Authentication device, authentication method, and recording medium

Abstract

An authentication device according to the present invention includes: a face image acquisition means for acquiring a face image of a subject; an age information acquisition means for acquiring age information on the age of the subject; an authentication means for performing face authentication of the subject using the face image and a registered face image that is registered; a determination means for determining a first period related to updating of the registered face image on the basis of the age information; and an updating means for updating the registered face image when an authentication score related to the face authentication by the authentication means is equal to or less than a predetermined updating threshold in the first period.

Description

Authentication device, authentication method, and recording medium

[0001] The present disclosure relates to the technical fields of an authentication device, an authentication method, and a recording medium.

[0002] It is known that in an authentication device that performs face authentication, registered face images are updated in predetermined cases. Patent Document 1 discloses that, when authentication of a person to be authenticated fails, it is recommended to update biometric information stored in a database.

[0003] International Publication No. 2021 / 255821

[0004] The present disclosure aims to provide an authentication device, an authentication method, and a recording medium that improve upon the techniques disclosed in prior art documents.

[0005] One aspect of the authentication device includes a facial image acquisition means for acquiring a facial image of a subject, an age information acquisition means for acquiring age information related to the age of the subject, an authentication means for performing facial authentication of the subject using the facial image and a registered facial image, a determination means for determining a first period for updating the registered facial image based on the age information, and an update means for updating the registered facial image if, during the first period, an authentication score related to facial authentication by the authentication means is equal to or less than a predetermined update threshold.

[0006] One aspect of the authentication method is an authentication method performed by an authentication device that includes a facial image acquisition means for acquiring a facial image of a subject, and an authentication means for performing facial authentication of the subject using the facial image and a registered facial image, wherein age information regarding the age of the subject is acquired, a first period for updating the registered facial image is determined based on the age information, and if, during the first period, an authentication score regarding facial authentication by the authentication means is equal to or less than a predetermined update threshold, the registered facial image is updated.

[0007] One aspect of the recording medium is an authentication method executed by an authentication device that includes a facial image acquisition means that acquires a facial image of a subject, and an authentication means that performs facial authentication of the subject using the facial image and a registered facial image.The recording medium has recorded thereon a computer program that causes a computer to execute the authentication method, which acquires age information regarding the age of the subject, determines a first period for updating the registered facial image based on the age information, and updates the registered facial image if the authentication score regarding facial authentication by the authentication means is equal to or less than a predetermined update threshold during the first period.

[0008] FIG. 1 is a block diagram showing an example of a configuration of an authentication device according to the present disclosure. FIG. 2 is a flowchart showing an example of an authentication operation of the authentication device according to the present disclosure. FIG. 3 is a block diagram showing an example of a configuration of an authentication device according to the present disclosure. FIG. 4 is a flowchart showing an example of an authentication operation of the authentication device according to the present disclosure. FIG. 5 is a conceptual diagram showing an example of an authentication operation of the authentication device according to the present disclosure. FIG. 6 is a conceptual diagram showing an example of an authentication operation of the authentication device according to the present disclosure. FIG. 7 is a block diagram showing an example of a configuration of an authentication device according to the present disclosure. FIG. 8 is a flowchart showing an example of an authentication operation of the authentication device according to the present disclosure. FIG. 9 is a block diagram showing an example of a configuration of an authentication device according to the present disclosure. FIG. 10 is a conceptual diagram showing an example of an authentication operation of the authentication device according to the present disclosure.

[0009] Hereinafter, an embodiment of an authentication device, an authentication method, and a recording medium will be described with reference to the drawings. [1: First Embodiment]

[0010] A first embodiment of an authentication device, an authentication method, and a recording medium will be described. Hereinafter, the first embodiment of an authentication device, an authentication method, and a recording medium will be described using an authentication device 1 according to this disclosure. [1-1: Configuration of Authentication Device 1]

[0011] The configuration of an authentication device 1 according to this disclosure will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of an authentication device 1 according to this disclosure.

[0012] 1, the authentication device 1 includes a computing device 11, a storage device 12, and a communication device 13. The computing device 11, the storage device 12, and the communication device 13 may be connected via a data bus 16.

[0013] The arithmetic device 11 includes at least one processor (i.e., one processor or multiple processors) as hardware. The processor may include, for example, a processor conforming to a von Neumann computer architecture. The processor conforming to the von Neumann computer architecture may include at least one of a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processor may include, for example, a processor conforming to a non-von Neumann computer architecture. The processor conforming to the non-von Neumann computer architecture may include at least one of an FPGA (Field Programmable Gate Array) and an ASIC (Application Specific Circuit).

[0014] The arithmetic device 11 reads a computer program 121 including at least one of computer program code and computer program instructions. For example, the arithmetic device 11 may read the computer program 121 stored in the storage device 12. For example, the arithmetic device 11 may read the computer program 121 stored in a computer-readable, non-transitory storage medium using a storage medium reading device (not shown) included in the authentication device 1. The computer program 121 read from the storage medium may be stored in the storage device 12. The arithmetic device 11 may acquire (i.e., download or read) the computer program 121 from a device (not shown) located outside the authentication device 1 via the communication device 13 (or another communication device). The downloaded computer program 121 may be stored in the storage device 12.

[0015] The arithmetic device 11 executes the loaded computer program 121. As a result, a logical functional block for executing the processing to be performed by the authentication device 1 (e.g., the authentication processing described below) is realized within the arithmetic device 11. In other words, the arithmetic device 11, together with the storage device 12 in which the computer program 121 is recorded (in other words, together with the storage device 12 and the computer program 121 recorded in the storage device 12), can function as a controller or computer for realizing the logical functional block for executing the processing to be performed by the authentication device 1. In other words, the at least one processor included in the arithmetic device 11, the memory (recording medium) included in the storage device 12, and the computer program 121 are configured so that the authentication device 1 performs the processing to be performed by the authentication device 1 (e.g., the authentication processing described below). The arithmetic device 11 may output information to another computer, cloud server, or other device (not shown) provided outside the authentication device 1 via the communication device 13 (or another communication device).

