JP2020004238A - Authenticity determination device and program - Google Patents

Abstract

To provide an authenticity determination device that suitably detects a false ID card.SOLUTION: An authenticity determination system 1 comprises: a reading device 2 that reads an ID card 10; and an authenticity determination device 3 that performs authenticity determination of the ID card 10. The authenticity determination device 3 performs authenticity determination of the ID card 10 on the basis of a change in density value in a predetermined direction in an image of a pre-printed portion of the ID card 10. At this time, the authenticity determination device 3 determines the distribution of the degree of difference in density between pixels adjacent in the predetermined direction and determines the authenticity of the ID card 10 with the degree distribution.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an authenticity determination device and a program thereof.

  Financial institutions and mobile phone carriers require identity verification with an ID card such as a driver's license at the time of contract, but the number of cases where counterfeiting ID cards to make a contract impersonating another person is increasing.

  In general, an ID card has characters and ruled lines (referred to as pre-printed portions) commonly used in each card formed on the card in advance by an offset printing method, a letterpress printing method, or the like. It is manufactured by printing information (referred to as on-demand information) that differs depending on each card, such as name, date of birth, address, and face image, by a thermal transfer method such as a fusion-type thermal transfer method or a sublimation-type thermal transfer method.

  As an example of an ID card counterfeiting method, there is a method in which a fake sheet image with changed on-demand information is printed by an inkjet printer and attached to the entire surface of the ID card. Patent Document 1 detects such counterfeiting. In order to detect moiré fringes that appear when printing is performed by an ink jet printer, an authenticity determination device is described.

JP 2011-34535 A

  However, the method of Patent Document 1 detects moiré fringes peculiar to the ink jet system, and can detect only forgery using a printer of the ink jet system.

  For example, ID card forgery methods include printing a fake sheet image with changed on-demand information using a sublimation-type thermal transfer printer and attaching it to the entire surface of the ID card. Is difficult to detect by the method of Patent Document 1.

  The present invention has been made in view of the above problems, and has as its object to provide an authenticity determination device and the like that preferably detect a fake ID card.

  According to a first aspect of the present invention, there is provided an authenticity determination apparatus for determining the authenticity of an ID card, the method comprising: determining a density of a pre-printed portion of the ID card in a predetermined direction; An authenticity determination device for determining the authenticity of an ID card.

  As described above, the preprinted portion of the ID card is formed by the offset printing method, the relief printing method, or the like, and the edge of the boundary of the line clearly appears. In the present invention, by utilizing such characteristics of the pre-printed portion, based on the change in the density value of the image of the pre-printed portion, any image whose edge does not clearly appear as described above can be determined as a fake ID card. . For example, gradation appears at the boundary of the line printed by the sublimation type thermal transfer method, so when a sheet image printed by the sublimation type thermal transfer method is pasted on the entire surface of the ID card, the line corresponding to the pre-printed part is also printed. Since a gradation occurs at the boundary, which is different from a regular ID card, the ID card can be determined to be false.

It is preferable that the authenticity determination device obtains a frequency distribution of density differences between pixels adjacent in the predetermined direction, and determines the authenticity of the ID card from the frequency distribution. For example, the authentication device determines the authenticity of the ID card by comparing the frequency of the frequency distribution with a threshold.
According to the present invention, as a change in the density value, for example, the density difference between adjacent pixels in a predetermined direction is obtained, and the authenticity of the ID card can be determined based on the shape of the frequency distribution. As a method of authenticity determination, for example, for a specific density difference or a range of the density difference, the frequency of the frequency distribution is compared with a threshold value, so that the authentication can be suitably performed.

It is preferable that the authentication device performs the authentication of the ID card by using images of a plurality of preprinted portions.
Thereby, even when the ID card is warped, the accuracy of the authenticity determination can be improved.

The preprinted portion is, for example, a character.
Since the characters are dense in lines, the characters can be suitably used in the authenticity judgment method of the present invention in which the authenticity is judged using the difference in density change at the boundary of the lines.

  According to a second aspect of the present invention, there is provided an authentication apparatus for performing authentication on an ID card, wherein the computer determines the authenticity of the ID card based on a change in a density value of an image of a preprinted portion of the ID card in a predetermined direction. This is a program for functioning as an authenticity determination device for performing

  According to the present invention, it is possible to provide an authentication apparatus and the like that preferably detects a fake ID card.

