JP4104590B2 - Copy management system, watermark information extraction apparatus, watermark information extraction method, and program thereof - Google Patents

Description

  The present invention relates to a technique for extracting watermark information embedded in a recorded matter such as characters and / or images.

  There has been known a digital watermark technique for embedding watermark information in digital image data by making a subtle modification to digital image data such as a picture or a movie. This digital watermarking technology uses embedded watermark information even if the digital image data with embedded watermark information undergoes transformations such as enlargement / reduction, processing such as partial clipping, and media changes such as format conversion. Is preferably extracted correctly. As a method for realizing such a function, watermark information is embedded in digital image data by regularly arranging an image pattern corresponding to watermark information (hereinafter referred to as a watermark pattern) in the original digital image data. A technique for extracting embedded information by superimposing a watermark pattern extracted from digital image data in which watermark information is embedded based on an arrangement rule is known.

  However, in the above-described conventional technology, the regularity of the embedded watermark pattern is shifted with respect to a local deformation in which the degree of deformation of the image is slightly different in each part, and therefore, it is extracted from the digital image data. Even if the watermark pattern is superimposed, the embedded watermark information may not be extracted properly. Local deformation is likely to occur when digital image data in which watermark information is embedded is recorded on a recording medium such as paper, the recording medium is read by a scanner, and digitized again. As a technique for avoiding such inconvenience, there is a technique for dividing an image recorded on a recording medium into small areas (hereinafter referred to as extraction unit areas) and extracting watermark information for each extraction unit area. Known (for example, refer to Patent Document 1 or 2). Even when the image recorded on the recording medium is locally deformed, by dividing the image into a plurality of extraction unit regions, each extraction unit region is uniformly deformed over the entire extraction unit region. By performing geometric correction such as enlargement / reduction or rotation on the entire extraction unit area, watermark information can be extracted for each extraction unit area.

  Further, when embedding watermark information in digital image data, it is preferable to embed the watermark information in a location where the luminance change of the digital image data is relatively severe. Thereby, the embedded watermark information can be made less conspicuous than the watermark information embedded at a relatively gradual change in the luminance of the digital image data.

US Pat. No. 6,108,434 US Patent Application Publication No. 2002/0021823

  However, in the techniques described in Patent Documents 1 and 2 described above, when the embedded watermark information is extracted, the extraction of the watermark information is tried in order for each of all the extraction unit regions. Therefore, when the image size is large, it may take time to complete the watermark information extraction process. In addition, since it tries to extract watermark information even in places where the change in luminance of digital image data is relatively slow, where there is a low possibility that a watermark image is embedded, information that is different from the originally embedded information is erroneously extracted. There was a case.

  SUMMARY An advantage of some aspects of the invention is that it provides a copy management system, a watermark information extraction device, a watermark information extraction method, and a program thereof that can solve the above-described problems. For example, the watermark information can be quickly extracted from the recorded material in which the watermark information is embedded.

  In order to solve the above-described problem, the watermark information extraction apparatus divides image data into a plurality of unit areas, and based on the distribution of luminance values for each unit area, the watermark information sequentially from the unit area having the highest luminance value distribution. Try to extract.

  For example, a watermark information extraction apparatus that extracts watermark information embedded in a recorded material, the scanner unit converting the recorded material into image data that is electronic data, and the luminance of pixels included in the image data captured by the scanner unit A filter unit for removing low frequency components of change, and a variance calculating unit for calculating variance of luminance values in a unit area of a predetermined area for image data from which the low frequency components of luminance change have been removed by the filter unit; The unit area is shifted in the image data, and the variance calculation instruction unit for causing the variance calculation unit to calculate the variance of the luminance value in the unit area at each location of the image data, and according to the instruction from the variance calculation instruction unit Based on the luminance value variance of each unit area calculated by the variance calculation unit, the watermark information is extracted in order from the unit area with the highest variance of the luminance value. Providing the visible information extracting unit, if the watermark information extraction unit is able to extract the watermark information from the recorded material, the watermark information extraction device characterized by comprising a watermark information output unit that outputs to that effect.

  According to the present invention, watermark information can be quickly extracted from a recorded material.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 shows a configuration of a watermark information extraction system 10 according to an embodiment of the present invention. The watermark information extraction system 10 includes a computer 20 and a watermark information extraction device 30. The watermark information extraction device 30 converts a recorded matter such as characters and / or images into image data that is electronic data, and extracts watermark information embedded in the converted image data. In response to a user operation, the computer 20 causes the watermark information extraction device 30 to start extracting watermark information, and displays the watermark information extracted from the recorded material by the watermark information extraction device 30.

  In the present embodiment, the recording medium includes not only recording paper but also a CD-ROM, a circuit board, and the like. In addition, the recorded matter indicates the contents recorded on the recording medium, and includes characters and images recorded on recording paper, labels recorded on a CD-ROM, circuit patterns recorded on a circuit board, and the like. It is.