[0016] The recording medium for recording the computer program 121 executed by the arithmetic device 11 may be at least one of a CD-ROM, CD-R, CD-RW, flexible disk, MO, DVD-ROM, DVD-RAM, DVD-R, DVD+R, DVD-RW, DVD+RW, and Blu-ray (registered trademark) optical disk, magnetic medium such as magnetic tape, magneto-optical disk, semiconductor memory such as USB memory, and any other medium capable of storing a program. The recording medium may include a device capable of recording the computer program 121 (for example, a general-purpose device or a dedicated device in which the computer program 121 is implemented in a state in which it can be executed in at least one of the forms of software and firmware). Furthermore, each process or function included in the computer program 121 may be realized by a logical processing block realized within the arithmetic device 11 when the arithmetic device 11 (i.e., processor) executes the computer program 121, or may be realized by hardware such as a predetermined gate array (FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit)) included in the arithmetic device 11, or may be realized in a form that mixes logical processing blocks and partial hardware modules that realize some elements of the hardware.

[0017] 1 shows an example of logical functional blocks implemented in the arithmetic device 11 to execute the authentication process. As shown in Fig. 1, the arithmetic device 11 implements a face image acquisition unit 111, an age information acquisition unit 112, an authentication unit 113, a determination unit 114, and an update unit 115. The processes performed by the face image acquisition unit 111, the age information acquisition unit 112, the authentication unit 113, the determination unit 114, and the update unit 115 will be described later with reference to Fig. 2.

[0018] The storage device 12 includes at least one memory capable of storing desired data. In other words, the storage device 12 includes at least one memory containing desired data. For example, the storage device 12 may store a computer program 121 executed by the arithmetic device 11. In this case, the storage device 12 (memory) may be used as the above-mentioned recording medium for recording the computer program 121 executed by the arithmetic device 11. The storage device 12 may temporarily store data used by the arithmetic device 11 when the arithmetic device 11 is executing the computer program 121. The storage device 12 may also store data to be stored long-term by the authentication device 1. The storage device 12 may include at least one of a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk device, a magneto-optical disk device, an SSD (Solid State Drive), and a disk array device. In other words, the storage device 12 may include a non-transitory recording medium.

[0019] The communication device 13 can communicate with devices external to the authentication device 1 via a communication network (not shown). The communication device 13 may be a communication interface based on standards such as Ethernet (registered trademark), Wi-Fi (registered trademark), Bluetooth (registered trademark), or USB (Universal Serial Bus). [1-2: Authentication Method Executed by the Authentication Device 1]

[0020] The authentication method executed by the authentication device 1 will be described with reference to Fig. 2. Fig. 2 is a flowchart showing an example of the flow of the authentication method executed by the authentication device 1.

[0021] 2, the face image acquisition unit 111 acquires a face image of the subject (step S11). The age information acquisition unit 112 acquires age information related to the age of the subject (step S12). The authentication unit 113 performs face authentication of the subject using the face image and a registered face image (step S13).

[0022] The determination unit 114 determines a first period for updating the registered face image based on the age information (step S14). If the authentication score related to face authentication by the authentication unit 113 during the first period is equal to or less than a predetermined update threshold, the update unit 115 updates the registered face image (step S15). The authentication score indicates the degree of similarity between the face image and the registered face image. The higher the authentication score, the more similar the face image and the registered face image are. [1-3: Technical Effects of Authentication Device 1]

[0023] The authentication device 1 according to this disclosure determines the period for updating the registered face image based on age information, and can therefore update the registered face image of the subject in the update period appropriate for the subject's age. The authentication device 1 updates the registered face image of the subject when the authentication score falls below a threshold in the update period appropriate for the subject. In other words, the authentication device 1 can update the registered face image of the subject when the desired degree of similarity between the face image of the subject and the registered face image is no longer achieved. The authentication device 1 capable of performing such operations can permanently perform appropriate face authentication. [2: Second Embodiment]

[0024] A second embodiment of an authentication device, an authentication method, and a recording medium will be described below. The second embodiment of the authentication device, the authentication method, and the recording medium will be described below using the authentication device 2 according to this disclosure. The authentication operation in this embodiment may be applied to various situations where identity verification is required, such as entering and exiting a restricted area, unlocking a door, making a payment, etc. [2-1: Configuration of the authentication device 2]

[0025] The configuration of the authentication device 2 according to this disclosure will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the configuration of the authentication device 2 according to this disclosure.

[0026] 3, the authentication device 2 may further include an input device 14 and an output device 15 in addition to the calculation device 11, the storage device 12, and the communication device 13. However, the authentication device 2 may not include at least one of the input device 14 and the output device 15. The calculation device 11, the storage device 12, the communication device 13, the input device 14, and the output device 15 may be connected via a data bus 16.

[0027] The input device 14 is a device that accepts information input to the authentication device 2 from outside the authentication device 2. For example, the input device 14 may include an operation device (e.g., at least one of a keyboard, a mouse, and a touch panel) that can be operated by an operator of the authentication device 2. For example, the input device 14 may include a reading device that can read information recorded as data on a recording medium that can be attached externally to the authentication device 2.

[0028] The output device 15 is a device that outputs information to the outside of the authentication device 2. For example, the output device 15 may output information as an image. That is, the output device 15 may include a display device (a so-called display) that can display an image showing the information to be output. For example, the output device 15 may output information as sound. That is, the output device 15 may include an audio device (a so-called speaker) that can output sound. For example, the output device 15 may output information on paper. That is, the output device 15 may include a printing device (a so-called printer) that can print desired information on paper. [2-2: Operations Executed by the Authentication Device 2]

[0029] Before the authentication operation is performed by the authentication device 2, the subject registers registration information including the subject's facial image in the registration information database. The registration information database may be realized, for example, in the storage device 12. Furthermore, if the subject is under a predetermined age, the subject's guardian may register the registration information in the registration information database. The registration information may include age information indicating the subject's age, contact information such as an email address, payment information such as a credit card used for payment, etc.

[0030] The authentication method executed by the authentication device 2 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the flow of the authentication method executed by the authentication device 2.

