Device for correcting biological data, method for correcting biological data, and system for correcting biological data

Abstract

This corrects the angles of biological tissues included in biological images acquired in free space. [Solution] The biometric data correction device comprises: an acquisition unit that acquires a fingerprint image of a fingerprint captured in a non-contact state; a detection unit that detects the first central position of the fingerprint in the fingerprint image; a calculation unit that calculates a plurality of correction control points that correct the first central position of the fingerprint to the second central position of the fingerprint image based on the first central position of the fingerprint with respect to the field of view of the fingerprint image; and a correction unit that outputs a corrected image in which the coordinates of pixels on the fingerprint image have been corrected based on the plurality of correction control points.

Description

Technical Field

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[0001] The present disclosure relates to a biological data correction device, a biological data correction method, and a biological data correction system.

Background Art

[0002] In Patent Document 1, in a fingerprint image shown by fingerprint image data in which a person's fingerprint is depicted, or a gradation value indicating the gradation of each pixel constituting the fingerprint image, or difference information obtained from the gradation value of each pixel and the gradation values of surrounding pixels, in the extraction image created based on the above, regarding the fingerprint image or the extraction image as a two-dimensional plane, on the two-dimensional plane, a first approximate straight line that approximates a set of points on the coordinates corresponding to the pixels where the fingerprint is supposed to be projected to an approximate straight line, the inclination difference between the first approximate straight line which is the approximated approximate straight line and a reference line which is a line predetermined for the fingerprint image is calculated as a rotation angle which is the angle by which the fingerprint region, which is the region where the fingerprint exists, is inclined with respect to the reference line, and a fingerprint image rotation angle calculation device is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In view of the above-described conventional circumstances, the present disclosure aims to provide a biological data correction device, a biological data correction method, and a biological data correction system that correct the angle of a biological part included in a biological image acquired in free space.

Means for Solving the Problems

[0005] This disclosure provides a biometric data correction device comprising: an acquisition unit that acquires a fingerprint image of a fingerprint captured in a non-contact state; a detection unit that detects a first central position of the fingerprint as depicted in the fingerprint image; a calculation unit that calculates a plurality of correction control points that correct the first central position of the fingerprint to a second central position of the fingerprint image based on the first central position of the fingerprint with respect to the field of view of the fingerprint image; and a correction unit that outputs a corrected image in which the coordinates of pixels on the fingerprint image have been corrected based on the plurality of correction control points.

[0006] Furthermore, this disclosure provides a biometric data correction method performed by at least one processor, which includes acquiring a fingerprint image of a fingerprint captured in a non-contact state, detecting a first central position of the fingerprint as depicted in the fingerprint image, calculating a plurality of correction control points that correct the first central position of the fingerprint to a second central position of the fingerprint image based on the first central position of the fingerprint with respect to the field of view of the fingerprint image, and outputting a corrected image in which the coordinates of pixels on the fingerprint image have been corrected based on the plurality of correction control points.

[0007] Furthermore, this disclosure provides a biometric data correction system comprising: an imaging device for capturing a fingerprint of a person to be authenticated in a non-contact state; and a correction device capable of communicating with the imaging device, wherein the imaging device transmits an image of at least one fingertip to the correction device; the correction device extracts a region including the first joint of the fingertip from the image to generate a fingerprint image of the fingerprint; detects a first central position of the fingerprint in the fingerprint image; calculates a plurality of correction control points that correct the first central position of the fingerprint to a second central position of the fingerprint image based on the first central position of the fingerprint with respect to the field of view of the fingerprint image; and outputs a corrected image in which the coordinates of pixels on the fingerprint image have been corrected based on the plurality of correction control points. [Effects of the Invention]

[0008] According to this disclosure, the angles of biological parts included in biological images acquired in free space can be corrected. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the overall configuration of the biometric data correction system according to Embodiment 1. [Figure 2] Block diagram showing an example of the internal configuration of the biometric data correction system according to Embodiment 1. [Figure 3] Flowchart illustrating an example of the operation procedure of the correction device in this disclosure. [Figure 4] A diagram showing an example of correction control points before and after correction. [Figure 5] Figure showing examples of fingerprint images before and after correction, and authentication fingerprint images. [Figure 6] This figure shows an example of the overall configuration of the biometric data correction system according to Embodiment 2. [Figure 7] Block diagram showing an example of the internal configuration of the biometric data correction system according to Embodiment 2. [Modes for carrying out the invention]

[0010] (Background leading to this disclosure) Generally, biometric authentication using fingerprints works by matching the characteristic points that indicate the individuality of the fingerprint, which are contained in the fingerprint data registered at the time of registration and the fingerprint data obtained for authentication. Therefore, a challenge with biometric authentication is that if there is a difference in the central position between the fingerprint registered at the time of registration and the fingerprint obtained for authentication, the characteristic points of each fingerprint will also be misaligned, resulting in a decrease in authentication accuracy.