  FIG. 2 is a block diagram illustrating an example of a detailed configuration of the computer 20 and the watermark information extraction device 30. The computer 20 includes an input unit 200 and a display unit 202. The input unit 200 receives an operation input from the user via, for example, a keyboard or a mouse, and instructs the watermark information extraction device 30 to start extraction of watermark information in accordance with the received operation input. Further, the input unit 200 accepts input of parameters (details will be described later) used for extracting watermark information of the watermark information extracting device 30 in accordance with an operation from the user, and the received parameters are used as the watermark information extracting device 30. Send to. The display unit 202 displays an input screen for allowing the user to input the watermark information extraction parameter of the watermark information extraction device 30 via the input unit 200. The display unit 202 displays the watermark information extracted from the recorded material by the watermark information extraction device 30.

  The watermark information extraction device 30 includes a variance calculation instruction unit 300, a variance calculation unit 302, a scanner unit 304, a filter unit 306, a watermark information extraction unit 308, and an extraction result output unit 310. The scanner unit 304 converts the recorded material into image data that is electronic data.

  The filter unit 306 removes the low frequency component of the luminance change of the pixels included in the image data converted by the scanner unit 304. The filter unit 306 calculates the luminance value Y of each pixel, for example, according to mathematical formula 1 shown below.

ここで、Ｙ(ｉ，ｊ)は画素（ｉ，ｊ）の輝度値を示し、Ｒ(ｉ，ｊ)は画素（ｉ，ｊ）の赤の信号レベルを示し、Ｇ(ｉ，ｊ)は画素（ｉ，ｊ）の緑の信号レベルを示し、Ｂ(ｉ，ｊ)は画素（ｉ，ｊ）の青の信号レベルを示す。

Here, Y (i, j) represents the luminance value of the pixel (i, j), R (i, j) represents the red signal level of the pixel (i, j), and G (i, j) is The green signal level of the pixel (i, j) is indicated, and B (i, j) is the blue signal level of the pixel (i, j).

  Then, the filter unit 306 calculates a spatial frequency that is a luminance change of the pixels in the image data, and extracts only pixels corresponding to the luminance change equal to or higher than a predetermined frequency. By embedding the watermark information in a portion where the luminance change is relatively severe in the image data, the embedded watermark information can be made less noticeable than the watermark information embedded in a portion where the luminance change of the image data is relatively gradual. Therefore, by extracting only pixels corresponding to a luminance change of a predetermined frequency or higher, the filter unit 306 can reduce pixels that are unlikely to include watermark information, and erroneously sets the watermark information. The possibility of extraction can be reduced.

The variance calculating unit 302 calculates the variance of the luminance value in the unit area, which is an area on the image data having a predetermined area, for the image data from which the low frequency component of the luminance change is removed by the filter unit 306. The variance calculation unit 302 calculates, for example, the variance V of the luminance value of the unit area surrounded by the pixel (i ₁ , j ₁ ) from the pixel (i ₀ , j ₀ ) according to the following mathematical formula 2.

また、他の例として、分散算出部３０２は、以下に示す数学式３または４に従って、単位領域の輝度値の分散Ｖを算出してもよい。

As another example, the variance calculation unit 302 may calculate the variance V of the luminance value of the unit region according to the following mathematical formula 3 or 4.

なお、一般的なＣＰＵに用いられる浮動小数演算装置は、絶対値の計算に必要な条件分岐演算よりも乗算のほうが高速に処理することができる場合が多いので、分散算出部３０２は、数学式３または４ではなく、数学式２に従って分散Ｖを算出することが好ましい。

Note that the floating point arithmetic unit used in a general CPU can often perform multiplication faster than the conditional branch operation necessary for calculating the absolute value. It is preferable to calculate the variance V according to mathematical formula 2 instead of 3 or 4.

  Further, when using a special CPU having a high floating point arithmetic speed of the floating point arithmetic unit, the variance calculation unit 302 preferably calculates the variance V according to the following mathematical formula 5 rather than the mathematical formula 2.

数学式２では、いったんデジタル画像データの画素の輝度値Ｙ(ｉ，ｊ)の平均を計算した後、もう一度画像データを走査して、平均との差分の二乗を計算する必要があるが、数学式５では、一度の走査で画素の輝度値Ｙ(ｉ，ｊ)の和とその二乗和を計算すれば分散Ｖを求めることができるので、より高速に分散Ｖを算出することができる。

In mathematical formula 2, it is necessary to once calculate the average of the luminance values Y (i, j) of the pixels of the digital image data and then scan the image data again to calculate the square of the difference from the average. In Equation 5, since the variance V can be obtained by calculating the sum of the luminance values Y (i, j) of the pixels and the sum of squares thereof in one scan, the variance V can be calculated at a higher speed.

  The variance calculation instruction unit 300 causes the variance calculation unit 302 to calculate the variance of the luminance value in the unit area at each location of the image data by shifting the unit area in the image data. In this example, the unit by which the variance calculation instruction unit 300 shifts the unit area on the image data is a multiple of pixels. The unit by which the variance calculation instruction unit 300 shifts the unit area in the vertical direction of the image data is smaller than the number of vertical pixels of the unit area, and the unit by which the variance calculation instruction unit 300 shifts the unit area in the horizontal direction of the image data Is preferably smaller than the number of pixels beside the unit area. Thereby, even when the watermark information extends over a plurality of unit areas, the possibility that the watermark information can be correctly extracted can be increased.