[0031] 4, when a request for face authentication is received (step S20: Yes), the authentication device 2 starts operation. For example, if the subject wants to purchase a product, the authentication device 2 may receive a request for face authentication when the subject decides on the product to purchase and confirms the presented payment amount. [2-2-1: Face Authentication]

[0032] The facial image acquisition unit 211 acquires a facial image of the subject (step S21). The facial image acquisition unit 211 may acquire the facial image by photographing. The authentication device 2 may activate a camera installed therein, and the facial image acquisition unit 211 may acquire the facial image of the subject photographed by the camera. Furthermore, if the authentication device 2 and a device operated by the subject (for example, a terminal device carried by the subject) are separate devices, the facial image acquisition unit 211 may acquire the facial image photographed by the camera of the terminal device via communication.

[0033] The authentication unit 213 performs face authentication of the subject using the face image and the registered face image (step S22). The authentication unit 213 determines whether face authentication of the subject has been successful (step S23). The authentication unit 213 determines that face authentication has been successful when the authentication score exceeds a predetermined face authentication threshold. In other words, the authentication unit 213 determines whether the authentication score exceeds the predetermined face authentication threshold.

[0034] If the authentication score exceeds a predetermined facial authentication threshold (step S23: Yes), an operation desired by the subject, such as payment, is executed. If the authentication score does not exceed a predetermined facial authentication threshold (step S23: No), the authentication operation ends. In this case, the facial image acquisition unit 211 may acquire a facial image again, and the authentication unit 213 may perform facial authentication again. Note that if the subject wishes to make a payment, the authentication device 2 will not execute the payment operation until facial authentication is successful. [2-2-2: Determination of First Period and Second Period]

[0035] The age information acquisition unit 212 acquires age information related to the age of the subject (step S24). The determination unit 214 may acquire age information by age estimation using the acquired face image. Note that when estimating age, it is not necessary to estimate the actual age. For example, if the face is likely to change easily, an age lower than the actual age may be estimated. Also, if the face is unlikely to change, an age higher than the actual age may be estimated. In this embodiment, when to update the registered face image is determined based on age, but age is used as an index of facial changeability. Therefore, accurate age is not necessarily required. Therefore, it is sufficient to estimate an age that is useful as an index of facial changeability.

[0036] Alternatively, the age information acquisition unit 212 may acquire registered age information. The age information may be information indicating the subject's date of birth. In this case, the age information acquisition unit 212 calculates the subject's age from the date of birth and the current date. Alternatively, the age information acquisition unit 212 may acquire registered age information in addition to estimating the subject's age.

[0037] The determination unit 214 determines a first period and a second period for updating the registered face image based on the age information (step S25). First, the determination unit 214 determines the necessary time for updating the registered face image of the subject based on the age information. For example, if the subject is of legal age or older, the necessary time may be determined to be five years after the last update of the registered face image. Alternatively, if the subject is under legal age, i.e., a minor, the necessary time may be determined to be three years after the last update of the registered face image. The necessary time for updating the registered face image may be considered to be the time when face authentication cannot be performed properly. The inability to perform face authentication properly includes a case where the registered face image and the currently acquired face image are no longer similar to each other, even though the face image is the subject's face image.

[0038] Furthermore, age groups may be set more precisely, and the necessary period may be determined according to the set age group. For example, a table as shown in FIG. 5 may be prepared in advance, associating age groups with the validity periods of registered face images. The determination unit 214 may refer to the table to determine which age group the subject falls into and how long the registered face image is valid. In the example shown in FIG. 5, for example, if the subject is 12 years old or younger, the necessary period may be determined to be one year after the last update of the registered face image. If the subject is 13 to 15 years old, the necessary period may be determined to be two years after the last update of the registered face image. If the subject is 16 to 18 years old, the necessary period may be determined to be three years after the last update of the registered face image. If the subject is 19 to 22 years old, the necessary period may be determined to be four years after the last update of the registered face image. If the subject is 23 years old or older, the necessary period may be determined to be five years after the last update of the registered face image.

[0039] Next, the determination unit 214 determines a period before the determined necessary time as the first period. Also, the determination unit 214 determines a period after the determined necessary time as the second period. As illustrated in Fig. 6, the determination unit 214 may determine a period from the previous update time to the necessary time as the first period. If the subject has not yet updated the registered face image, the previous update time may be the time when the registered face image was first registered.

[0040] The operation of determining the first and second periods may be performed when the registered face image is updated the previous time, and information indicating the first and second periods may be registered together with the registered face image. In this case, the determination unit 214 may acquire the registered information indicating the first and second periods in step S25. In this case, the operation of acquiring age information in step S22 may be omitted. [2-2-3: Determining Whether Registered Face Image Needs to Be Updated]

[0041] The determination unit 214 determines whether the current time belongs to the first period or the second period (step S26). For example, if the current time is current time 1 illustrated by the dashed line in Fig. 6, the current time belongs to the first period. On the other hand, if the current time is current time 2 illustrated by the dashed line in Fig. 6, the current time belongs to the second period.

[0042] If the current time falls within the first period (step S26: first period), the update unit 215 determines whether the authentication score related to face authentication by the authentication unit 213 is equal to or less than a predetermined update threshold (step S27). The predetermined update threshold is greater than the predetermined face authentication threshold. For example, if the authentication score can take values ​​from 0 to 100, the predetermined face authentication threshold may be set to 80, and the predetermined update threshold may be set to 90. These numerical values ​​are merely examples and can be set arbitrarily depending on requirements. The predetermined face authentication threshold may be set so that it can be determined that the person appearing in the face image and the person appearing in the registered face image are the same person.

[0043] If the authentication score is equal to or less than the predetermined update threshold (step S27: Yes), the update unit 215 updates the registered face image (step S28). That is, if the authentication score is equal to or less than the predetermined update threshold and exceeds the predetermined authentication threshold during the first period, the update unit 215 updates the registered face image. Using the authentication score, the authentication device 2 can not only determine whether face authentication has been successful, but also determine whether the registered face image needs to be updated.

[0044] The update unit 215 may update the registered face image with the face image acquired in step S21. Alternatively, the face image acquisition unit 211 may further acquire a face image for the registered face image and update the registered face image with the further acquired face image.

