Information processing system, information processing method, and recording medium for determining whether a user is a living body

1 . An information processing system comprising: at least one memory that is configured to store instructions; and

at least one processor that is configured to execute the instructions to obtain a face direction of a user;

obtain a gaze direction of the user;

calculate a difference between the face direction and the gaze direction based on an angle of the face direction being greater than or equal to a predetermined threshold;

determine whether or not the user is a living body, based on the difference between the face direction and the gaze direction;

output a result of the determination;

calculate a score indicating a possibility that the user is a living body, from the difference between the face direction and the gaze direction;

correct the score in accordance with the angle of the face direction; and

determine whether or not the user is a living body, based on the corrected score.

2 . The information processing system according to claim 1 , wherein the at least one processor is configured to execute the instructions to correct the score such that a larger correction amount is subtracted from the score as the angle of the face direction is larger.

3 . The information processing system according to claim 1 , wherein the at least one processor is configured to execute the instructions to store a plurality of correction equations for correcting the score, and select the correction equation in accordance with information about the user, thereby to correct the score.

4 . The information processing system according to claim 1 , wherein the at least one processor is configured to execute the instructions to:

determine whether or not the user is a living body based on the corrected score, and determine whether or not the user is a living body based on the score before corrected, and

notify a change in a determination result when the determination result is changed before and after correction.

5 . The information processing system according to claim 1 , wherein the at least one processor is configured to execute the instructions to:

obtain the face direction and the gaze direction at a plurality of timings, from a plurality of images captured during an action in which the user shakes the head to a side, and

determine whether or not the user is a living body, based on differences between the face directions and the gaze directions at the plurality of timings.

6 . The information processing system according to claim 5 , wherein the at least one processor is configured to execute the instructions to instruct the user how to properly shake the head, when it is detected that the user does not properly shake the head.

7 . An information processing method comprising: obtaining a face direction of a user;

obtaining a gaze direction of the user;

calculate a difference between the face direction and the gaze direction based on an angle of the face direction being greater than or equal to a predetermined threshold;

determining whether or not the user is a living body, based on the difference between the face direction and the gaze direction;

outputting a result of the determination;

calculating a score indicating a possibility that the user is a living body, from the difference between the face direction and the gaze direction;

correcting the score in accordance with the angle of the face direction; and

determining whether or not the user is a living body, based on the corrected score.

8 . A non-transitory recording medium on which a computer program that allows a computer to execute an information processing method is recorded, the information processing method including:

obtaining a face direction of a user; obtaining a gaze direction of the user;

calculate a difference between the face direction and the gaze direction based on an angle of the face direction being greater than or equal to a predetermined threshold;

determining whether or not the user is a living body, based on the difference between the face direction and the gaze direction;

outputting a result of the determination;

calculating a score indicating a possibility that the user is a living body, from the difference between the face direction and the gaze direction;

correcting the score in accordance with the angle of the face direction; and

determining whether or not the user is a living body, based on the corrected score.