Face authentication method

A method for fraud detection during an authentication of a face presented to a device comprising an imager, a screen and a processing unit, comprising the steps in which:

• the imager acquires at least one initial image of a face presented in the acquisition field of the imager,
• the processing unit determines a pose of the face from the initial image, and from this face pose, determines a reference pose, a face pose being defined by at least two pose angles representative of an orientation of the face appearing in an image, and the processing unit determines a target position placed randomly or pseudo-randomly in a target space at a distance from a reference position corresponding to the reference pose, said target position corresponding to a target pose of the face,
• the screen displays a displayed image comprising at least one visual orientation mark initially at the reference position determined from the pose of the face in the initial image, and a visual target at the target position,
• the imager acquires a stream of images of the face presented in the acquisition field, and for each image of a plurality of successive images of said image stream:
• the processing unit determines a new pose of the face in said each image of the plurality of successive images of said image stream, and
• determines a new position of the visual orientation mark in image corresponding to the new pose of the face with respect to the reference pose in said each image of the plurality of successive images of said image stream,
• the displayed image displayed by the screen is updated by moving the visual orientation mark in the displayed image to the new position of the visual orientation mark in the displayed image corresponding to the new pose of the face with respect to the reference pose in said each image of the plurality of successive images of said image stream,
• the processing unit authenticates the presented face when, following the successive displacement of the visual orientation mark on the successive new positions of said visual orientation mark in the successively updated displayed image, there is a match between a new position of the visual orientation mark successively moved in the updated displayed image and the target position where the visual target is located in the updated displayed image, corresponding to a match between the face pose and the target pose, otherwise the face presented in the acquisition field is considered as fraud.