[0045] When updating the registered face image, the output unit 216 may output notification information notifying the user that the registered face image will be updated. The output unit 216 may output a guidance screen guiding the user to update the registered face image. For example, when acquiring a further face image for the registered face image, the output unit 216 may output guidance information guiding the user to acquire a further face image for the registered face image. For example, the output unit 216 may display the registered face image to be registered on a device carried by the subject.

[0046] If the authentication score exceeds the predetermined update threshold (step S27: No), the series of operations ends. In other words, if the authentication score exceeds the predetermined update threshold in the first period, the update unit 215 does not update the registered face image.

[0047] If the current time point belongs to the second period (step S26: second period), the update unit 215 updates the registered face image (step S28). That is, if the authentication score related to face authentication by the authentication unit 213 exceeds a predetermined face authentication threshold during the second period, the update unit 215 updates the registered face image.

[0048] Note that, if the authentication score is equal to or less than a predetermined face authentication threshold during the second period, the update unit 215 does not update the registered face image. That is, even during the second period, if the authentication score is equal to or less than a predetermined face authentication threshold, the update unit 215 does not update the registered face image because there is a possibility that the person is not the actual person.

[0049] When face authentication is performed, the authentication device 2 may store information indicating the time when face authentication was performed and information related to the face authentication of the subject, including the authentication score, in the storage device 12. In the embodiment described later, an operation may be performed using the information related to face authentication.

[0050] The facial recognition mechanism and the mechanism for determining the timing and period for updating may operate in parallel. In this case, too, the determination of whether to update the registered facial image is made based on the authentication score and the period determined based on age information.

[0051] Furthermore, in the above embodiment, a case where a facial image is registered has been described, but the registered information may be feature information extracted from the facial image. In this case, the authentication unit 213 extracts feature information from the acquired facial image and compares the feature information with each other. The authentication score may be, for example, a score obtained by comparing the feature information extracted from the facial image with each other. [2-3: Technical Effects of Authentication Device 2]

[0052] Facial recognition technology is used in a variety of situations where identity verification is required, such as entering and exiting restricted areas, unlocking doors, and making payments. Identity verification using facial recognition technology is often applied to children as well as adults. Here, "adults" refer to people at an age where their facial features change relatively little over time. In contrast, "children" refer to people who are in the process of growing up or who experience relatively large changes in their facial features over time.

[0053] The authentication accuracy of adult subjects is often maintained even several years after the start of facial recognition technology use. In contrast, for child subjects, changes occur in the face as they grow, and authentication accuracy may be affected within one year of starting to use facial recognition technology. Therefore, facial recognition cannot be performed permanently using the facial image registered when facial recognition technology is first used. Each time facial recognition fails, the subject must log in to the app or other device and update it.

[0054] The authentication device 2 according to this disclosure determines the period for updating the registered face image based on age information, and can therefore update the registered face image of the subject in the update period appropriate for the subject's age. The authentication device 2 updates the registered face image of the subject when the authentication score falls below a threshold in the update period appropriate for the subject. That is, the authentication device 2 can update the registered face image of the subject when the desired degree of similarity between the face image of the subject and the registered face image is no longer achieved. The authentication device 2 capable of performing such operations can permanently perform appropriate face authentication. Furthermore, the authentication device 2 outputs notification information notifying the subject that the registered face image will be updated, allowing the subject to know that the registered face image will be updated. [3: Third Embodiment]

[0055] A third embodiment of an authentication device, an authentication method, and a recording medium will be described below. The third embodiment of an authentication device, an authentication method, and a recording medium will be described below using an authentication device 3 according to this disclosure. In the third embodiment, the operation of the determination unit 314 differs from that of the second embodiment. [3-1: Authentication operation performed by authentication device 3]

[0056] 8, when a request for face authentication is received (step S20: Yes), the authentication device 3 starts operation. The face image acquisition unit 211 acquires a face image of the subject (step S21). The authentication unit 213 performs face authentication of the subject using the face image and a registered face image (step S22). The authentication unit 213 determines whether face authentication of the subject is successful (step S23).

[0057] If the authentication score exceeds a predetermined facial recognition threshold (step S23: Yes), the operation desired by the subject, such as payment, is executed. If the authentication score does not exceed a predetermined facial recognition threshold (step S23: No), the authentication operation ends. [3-1-1: Determining the First Period, Second Period, and Third Period]

[0058] The age information acquisition unit 212 acquires age information regarding the age of the subject (step S24). The determination unit 214. The determination unit 314 determines a first period, a second period, and a third period for updating the registered face image based on the age information (step S35). First, the determination unit 314 uses the age information to determine a necessary period when updating the registered face image is necessary and an unnecessary period when updating the registered face image is unnecessary. The unnecessary period is a period earlier than the necessary period. Next, as illustrated in FIG. 9, the determination unit 314 determines the period from the determined unnecessary period to the determined necessary period as the first period. Furthermore, the determination unit 314 determines the period after the determined necessary period as the second period. Furthermore, the determination unit 314 may determine the period before the determined unnecessary period as the third period. As illustrated in FIG. 9, the determination unit 314 may determine the period from the previous update period to the unnecessary period as the third period. [3-1-2: Determination of Whether or Not to Update the Registered Face Image]

[0059] The determination unit 314 determines whether the current time belongs to the first period, the second period, or the third period (step S36). If the current time belongs to the first period (step S36: first period), the update unit 215 determines whether the authentication score related to face authentication by the authentication unit 213 is equal to or less than a predetermined update threshold (step S27). If the authentication score is equal to or less than the predetermined update threshold (step S27: Yes), the update unit 215 updates the registered face image (step S28). If the authentication score exceeds the predetermined update threshold (step S27: No), the series of operations ends. If the current time belongs to the second period (step S36: second period), the update unit 215 updates the registered face image (step S28).