FIG. 1 is a diagram showing an authenticity determination system 1. FIG. 2 is a diagram illustrating a hardware configuration of the authenticity determination device 3. 4 is an example of a face of an ID card 10. Example of pre-printed part. FIG. 2 is a diagram showing a sublimation type thermal transfer printer 100 and a thermal transfer ribbon 200. FIG. 3 is a diagram illustrating a printing method using a sublimation type thermal transfer method. 5 is a flowchart illustrating an authentication method. 4 is an example of an image 300 of a preprinted portion. The figure explaining the authentication method. The figure explaining the authentication method. An example in which images of a plurality of preprinted portions are used for determination.

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

(1. Authentication system 1)
FIG. 1 is a diagram illustrating an authentication system 1 including an authentication device 3 according to an embodiment of the present invention. As shown in FIG. 1, the authentication system 1 includes a reading device 2 and an authentication device 3. The reading device 2 and the authenticity determination device 3 are communicably connected by wireless or wired communication means.

  The reading device 2 reads the ID card 10 and has a camera 21 and the like. The camera 21 is for photographing the face of the ID card 10, and for example, a known camera having a light receiving lens, an image sensor, an A / D (Analog / digital) converter, and the like can be used.

  The authenticity determination device 3 determines the authenticity of the ID card 10 from the image of the ID card 10 and detects the fake ID card 10.

  FIG. 2 is a diagram illustrating a hardware configuration of the authenticity determination device 3. As shown in FIG. 2, the authenticity determination device 3 can be realized by a computer configured by connecting a control unit 31, a storage unit 32, a display unit 33, an input unit 34, a communication control unit 35, and the like via a bus or the like. However, the present invention is not limited to this, and various configurations can be appropriately adopted.

  The control unit 31 includes a CPU, a ROM, a RAM, and the like. The CPU calls a program related to the processing of the authentication device 3 stored in the storage unit 32 or a storage medium such as a ROM into a work area on the RAM and executes the program. The ROM is a non-volatile memory, and permanently stores programs such as a boot program and a BIOS, data, and the like. The RAM is a volatile memory, and temporarily stores programs and data loaded from the storage unit 32, the ROM, and the like, and includes a work area used by the control unit 31 to perform various processes.

  The storage unit 32 is a hard disk drive, a solid state drive, a flash memory, or the like, and stores a program to be executed by the authenticity determination device 3 in processing described later, data necessary for executing the program, an OS, and the like. These programs and data are read and executed by the control unit 31 as needed.

The display unit 33 includes a liquid crystal display and the like.
The input unit 34 is for inputting various settings to the authenticity determination device 3.
The communication control unit 35 is a communication interface that mediates wireless communication, and performs communication with the reading device 2.

(2. ID card 10)
The ID card 10 is a personal identification medium to be authenticated in the present embodiment. FIG. 3A is a diagram schematically showing the ID card 10, which schematically shows an example of the face of the ID card 10. The ID card 10 is, for example, a driver's license, my number card, residence card, special permanent resident card, or the like.

  The ID card 10 is used for identification at a financial institution, a mobile phone carrier, and the like. The ID card 10 has a name, a date of birth 13, an address 14, a face image 18, a date of issuance 15 of the ID card 10, and an issue number 16 on a substantially rectangular card base material long horizontally. , Expiration date 17 and the like.

  In the ID card 10, characters excluding “year”, “month”, “day”, and “birth” of the name 12, date of birth 13, address 14, face image 18, and “year” “month” “ The characters excluding “date”, the characters excluding “No.” and “No.” of the issue number 16, and the expiration date 17 are on-demand information that differs depending on the ID card 10, and are determined by a thermal transfer method such as a fusion-type thermal transfer method and a sublimation-type thermal transfer method. It is formed by printing on a card base material.

  On the other hand, characters such as “name”, “address”, “grant date”, and “number” indicating the description columns of the name 12, address 14, grant date 15, and issue number 16, name 12, birth date 13, address 14, the delivery date 15, the ruled line of the column of the issue number 16, the characters "year", "month", "day" and "birth" of the date of birth 13, "year" "month" " The characters "day" and the characters "daily" and "number" of the issue number 16 are commonly used by the ID cards 10.

  Before printing the on-demand information, these characters or ruled lines are previously formed at predetermined positions on the card base material by a printing method such as an offset printing method or a letterpress printing method, and are called preprinted portions. FIG. 3B shows a pre-printed portion extracted from the ID card 10. The on-demand information is printed by printing the above-mentioned on-demand information on a card base on which a pre-printed portion is formed in advance as shown in FIG. The card 10 is manufactured. The configuration of the on-demand information and the pre-printed portion differs depending on the type of the ID card 10 such as a driver's license, a my number card, a residence card, and a special permanent resident card.

