Face authentication apparatus

Abstract

A face authentication apparatus includes a face image acquisition unit, a collation unit, a time measurement unit, and a threshold change unit. The face image acquisition unit acquires a face image of an authentication target. The collation unit performs face authentication on the face image of the authentication target on the basis of a threshold. The time measurement unit measures the elapsed time from the time of starting operation of the face authentication apparatus. The threshold change unit restricts changing of the threshold to a value larger than a value determined depending on the measured elapsed time.

1 . A face authentication apparatus comprising:
 a memory containing program instructions; and   a processor coupled to the memory, wherein the processor is configured to execute the program instructions to:   acquire a face image of an authentication target;   perform face authentication on the face image of the authentication target on a basis of a threshold;   measure elapsed time from a time of starting operation of the face authentication apparatus; and   restrict changing of the threshold to a value larger than a value determined depending on the elapsed time measured.   
     
     
         2 . The face authentication apparatus according to  claim 1 , wherein
 the changing of the threshold includes setting the threshold to be smaller relative to a target value at the time of starting the operation of the face authentication apparatus.   
     
     
         3 . The face authentication apparatus according to  claim 1 , wherein
 the changing of the threshold includes, before changing the threshold in accordance with a request from a user, checking whether or not a value of the threshold after the change is larger than the value determined depending on the elapsed time measured, and if the value is larger, rejecting the request.   
     
     
         4 . The face authentication apparatus according to  claim 1 , wherein
 the changing of the threshold includes gradually incrementing the threshold until the threshold reaches a target value in accordance with the value determined depending on the elapsed time measured.   
     
     
         5 . The face authentication apparatus according to  claim 1 , further comprising
 a threshold changing schedule that is a schedule of changing the threshold after the time of starting the operation of the face authentication apparatus and in which a value of the threshold after the change becomes larger as the elapsed time from the time of starting the operation is longer, wherein   the changing of the threshold includes calculating the value determined depending on the elapsed time measured, on a basis of the threshold changing schedule and the elapsed time measured.   
     
     
         6 . The face authentication apparatus according to  claim 5 , further comprising
 a plurality of types of the threshold changing schedules, wherein   the changing of the threshold includes selecting, from the plurality of the types of the threshold changing schedules, a threshold changing schedule to be used for calculating the value determined depending on the elapsed time measured, on a basis of a history of face authentication success.   
     
     
         7 . The face authentication apparatus according to  claim 1 , wherein the processor is configured to further execute the program instructions to:
 output a result of the face authentication.   
     
     
         8 . The face authentication apparatus according to  claim 7 , wherein
 the acquiring the face image includes acquiring a face image of a user who passes through a gate apparatus as the face image of the authentication target, and   the outputting includes outputting, to the gate apparatus, a result of the face authentication for controlling open and close operation of the gate apparatus.   
     
     
         9 . The face authentication apparatus according to  claim 1 , wherein
 in the face authentication, a feature amount of a face extracted from the face image of the authentication target and a feature amount of a face extracted from a reference face image of each registered user are collated with each other, and similarly between the face image of the authentication target and the reference face image is calculated.   
     
     
         10 . A face authentication method performed by a face authentication apparatus, the method comprising:
 acquiring a face image of an authentication target;   performing face authentication on the face image of the authentication target on a basis of a threshold;   measuring elapsed time from a time of starting operation of the face authentication apparatus; and   restricting changing of the threshold to a value larger than a value determined depending on the elapsed time measured.   
     
     
         11 . The face authentication method according to  claim 10 , wherein
 the threshold is set to be smaller relative to a target value at the time of starting the operation of the face authentication apparatus.   
     
     
         12 . The face authentication method according to  claim 10 , wherein
 the restricting the changing of the threshold includes, before changing the threshold in accordance with a request from a user, checking whether or not a value of the threshold after the change is larger than the value determined depending on the elapsed time measured, and if the value is larger, rejecting the request.   
     
     
         13 . The face authentication method according to any of  claim 10 , further comprising
 gradually incrementing the threshold until the threshold reaches a target value in accordance with the value determined depending on the elapsed time measured.   
     
     
         14 . The face authentication method according to  claim 10 , wherein
 the face authentication apparatus includes a threshold changing schedule that is a schedule of changing the threshold after the time of starting the operation of the face authentication apparatus and in which a value of the threshold after the change becomes larger as the elapsed time from the time of starting the operation is longer, and   the method further comprises calculating the value determined depending on the elapsed time measured, on a basis of the threshold changing schedule and the elapsed time measured.   
     
     
         15 . The face authentication method according to  claim 14 , wherein
 the face authentication apparatus includes a plurality of types of the threshold changing schedules, and   the method further comprises selecting, from the plurality of the types of the threshold changing schedules, a threshold changing schedule to be used for calculating the value determined depending on the elapsed time measured, on a basis of a history of face authentication success.   
     
     
         16 . The face authentication method according to  claim 10 , further comprising
 outputting a result of the face authentication.   
     
     
         17 . The face authentication method according to  claim 16 , wherein
 the acquiring the face image includes acquiring a face image of a user who passes through a gate apparatus as the face image of the authentication target, and   the outputting the result of the face authentication includes outputting, to the gate apparatus, a result of the face authentication for controlling open and close operation of the gate apparatus.   
     
     
         18 . The face authentication method according to  claim 10 , wherein
 in the face authentication, a feature amount of a face extracted from the face image of the authentication target and a feature amount of a face extracted from a reference face image of each registered user are collated with each other, and similarly between the face image of the authentication target and the reference face image is calculated.   
     
     
         19 . A non-transitory computer-readable medium storing a program comprising instructions for causing a computer to perform processing to:
 acquire a face image of an authentication target;   perform face authentication on the face image of the authentication target on a basis of a threshold;   measure elapsed time from a time of starting operation of the face authentication apparatus; and   restrict chanting of the threshold to a value larger than a value determined depending on the elapsed time measured.