[0011] Here, there are two methods for obtaining fingerprints used in biometric authentication: one involves acquiring fingerprints from a user's body part while it is in contact with a predetermined surface, and the other involves acquiring fingerprints from a user's fingers in a non-contact state, held in free space. Fingerprints acquired in a contact state are pressed against the predetermined surface, which can lead to discrepancies in the orientation of the fingerprint relative to that surface. In particular, fingerprints acquired in a non-contact state are held in free space, which presents a challenge because discrepancies are likely to occur not only in the orientation of the fingerprint but also in its angle (position).

[0012] The fingerprint image rotation angle calculation device described above corrects the tilt (orientation) of the fingerprint in the fingerprint image by rotating the fingerprint image or extraction image based on the rotation angle of the fingerprint area captured in the fingerprint image in a non-contact state. However, as mentioned above, fingerprints acquired in a non-contact state are prone to discrepancies in both the orientation of the fingerprint and the angle (orientation) of the body part. Therefore, there has been a need for a method to correct the discrepancy in the angle (orientation) of the fingerprint in biometric authentication.

[0013] Hereinafter, with reference to the drawings as appropriate, each embodiment that specifically discloses the configuration and operation of the biometric data correction device, biometric data correction method, and biometric data correction system relating to this disclosure will be described in detail. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The attached drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0014] (Embodiment 1) The biodata correction system 100 according to Embodiment 1 will be described with reference to Figures 1 and 2, respectively. Figure 1 is a diagram showing an example of the overall configuration of the biodata correction system 100 according to Embodiment 1. Figure 2 is a block diagram showing an example of the internal configuration of the biodata correction system 100 according to Embodiment 1.

[0015] In Embodiment 1, the biological data correction system 100 generates a fingerprint image used for fingerprint authentication by correcting the captured image captured by the fingerprint acquisition device P1 with the correction device P2. The biological data correction system 100 includes, as an example, the fingerprint acquisition device P1 and the correction device P2. Note that the configuration of the biological data correction system 100 shown in FIGS. 1 and 2 is an example and is not necessarily limited thereto. Other configurations will be described later. Note that the biological data correction system 100 in the present disclosure can not only generate an authentication fingerprint image used for fingerprint authentication, but also register a fingerprint image used for fingerprint authentication, or execute fingerprint authentication using the authentication fingerprint image, etc.

[0016] The fingerprint acquisition device P1 is connected to be able to communicate with the correction device P2 by wire or wirelessly, and executes data transmission and reception. The fingerprint acquisition device P1 captures the fingerprint of the user used for fingerprint authentication, and is realized by, for example, a camera, a smartphone, or a tablet terminal. The fingerprint acquisition device P1 includes a communication unit 10, a processor 11, and a memory 12.

[0017] The communication unit 10 is connected to be able to communicate wirelessly or by wire with the correction device P2 respectively. Here, the wireless communication mentioned here is, for example, short-range wireless communication such as Bluetooth (registered trademark) and NFC (registered trademark), or communication via a wireless Local Area Network (LAN) such as Wi-Fi (registered trademark). The communication unit 10 transmits the captured image captured by the imaging unit 13 to the correction device P2. In addition, the communication unit 10 outputs various data or various information transmitted from the correction device P2 to the processor 11.

[0018] The processor 11 is configured using, for example, a Central Processing Unit (hereinafter referred to as "CPU"), a Field Programmable Gate Array (hereinafter referred to as "FPGA"), or a Graphics Processing Unit (hereinafter referred to as "GPU"), and performs various processes and controls in cooperation with the memory 12. Specifically, the processor 11 realizes the functions of the fingerprint acquisition device P1 by referring to the programs and data held in the memory 12 and executing those programs.

[0019] The memory 12 includes, for example, a Random Access Memory (hereinafter referred to as "RAM") as a work memory used when executing each process of the processor 11, and a Read Only Memory (hereinafter referred to as "ROM") that stores programs and data defining the operation of the processor 11. Data or information generated or acquired by the processor 11 is temporarily stored in the RAM. A program defining the operation of the processor 11 is written in the ROM.

[0020] The imaging unit 13 is realized by, for example, an optical system including a lens and an image sensor, and images a fingerprint in a non-contact state with any object. Note that the imaging unit 13 may image one fingertip (fingerprint) in one imaging, or may simultaneously image a plurality of fingertips (fingerprints) in one imaging. The imaging unit 13 outputs the captured image to the processor 11.