  FIG. 4A is an example of enlarging a part of a “number” of a “number” as a part of a pre-printed part of the ID card 10 using an offset printing method, a letterpress printing method, or the like. The formed line has no blurring or blurring, and the edge of the boundary clearly appears. If this portion is printed by the sublimation type thermal transfer method, gradation is generated without a clear edge appearing at the boundary of the line as shown in FIG. 4B. Since this is based on a sublimation type thermal transfer printing method, the printing method will be briefly described below.

(3. Sublimation type thermal transfer printing method)
Printing by the sublimation type thermal transfer system is performed by the sublimation type thermal transfer printer 100 shown in FIG. In the sublimation type thermal transfer printer 100, the thermal transfer ribbon 200 wound around the supply reel 101 is unwound and conveyed in the direction shown by the arrow a, and heat is applied to the thermal transfer ribbon 200 by the thermal head 110 in the middle thereof. The sublimable dye of the transfer layer is transferred to the printing target 11. After the transfer, the thermal transfer ribbon 200 is taken up by a take-up reel 102.

  FIG. 5B shows an example of the transfer layer 202 of the thermal transfer ribbon 200. The transfer layers 202 of Y (yellow), M (magenta), and C (cyan) are arranged on the base material of the thermal transfer ribbon 200 in a plane-sequential manner. Is done.

  In the sublimation type thermal transfer printer 100, the sublimation dye of the transfer layer 202 on the base material 201 is transferred to the printing target 11 as shown in FIG. When receiving a signal from a control unit (not shown), the thermal head 110 sets the thermal head element 111 at a predetermined temperature and applies heat from the thermal head element 111 to the thermal transfer ribbon 200.

  When the thermal head element 111 applies heat to the area C of the transfer layer 202 in FIG. 6A, the sublimable dye in the area C of the transfer layer 202 is vaporized and heat is applied to the receiving layer 11a provided on the printing target 11. The dye in the transfer layer 202 is diffused and transferred to the printing target 11. The transfer of the transfer layer 202 can be performed at 256 gradations. By transferring the Y, M, and C transfer layers 202 to predetermined positions on the print target 11 while reciprocating the print target 11, printing of characters and the like can be performed. Done.

  As described above, the temperature of the thermal head element 111 is controlled by the control unit, and an ON / OFF signal is given so that the temperature is set to a predetermined temperature only when the transfer layer 202 is transferred. However, as shown in FIG. 6B, even when the ON signal is given at time t1, a delay dt1 occurs until the thermal head element 111 reaches a predetermined temperature, and thereafter, the OFF signal is given to the thermal head element 111 at time t2. , A delay dt2 occurs until the thermal head element 111 returns to the original temperature.

  While the temperature of the thermal head element 111 rises to a predetermined temperature and while the temperature drops from the predetermined temperature to the original temperature, the sublimable dye of the transfer layer 202 is vaporized and transferred to some extent, and the transfer amount of the dye increases. It is proportional to the temperature during or falling. This is the reason why a clear edge does not appear at the boundary of the line printed by the sublimation type thermal transfer method and a gradation as shown by G in FIG. 6B occurs.

  As described above, in the regular ID card 10, the preprinted portion is formed by the offset printing method or the letterpress printing method, and a clear edge appears at the boundary of the line. Can be detected as a fake ID card 10. Therefore, in the present embodiment, based on the change in the density value of the image of the preprinted portion, the authenticity of the ID card 10 is determined using the difference in the density change at the line boundary as described above.

(4. Authentication method)
FIG. 7 is a flowchart showing the authenticity determination method of the present embodiment. S1 and S2 in FIG. 7 are processes executed by the reading device 2, and S3 and S7 are processes executed by the control unit 31 of the authenticity determination device 3. The process in FIG. 7 is started by, for example, setting the ID card 10 at a specified position and transmitting an instruction to start the process from the authentication device 3 to the reading device 2.

  In the present embodiment, first, the reading device 2 takes an image of the face of the ID card 10 with the camera 21 (S1), and transmits the face image of the ID card 10 to the authenticity determination device 3 (S2). In the present embodiment, the image of the ID card 10 is photographed by the camera 21 having a resolution of 300 dpi (one pixel is approximately 84 microns) to obtain a gray scale image having 256 density gradations, but is not limited to this.

  Upon receiving the ticket image (S3), the authenticity determination device 3 extracts an image of a predetermined preprint portion from the ticket image (S4).

  Here, it is assumed that an image of the above-mentioned “number” character is extracted as a predetermined pre-printed portion, and a range including the previously set “number” character is cut out from the ticket surface image. In the present embodiment, since the authenticity determination is performed by using the difference in density change at the boundary of the line, an image of a character with dense lines is suitable for the determination. ing.