  The watermark information extraction unit 308 performs watermarking in order from the unit region having the highest variance of luminance values based on the variance of the luminance values of the respective unit regions calculated by the variance calculation unit 302 according to the instruction from the variance calculation instruction unit 300. Attempt to extract information. When the watermark information extraction unit 308 can extract the watermark information from the target unit area to which the watermark information is to be extracted, the watermark information extraction unit 308 sends the extracted watermark information to the extraction result output unit 310. In this example, the watermark information includes a predetermined number of predetermined digits, and the watermark information extraction unit 308 determines that the number included in the extracted watermark information is a predetermined number. Then, it is determined that the watermark information has been correctly extracted.

  If the watermark information cannot be extracted from the target unit area for which the extraction of the watermark information is attempted, the watermark information extraction unit 308 tries to extract the watermark information for the unit area having the next highest luminance value variance. The watermark information extraction unit 308 receives a dispersion threshold, which is a threshold value of luminance value dispersion, from the user via the input unit 200, and extracts watermark information for all unit areas having a luminance value distribution equal to or greater than the received distribution threshold value. If not, the extraction result output unit 310 is notified that the watermark information is not embedded in the image data, and the extraction of the watermark information for the unit area having the luminance value variance less than the variance threshold is stopped. . If the watermark information cannot be extracted, the watermark information extraction unit 308 performs geometric correction such as rotation, enlargement, and parallel movement on the target unit area for which the watermark information is to be extracted, and then again. You may try to extract watermark information.

  The extraction result output unit 310 causes the display unit 202 to display the watermark information extracted by the watermark information extraction unit 308 when the watermark information extraction unit 308 extracts watermark information from any unit area in the image data. On the other hand, when the watermark information extraction unit 308 cannot extract the watermark information from all the unit areas in the image data equal to or greater than the dispersion threshold, the extraction result output unit 310 embeds the watermark information in the image data. The display unit 202 displays that there is no information.

  FIG. 3 shows an example of the hardware configuration of the watermark information extraction device 30. The watermark information extraction device 30 includes a CPU 320, a RAM 322, a ROM 324, a communication interface 326, a scanner device 328, and a media interface 330. The CPU 320 operates based on programs stored in the RAM 322 and the ROM 324 and controls each unit. The ROM 324 stores a boot program executed by the CPU 320 when the watermark information extracting device 30 is started up, a program depending on the hardware of the watermark information extracting device 30, and the like. The RAM 322 stores programs executed by the CPU 320, data used by the CPU 320, and the like. The communication interface 326 receives the watermark information extraction start instruction from the computer 20 and sends it to the CPU 320, and transmits the watermark information detected by the watermark information extraction device 30 to the computer 20. The scanner device 328 is controlled by the CPU 320 and converts a recorded material into image data. The media interface 330 reads a program or data from the storage medium 332 and provides it to the RAM 322.

  A program provided to the CPU 320 via the RAM 322 is stored in the storage medium 332 and provided from the user. The program is read from the storage medium 332, installed in the watermark information extraction device 30 via the storage medium 332, and executed in the watermark information extraction device 30. The program that is installed and executed in the watermark information extraction device 30 includes the watermark information extraction device 30, a variance calculation instruction unit 300, a variance calculation unit 302, a scanner unit 304, a filter unit 306, a watermark information extraction unit 308, and an extraction result. Each of them functions as the output unit 310.

  The storage medium 332 may be, for example, an optical recording medium such as a DVD or PD, a magneto-optical recording medium such as an MD, a tape medium, a magnetic recording medium, or a semiconductor recording device. The watermark information extraction device 30 reads these programs from the storage medium 332 and executes them. The watermark information extraction device 30 may acquire these programs via a communication line such as the Internet network.

  FIG. 4 shows an example of an input screen 40 for inputting parameters for extracting watermark information. The display unit 202 displays a check box 408, an extraction start button 412, and a plurality of input boxes 400, 402, 404, 406, 410 in the input screen 40. In the input boxes 400 and 402, the horizontal and vertical lengths of the unit area are input in units of pixels, respectively. In the input boxes 404 and 406, the step of moving the unit area horizontally and vertically on the image data is input in units of pixels.

  When the check box 408 is checked, the variance threshold value input to the input box 410 becomes valid. If the check box 408 is not checked, 0 is set as the dispersion threshold, and the watermark information extraction unit 308 attempts to extract watermark information for all unit areas. When the extraction start button 412 is clicked via a mouse or the like, the computer 20 causes the watermark information extraction device 30 to start extracting watermark information.

  In this example, the unit area size, the unit area moving step, and the dispersion threshold are set as parameters for detecting the watermark information. In addition to this, when the watermark information could not be extracted from the unit area In addition, parameters for specifying the degree of geometric correction performed by the watermark information extraction unit 308 on the unit area may be set as parameters for detecting the watermark information.

  FIG. 5 is a conceptual diagram for explaining a process in which image data is simply divided into a plurality of unit areas and the variance is calculated for each unit area. FIG. 5A shows the image data 50 converted by the scanner unit 304. FIG. 5B shows the image data 52 from which the low frequency component of the luminance change is removed by the filter unit 306. FIG. 5C shows image data 54 in which the luminance value variances of the respective unit areas calculated by the variance calculating unit 302 are arranged.

  In FIG. 5A, the image data 50 includes a tree 500, a cloud 502, a house 504, and a road 506. Here, it is assumed that the luminance change of the tree 500 is the highest compared to the cloud 502, the house 504, and the road 506, and the luminance change of the road 506 is the lowest compared to the tree 500, the cloud 502, and the house 504.