[0060] If the current time falls within the third period (Step S36: Third Period), the series of operations ends. In other words, if the current time is before the period when updating of the registered face image is not required, the authentication device 3 does not update the registered face image. [3-2: Technical Effects of the Authentication Device 3] The authentication device 3 according to this disclosure does not update the registered face image for a predetermined period from the time of the previous update of the registered face image, and therefore, it is possible to suppress frequent updates of the registered face image. [4: Fourth Embodiment]

[0061] A fourth embodiment of an authentication device, an authentication method, and a recording medium will be described below. The fourth embodiment of the authentication device, the authentication method, and the recording medium will be described below using the authentication device 4 according to this disclosure. In the fourth embodiment, even if the current time belongs to the third period, the registered face image is updated depending on the situation. As shown in FIG. 10 , in the fourth embodiment, an analysis unit 417 is implemented in the calculation device 11. [4-1: Operation Performed by the Authentication Device 4] As shown in FIG. 11 , when a request for face authentication is received (step S20: Yes), the authentication device 3 starts operation. The face image acquisition unit 211 acquires a face image of the subject (step S21). The authentication unit 213 performs face authentication of the subject using the face image and the registered face image (step S22). The authentication unit 213 determines whether face authentication of the subject is successful (step S23).

[0062] If the authentication score exceeds a predetermined face authentication threshold (step S23: Yes), an operation desired by the subject, such as payment, is executed. If the authentication score does not exceed the predetermined face authentication threshold (step S23: No), the authentication operation ends.

[0063] The age information acquisition unit 212 acquires age information regarding the age of the subject (step S24). The determination unit 314 determines a first period, a second period, and a third period for updating the registered face image based on the age information (step S35). First, the determination unit 314 uses the age information to determine a necessary period when updating of the registered face image is necessary and an unnecessary period when updating of the registered face image is not necessary. The unnecessary period is a period earlier than the necessary period. Next, the determination unit 314 determines the period from the determined unnecessary period to the determined necessary period as the first period. Furthermore, the determination unit 314 determines the period after the determined necessary period as the second period. Furthermore, the determination unit 314 determines the period earlier than the determined unnecessary period as the third period.

[0064] The determination unit 314 determines whether the current time belongs to the first period, the second period, or the third period (step S36). If the current time belongs to the first period (step S36: first period), the update unit 215 determines whether the authentication score related to face authentication by the authentication unit 213 is equal to or less than a predetermined update threshold (step S27). If the authentication score is equal to or less than the predetermined update threshold (step S27: Yes), the update unit 215 updates the registered face image (step S28). If the authentication score exceeds the predetermined update threshold (step S27: No), the series of operations ends. If the current time belongs to the second period (step S36: second period), the update unit 215 updates the registered face image (step S28). [Operation when the current time belongs to the third period]

[0065] If the current time point belongs to the third period (Step S36: Third Period), the update unit 415 determines whether the authentication score is equal to or less than a predetermined analysis threshold (Step S41). The predetermined analysis threshold may be the same value as the predetermined update threshold. Alternatively, the predetermined analysis threshold may be a value different from the predetermined update threshold. If the authentication score exceeds the predetermined analysis threshold (Step S41: No), the series of operations ends.

[0066] If the authentication score is equal to or less than a predetermined analysis threshold (step S41: Yes), the analysis unit 417 analyzes the fluctuation of the authentication score from past authentication scores related to past face authentication (step S42). The analysis unit 417 may analyze the fluctuation of the authentication score using, for example, information registered in the storage device 12, indicating the time when face authentication was performed and information related to the face authentication of the subject, including the authentication score.

[0067] The update unit 415 determines whether to update the registered face image based on the degree of change (step S43). That is, the update unit 415 may determine to update the registered face image even during the third period based on the degree of change. If it is determined to update the registered face image (step S43: Yes), the update unit 415 updates the registered face image (step S28).

[0068] The analysis unit 417 may output, as an analysis result of the fluctuation of the authentication score, information indicating that the authentication score is temporarily low, information indicating that the authentication score has been similarly low in the past, information indicating that the authentication score is gradually decreasing, or the like. When, for example, information indicating that the authentication score is temporarily low is output as an analysis result of the fluctuation of the authentication score, the update unit 415 may determine not to update the registered face image. For example, authentication accuracy may temporarily decrease due to external influences such as outside light. In such cases, it is highly likely that the decrease in authentication score is not caused by a change in face. Even if the authentication result is not good, such as the authentication score slightly exceeding the face recognition threshold, if the authentication score is low and not caused by a change in face, there is no need to update the registered face image.

[0069] As a result of analyzing the fluctuation of the authentication score, for example, when information indicating that the authentication score has been low in the past and information indicating that the authentication score is gradually decreasing are output, the update unit 415 may determine that the registered face image should be updated. For example, if the previously updated registered face image is a face image that is inappropriate for face authentication, the authentication score will always be low. In other words, if the authentication score is always low regardless of whether it has been a short time since the last update, there is a high possibility that the currently registered registered face image is a face image that should be updated. Furthermore, if the authentication score is gradually decreasing, there is a possibility that the authentication score will further decrease when the next face authentication is performed. For this reason, it can be determined that the registered face image should be updated even before the time when it is no longer necessary. [4-2: Modification]

[0070] If the authentication score is equal to or less than a predetermined analysis threshold during the first period, the analysis unit 417 may analyze the degree of change in the authentication score from past authentication scores related to past face authentication. In this case, the predetermined analysis threshold may be a value greater than a predetermined update threshold. If the authentication score is equal to or less than a predetermined analysis threshold and exceeds a predetermined update threshold during the first period, the analysis unit 417 may analyze the degree of change in the authentication score from past authentication scores related to past face authentication.

[0071] If the authentication score is equal to or less than a predetermined analysis threshold and exceeds a predetermined update threshold during the first period, the update unit 415 determines whether to update the registered face image based on the degree of fluctuation. For example, if the analysis unit 417 outputs information indicating a gradual decline in the authentication score as a result of analyzing the degree of fluctuation in the authentication score, there is a possibility that the authentication score will be equal to or less than the predetermined update threshold when the next face authentication is performed. Therefore, the update unit 415 may determine to update the registered face image at the current time. Note that the update unit 415 updates the registered face image when the authentication score is equal to or less than the predetermined update threshold during the first period. [4-3: Technical Effects of Authentication Device 4] The authentication device 4 according to this disclosure analyzes the degree of fluctuation in the authentication score, and therefore can update the registered face image if necessary, even if, for example, it has been a short time since the last update of the registered face image. [5: Fifth Embodiment]

[0072] A fifth embodiment of an authentication device, an authentication method, and a recording medium will be described below. The fifth embodiment of an authentication device, an authentication method, and a recording medium will be described below using an authentication device 5 according to this disclosure. The authentication device 5 further performs an operation of adjusting the timing of updating registered face images depending on the frequency of face authentication.