  FIG. 8 is an example of an image 300 in which the character of “number” is extracted. In this example, forgery is performed in which a fake ticket image with changed on-demand information printed by a sublimation type thermal transfer method is attached to the entire surface of the ID card 10, and corresponds to a preprinted portion such as "number". Also, the gradation by the sublimation type thermal transfer method is generated at the boundary of the line in the portion where the line is formed.

  The authenticity determination device 3 determines the authenticity of the ID card 10 from the preprinted image 300 extracted in S4. Although the authenticity determination is performed based on a change in the density value of the image 300 in a predetermined direction, here, the image 300 is scanned in a predetermined direction as shown by an arrow b in FIG. All the density differences between the pixels 301 adjacent in the direction b are calculated (S5).

  The predetermined direction b can be determined in advance. In this case, the direction in which the gradation appears, that is, the conveying direction of the thermal transfer ribbon 200 when the face image is printed by the sublimation thermal transfer method when the ID card 10 is forged (see FIG. 5 (a)). In the example of FIG. 9, the predetermined direction b is set to the horizontal direction of the ID card 10, and the processing of calculating all (absolute values) of the density differences between the pixels 301 adjacent in the horizontal direction is performed on the pixels 301 in all the vertical stages. Do.

  Then, the authenticity determination device 3 determines the authenticity of the ID card 10 from the frequency distribution of the density difference between the adjacent pixels 301 (S6).

  In the present embodiment, first, as shown in FIG. 10A, the frequency distribution of the density difference between adjacent pixels 301 is obtained, and the frequency is accumulated in order from the maximum value of the density difference to the minimum value (hereinafter, referred to as the frequency distribution). (Referred to as a cumulative frequency distribution) is created as shown by the solid line in FIG.

  FIG. 10A is an example of the frequency distribution of the density difference in the fake ID card 10 in which the preprinted portion is printed by the sublimation type thermal transfer method, and a gradation occurs without a clear edge appearing at the boundary of the line. As a result, the portion where the density difference is large is relatively small, and the portion where the density difference has an intermediate value increases. Further, since the line of the preprinted portion is printed with the YMC dye superimposed, the maximum value of the density difference itself is relatively small.

  On the other hand, FIG. 10B is an example of the frequency distribution of the density difference in the normal ID card 10 in which the preprinted portion is formed by the offset printing method or the letterpress printing method. As a result, a clear edge appears in the portion and the shading changes sharply only at the edge portion. As a result, a portion with a large density difference and a portion with a small density increase, and the maximum value of the density difference itself is large.

  As a result, the cumulative frequency distribution of the false ID card 10 (see the solid line in FIG. 11C) and the cumulative frequency distribution of the legitimate ID card 10 (see the chain line in FIG. 11C) have the shape of the cumulative frequency distribution. A difference occurs, and in the present embodiment, the authenticity of the ID card 10 is determined based on such a difference in the cumulative frequency distribution.

  A specific determination method is not particularly limited as long as the above difference can be determined. For example, a predetermined threshold value V1 is set for a specific density difference X1, and the (accumulated) frequency in the density difference X1 is compared with the threshold value V1. If the frequency is equal to or more than the threshold value V1, the ID card 10 is determined to be a legitimate ID card 10; Alternatively, a predetermined threshold value V2 is set for each density difference in the specific density difference range X2, and if a value obtained by subtracting the sum of the threshold values V2 from the sum of the frequencies of these density differences is equal to or greater than the predetermined value, the normal ID is obtained. The card 10 may be used. Otherwise, the fake ID card 10 may be used. It is also possible to set a specific range X3 with a large density difference, and if the sum of the frequencies in the range X3 is equal to or more than a threshold value, use the normal ID card 10; otherwise, use the false ID card 10. .

  The authenticity determination device 3 displays the determination result on the display unit 33 (S6), and ends the process. The operator can see whether the ID card 10 is genuine or forged by looking at the judgment result displayed on the display unit 33 of the authenticity judgment device 3.

  As described above, the present embodiment utilizes the fact that a clear edge appears at the boundary of a line formed by an offset printing method, a letterpress printing method, or the like, and uses the ID card 10 in which such an edge does not clearly appear. Can be determined to be a fake ID card 10 based on a change in the density value of the image of the preprinted portion. Therefore, it is possible to detect forgery or the like in which a printed image of the ticket surface is attached to the entire surface of the ID card 10 by the sublimation type thermal transfer method.