  By removing the low frequency component of the luminance change by the filter unit 306, image data 52 as shown in FIG. 5B is obtained. Here, a pixel from which the frequency component of luminance change has not been removed by the filter unit 306 is shown in white, and a pixel from which the frequency component of luminance change has been removed by the filter unit 306 is shown in black. Since the frequency component of the luminance change is high in the portion of the image data 52 corresponding to the tree 500, the frequency component of the luminance change is not removed by the filter unit 306 and is displayed in white. On the other hand, the portion of the image data 52 corresponding to the road 506 has a low frequency component of luminance change, and thus the frequency component of luminance variation is removed by the filter unit 306 and is displayed in black.

  The variance calculation unit 302 calculates the variance of the luminance change for each unit area in the image data 52, and obtains the image data 54 shown in FIG. Here, a unit region with a high luminance value dispersion is shown to be white, and a unit region with a low luminance value dispersion is shown to be black. The unit areas 540 and 542, which are portions of the image data 54 corresponding to the tree 500, are displayed in white because of the high variance of the luminance values. On the other hand, the unit area 544, which is the portion of the image data 52 corresponding to the road 506, is displayed in black because the variance of luminance values is low.

  The watermark information extraction unit 308 attempts to extract watermark information from a unit area in the image data 52 corresponding to the unit area 542, which is the unit area having the highest luminance value dispersion. If the watermark information cannot be extracted from the unit area in the image data 52 corresponding to the unit area 542, the image data 52 in the image data 52 corresponding to the unit area 540, for example, is the unit area having the next highest luminance value variance. Attempts to extract watermark information from the unit area. When the watermark information cannot be extracted from all unit areas having a luminance value variance equal to or greater than the variance threshold input by the user via the input unit 200, the variance of the luminance value less than the variance threshold is provided. The watermark information extraction unit 308 sends to the extraction result output unit 310 that the watermark information is not embedded in the image data 50 without attempting to extract the watermark information for the unit region, for example, the unit region 546.

  FIG. 6 is a flowchart illustrating an example of the operation of the watermark information extraction device 30. The operation of the watermark information extracting apparatus 30 shown in this flowchart starts at a predetermined timing such as when the extraction start button 412 on the input screen 40 is clicked. First, the scanner unit 304 converts the recorded matter into image data that is electronic data (S100). Next, the filter unit 306 removes the low frequency component of the luminance change of the pixels included in the image data converted by the scanner unit 304 (S102). Next, the variance calculation unit 302 determines a unit area having a predetermined area for the image data from which the low-frequency component of the luminance change has been removed by the filter unit 306 on the image data according to the instruction from the variance calculation instruction unit 300. While shifting, the variance of the luminance value in each unit area is calculated (S104).

  Next, the watermark information extraction unit 308 is based on the luminance value variance of each unit area calculated by the variance calculation unit 302 according to the instruction from the variance calculation instruction unit 300, and the unit region having the highest luminance value variance. The extraction of watermark information is tried in order (S106). Then, the watermark information extraction unit 308 determines whether or not the watermark information can be extracted from the target unit area (S108). When the watermark information can be extracted (S108: Yes), the extraction result output unit 310 displays the watermark information extracted by the watermark information extraction unit 308 on the display unit 202 (S114), and the watermark information shown in this flowchart is displayed. The operation of the extraction device 30 ends.

  If the watermark information could not be extracted in step 108 (S108: No), it is determined whether or not the extraction of the watermark information has been attempted for all unit areas equal to or greater than the dispersion threshold (S110). When extraction of watermark information is attempted for all unit areas equal to or greater than the dispersion threshold (S110: Yes), the extraction result output unit 310 displays on the display unit 202 that the watermark information has not been detected (S112). The operation of the watermark information extracting device 30 shown in this flowchart is finished.

  If it is determined in step 110 that extraction of watermark information has not been attempted for all unit regions that are equal to or greater than the dispersion threshold (S110: No), the watermark information extraction unit 308 performs watermark information from the unit region having the next highest luminance value dispersion. (S106).

  FIG. 7 shows a configuration of a copy management system 60 according to another embodiment of the present invention. The copy management system 60 includes a network 66, a copy apparatus 70, and a copy management server 80. The network 66 connects the copying apparatus 70 and the copy management server 80 to communicate with each other. When the copying apparatus 70 receives a copy instruction for the recorded matter 64 from the user 62, the copying apparatus 70 inquires of the copy management server 80 about whether or not the recorded matter 64 can be copied, and permits the copying from the copy management server 80. In response to the instruction from the user 62, the recorded matter 64 is copied to another recording medium. When the copy management server 80 receives an inquiry about whether or not copying is possible from the copying apparatus 70, the copying management server 80 determines whether or not the recorded matter 64 can be copied with reference to a database described later, and the determination result is sent via the network 66 to the copying apparatus. 70 is notified.

  FIG. 8 is a block diagram illustrating an example of a detailed configuration of the copying apparatus 70. The copying apparatus 70 includes a variance calculation instruction unit 700, a variance calculation unit 702, an input unit 704, a scanner unit 706, a filter unit 708, a watermark information extraction unit 710, a watermark information output unit 712, a display unit 714, and a copy unit 716. .

