A fingerprint authentication apparatus has a combined visible/infrared light
source,
which illuminates a finger placed on an optical image sensor with both infrared
light and visible light. The optical image sensor has a block with infrared sensitivity
and a block within infrared sensitivity, and generates a fingerprint image from
light scattered by the finger. The infrared sensitivity of the infrared-sensitive
block of the optical image sensor is such that a clear image is obtained from a
living organism, and an unclear image is obtained from a replica. If the finger
is an actual living finger, the fingerprint images from both blocks are clear,
but in the case of a replica, the image from the block having infrared sensitivity
is clear, and the image from the block without having infrared sensitivity is unclear.
A reference processing section compares the clarity of the fingerprint images from
the block with infrared sensitivity and the block without having infrared sensitivity,
and if there is a difference therebetween, judges that the finger was a replica.
After this is done, an image processing section 14 extracts minutiae from
the fingerprint image, and a comparison section compares the fingerprint data with
fingerprint in a database.
