AUTHENTICATION METHOD, MOBILE DEVICE, AND STORAGE MEDIUM

1 . An authentication method executed by a processor included in a mobile device having a camera, the authentication method comprising:

displaying an image captured by the camera and including irises of a user on a screen of the mobile device based on a position of a displayed guide image specifying positions of eyes;

calculating, based on positional relationships between light spots and the regions of the irises, when the light spots included in the image overlap regions of the irises, shift vectors of the light spots when the light spots are shifted until the light spots do not overlap the regions of the irises; and

moving the displayed guide image in a movement direction determined based on the shift vectors and executing authentication on the user using the irises displayed based on the position of the displayed guide image after the movement of the guide image.

2 . The authentication method according to claim 1 , further comprising:

calculating areas of the regions of the irises exposed from eyelids and areas of light spot portions included in the light spots and overlapping the regions of the irises;

calculating ratios of the areas of the light spot portions to the areas of the regions of the irises; and

determining that the light spots overlap the regions of the irises when the calculated ratios are larger than a predetermined threshold.

3 . The authentication method according to claim 1 ,

wherein the calculating the shift vectors includes acquiring information of coordinates of centers of the regions of the irises, coordinates of centers of regions of the light spots, radii of the regions of the irises, and radii of the regions of the light spots and using the information of the coordinates of the centers and the radii to calculate the minimum shift vectors of the light spots when the light spots are shifted until the light spots do not overlap the regions of the irises.

4 . The authentication method according to claim 1 ,

wherein the user wears glasses.

5 . The authentication method according to claim 1 ,

wherein the shift vectors have a direction parallel to a predetermined coordinate axis extending in a direction in which the screen extends.

6 . The authentication method according to claim 5 ,

wherein the predetermined coordinate axis is parallel to a straight line included in a contour of the screen.

7 . The authentication method according to claim 1 ,

wherein the moving includes moving the guide image toward a direction opposite to orientations of the shift vectors.

8 . The authentication method according to claim 1 , further comprising:

calculating an amount of the movement of the guide image by multiplying magnitudes of the shift vectors by a predetermined coefficient,

wherein the moving includes moving, in the movement direction determined based on the shift vectors, the guide image based on the calculated amount of the movement.

9 . The authentication method according to claim 1 ,

wherein the displaying includes mirror reversing and displaying the image.

10 . A mobile device comprising:

a camera; and

a processor coupled to the camera and configured to:

display an image captured by the camera and including irises of a user on a screen of the mobile device based on a position of a guide image specifying positions of eyes;

calculate, based on positional relationships between light spots and the regions of the irises, when the light spots included in the image overlap regions of the irises, shift vectors of the light spots when the light spots are shifted until the light spots do not overlap the regions of the irises; and

move the guide image in a movement direction determined based on the shift vectors and executing authentication on the user using the irises displayed based on the position of the guide image after the movement of the guide image.

11 . The mobile device according to claim 10 , wherein the processor is configured to:

calculate areas of the regions of the irises exposed from eyelids and areas of light spot portions included in the light spots and overlapping the regions of the irises;

calculate ratios of the areas of the light spot portions to the areas of the regions of the irises; and

determine that the light spots overlap the regions of the irises when the calculated ratios are larger than a predetermined threshold.

12 . The mobile device according to claim 10 , wherein the processor is configured to

acquire information of coordinates of centers of the regions of the irises, coordinates of centers of regions of the light spots, radii of the regions of the irises, and radii of the regions of the light spots and using the information of the coordinates of the centers and the radii to calculate the minimum shift vectors of the light spots when the light spots are shifted until the light spots do not overlap the regions of the irises.

13 . The authentication method according to claim 10 ,

wherein the user wears glasses.

14 . A non-transitory computer-readable storage medium storing a program that causes a processor included in a mobile device having a camera to execute a process, the process comprising:

displaying an image captured by the camera and including irises of a user on a screen of the mobile device based on a position of a guide image specifying positions of eyes;

calculating, based on positional relationships between light spots and the regions of the irises, when the light spots included in the image overlap regions of the irises, shift vectors of the light spots when the light spots are shifted until the light spots do not overlap the regions of the irises; and

moving the guide image in a movement direction determined based on the shift vectors and executing authentication on the user using the irises displayed based on the position of the guide image after the movement of the guide image.