  The input unit 704 is, for example, a keypad or a touch panel, and instructs the scanner unit 706 to convert the recorded matter 64 into image data in accordance with an operation from the user 62. The input unit 704 also detects the size of the detection unit region, the size of the detection unit region moving step, the dispersion threshold, and the like used for extracting the watermark information of the copying apparatus 70 in response to an operation from the user 62. The input of parameters and a user ID for identifying the user 62 is accepted, and the accepted parameters and user ID are sent to the variance calculation instructing unit 700 and the watermark information extracting unit 710. The display unit 714 displays an input screen for allowing the user 62 to input parameters for extracting watermark information. Further, when the copy management server 80 notifies that the copying is not permitted, the display unit 714 notifies the user 62 by displaying that fact.

  The variance calculation instruction unit 700, the variance calculation unit 702, the scanner unit 706, the filter unit 708, the watermark information extraction unit 710, and the watermark information output unit 712 respectively include the variance calculation instruction unit 300 and the variance calculation unit 302 described in FIG. The scanner unit 304, the filter unit 306, the watermark information extraction unit 308, and the extraction result output unit 310 have the same or similar functions and configurations, and detailed description thereof will be omitted except for the points described below. The watermark information output unit 712 instructs the copying of the recorded material 64 with the watermark information extracted by the watermark information extraction unit 710 when the watermark information extraction unit 710 extracts the watermark information from any unit area in the image data. It is transmitted to the copy management server 80 via the network 66 together with the user ID of the user 62. On the other hand, when the watermark information extraction unit 710 cannot extract the watermark information from all unit areas in the image data equal to or greater than the dispersion threshold, the watermark information output unit 712 has the watermark information embedded in the image data. The copying unit 716 is notified of the absence. In this example, the watermark information embedded in the recorded material is a predetermined number of digits and a predetermined number for determining whether or not the watermark information has been correctly detected, and a record for identifying the recorded material. Contains the object ID.

  When the copy unit 716 receives a copy permission from the copy management server 80 or receives a message that the watermark information is not embedded from the watermark information output unit 712, the copy unit 716 receives the image data converted by the scanner unit 706. By recording on the recording medium, the recorded matter 64 is copied to another recording medium.

  FIG. 9 is a block diagram illustrating an example of a detailed configuration of the copy management server 80. The copy management server 80 includes a copy permission / inhibition notification unit 800, a copy permission information storage unit 802, and a copy history storage unit 804. The copy permission information storage unit 802 stores the user ID of the user 62 who permits copying of the recorded material 64 in association with the recorded material ID. When copying of the recorded material 64 is permitted, the copy history storage unit 804 stores the recorded material ID of the recorded material 64 permitted to be copied in association with the user ID of the user 62 permitted to copy.

  When receiving the watermark information of the recorded material 64 together with the user ID of the user 62 who has instructed copying from the copying apparatus 70 via the network 66, the copy permission / inhibition notifying unit 800 extracts the recorded material ID from the watermark information and permits the copying. With reference to the information storage unit 802, it is determined whether or not the user ID received together with the watermark information is stored in the copy permission information storage unit 802 in association with the recorded product ID extracted from the watermark information. When the user ID is associated with the recorded material ID and stored in the copy permission information storage unit 802, the copy permission / inhibition notification unit 800 receives the recorded material 64 in which the received watermark information is embedded. The copying apparatus 70 is notified via the network 66 that copying is permitted by the user 62 corresponding to. The copy permission / inhibition notifying unit 800 stores the user ID of the user 62 permitted to copy in the copy history storage unit 804 in association with the recorded material ID of the recorded material 64 permitted to copy.

  FIG. 10 shows an example of a data structure stored in the copy permission information storage unit 802. The copy permission information storage unit 802 stores a copy permission person ID 8022 that is a user ID of the user 62 who permits copying of the recorded material 64 in association with the recorded material ID 8020. By referring to the copy permission information storage unit 802, the copy permission / inhibition notification unit 800 copies the recorded matter 64 in which the watermark information is embedded in the user 62 corresponding to the user ID received from the copying apparatus 70 together with the watermark information. It is possible to determine whether or not to permit.

  If the user ID received together with the watermark information is not stored in the copy permission information storage unit 802 in association with the recorded product ID extracted from the watermark information, the copy permission notification unit 800 embeds the received watermark information. The copying apparatus 70 is notified that the recorded material 64 is not permitted to be copied by the user 62 corresponding to the user ID received together with the watermark information. As a result, the copy management system 60 can reliably prevent copying of the recorded matter 64 by the user 62 who is not permitted to copy the recorded matter 64.

  Further, the copy permission information storage unit 802 may further store the remaining number of copies that can be copied for each user 62 in association with each copy authorizer ID 8022. In this case, after receiving the user ID together with the watermark information from the copying apparatus 70, the copy permission / inhibition notifying unit 800 refers to the copy permission information storage unit 802 and associates one or more remaining copyable numbers with the received user ID. If the copy permission information storage unit 802 stores the copy permission information, the copying apparatus 70 is notified that copying is permitted, and the remaining copyable number stored in the copy permission information storage unit 802 is reduced by one. As a result, the copy management system 60 can also limit the number of copies of the user 62 who is permitted to copy the recorded matter 64, and can manage the copy of the recorded matter 64 more strictly.