[0073] Specifically, as shown in Fig. 12, in the fifth embodiment, a generation unit 518 is realized in the calculation device 11. Also, the operation of step S35 shown in Figs. 8 and 11 (or step S25 shown in Fig. 4) differs from the second to fourth embodiments. In the fifth embodiment, frequency information relating to the frequency of authentication of the subject is used in addition to age information to determine whether to update the registered face image. [5-1: Operation Performed by Authentication Device 5]

[0074] The generation unit 518 generates frequency information regarding the frequency of implementation of facial authentication based on the timing of implementation of facial authentication of the subject in the past. The generation unit 518 may generate the frequency information using information indicating the timing of implementation of facial authentication, which is registered in the storage device 12, for example.

[0075] The determination unit 514 determines the necessary time based on the age information and the frequency information. For example, when the determination unit 514 determines that the subject performs face authentication infrequently based on the frequency information, the determination unit 514 may determine the necessary time to be earlier than the necessary time determined based only on the age information, as illustrated in Fig. 13. For example, when the determination unit 514 determines that the subject performs face authentication infrequently based on the frequency information and the age information indicates that the necessary time is three years after the previous update, the determination unit 514 may determine that the necessary time is two years after the previous update.

[0076] Furthermore, the determination unit 514 may determine the unnecessary period based on age information and frequency information. When the determination unit 514 determines that the subject performs face authentication infrequently based on the frequency information, the determination unit 514 may determine the unnecessary period to be earlier than the unnecessary period determined based on only the age information, as illustrated in Fig. 13. For example, when the determination unit 514 determines that the subject performs face authentication infrequently based on the frequency information and the age information indicates that the unnecessary period is two years after the previous update, the determination unit 514 may determine that the unnecessary period is one year after the previous update.

[0077] Furthermore, the determination unit 514 may determine the necessary period and the unnecessary period based on the age information and the frequency information. The determination unit 514 determines at least one of the necessary period and the unnecessary period based on the age information and the frequency information.

[0078] In the fifth embodiment, as in the fourth embodiment, if the authentication score is equal to or less than a predetermined determination threshold in the third period, the degree of change in the authentication score may be analyzed from past authentication scores related to past face authentication. That is, the authentication device 5 may perform both the operation of determining at least one of the necessary period and unnecessary period when the frequency of implementation is low, and the operation of analyzing the degree of change when the authentication score is low. [5-2: Technical Effects of the Authentication Device 5]

[0079] If the frequency of authentication is low, the next authentication may occur well after the required time. In this case, depending on the subject, the face may have changed so much that authentication is not successful. In other words, for subjects who perform facial authentication infrequently, the face may have changed significantly by the time of the next facial authentication, and facial authentication may not be successful. In particular, for young people whose faces are prone to change, there is a possibility that facial authentication will not be successful when the next facial authentication is performed.

[0080] The authentication device 5 according to this disclosure determines the necessary time using frequency information in addition to age information, and advances the update time, thereby preventing a situation in which face authentication is not successful. In other words, the authentication device 5 can update the registered face image at a time when face authentication is successful. [6: Sixth Embodiment]

[0081] A sixth embodiment of an authentication device, an authentication method, and a recording medium will be described below. The sixth embodiment of an authentication device, an authentication method, and a recording medium will be described below using an authentication device 6 according to this disclosure. As in the fifth embodiment, the authentication device 6 further performs an operation of adjusting the timing of updating registered face images depending on the frequency of face authentication.

[0082] In the sixth embodiment, an adjustment unit 619 is implemented in the calculation device 11. Also, in the sixth embodiment, as in the fifth embodiment, a generation unit 618 is implemented in the calculation device 11. In the sixth embodiment, as in the fifth embodiment, frequency information regarding the frequency of authentication of the subject is used in addition to age information to determine whether to update the registered face image. [6-1: Authentication operation performed by authentication device 6]

[0083] The generating unit 618 generates frequency information regarding the frequency of implementation of face authentication based on the timing of past implementation of face authentication of the subject. The generating unit 618 may generate the frequency information using information indicating the timing of implementation of face authentication, which is registered in the storage device 12, for example.

[0084] The adjustment unit 619 adjusts the predetermined update threshold based on the frequency information. For example, if the subject performs face authentication relatively infrequently, the adjustment unit 619 may adjust the predetermined update threshold for the subject higher than when the subject performs face authentication relatively infrequently. This makes it easier to update the registered face images of subjects who perform face authentication relatively infrequently before the necessary time. The adjustment unit 619 may adjust the predetermined update threshold by taking age information into account in addition to the frequency information.

[0085] In the sixth embodiment, as in the fifth embodiment, at least one of the operations for determining the necessary time and the unnecessary time when the implementation frequency is low may be performed. That is, the authentication device 6 may perform both the operation for adjusting the threshold value when the implementation frequency is low and the operation for determining at least one of the operations for determining the necessary time and the unnecessary time when the implementation frequency is low.

[0086] Also, in the sixth embodiment, as in the fourth embodiment, if the authentication score is equal to or less than a predetermined determination threshold in the third period, the degree of change in the authentication score may be analyzed from past authentication scores related to past face authentication. That is, the authentication device 6 may perform both the threshold adjustment operation performed when the execution frequency is low and the change analysis operation performed when the authentication score is low. [6-2: Technical Effects of the Authentication Device 6]

[0087] The authentication device 6 according to this disclosure adjusts the update threshold using frequency information and brings forward the update time, thereby preventing a situation in which face authentication is not successful. [7: Seventh Embodiment]

[0088] A sixth embodiment of an authentication device, an authentication method, and a recording medium will be described below. Hereinafter, the seventh embodiment of an authentication device, an authentication method, and a recording medium will be described using an authentication device 7 according to this disclosure. As shown in FIG. 15 , in the seventh embodiment, the operation of the authentication unit 713 differs from the second to sixth embodiments. [7-1: Authentication Operation Performed by Authentication Device 7] As shown in FIG. 16 , when a request for face authentication is received (step S20: Yes), the authentication device 7 starts operation. The face image acquisition unit 211 acquires a face image of the subject (step S21). The authentication unit 713 performs face authentication of the subject using the face image and a registered face image (step S22). The authentication unit 713 determines whether face authentication of the subject is successful (step S23).