  Also, when printing is performed by the ink jet method, since the density is expressed by the error diffusion method, bleeding or blur occurs at the boundary of the line, so that the ID card 10 on which the pre-printed portion is printed by the ink jet method is similarly false. Can be determined. As described above, the authenticity determination method of the present embodiment is not limited to the sublimation type thermal transfer method, but may be an ink jet method or a printing method (for example, an electrophotographic printing method) in which a gradation is expressed by the area of a dot. It is possible to detect all counterfeiting by a printing method in which the edge of the boundary does not clearly appear.

  In the present embodiment, as the above-described change in the density value, the density difference between adjacent pixels in a predetermined direction is obtained, and the authenticity of the ID card 10 can be determined based on the shape of the frequency distribution. As a method of authenticity determination, for example, for a specific density difference X1 or a range of density differences X2 and X3, the frequency of the frequency distribution is compared with a threshold value, so that the authentication can be suitably performed. In this embodiment, the cumulative frequency distribution as shown in FIG. 11C is used for authenticity determination, but the normal (non-cumulative frequency distribution) frequency distribution shown in FIGS. 11A and 11B is used. In the same manner as described above, the authenticity can be determined by comparing the frequency with a threshold.

  In the present embodiment, the authenticity is determined from the image of the character in the pre-printed portion. Since the characters are dense in lines, the characters can be suitably used in the authenticity determination method of the present embodiment in which the authenticity is determined using the difference in density change at the boundary of the lines.

  However, the present invention is not limited to this. For example, if the ID card 10 is inserted into the back pocket of the pants or the like, the ID card 10 is warped, the focus of the ID card 10 at the time of photographing is out of focus, and the image of the preprinted portion extracted in S4 may be blurred. Such blurring is a cause of misjudgment of the legitimate ID card 10 as the fake ID card 10, and in order to prevent this, the images of the pre-printed portion around the card and the inside of the card are used for the judgment. If at least one image has the focus, the determination can be made correctly (the legitimate ID card 10 can be determined as the legitimate ID card 10). Thereby, the determination accuracy can be improved.

  For example, as shown in FIGS. 11A to 11C, the processing of S5 to S6 is performed on each of the image of the character “number” and “raw” around the card and the image of the character “go” at the center of the card. If at least one image is determined to be a legitimate ID card 10, the ID card 10 is determined to be a legitimate ID card 10 irrespective of the determination result for another image.

  It is also possible to use the image of the ruled line in the pre-printed portion instead of the character for authenticity judgment, and other lines in the pre-printed portion may be used for authenticity judgment. The line may be formed in a direction inclined with respect to the vertical or horizontal direction of the ID card 10. These characters, ruled lines, and other lines may be printed in monochrome or in color.

  Further, in the present embodiment, as described above, the image of the pre-printed portion is scanned in a predetermined direction to check a change in the density value in the predetermined direction. In the above example, the predetermined direction corresponds to the transport direction of the thermal transfer ribbon 200 when printing the face image of the fake ID card 10 by the sublimation thermal transfer method, and is usually the vertical direction or the horizontal direction of the ID card 10. . However, since it is often not known in the inspection stage which direction the transport direction of the thermal transfer ribbon 200 is, a predetermined direction is set to a plurality of directions, for example, when the ID card 10 is a vertical direction and a horizontal direction, S5 to S6 respectively. When the process is performed and it is determined that the ID card 10 is false when scanning in any direction, the ID card 10 can be false. Alternatively, the image of the pre-printed portion may be scanned in a direction inclined with respect to the vertical direction and the horizontal direction of the ID card 10, and in this case, the transport direction of the thermal transfer ribbon 200 is the vertical direction and the horizontal direction of the ID card 10. The determination can be made in either case.

  As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. I understand.

1: Authentication system 2: Reading device 3: Authentication device 10: ID card 100: Sublimation type thermal transfer printer 200: Thermal transfer ribbon 300: Image

Claims (6)

An authentication device for determining the authenticity of an ID card,
An authenticity judging device for judging the authenticity of the ID card based on a change in a density value of an image of a preprinted portion of the ID card in a predetermined direction.   2. The apparatus according to claim 1, wherein the authentication apparatus obtains a frequency distribution of density differences between pixels adjacent in the predetermined direction, and determines the authenticity of the ID card from the frequency distribution.   The authenticity determination device according to claim 2, wherein the authentication device determines the authenticity of the ID card by comparing the frequency of the frequency distribution with a threshold value.   The authentication device according to any one of claims 1 to 3, wherein the authentication device performs authentication of the ID card using images of a plurality of preprinted portions.   The authentication device according to claim 1, wherein the preprinted portion is a character. Computer
An authentication device for determining the authenticity of an ID card,
A program for functioning as an authenticity determination device that determines the authenticity of the ID card based on a change in density value in a predetermined direction in an image of a preprinted portion of the ID card.