  FIG. 11 shows an example of a data structure stored in the copy history storage unit 804. The copy history storage unit 804 stores a copy person ID 8042 that is the user ID of the user 62 permitted to copy the recorded matter 64 and the number of copies 8044 that is the number of copies by the user 62 in association with the recorded matter ID 8040. By referring to the copy history storage unit 804, it is possible to manage which recorded matter 64 is copied by which user 62.

  FIG. 12 is a flowchart showing an example of the operation of the copying apparatus 70. The operation of the copying apparatus 70 shown in this flowchart starts at a predetermined timing such as when a copy instruction is input from the user 62 via the input unit 704. First, the input unit 704 acquires a watermark ID detection parameter received from the user 62 via a keypad, a touch panel, or the like, a user ID of the user 62 who has instructed copying, and the like (S200). Next, the scanner unit 706 converts the recorded matter 64 into image data that is electronic data (S202).

  Next, the filter unit 708 removes the low frequency component of the luminance change of the pixels included in the image data converted by the scanner unit 706 (S204). Next, the variance calculation unit 702 applies a unit area having a predetermined area to the image data from which the low-frequency component of the luminance change has been removed by the filter unit 708 on the image data according to an instruction from the variance calculation instruction unit 700. While shifting, the variance of the luminance value in each unit area is calculated (S206).

  Next, the watermark information extraction unit 710 performs the unit region with the highest luminance value variance based on the luminance value variance of each unit region calculated by the variance calculation unit 702 according to the instruction from the variance calculation instruction unit 700. The extraction of watermark information is tried in order (S208). Then, the watermark information extraction unit 710 determines whether the watermark information has been extracted from the target unit area (S210). If the watermark information could not be extracted (S210: No), it is determined whether or not the extraction of the watermark information has been attempted for all the unit areas equal to or greater than the dispersion threshold (S212). If the extraction of the watermark information is not attempted for all unit areas equal to or greater than the dispersion threshold (S212: No), the watermark information extraction unit 710 attempts to extract the watermark information from the unit area having the next highest luminance value dispersion. (S208).

  In step 212, when the extraction of watermark information is attempted for all unit areas equal to or larger than the dispersion threshold (S212: Yes), the watermark information output unit 712 notifies the copying unit 716 that the watermark information has not been detected. . The copying unit 716 records the image data converted by the scanner unit 706 on another recording medium, thereby copying the recorded matter 64 to another recording medium (S214), and the operation of the copying apparatus 70 shown in this flowchart. Ends.

  If the watermark information can be extracted in step 210 (S210: Yes), the watermark information output unit 712 sends the watermark information extracted by the watermark information extraction unit 710 to the copy management server 80 via the network 66 ( S216). Next, the copy unit 716 determines whether or not a copy permission is received from the copy management server 80 (S218). When a copy permission is received from the copy management server 80 (S218: Yes), the copy unit 716 copies the image data converted by the scanner unit 706 to another recording medium (S214), and the copy shown in this flowchart. The operation of the device 70 ends.

  If it is determined in step 218 that copying is not permitted from the copy management server 80 (S218: No), the display unit 714 displays that copying is not permitted, thereby copying the recorded matter 64. Is notified to the user 62 (S220), and the operation of the copying apparatus 70 shown in this flowchart ends.

  In this example, when the watermark information cannot be extracted from the recorded material 64 in steps 208 to 212, the recorded material 64 is copied in step 214. However, as another example, the watermark information is The recorded matter 64 may be copied only when copying is permitted and copying permission is notified based on the extracted watermark information and user ID. Thereby, the copy of the recorded matter 64 can be managed more reliably.

  FIG. 13 is a flowchart showing an example of the operation of the copy management server 80. The operation of the copy management server 80 shown in this flowchart starts at a predetermined timing such as when the power is turned on. First, the copy permission / inhibition notifying unit 800 determines whether it has been received from the watermark information copying apparatus 70 together with the user ID (S300). When the watermark information is not received together with the user ID (S300: No), the copy permission / inhibition notifying unit 800 repeats step 300 until the watermark information is received together with the user ID.

  In step 300, when the watermark information is received together with the user ID (S300: Yes), the copy permission / notification unit 800 extracts the recorded material ID from the watermark information received together with the user ID from the copying apparatus 70, and copies the copy permission information storage unit. Referring to 802, it is determined whether or not the user ID received together with the watermark information is stored in the copy permission information storage unit 802 in association with the recorded matter ID extracted from the watermark information (S302). When the received user ID is not associated with the extracted recorded matter ID and stored in the copy permission information storage unit 802 (S302: No), the copy permission notification unit 800 notifies the copying apparatus 70 that copying is not permitted. Notification is made (S308), and the processing shown in step 300 is performed again.

  In step 302, if the received user ID is stored in the copy permission information storage unit 802 in association with the extracted recorded product ID (S302: Yes), the copy permission / inhibition notification unit 800 embeds the received watermark information. The copying device 70 is notified via the network 66 that the recorded material 64 is permitted to be copied by the user 62 corresponding to the received user ID (S304). Then, the copy permission / inhibition notifying unit 800 stores the user ID of the user 62 permitted to copy in the copy history storage unit 804 in association with the recorded material ID of the recorded material 64 permitted to copy (S306). Perform the process shown in.