[0021] The correction device P2 is connected to be capable of wired or wireless communication with the fingerprint acquisition device P1 and executes data transmission and reception. The correction device P2 acquires a fingerprint image obtained by cutting out the area where the fingerprint appears from the captured image transmitted from the fingerprint acquisition device P1, corrects this fingerprint image, and generates an authentication fingerprint image for use in fingerprint authentication. The correction device P2 includes a communication unit 20, a processor 21, a memory 22, a fingerprint acquisition unit 23, a monitor 24, and a registered fingerprint database DB.

[0022] Note that the fingerprint acquisition unit 23, monitor 24, and registered fingerprint database DB are not mandatory components and may be omitted. For example, the fingerprint acquisition unit 23 performs the same function as the imaging unit 13 of the fingerprint acquisition device P1 when the fingerprint acquisition device P1 and the correction device P2 are configured as an integrated unit. For example, the monitor 24 may be implemented by an external monitor that can communicate with the correction device P2. Also, for example, the registered fingerprint database DB may be configured separately from the correction device P2, and may be omitted if the correction device P2 does not perform fingerprint authentication.

[0023] The communication unit 20 is connected to the fingerprint acquisition device P1 via wireless or wired communication. The communication unit 20 transmits various data or information received from the processor 21 to the fingerprint acquisition device P1. The communication unit 20 also outputs various data (e.g., captured images) or information received from the fingerprint acquisition device P1 to the processor 21.

[0024] The processor 21 is configured using, for example, a CPU, FPGA, or GPU, and works in cooperation with the memory 22 to perform various processes and controls. Specifically, the processor 21 refers to the programs and data held in the memory 22 and executes those programs to realize the functions of each part. These parts include, for example, the correction unit 211, the registration unit 212, and the authentication unit 213. Note that the registration unit 212 and the authentication unit 213 are not mandatory and may be omitted.

[0025] The correction unit 211 analyzes the captured image taken by the fingerprint acquisition device P1 and detects each finger in the fingerprint image and the area in which the fingerprint of each finger is captured (hereinafter referred to as the "fingerprint area"). The fingerprint area is an area that includes at least the first joint of the fingertip. The correction unit 211 generates a fingerprint image IMG11 for each finger by cutting out the detected fingerprint area. The correction unit 211 corrects the generated fingerprint image IMG11 for each finger into an authentication fingerprint image IMG12 suitable for fingerprint authentication. Specifically, the correction unit 211 generates an authentication fingerprint image IMG12 in which the position and orientation of the fingerprints in the fingerprint image are corrected so that the fingerprint is located approximately in the center of the fingerprint image, as if the fingerprint was captured from the front.

[0026] The registration unit 212 registers (stores) fingerprint images of users whose fingerprint images used for biometric authentication have not yet been registered. When the registration unit 212 registers a fingerprint image, it obtains the authentication fingerprint image corrected by the correction unit 211 and registers (stores) it in the registered fingerprint database DB as the registered fingerprint image used for biometric authentication.

[0027] The authentication unit 213 acquires the authentication fingerprint image IMG12 corrected by the correction unit 211. The authentication unit 213 compares the authentication fingerprint image IMG12 with at least one registered fingerprint image registered in the registered fingerprint database DB and performs fingerprint authentication. The authentication unit 213 outputs the authentication result to the monitor 24. Note that the destination for sending and outputting the authentication result is not limited to the example described above.

[0028] Memory 22 includes, for example, RAM as work memory used when executing each process of the processor 21, and ROM which stores programs and data that define the operation of the processor 21. Data or information generated or acquired by the processor 21 is temporarily stored in RAM. Programs that define the operation of the processor 21 are written in ROM. Memory 22 also stores various data, software, and programs for realizing functions such as the correction unit 211 or the authentication unit 213.

[0029] The fingerprint acquisition unit 23 is implemented, for example, by an optical system including a lens and an image sensor, and captures a fingerprint in a non-contact state with any object. The fingerprint acquisition unit 23 may capture one fingertip (fingerprint) in a single capture, or it may capture multiple fingertips (fingerprints) simultaneously in a single capture. The fingerprint acquisition unit 23 outputs the captured image to the processor 21 as an image containing a fingerprint to be used for authentication or registration.

[0030] The monitor 24 is configured using, for example, a Liquid Crystal Display (hereinafter referred to as "LCD") or an organic electroluminescence (hereinafter referred to as "EL"). The monitor 24 outputs and displays various screens that notify the captured image taken by the fingerprint acquisition device P1 or the fingerprint acquisition unit 23, or the authentication result from the authentication unit 213.

[0031] The registered fingerprint database DB is a type of storage, configured using storage media such as flash memory, a hard disk drive (HDD), or a solid state drive (SSD). The registered fingerprint database DB is used for biometric authentication and stores (registers) registered fingerprint images, which are matched against authentication fingerprint images, and information about the user corresponding to these registered fingerprint images, linked together for each user. If multiple fingerprints are registered for a single user, the registered fingerprint database DB may further link and store information indicating whether the fingerprints in the registered fingerprint images belong to the left or right hand.

