 202 includes a shortened code generation unit 503, a digital watermark pattern generation unit 504, and a binarization processing unit 206.

  The shortened code generation unit 503 generates a shortened code obtained by a hash function or the like based on the ID information represented by the two-dimensional code printed on the print medium received by the input unit 500, and generates a digital watermark pattern. Output to the unit 504.

  The digital watermark pattern generation unit 504 acquires the image size of the entire print medium (W × H pixel size of the entire print medium) captured by the emboss ID embedding device 403 received by the input unit 500 and the shortened code generation unit 503. A digital watermark pattern is generated based on the shortened code and output to the binarization processing unit 206. In the second embodiment, the shortened code is an emboss ID, which is ID information to be embedded, and is assumed to be k-bit.

<Configuration of Information Detection Apparatus According to Second Embodiment>
Next, the configuration of the information detection device according to the second embodiment will be described. As shown in FIG. 12, an information detection device 600 according to the second embodiment is a computer including a CPU, a RAM, and a ROM storing programs and various data for executing a detection processing routine described later. Can be configured. This information detection device 600 functionally includes a camera input unit with auxiliary illumination 610, a calculation unit 620, and a result output unit 690 as shown in FIG.

  The auxiliary illumination-equipped camera input unit 610 captures an image of a target print medium using a digital camera or the like as a capturing device, and receives each digital data image. In addition, the camera input unit with auxiliary illumination 610 acquires the ID information represented by the two-dimensional code from the two-dimensional code printed on the target print medium based on an arbitrary method.

  The calculation unit 320 includes a frame edge detection geometric correction unit 322, a difference image calculation unit 324, an unevenness degree determination unit 326, a shortened code generation unit 622, an emboss ID detection unit 624, and a determination unit 626. Have been.

  The abbreviated code generation unit 622 generates abbreviated code based on the ID information represented by the two-dimensional code acquired by the camera input unit with auxiliary illumination 610 by the same method as the abbreviated code generation unit 503 described above, 626.

  The emboss ID detection unit 624 detects an emboss ID embedded as an electronic watermark from the difference image acquired by the difference image calculation unit 324, and outputs the emboss ID to the determination unit 626.

  The determination unit 626 compares the abbreviated code acquired from the abbreviated code generation unit 622 and the emboss ID acquired from the emboss ID detection unit 624, and outputs the emboss ID to the result output unit 690 as a final result when they match. I do. On the other hand, if they do not match, a result indicating that they do not match is output to the result output unit 690 as a final result.

  The result output unit 690 outputs the determination result of the unevenness determination unit 326 or the determination result of the determination unit 626.

<Operation of Pattern Generation Apparatus According to Second Embodiment>
Next, the operation of the pattern generation device 405 according to the second embodiment will be described. When the pattern generation device 405 receives the image data of the entire print medium and the data represented by the two-dimensional code from the emboss ID embedding device 403, the CPU executes the program stored in the ROM of the pattern generation device 405. By doing so, the pattern generation processing routine shown in FIG. 13 is executed.

  First, in step S400, a shortened code obtained by a hash function or the like is generated based on the ID information represented by the received two-dimensional code.

  Next, in step S402, a digital watermark pattern is generated based on the shortened code acquired in step S400 and the received image size of the entire print medium.

<Operation of Information Detection Device According to Second Embodiment>
Next, the operation of the information detection device 600 according to the second embodiment will be described. The information detection apparatus 600 uses the auxiliary illumination-equipped camera input unit 610 to display each of the digital data images of the target print medium each time the shooting environment is changed and the two-dimensional code printed on the print medium. Upon receiving the ID information to be expressed, the CPU executes a program stored in the ROM of the information detection device 600, thereby executing a detection processing routine shown in FIG.

  In step S500, based on the ID information represented by the obtained two-dimensional code, a shortened code is generated using the same method as in step S400 described above.

  Next, in step S502, it is determined whether or not the emboss ID acquired in step S210 matches the shortened code acquired in step S500. If the emboss ID matches the abbreviated code, the detection processing routine proceeds to step S504. On the other hand, when the emboss ID does not match the shortened code, the detection processing routine proceeds to step S506.

  Next, in step S504, the emboss ID acquired in step S210 is output as a final result from the result output unit 690, and the detection processing routine ends.

  In step S506, the detection processing routine output from the result output unit 690 is terminated as a final result that the emboss ID does not match the shortened code.

  As described above, according to the information detection device according to the second embodiment, it is possible to make a system for performing authenticity determination of a two-dimensional code.

  Also, at the time of detection, the authenticity determination can be realized by collating the shortened code obtained from the two-dimensional code with the shortened code obtained from the emboss ID. Further, according to the information detecting device of the second embodiment, since the duplication by the copier can be suppressed, the authenticity of the printed two-dimensional code can be guaranteed with high accuracy. Note that a one-dimensional barcode may be used instead of the two-dimensional code.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made without departing from the gist of the present invention.

  For example, in the first and second embodiments, a case has been described in which a frame border applying device overwrites a frame of an input print medium with a rectangular frame line. However, the present invention is not limited to this. For example, in the case of using a digital watermarking method capable of specifying the position of a digital watermark pattern without a frame, a configuration may be adopted in which the above-described frame edge providing device and frame edge detection geometric correction unit are omitted. However, in the case of using a digital watermarking method capable of specifying the position of the digital watermark area even without a frame, the frame border providing device 102 and the frame border detection geometric correction unit 322 may be omitted.

