Method of enrolling a fingerprint

1. A method of enrolling a fingerprint of a user's finger, by means of a fingerprint detection arrangement comprising a fingerprint sensor and an optical sensor and a light receiving device, the method comprising:

capturing, by the fingerprint sensor, a first enrollment image of a fingerprint of a user's finger placed on the fingerprint sensor at a first position thereon;

emitting light, by the light emitting source of the optical sensor, towards the user's finger;

receiving, by the light receiving device at least a portion of the light emitted by the light emitting source when the finger is placed at the first position on the fingerprint sensor;

determining a first light response profile based on the light received by the light receiving device; and

forming a fingerprint template comprising a fingerprint representation based on the first enrollment image and the first light response profile by combining the first enrollment image and the first light response profile when the finger is placed at the first position of the fingerprint sensor.

2. The method according to claim 1 , wherein determining the first light response profile is further based on the light emitted by the light emitting source.

3. The method according to claim 1 , wherein determining the first light response profile comprises:

determining an emitted light intensity of the light emitted by the light emitting source;

determining a received light intensity of the light received by the light receiving device;

comparing the received light intensity with the emitted light intensity; and

determining the first light response profile based on a difference in light intensity between the received light intensity and the emitted light intensity.

4. The method according to claim 1 , wherein the light emitting device is arranged to emit light of at least two distinct wavelengths, and the light receiving device is arranged to receive at least a portion of the light of the at least two distinct wavelengths.

5. The method according to claim 1 , further comprising:

determining the first position on the fingerprint sensor based on the enrollment image captured by the fingerprint sensor.

6. The method according to claim 5 , wherein the optical sensor is a first optical sensor comprising a first light emitting source and a first light receiving device, wherein the fingerprint detection arrangement further comprises a second optical sensor comprising a second light emitting source and a second light receiving device, wherein the method further comprises:

comparing the determined first position on the fingerprint sensor with at least a first and a second pre-set finger position on the fingerprint sensor;

controlling the first optical sensor to emit light by the first light emitting source and to receive at least a portion of the emitted light by the first light receiving device if the first position substantially corresponds to the first pre-set finger position.

7. The method according to claim 6 , further comprising:

inhibiting the second optical sensor from emitting light if the first position substantially corresponds to the first pre-set finger position.

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

capturing, by the fingerprint sensor, a second enrollment image of the fingerprint of the user's finger placed on the fingerprint sensor at a second position thereon, the second position being different in comparison to the first position;

emitting light, by the light emitting source of the optical sensor, towards the user's finger;

receiving, by the light receiving device, at least a portion of the light emitted by the light emitting source when the finger is placed at the second position on the fingerprint sensor; and

determining a second light response profile based on the light received by the light receiving device when the finger is placed at the second position on the fingerprint sensor;

wherein forming the fingerprint template comprising the fingerprint representation is further based on the second enrollment image and the second light response profile when the finger is placed at the second position.

9. The method according to claim 8 , wherein the second position of the user's finger corresponds to a position being rotated on a surface of the fingerprint sensor relative to the first position.

10. The method according to claim 8 , wherein the second position of the user's finger corresponds to a position being moved along a surface of the fingerprint sensor relative to the first position.

11. The method according to claim 1 , wherein the fingerprint sensor is one of a capacitive fingerprint sensor and an ultrasound fingerprint sensor.

12. A method for authenticating a user of an electronic device comprising a fingerprint detection arrangement, the fingerprint detection arrangement comprising a fingerprint sensor and an optical sensor comprising a light emitting source and a light receiving device, the method comprising:

receiving, by the fingerprint sensor, a first authentication image of a fingerprint of a user's finger placed on the fingerprint sensor;

emitting light, by the light emitting source of the optical sensor, towards the user's finger;

receiving, by the light receiving device at least a portion of the light emitted by the light emitting source when the finger is placed on the fingerprint sensor;

determining a first light authentication response profile based on the light received by the light receiving device; and

matching the first authentication image and the first light authentication response profile against a fingerprint template for authenticating the user, wherein the fingerprint template comprises a fingerprint representation for a finger of the user for at least one previously enrolled position of the finger at the fingerprint sensor and an associated light response profile.

13. The method according to claim 12 , wherein matching the first authentication image and the first light authentication response profile against the fingerprint template further comprises:

determining a position of the finger on the fingerprint sensor based on the first authentication image of the fingerprint.

14. The method according to claim 13 , wherein matching the first authentication image and the first light authentication response profile against the fingerprint template further comprises:

determining a correspondence between the determined position of the finger on the fingerprint sensor and the fingerprint representation for the finger of the user for the at least one previously enrolled position.

15. A fingerprint detection arrangement comprising a fingerprint sensor and an optical sensor, the optical sensor comprising a light emitting source and a light receiving device, and a control unit connected to the fingerprint sensor and the optical sensor, wherein, when a user enrolls a fingerprint, the control unit is configured to:

control the fingerprint sensor to capture a first enrollment image of a fingerprint of a user's finger when the finger is placed on the fingerprint sensor at a first position thereon;

control the light emitting source of the optical sensor to emit light towards the user's finger;

control the light receiving device to receive at least a portion of the light emitted by the light emitting source when the finger is placed at the first position on the fingerprint sensor;

determine a first light response profile based on the light received by the light receiving device; and

form a fingerprint template comprising a fingerprint representation based on the first enrollment image and the first light response profile by combining the first enrollment image and the first light response profile when the finger is placed at the first position of the fingerprint sensor.

16. A fingerprint detection arrangement of an electronic device, the fingerprint detection arrangement comprising a fingerprint sensor and an optical sensor, the optical sensor comprising a light emitting source and a light receiving device, and a control unit connected to the fingerprint sensor and the optical sensor, wherein, when authenticating a user of the electronic device, the control unit is configured to:

control the fingerprint sensor to receive a first authentication image of a fingerprint of a user's finger when the finger is placed on the fingerprint sensor;

control the light emitting source of the optical sensor to emit light towards the user's finger;

control the light receiving device to receive at least a portion of the light emitted by the light emitting source when the finger is placed at the first position on the fingerprint sensor;

determine a first light authentication response profile based on the light received by the light receiving device; and

match the first authentication image and the first light authentication response profile against a fingerprint template for authenticating the user, wherein the fingerprint template comprises a fingerprint representation for a finger of the user for at least one previously enrolled position of the finger at the fingerprint sensor and an associated light response profile.