[0032] <Method for correcting fingerprint images> Next, a method for correcting fingerprint images will be described with reference to Figure 3. Figure 3 is a flowchart showing an example of the operation procedure of the correction device P2 in this disclosure. Figure 4 shows an example of correction control points before and after correction. Figure 5 shows an example of fingerprint image IMG11 and authentication fingerprint image IMG12. Note that the operation procedure shown in Figure 3 is a process that is performed for each fingerprint image from which the fingerprint of each finger has been extracted.

[0033] The processor 21 acquires the user's fingerprint image IMG11 (St11). The processor 21 detects the center position of the fingerprint in the fingerprint image IMG11 (St12).

[0034] Furthermore, known techniques may be used to detect the central position of a fingerprint. For example, it may be detected using a rule-based method based on manutsier features, or it may be detected using a deep learning model capable of detecting the central position of a fingerprint.

[0035] Here, the central position of the fingerprint in this disclosure will be explained. Fingerprint patterns include many types classified based on the characteristics of the pattern, such as loop-shaped patterns, arch-shaped patterns, whorl patterns, variant patterns, type A loop-shaped patterns, or type B loop-shaped patterns. Furthermore, fingerprints tend to have patterns depending on the type of finger (e.g., index finger, middle finger) depending on race or ethnicity. Therefore, the central position of the fingerprint in this disclosure is not limited to the literal central position of the fingerprint pattern, but may be defined for each type of fingerprint (pattern). In such cases, the processor 21 may perform pattern estimation based on the fingerprint pattern captured in the fingerprint image, and then detect the central position of the fingerprint defined based on the estimated pattern. Known techniques may be used for this pattern estimation method. Also, for example, if the biometric data correction system 100 is used in a place where the user's race, genes, or nationality can be obtained using an identification document such as a passport, such as a hospital, airport, or port, the processor 21 may perform pattern estimation using the obtained user's race, genes, or nationality.

[0036] The processor 21 calculates the confidence level (detection confidence level) of the detected center position of the fingerprint (St13). The processor 21 determines whether the calculated detection confidence level is above a threshold (St13). Note that known techniques may be used for the detection confidence level calculation process. Furthermore, the calculation and determination processes for the detection confidence level of the center position of the fingerprint (step St13) are not mandatory processes and may be omitted.

[0037] If the processor 21 determines that the calculated detection confidence level is below a threshold (St13, NO), it determines that it is difficult to generate an authentication fingerprint image suitable for fingerprint authentication through correction, and omits the fingerprint image correction process. The processor 21 then performs fingerprint authentication by comparing the uncorrected fingerprint image IMG11 with the registered fingerprint image (St17).

[0038] On the other hand, if the processor 21 determines that the calculated detection confidence level is above a threshold (St13, YES), it starts correcting (converting) the fingerprint image IMG11 in order to generate an authentication fingerprint image IMG12, which is an image of the fingerprint taken from the front, in which the center position Pt11 of the fingerprint is captured at the approximate center position Pt12 of the field of view.

[0039] The processor 21 calculates control points (hereinafter referred to as "correction control points") that transform the pixels of the entire fingerprint image IMG11. The processor 21 performs spline interpolation (specifically, Thin Plate Spline (TPS processing)) based on the center position Pt11 of the fingerprint relative to both ends of the X-axis and Y-axis directions of the fingerprint image IMG11 (the peripheral parts of the field of view of the fingerprint image IMG11). The processor 21 calculates each of the multiple correction control points (St14). The number of correction control points may be arbitrary.

[0040] For example, in the example shown in Figure 4, the processor 21 performs spline interpolation based on the position of the center position Pt11 of the fingerprint relative to both ends of the fingerprint image IMG11 in the X-axis and Y-axis directions (the field of view of the fingerprint image IMG11). By performing spline interpolation, the processor 21 calculates a total of 100 correction control points Cn01A to Cn100A, with the center position Pt11 of the fingerprint as the center, and five points each extending from the center position Pt11 toward both ends in the X-axis and Y-axis directions.

[0041] The processor 21 corrects the fingerprint center position so that the center position Pt11 of the fingerprint becomes the center position Pt12 of the fingerprint image IMG11 (i.e., the field of view) (St15). The processor 21 corrects each of the multiple correction control points Cn01A to Cn100A so that they are arranged at equal intervals at both ends of the X-axis and Y-axis directions, with the center position Pt12 as the center. The processor 21 generates the authentication fingerprint image IMG12 by performing a process to smoothly transform the position of each pixel included in the fingerprint image IMG11 so that the pixels at each coordinate of the correction control points Cn01A to Cn100A are located at the respective coordinates of the correction control points Cn01B to Cn100B after they have been arranged at equal intervals (St16).