  As is clear from the above description, according to the watermark information extraction system 10 of the present embodiment, watermark information can be quickly extracted from a recorded material.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in embodiment mentioned above. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above-described embodiment. Furthermore, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  For example, a general-purpose computer or the like is caused to function as the variance calculation instruction unit 300, the variance calculation unit 302, the filter unit 306, the watermark information extraction unit 308, and the extraction result output unit 310, and a general-purpose scanner device is used instead of the scanner unit 304. Thus, the function of the watermark information extraction device 30 may be realized using a general-purpose computer and a general-purpose scanner device. Each of the plurality of functional blocks included in the watermark information extraction device 30 may be realized in hardware by an integrated logic IC such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). A digital signal processor) or a general-purpose computer may be implemented in software, or functional blocks partially implemented in hardware or software may be combined.

It is a figure which shows the structure of the watermark information extraction system 10 which concerns on one Embodiment of this invention. 2 is a block diagram illustrating an example of a detailed configuration of a computer 20 and a watermark information extraction device 30. FIG. 2 is a diagram illustrating an example of a hardware configuration of a watermark information extraction device 30. FIG. It is a figure which shows an example of the input screen 40 for inputting the parameter for extracting watermark information. It is a conceptual diagram for explaining a process of dividing image data simply by dividing a plurality of unit areas and calculating variance for each unit area. 4 is a flowchart showing an example of the operation of the watermark information extracting device 30. It is a figure which shows the structure of the copy management system 60 which concerns on other embodiment of this invention. 3 is a block diagram showing an example of a detailed configuration of a copying apparatus 70. FIG. 3 is a block diagram showing an example of a detailed configuration of a copy management server 80. FIG. 6 is a diagram illustrating an example of a data structure stored in a copy permission information storage unit 802. FIG. 6 is a diagram illustrating an example of a data structure stored in a copy history storage unit 804. FIG. 5 is a flowchart showing an example of the operation of the copying apparatus 70. 5 is a flowchart showing an example of the operation of the copy management server 80.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Watermark information extraction system, 20 ... PC, 200 ... Input part, 704 ... Input part, 202 ... Display part, 714 ... Display part, 30 ... Watermark information extraction 300, dispersion calculation instruction unit, 700 ... dispersion calculation instruction unit, 302 ... dispersion calculation unit, 702 ... dispersion calculation unit, 304 ... scanner unit, 706 ... scanner unit, 306 ... Filter unit, 708 ... Filter unit, 308 ... Watermark information extraction unit, 710 ... Watermark information extraction unit, 310 ... Extraction result output unit, 320 ... CPU, 322,. RAM, 324 ... ROM, 326 ... communication interface, 328 ... scanner device, 330 ... media interface, 332 ... storage medium, 40 ... input screen, 400, 402, 4 4, 406, 410 ... input box, 408 ... check box, 412 ... extraction start button, 500 ... tree, 502 ... cloud, 504 ... house, 506 ... road, 50, 52, 54 ... image data, 540, 542, 544, 546 ... unit area, 60 ... copy management system, 62 ... user, 64 ... recorded matter, 66 ... network , 70 ... Copy apparatus, 712 ... Watermark information output unit, 716 ... Copy unit, 80 ... Copy management server, 800 ... Copy permission / notification notification unit, 802 ... Copy permission information storage unit , 8020, 8040 ... recorded matter ID, 8022 ... copy author ID, 804 ... copy history storage, 8042 ... copy ID, 8044 ... number of copies

Claims (10)