[0089] If the authentication score exceeds a predetermined face authentication threshold (step S23: Yes), an operation desired by the subject, such as payment, is executed. If the authentication score does not exceed the predetermined face authentication threshold (step S23: No), the authentication operation ends.

[0090] The age information acquisition unit 212 acquires age information about the age of the subject (step S24). The determination unit 214 determines a first period and a second period for updating the registered face image based on the age information (step S25).

[0091] The determination unit 214 determines whether the current time belongs to the first period or the second period (step S26). If the current time belongs to the first period (step S26: first period) and the authentication score is equal to or less than a predetermined update threshold (step S27: Yes), the authentication unit 713 performs authentication of the subject (hereinafter referred to as "second authentication") using a method other than facial authentication (step S51). That is, the authentication unit 713 performs two-factor authentication. If the authentication score is not good, the authentication unit 713 performs two-factor authentication to ensure security. The authentication unit 713 may employ any method other than facial authentication, such as other biometric authentication or password authentication. Furthermore, if the current time belongs to the second period (step S26: second period), the authentication unit 713 also performs second authentication (step S51).

[0092] The authentication unit 713 determines whether the second authentication is successful (step S52). If the second authentication is successful (step S52: Yes), the update unit 215 updates the registered face image (step S28). If the second authentication is unsuccessful (step S52: No), the update unit 215 does not update the registered face image. If the second authentication is unsuccessful, information prompting re-authentication may be notified. [7-2: Technical Effects of Authentication Device 7]

[0093] The authentication device 7 disclosed herein authenticates the subject using a method different from facial authentication if facial authentication is successful with a relatively low authentication score, and therefore can ensure authentication accuracy even if facial authentication is successful with a relatively low authentication score.

[0094] In any of the above embodiments, when the authentication device is operated, age information, the time of authentication, the authentication score, etc. are collected, and more appropriate timing, thresholds, etc. can be determined based on this information. The timing, thresholds, etc. can be updated as appropriate. [8: Supplementary Note]

[0095] The following supplementary notes are further disclosed with respect to the above-described embodiment. [Supplementary Note 1] An authentication device comprising: face image acquisition means for acquiring a face image of a subject; age information acquisition means for acquiring age information related to the age of the subject; authentication means for performing face authentication of the subject using the face image and a registered face image; determination means for determining a first period for updating the registered face image based on the age information; and update means for updating the registered face image if, during the first period, an authentication score related to face authentication by the authentication means is equal to or less than a predetermined update threshold. [Supplementary Note 2] The authentication device according to Supplementary Note 1, further comprising: output means for outputting notification information notifying that the registered face image will be updated. [Supplementary Note 3] The authentication device according to Supplementary Note 1, wherein the determination means determines a necessary time when the registered face image needs to be updated based on the age information, and determines a period prior to the necessary time as the first period. [Supplementary Note 4] The authentication device according to Supplementary Note 1, wherein the authentication means determines that the face authentication is successful when the authentication score exceeds a predetermined face authentication threshold, and the predetermined update threshold is greater than the face authentication threshold. [Supplementary Note 5] The authentication device according to Supplementary Note 4, wherein the determination means uses the age information to determine a necessary time when the registered face image needs to be updated and determines a period after the necessary time as a second period, and the update means updates the registered face image when, during the second period, the authentication score related to face authentication by the authentication means exceeds the predetermined face authentication threshold. [Supplementary Note 6] The authentication device according to Supplementary Note 4, wherein the update means updates the registered face image when, during the first period, the authentication score is equal to or less than the predetermined update threshold and exceeds the predetermined authentication threshold. [Supplementary Note 7] The authentication device according to Supplementary Note 1, wherein the determining means uses the age information to determine a necessary period when the registered face image needs to be updated and a period when the registered face image does not need to be updated, determines the period from the unnecessary period to the necessary period as the first period, and determines the period before the unnecessary period as a third period.[Supplementary Note 8] The authentication device according to Supplementary Note 7, further comprising: analysis means for analyzing a fluctuation in the authentication score from past authentication scores related to past face authentication when the authentication score is equal to or less than a predetermined analysis threshold; and the update means for determining whether to update the registered face image based on the fluctuation. [Supplementary Note 9] The authentication device according to Supplementary Note 8, further comprising: analysis means for analyzing a fluctuation in the authentication score from past authentication scores related to past face authentication when the authentication score is equal to or less than the predetermined analysis threshold during the third period; and the update means for determining whether to update the registered face image based on the fluctuation. [Supplementary Note 10] The authentication device according to Supplementary Note 7, further comprising: generation means for generating frequency information related to the frequency of face authentication implementation based on the time when face authentication was implemented in the past for the subject; and the determination means for determining at least one of the necessary time and the unnecessary time based on the age information and the frequency information. [Supplementary Note 11] The authentication device according to Supplementary Note 1, further comprising: generation means for generating frequency information related to the frequency of face authentication implementation based on the time when face authentication was implemented in the past for the subject; and adjustment means for adjusting the predetermined update threshold based on the frequency information. [Supplementary Note 12] The authentication device according to Supplementary Note 1, further comprising: generation means for generating frequency information related to the frequency of face authentication implementation based on the time when face authentication was implemented in the past for the subject; and adjustment means for adjusting the predetermined update threshold based on the frequency information. [Supplementary Note 13] The authentication device according to Supplementary Note 1, wherein the authentication means authenticates the subject using a method different from the face authentication when the authentication score is equal to or lower than the predetermined update threshold. [Supplementary Note 14] The authentication device according to Supplementary Note 1, wherein the update means does not update the registered face image when the authentication score exceeds the predetermined threshold during the first period. [Supplementary Note 15] The authentication device according to Supplementary Note 1, wherein the update means updates the registered face image using the face image. [Supplementary Note 16] The authentication device according to Supplementary Note 5, wherein the update means does not update the registered face image when the authentication score is equal to or lower than the predetermined face authentication threshold during the second period. [Supplementary Note 17] The authentication device according to Supplementary Note 1, wherein the age information acquisition means acquires the registered age information. [Supplementary Note 18] The authentication device according to Supplementary Note 1, wherein the authentication score is a score indicating a degree of similarity between the face image and the registered face image, and wherein a higher authentication score indicates a greater similarity between the face image and the registered face image.[Supplementary Note 19] An authentication method executed by an authentication device comprising: face image acquisition means for acquiring a face image of a subject; and authentication means for performing face authentication of the subject using the face image and a registered face image, the authentication method comprising: acquiring age information related to the age of the subject; determining a first period for updating the registered face image based on the age information; and updating the registered face image if, during the first period, an authentication score related to face authentication by the authentication means is equal to or lower than a predetermined update threshold. [Supplementary Note 20] A recording medium having recorded thereon a computer program causing a computer to execute an authentication method executed by an authentication device comprising: face image acquisition means for acquiring a face image of the subject; and authentication means for performing face authentication of the subject using the face image and a registered face image, the authentication method comprising: acquiring age information related to the age of the subject; determining a first period for updating the registered face image based on the age information; and updating the registered face image if, during the first period, an authentication score related to face authentication by the authentication means is equal to or lower than a predetermined update threshold.