[0042] For example, in the example shown in Figure 4, each of the correction control points Cn01A to Cn100A is the correction control point before correction. Each of the correction control points Cn01B to Cn100B is the correction control point after correction. The processor 21 corrects (transforms) the pixels corresponding to the coordinates of correction control points Cn01A to Cn100A to the coordinate positions of correction control points Cn01B to Cn100B, respectively. Note that the same code is assigned to each correction control point, except for the letter at the end, in order to make it easier to understand the positional relationship of the correction control points that changes before and after correction.

[0043] By performing this correction process, the processor 21 can correct a fingerprint image IMG11, which was captured when the angle of the fingertip FN11 (fingerprint PTN11) was not approximately parallel to the image sensor of the imaging unit 13, into an authentication fingerprint image IMG12 in which the center position Pt11 of the fingerprint PTN11 is corrected to the center position Pt12 of the fingerprint image IMG11. As shown in Figure 5, the authentication fingerprint image IMG12 obtained by the correction is an image in which the fingertip FN12 is captured from the front and the fingerprint PTN12 is captured at the center position Pt12 of the fingerprint image IMG11.

[0044] The processor 21 performs fingerprint authentication by comparing the generated authentication fingerprint image IMG12 with the registered fingerprint image (St17). The processor 21 outputs the authentication result to the monitor 24 (St18).

[0045] As a result, the correction device P2 in Embodiment 1 can correct the orientation of the finger (fingerprint) by extracting the fingerprint region from the captured image and generating a fingerprint image IMG11. Furthermore, the correction device P2 corrects the orientation and angle of the finger by generating an authentication fingerprint image IMG12 in which the center position Pt11 of the fingerprint has been corrected, and can obtain an authentication fingerprint image IMG12 that appears as if the pad of the finger was captured in a state where it was approximately parallel to the image sensor of the imaging unit 13. In summary, the correction device P2 can more effectively suppress the decrease in matching accuracy in fingerprint authentication by generating an authentication fingerprint image IMG12 in which the center position of the fingerprint captured in the fingerprint image IMG11 has been corrected.

[0046] Furthermore, as described above, the correction device P2 in Embodiment 1 performs correction processing for each fingerprint image. Therefore, by capturing fingerprints from multiple fingers together, the correction device P2 can generate authentication fingerprint images IMG12 for each finger from a single captured image, even if there are variations in the orientation and angle of fingerprints due to the individuality of the user's fingers (e.g., distortion of each finger) or the way the fingers are held. Thus, even when fingerprints from multiple fingers are captured together, the correction device P2 can more effectively suppress the decrease in matching accuracy in fingerprint authentication.

[0047] (Embodiment 2) The first embodiment of the biometric data correction system 100 described an example in which the correction device P2 performs correction of the fingerprint image, registration of the registered fingerprint image, and fingerprint authentication. The second embodiment of the biometric data correction system 100A described below describes an example in which the device that performs correction of the fingerprint image (correction device P2A) and the device that performs registration of the registered fingerprint image and fingerprint authentication (authentication device P2B) are each configured as separate components.

[0048] The biodata correction system 100A according to Embodiment 2 has the same configuration and functions as the biodata correction system 100 according to Embodiment 1. Therefore, in the following description of Embodiment 2, the same configuration and functions as those of the biodata correction system 100 according to Embodiment 1 will not be described.

[0049] The biodata correction system 100A according to Embodiment 2 will be described with reference to Figures 6 and 7, respectively. Figure 6 is a diagram showing an example of the overall configuration of the biodata correction system 100A according to Embodiment 2. Figure 7 is a block diagram showing an example of the internal configuration of the biodata correction system 100A according to Embodiment 2.

[0050] In Embodiment 2, the biometric data correction system 100A generates a fingerprint image used for fingerprint authentication by correcting the captured image taken by the fingerprint acquisition device P1 with the correction device P2A. The biometric data correction system 100A then performs fingerprint authentication using the authenticated fingerprint image with the authentication device P2B.

[0051] The biometric data correction system 100A includes, as an example, a fingerprint acquisition device P1, a correction device P2A, an authentication device P2B, a registered fingerprint database DB, and a network NW. Note that the configuration of the biometric data correction system 100A shown in Figures 6 and 7 is an example and is not limited thereto.

[0052] The correction device P2A is connected to the fingerprint acquisition device P1 and the authentication device P2B via wired or wireless communication to perform data transmission and reception. The correction device P2A generates an authentication fingerprint image for use in fingerprint authentication and transmits it to the authentication device P2B. The correction device P2A includes a communication unit 20A, a processor 21A, a memory 22, and a fingerprint acquisition unit 23.

