Method and apparatus for identifying fake fingerprint
An apparatus for identifying a fake fingerprint, the apparatus comprising: a prism having a fingerprint contact surface with which a fingerprint comes in contacted; an internal light source configured to irradiate light from the inside of the prism; an external light source configured to irradiate light from the outside of the prism; an image sensor configured to acquire diffused light image by the internal light source and transmitted light image by the external light source; and a controller configured to compare the diffused light image and the transmitted light image acquired by the image sensor to determine whether the fingerprint is a fake fingerprint or not.
1. An apparatus for identifying a fake fingerprint, the apparatus comprising:
a prism having a fingerprint contact surface with which a fingerprint comes in contacted;
an internal light source configured to irradiate light from the inside of the prism;
an external light source configured to irradiate light from the outside of the prism;
an image sensor configured to acquire diffused light image by the internal light source and transmitted light image by the external light source; and
a controller configured to compare the diffused light image and the transmitted light image acquired by the image sensor to determine whether the fingerprint is a fake fingerprint or not.
2. The apparatus of claim 1 , wherein the external light source is configured to irradiate infrared rays.
3. The apparatus of claim 1 , wherein the controller comprises:
a light emitting control unit configured to turn on and turn off the internal light source and the external light source; and
a fake fingerprint determination module configured to compare brightness values of the diffused light image and transmitted light image acquired by the image sensor to determine whether the fingerprint is a fake fingerprint or not.
4. The apparatus of claim 3 , wherein the light emitting control unit is further configured to turn on one of the internal light source and the external light source in sequence.
5. The apparatus of claim 3 , wherein the fake fingerprint determination module comprises:
a brightness value acquiring unit configured to acquire brightness values (f internal (x,y), f external (x,y)) at the same positions of the diffused light image and transmitted light image that are acquired;
a function value calculating unit configured to calculate function values K (x,y) (f internal (x,y), f external (x,y)) indicating the degree of access to the positions of (f internal (x,y), f external (x,y) when the position of a real fingerprint is (f internal (x,y), f external (x,y)) in a plane having coordinates (f internal (x,y), f external (x,y));
a summation unit configured to add one or more of the values K (x,y) (f internal (x,y), f external (x,y)); and
a determination unit configured to determine whether the fingerprint is a faked fingerprint or not depending on whether the sum value is above a preset threshold value.
6. A method for identifying a fake fingerprint in an apparatus, wherein the apparatus includes a prism having a fingerprint contact surface with which a fingerprint comes in contacted; an internal light source configured to irradiate light from the inside of the prism; and an external light source configured to irradiate light from the outside of the prism, the method comprising:
acquiring diffused light image by the internal light source and transmitted light image by the external light source; and
determining whether or not the fingerprint is a fake fingerprint by comparing brightness values of the diffused light image and the transmitted light image that are acquired.
7. The method of claim 6 , wherein said acquiring diffused light image and transmitted light image comprises:
acquiring one of the diffused light image and the transmitted light image in sequence.
8. The method of claim 6 , wherein said determining whether or not the fingerprint is a fake fingerprint comprises:
acquiring brightness values (f internal (x,y), f external (x,y)) at the same positions of the diffused light image and transmitted light image that are acquired;
calculating function values K (x,y) (f internal (x,y), f external (x,y)) indicating the degree of access to the positions of (f internal (x,y), f external (x,y)) when the position of a real fingerprint is (f internal (x,y), f external (x,y)) in a plane having coordinates (f internal (x,y), f external (x,y));
summing one or more of the function values K (x,y) (f internal (x,y), f external (x,y)) calculated; and
determining whether or not the fingerprint is a faked fingerprint depending on whether the sum value is above a preset threshold value.
9. The method of claim 8 , wherein the function values K (x,y) (f internal (x,y), f external (x,y)) are stored as the distribution of possible brightness values at their relevant positions of the fake and real fingerprint that are analyzed/determined in advance.
10. The method of claim 8 , wherein the function values K (x,y) (f internal (x,y), f external (x,y)) are set in advance to be close to ‘1’ for the real fingerprint, and the function values K (x,y) (f internal (x,y), f external (x,y)) are set in advance to be close to ‘0’ for the fake fingerprint.
11. The method of claim 6 , wherein said determining whether or not the fingerprint is a fake fingerprint comprises:
acquiring brightness values (f internal (x,y), f external (x,y)) at the same positions of the diffused light image and transmitted light image that are acquired,
wherein the brightness values are the brightness values acquired in a unit of blocks composed of two or more pixels.