[0096] Although this disclosure has been described above with reference to the embodiments, this disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of this disclosure within the scope of this disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0097] 1, 2, 3, 4, 5, 6, 7 Authentication device 111, 211 Facial image acquisition unit 112, 212 Age information acquisition unit 113, 213, 713 Authentication unit 114, 214, 314, 414, 514 Determination unit 115, 215, 315, 415 Update unit 216 Output unit 417 Analysis unit 518 Generation unit 619 Adjustment unit

Claims

1. An authentication device comprising: a facial image acquisition means for acquiring a facial image of a subject; an age information acquisition means for acquiring age information relating to the age of the subject; an authentication means for performing facial authentication of the subject using the facial image and a registered facial image; a determination means for determining a first period for updating the registered facial image based on the age information; and an update means for updating the registered facial image if, during the first period, an authentication score relating to facial authentication by the authentication means is equal to or less than a predetermined update threshold.

2. The authentication device according to claim 1, further comprising an output means for outputting notification information notifying that the registered face image will be updated.

3. The authentication device according to claim 1, wherein the determining means determines a time when the registered face image needs to be updated based on the age information, and determines a period before the time when the registered face image needs to be updated as the first period.

4. The authentication device according to claim 1, wherein the authentication means determines that the face authentication has been successful when the authentication score exceeds a predetermined face authentication threshold, and the predetermined update threshold is greater than the face authentication threshold.

5. The authentication device according to claim 4, wherein the determining means uses the age information to determine a time when the registered face image needs to be updated, and determines a period after the time when the registered face image needs to be updated as a second period, and the updating means updates the registered face image if, during the second period, an authentication score related to face authentication by the authentication means exceeds the predetermined face authentication threshold.

6. The authentication device according to claim 4, wherein the update means updates the registered face image when the authentication score is equal to or less than the predetermined update threshold and exceeds the predetermined authentication threshold during the first period.

7. The authentication device according to claim 1, wherein the determination means uses the age information to determine a necessary period when the registered face image needs to be updated and a period when the registered face image does not need to be updated, determines the period from the unnecessary period to the necessary period as the first period, and determines the period before the unnecessary period as the third period.

8. The authentication device according to claim 7, further comprising an analysis means for analyzing the degree of change in the authentication score from past authentication scores relating to past face authentication when the authentication score is equal to or less than a predetermined analysis threshold, and the update means determines whether or not to update the registered face image based on the degree of change.

9. The authentication device according to claim 8, wherein the analysis means analyzes the degree of fluctuation if the authentication score is equal to or less than the predetermined analysis threshold during the third period.

10. An authentication device as described in claim 7, further comprising a generating means for generating frequency information regarding the frequency of face authentication based on the subject's past face authentication implementation times, and said determining means for determining at least one of the necessary time and the unnecessary time based on the age information and the frequency information.

11. The authentication device according to claim 1, comprising: a generating means for generating frequency information regarding the frequency of face authentication implementation based on the timing of past face authentication implementations of the subject; and an adjusting means for adjusting the predetermined update threshold based on the frequency information.

12. The authentication device according to claim 1, wherein the age information acquisition means acquires the age information by age estimation using the face image.

13. The authentication device according to claim 1, wherein the authentication means authenticates the subject using a method different from the face authentication when the authentication score is equal to or less than the predetermined update threshold.

14. The authentication device according to claim 1, wherein the update means does not update the registered face image if the authentication score exceeds the predetermined threshold during the first period.

15. The authentication device according to claim 1, wherein the updating means updates the registered face image with the face image.

16. The authentication device according to claim 5, wherein the update means does not update the registered face image if the authentication score is equal to or less than the predetermined face authentication threshold during the second period.

17. The authentication device according to claim 1, wherein the age information acquisition means acquires the registered age information.

18. The authentication device according to claim 1, wherein the authentication score indicates the degree of similarity between the facial image and the registered facial image, and the higher the authentication score, the more similar the facial image and the registered facial image are.

19. An authentication method performed by an authentication device comprising: a facial image acquisition means for acquiring a facial image of a subject; and an authentication means for performing facial authentication of the subject using the facial image and a registered facial image, the authentication method comprising: acquiring age information regarding the age of the subject; determining a first period for updating the registered facial image based on the age information; and updating the registered facial image if, during the first period, an authentication score regarding facial authentication by the authentication means is equal to or less than a predetermined update threshold.

20. A recording medium having recorded thereon a computer program that causes a computer to execute an authentication method performed by an authentication device comprising: a facial image acquisition means for acquiring a facial image of a subject; and an authentication means for performing facial authentication of the subject using the facial image and a registered facial image, the authentication method comprising the steps of: acquiring age information regarding the age of the subject; determining a first period for updating the registered facial image based on the age information; and updating the registered facial image if, during the first period, the authentication score regarding facial authentication by the authentication means is equal to or less than a predetermined update threshold.

Images