[0053] The communication unit 20A is connected to the fingerprint acquisition device P1 and the authentication device P2B via wireless or wired communication, respectively. The communication unit 20 transmits various data or information received from the processor 21 to the fingerprint acquisition device P1 or the authentication device P2B. The communication unit 20 also outputs various data (e.g., captured images) or information received from the fingerprint acquisition device P1 or the authentication device P2B to the processor 21.

[0054] The processor 21A is configured using, for example, a CPU, FPGA, or GPU, and works in cooperation with the memory 22 to perform various processes and controls. Specifically, the processor 21 refers to the programs and data held in the memory 22 and executes those programs to realize the functions of each part. These parts refer to functions such as the correction unit 211. Furthermore, the method of correcting the fingerprint image IMG11 by the processor 21A is the same as the operating procedure of the correction device P2 described with reference to Figures 3 to 5, so the explanation is omitted.

[0055] The authentication device P2B is connected to the correction device P2A via wired or wireless connection to perform data transmission and reception. The authentication device P2B performs biometric authentication by generating a fingerprint image IMG11 or authentication fingerprint image IMG12 for use in fingerprint authentication. The authentication device P2B includes a communication unit 30, a processor 31, a memory 32, and a monitor 33. In addition to biometric authentication using the authentication fingerprint image IMG12, the authentication device P2B may also be capable of registering the authentication fingerprint image IMG12 as a registered fingerprint image in a registered fingerprint database DB.

[0056] The communication unit 30 is connected to the authentication device P2B via wireless or wired communication. The communication unit 30 transmits various data or information received from the processor 31 to the authentication device P2B. The communication unit 30 also outputs various data (for example, fingerprint image IMG11 or authentication fingerprint image IMG12) or information received from the authentication device P2B to the processor 31.

[0057] The processor 31 is configured using, for example, a CPU, FPGA, or GPU, and works in cooperation with the memory 32 to perform various processes and controls. Specifically, the processor 31 refers to the programs and data held in the memory 32 and executes those programs to realize the functions of each part. These parts include, for example, the registration unit 311 and the authentication unit 312.

[0058] The registration unit 311 can perform the same functions as the registration unit 212 and performs the registration (storage) of fingerprint images of users whose fingerprint images used for biometric authentication have not yet been registered. When the registration unit 311 performs fingerprint image registration, it acquires the authentication fingerprint image IMG12 transmitted from the correction device P2A and registers (stores) it in the registered fingerprint database DB as a registered fingerprint image used for biometric authentication.

[0059] The authentication unit 312 can perform the same functions as the authentication unit 213 and acquires the authentication fingerprint image IMG12 transmitted from the correction device P2A. The authentication unit 312 compares the authentication fingerprint image IMG12 with at least one registered fingerprint image registered in the registered fingerprint database DB and performs fingerprint authentication. The authentication unit 312 outputs the authentication result to the monitor 33. Note that the destination for sending and outputting the authentication result is not limited to the example described above.

[0060] Memory 32 includes, for example, RAM as work memory used when executing each process of the processor 31, and ROM which stores programs and data that define the operation of the processor 31. Data or information generated or acquired by the processor 31 is temporarily stored in RAM. Programs that define the operation of the processor 31 are written in ROM. Memory 32 also stores various data, software, and programs for realizing functions such as the authentication unit 213.

[0061] The monitor 33 is configured using, for example, an LCD or an organic EL display. The monitor 33 outputs and displays various screens that notify the fingerprint image IMG11, the authentication fingerprint image IMG12, or the authentication result from the authentication unit 213.

[0062] The network NW performs the transmission and reception of data between the fingerprint acquisition device P1 and the correction device P2A.

[0063] As described above, the biometric data correction system 100A according to Embodiment 2 enables biometric authentication using a corrected authentication fingerprint image IMG12, even when, for example, the owner of the authentication device P2B that performs fingerprint authentication and the owner of the correction device P2A that corrects the fingerprint image are different people.

[0064] (Note) Based on the descriptions of the embodiments described above, the following technologies are disclosed.

[0065] (Technology 1) An acquisition unit (processor 21, 21A) acquires a fingerprint image IMG11 of a fingerprint captured in a non-contact state, A detection unit (processor 21, 21A) detects the first central position (central position Pt11) of the fingerprint captured in the fingerprint image IMG11, A calculation unit (processor 21, 21A) calculates a plurality of correction control points that correct the first center position (center position Pt11) of the fingerprint to the second center position (center position Pt12) of the fingerprint image IMG11 based on the first center position (center position Pt11) of the fingerprint with respect to the field of view of the fingerprint image IMG11, The system includes a correction unit (processor 21, 21A) that outputs a corrected image (authentication fingerprint image IMG12) in which the coordinates of pixels on the fingerprint image IMG11 are corrected based on the plurality of correction control points, Biological data correction device (Correction device P2, P2A). As a result, the correction devices P2 and P2A can correct the angle of the finger (fingerprint) by generating an authentication fingerprint image IMG12 with the center position Pt11 of the fingerprint corrected, and obtain an authentication fingerprint image IMG12 that appears as if the pad of the finger was captured in a state where it was approximately parallel to the image sensor of the imaging unit 13. Therefore, by generating an authentication fingerprint image IMG12 with the center position of the fingerprint captured in the fingerprint image IMG11 corrected, the correction devices P2 and P2A can more effectively suppress the decrease in matching accuracy in fingerprint authentication.