A watermark information extraction device for extracting watermark information embedded in a recorded material,
A scanner unit for converting the recorded matter into image data which is electronic data;
A filter unit for removing low frequency components of luminance change of pixels included in the image data converted by the scanner unit;
A variance calculating unit that calculates a variance of luminance values in a unit area of a predetermined area for the image data from which the low frequency component of the luminance change has been removed by the filter unit;
A variance calculation instruction unit that causes the variance calculation unit to calculate a variance of luminance values in the unit region at each location of the image data by shifting the unit region in the image data;
Based on the variance of the luminance value of each unit area calculated by the variance calculation unit in response to an instruction from the variance calculation instruction unit, watermark information is extracted in order from the unit area with the highest variance of the luminance value. A watermark information extraction unit that attempts to
A watermark information extraction apparatus, comprising: a watermark information output unit that outputs information when the watermark information extraction unit can extract the watermark information from the recorded matter. The watermark information extracting device according to claim 1,
The watermark information extraction unit
The watermark information output unit indicates that the watermark information is not embedded in the image data when the watermark information cannot be extracted for the unit area having the variance of the luminance value equal to or greater than a predetermined dispersion threshold. The watermark information extraction device is characterized in that the watermark information is not extracted thereafter for the unit area having the variance of the luminance value less than the variance threshold. The watermark information extraction device according to claim 2,
A dispersion threshold acceptance unit for accepting an input of the dispersion threshold from a user;
The watermark information extraction unit
The watermark information is not embedded in the image data when the watermark information cannot be extracted for the unit area having the variance of the luminance value greater than or equal to the variance threshold received by the variance threshold acceptance unit. A watermark information extraction apparatus that outputs the watermark information to the watermark information output unit and does not extract the subsequent watermark information for the unit area having the variance of the luminance value less than the variance threshold. The watermark information extraction device according to any one of claims 1 to 3,
The variance calculation instruction unit
The variance calculation of the variance of the luminance value in the unit area at each location of the image data is performed by shifting the unit area on the image data by a movement step in units of multiples of the pixels of the image data. The watermark information extracting apparatus is characterized in that the image information is calculated by a unit. The watermark information extraction device according to claim 4,
A moving step receiving unit that receives an input of the moving step from a user;
The variance calculation instruction unit
By shifting the unit area on the image data by the movement step received by the movement step receiving unit, the variance calculation unit is configured to distribute the variance of luminance values in the unit area at each location of the image data. A watermark information extraction apparatus characterized by being calculated. A watermark information extraction method of a watermark information extraction device for extracting watermark information embedded in a recorded material,
The watermark information extraction device comprises:
Converting the recorded matter into image data which is electronic data;
Removing a low frequency component of luminance change of pixels included in the converted image data;
Calculating a variance of luminance values in each unit area while shifting a unit area of a predetermined area on the image data for the image data from which the low frequency component of the luminance change is removed; ,
Trying to extract watermark information in order from the unit region having the highest variance of the luminance value based on the variance of the luminance value of each of the calculated unit regions;
And a step of outputting when the watermark information can be extracted from the recorded matter. A program for controlling a watermark information extraction device that extracts watermark information embedded in a recorded material,
In the watermark information extraction device,
A scanner function for converting the recorded matter into image data which is electronic data;
A filter function for removing a low frequency component of a luminance change of a pixel included in the image data converted by the scanner function;
A variance calculation function for calculating a variance of luminance values in a unit area of a predetermined area for the image data from which the low frequency component of the luminance change has been removed by the filter function;
A variance calculation instruction function that causes the variance calculation function to calculate a variance of luminance values in the unit area at each location of the image data by shifting the unit area in the image data;
Based on the variance of the luminance value of each unit area calculated by the variance calculation function in response to an instruction from the variance calculation instruction function, watermark information is extracted in order from the unit area with the highest variance of the luminance value. And a watermark information output function for outputting the watermark information when the watermark information extraction function can extract the watermark information from the recorded matter. A copy management system for managing copies of recorded materials,
A copying apparatus that converts the recorded matter into image data, which is electronic data, and records the converted image data in another recording medium, thereby copying the recorded matter to the other recording medium;
When watermark information is extracted from the image data converted by the copying apparatus, it is determined whether or not the recorded material can be copied based on the extracted watermark information, and copying of the recorded material is permitted. A copy determination server for causing the copying apparatus to copy the recorded matter,
The copying apparatus includes:
A scanner unit for converting the recorded matter into the image data;
A filter unit for removing low frequency components of luminance change of pixels included in the image data converted by the scanner unit;
A variance calculating unit that calculates a variance of luminance values in a unit area of a predetermined area for the image data from which the low frequency component of the luminance change has been removed by the filter unit;
A variance calculation instruction unit that causes the variance calculation unit to calculate a variance of luminance values in the unit region at each location of the image data by shifting the unit region in the image data;
Based on the variance of the luminance value of each unit area calculated by the variance calculation unit in response to an instruction from the variance calculation instruction unit, watermark information is extracted in order from the unit area with the highest variance of the luminance value. A watermark information extraction unit that attempts to
A watermark information output unit that outputs the extracted watermark information to the copy determination server when the watermark information extraction unit can extract the watermark information from the recorded matter;
A copy unit for copying the image data converted by the scanner unit to the other recording medium when receiving an instruction from the copy determination server to permit copying of the recorded matter;
The copy determination server
A copy permission information storage unit for storing information indicating whether or not to permit copying of the recorded material in association with the recorded material identification information of the recorded material;
Receiving the watermark information from the copying apparatus and referring to the recorded matter identification information of the recorded matter included in the watermark information, the fact that copying is permitted is associated with the recorded matter identification information of the recorded matter and the copying A copy management system, comprising: a copy permission / notification notifying unit for notifying the copying apparatus that copying of the recorded material is permitted when stored in a permission information storing unit. The copy management system according to claim 8,
The copying apparatus includes:
User identification information for identifying a user who requests a copy of the recorded material is received from the user, and the received user identification information is received by the watermark information output unit together with the watermark information extracted by the watermark information extraction unit. It further has an identification information receiving unit for outputting to the copy determination server,
The copy determination server
A copy authorized person storage unit for storing the user identification information of the user permitted to copy the recorded material in association with the recorded material identification information of the recorded material;
The copy permission / notification section
The user identification received in conjunction with the watermark information from the watermark information extraction device is that the copy permission information storage unit stores information indicating that copying is permitted in association with the recorded matter identification information of the recorded matter. When the information is stored in the copy authorized person storage unit that the copy is permitted in association with the recorded product identification information of the recorded product, the copy apparatus is notified that the copy of the recorded product is permitted. A copy management system characterized by notification. The copy management system according to claim 9,
The copy determination server
A copied list storage unit that stores the user identification information of the user permitted to copy in association with the recorded item identification information of the recorded material permitted to be copied when copying of the recorded material is permitted; A copy management system further comprising:

Images