  Further, in the first and second embodiments, a case has been described in which the frame border applying device overwrites the frame of the input print medium with the rectangular frame line. However, the present invention is not limited to this. For example, the addition is not limited to the frame, and a specific pattern such as a cutout symbol of a QR code (registered trademark) may be added. However, in such a case, it is necessary to replace the processing in the frame edge detection geometric correction unit with a detection method corresponding to a specific pattern or the like.

  Further, in the first and second embodiments, the process of embedding a digital watermark has been mainly described assuming a paper medium, but the present invention is not limited to this. For example, a 3D printer may be used to generate and output a molded product. In this case, the print medium input unit 101 may be configured to digitally input the shape data of the object and to process the frame edge providing device 102 and the emboss ID embedding device 103 as data.

  Further, in the first and second embodiments, in the information embedding system, in each of the frame edge providing device and the emboss ID embedding device, the print medium is photographed using a camera or the like, or is recognized by photographing. However, the present invention is not limited to this. For example, a rectangular frame line may be printed on a print medium by the frame edge applying device based on information (a pixel value, a size, and the like) of the print medium received by the print medium input unit and the transport speed of the transport unit. Alternatively, a digital watermark pattern may be generated by a pattern generation device.

  Further, in the first and second embodiments, a case has been described in which the emboss ID embedding device 103 embeds the emboss ID so as to fit exactly into the frame rectangle printed on the print medium. However, the emboss ID embedding device 103 is not limited to this. For example, a digital watermark pattern may be embedded in a corresponding arbitrary region based on a frame edge rectangle and a predetermined frame edge rectangle and positional relationship. Also, the size of the digitized pattern to be embedded may be an arbitrary predetermined size.

  In the first and second embodiments, the case where the target print medium is not determined in advance has been described. However, the present invention is not limited to this. For example, a target print medium may be determined in advance, and the above-described processing may be performed on the print medium. In this case, a rectangular frame line may be printed on the print medium by the frame edge applying device based on the information (size and the like) of the print medium determined in advance and the transport speed of the transport unit. Further, an electronic watermark pattern corresponding to a predetermined print medium may be generated in the pattern generation device in advance. In the emboss ID embedding device 103, the embosser may be changed to an embosser corresponding to a predetermined print medium in advance.

  In the first and second embodiments, the case where the embosser is changed for each process has been described. However, the present invention is not limited to this. For example, when a target print medium is determined in advance, the corresponding embosser may be changed in advance. Alternatively, a plurality of blocks of the concavo-convex pattern may be prepared, and an embosser corresponding to the print medium may be formed by combining the blocks of the concavo-convex pattern.

  In addition, if it is sufficient to enjoy only the copy suppression effect by embedding, embedding the single image using only ambient light instead of sequentially irradiating a plurality of light sources and emboss ID May be detected. In this case, any method may be used to detect the emboss ID. When an arbitrary method is used, the processes of the difference image calculation unit 324 and the unevenness degree determination unit 326 described above may be omitted.

  Also, in the specification of the present application, the embodiment is described as an embodiment in which the program is installed in advance. However, the program may be stored in a computer-readable recording medium and provided, or provided via a network. It is also possible.

100, 400 Information embedding system 101 Print medium input unit 102 Frame border giving device 103, 403 Emboss ID embedding device 104 Print medium output unit 105, 405 Pattern generation device 106, 406 Control unit 107 Transport unit 200, 500 Input unit 202, 502 Operation units 204, 504 Digital watermark pattern generation unit 206 Binarization processing unit 210, 510 Output unit 300, 600 Information detection device 310, 610 Camera input unit with auxiliary illumination 320, 620 Operation unit 322 Frame edge detection geometric correction unit 324 Difference Image calculation unit 326 Unevenness degree determination units 328, 624 Emboss ID detection units 390, 690 Result output unit 503 Short code generation unit 622 Short code generation unit 626 Determination unit

Claims (3)

An information detection device that detects ID information embedded in the medium by photographing a target medium,
A photographing device for photographing the medium, using at least one or more illumination light sources, photographing the medium for each lighting environment, and a camera input unit with auxiliary illumination to acquire as digital data;
Based on each of the acquired images, an image pair is created for all combinations of images, and for each of the image pairs, a difference value is calculated by calculating a difference value of a pixel value for each image included in the image pair. A difference image calculating unit that calculates an image, calculates a sum of absolute values of respective pixel values of the difference image for each of the difference images, and selects the difference image having the largest calculated sum. When,
Based on the total value of the selected difference image and a predetermined threshold, based on the unevenness degree determination unit that determines whether a shadow caused by the unevenness has been detected,
An emboss ID detection unit that detects ID information embedded as a concavo-convex pattern from the selected difference image when it is determined that the shadow has been detected;
An information detection device, including: Detecting ID information previously embedded in a target medium by photographing a target medium including a camera input unit with auxiliary illumination, a difference image calculating unit, an unevenness degree determining unit, and an emboss ID detecting unit An information detection method in an information detection device,
The auxiliary illumination-equipped camera input unit uses a photographing device for photographing the medium, and at least one or more illumination light sources, photographs the medium for each lighting environment, and acquires digital data.
The difference image calculation unit creates an image pair for all image combinations based on each of the acquired images, and calculates a difference between pixel values for each image included in the image pair for each of the image pairs. Calculating a difference image by calculating a value, for each of the difference images, calculating a sum of absolute values of respective pixel values of the difference image, and calculating the difference image having the largest sum. And select
The unevenness degree determination unit, based on the total value of the selected difference image and a predetermined threshold, determines whether or not a shadow caused by the unevenness has been detected,
The information detection method, wherein the emboss ID detection unit detects ID information embedded as a concavo-convex pattern from the selected difference image when it is determined that the shadow has been detected.   A program for causing a computer to function as each section of the information detection device according to claim 1.