[0066] (Technology 2) The aforementioned detection unit (processor 21, 21A) The reliability of the first central position (central position Pt11) of the aforementioned fingerprint is calculated. If it is determined that the calculated confidence level is above a threshold, the calculation unit (processor 21, 21A) and the correction unit (processor 21, 21A) are instructed to generate the corrected image (authentication fingerprint image IMG12). If it is determined that the calculated confidence level is not equal to or greater than the threshold, the generation of the corrected image (authentication fingerprint image IMG12) is omitted, and the fingerprint image IMG11 is output. (Technology 1) Biometric data correction device (correction device P2, P2A). As a result, the correction devices P2 and P2A can more effectively suppress the decrease in correction accuracy and fingerprint authentication accuracy by determining whether or not to perform the correction process based on the reliability of the detected center position Pt11 of the fingerprint.

[0067] (Technology 3) The acquisition unit (processor 21, 21A) acquires an image of at least one fingertip, and extracts a region including the first joint of the fingertip from the acquired image to acquire the fingerprint image IMG11 for each finger. A biological data correction device (correction device P2, P2A) as described in (Technology 1) or (Technology 2). As a result, correction devices P2 and P2A can acquire a fingerprint image of only one fingertip (fingerprint) from an image captured from multiple fingertips (fingerprints) simultaneously. Furthermore, correction devices P2 and P2A can correct the orientation of the fingerprint by extracting the fingerprint region from the captured image and generating a fingerprint image IMG11.

[0068] (Technology 4) The detection unit (processor 21, 21A) estimates the pattern of the fingerprint and detects the first central position (central position Pt11) of the fingerprint based on the estimated pattern. A biological data correction device (correction device P2, P2A) described in any one of (Technology 1) to (Technology 3). As a result, the correction devices P2 and P2A can improve the detection accuracy of the fingerprint's central position Pt11. Therefore, the correction devices P2 and P2A can correct the correction accuracy of the fingerprint image IMG11, that is, the angle of the finger (fingerprint), with higher precision, and thus generate an authentication fingerprint image IMG12 that is more suitable for fingerprint authentication.

[0069] (Technology 5) A method for correcting biometric data performed by at least one processor (processors 21, 21A), A fingerprint image IMG11 of a fingerprint captured in a non-contact state is obtained. The first central position (central position Pt11) of the fingerprint captured in the fingerprint image IMG11 is detected. Based on the first center position (center position Pt11) of the fingerprint relative to the field of view of the fingerprint image IMG11, a plurality of correction control points are calculated to correct the first center position (center position Pt11) of the fingerprint to the second center position (center position Pt12) of the fingerprint image IMG11. Based on the aforementioned multiple correction control points, a corrected image (authentication fingerprint image IMG12) is output, in which the coordinates of pixels on the fingerprint image IMG11 have been corrected. Methods for correcting biological data. As a result, the correction devices P2 and P2A can correct the angle of the finger (fingerprint) by generating an authentication fingerprint image IMG12 with the center position Pt11 of the fingerprint corrected, and obtain an authentication fingerprint image IMG12 that appears as if the pad of the finger was captured in a state where it was approximately parallel to the image sensor of the imaging unit 13. Therefore, by generating an authentication fingerprint image IMG12 with the center position of the fingerprint captured in the fingerprint image IMG11 corrected, the correction devices P2 and P2A can more effectively suppress the decrease in matching accuracy in fingerprint authentication.

[0070] (Technology 6) An imaging device (fingerprint acquisition device P1) that captures the fingerprint of a person to be authenticated (user) in a non-contact state, A biometric data correction system 100, 100A comprising correction devices P2, P2A that can communicate with the imaging device (fingerprint acquisition device P1), The aforementioned imaging device (fingerprint acquisition device P1) The captured image, in which at least one fingertip is captured, is transmitted to the correction devices P2 and P2A. The correction devices P2 and P2A are, The region including the first joint of the fingertip (fingerprint region) is extracted from the captured image to generate the fingerprint image IMG11 of the fingerprint. The first central position (central position Pt11) of the fingerprint captured in the fingerprint image IMG11 is detected. Based on the first center position (center position Pt11) of the fingerprint relative to the field of view of the fingerprint image IMG11, a plurality of correction control points are calculated to correct the first center position (center position Pt11) of the fingerprint to the second center position (center position Pt12) of the fingerprint image IMG11. Based on the aforementioned multiple correction control points, a corrected image (authentication fingerprint image IMG12) is output, in which the coordinates of pixels on the fingerprint image IMG11 have been corrected. Biological data correction system 100, 100A. As a result, the biometric data correction system 100, 100A can correct the angle of the finger (fingerprint) by generating an authentication fingerprint image IMG12 with the center position Pt11 of the fingerprint corrected, and obtain an authentication fingerprint image IMG12 that appears as if the pad of the finger was captured in a state where it was approximately parallel to the image sensor of the imaging unit 13. Therefore, by generating an authentication fingerprint image IMG12 with the center position of the fingerprint captured in the fingerprint image IMG11 corrected, the biometric data correction system 100, 100A can more effectively suppress the decrease in matching accuracy in fingerprint authentication.

[0071] Although various embodiments have been described above with reference to the attached drawings, this disclosure is not limited to such examples. It will be clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents can be conceived within the scope of the claims, and these will also be understood to fall within the technical scope of this disclosure. Furthermore, the components of the various embodiments described above can be combined arbitrarily without departing from the spirit of the invention. [Industrial applicability]

[0072] This disclosure is useful as a presentation of a biometric data correction device, a biometric data correction method, and a biometric data correction system for correcting the angles of biological parts included in biological images acquired in free space. [Explanation of Symbols]

[0073] 10, 20, 20A, 30 Communications Department 11,21,21A,31 processors 12,22,32 memory 13 Imaging Unit 23 Fingerprint acquisition section 24,33 monitors 100,100A Biometric Data Correction System 211 Correction Unit 212,311 Registration Department 213,312 Authentication Department Cn01A, Cn01B Correction control points Cn100A, Cn100B Correction control points DB Registered Fingerprint Database FN11,FN12 Fingertips IMG11 Fingerprint Image IMG12 Authentication Fingerprint Image NW Network P1 Fingerprint acquisition device P2,P2A correction device P2B Authentication Device Pt11,Pt12 center position PTN11,PTN12 Fingerprint

Claims

1. An acquisition unit that acquires a fingerprint image of a fingerprint captured in a non-contact state, A detection unit for detecting the first central position of the fingerprint captured in the fingerprint image, A calculation unit calculates a plurality of correction control points that correct the first center position of the fingerprint to the second center position of the fingerprint image based on the first center position of the fingerprint relative to the field of view of the fingerprint image, The system includes a correction unit that outputs a corrected image in which the coordinates of pixels on the fingerprint image are corrected based on the plurality of correction control points, Biological data correction device.

2. The detection unit is The reliability of the first central position of the aforementioned fingerprint is calculated, If it is determined that the calculated confidence level is equal to or greater than the threshold, the calculation unit and the correction unit are instructed to generate the corrected image. If it is determined that the calculated confidence level is not equal to or greater than the threshold, the generation of the corrected image is omitted and the fingerprint image is output. The biological data correction device according to claim 1.

3. The acquisition unit acquires an image of at least one fingertip, and extracts a region including the first joint of the fingertip from the acquired image to acquire a fingerprint image for each finger. The biological data correction device according to claim 1.

4. The detection unit estimates the pattern of the fingerprint and detects the first central position of the fingerprint based on the estimated pattern. The biological data correction device according to claim 1.

5. A method for correcting biometric data performed by at least one processor, A fingerprint image of a fingerprint captured in a non-contact manner is obtained. The first central position of the fingerprint captured in the fingerprint image is detected, Based on the first center position of the fingerprint relative to the field of view of the fingerprint image, a plurality of correction control points are calculated to correct the first center position of the fingerprint to the second center position of the fingerprint image. Based on the aforementioned plurality of correction control points, a corrected image is output in which the coordinates of pixels on the fingerprint image have been corrected. Methods for correcting biological data.

6. An imaging device that captures the fingerprint of a person being authenticated in a non-contact state, A biological data correction system comprising a correction device capable of communicating with the imaging device, The imaging device is The captured image, in which at least one fingertip is captured, is transmitted to the correction device. The correction device is, A region including the first joint of the fingertip is extracted from the captured image to generate a fingerprint image of the fingerprint. The first central position of the fingerprint captured in the fingerprint image is detected, Based on the first center position of the fingerprint relative to the field of view of the fingerprint image, a plurality of correction control points are calculated to correct the first center position of the fingerprint to the second center position of the fingerprint image. Based on the aforementioned plurality of correction control points, a corrected image is output in which the coordinates of pixels on the fingerprint image have been corrected. Biological data correction system.

Images