Fingerprint recognition systems are widely used in the field of biometrics. Many existing fingerprint sensors acquire fingerprint images as the user's fingerprint is contacted on a solid flat sensor. Because of this contact, input images from the same finger can be quite different and there are latent fingerprint issues that can lead to forgery and hygienic problems. For these reasons, a touchless fingerprint recognition system has been investigated, in which a fingerprint image can be captured without contact. While this system can solve the problems which arise through contact of the user's finger, other challenges emerge.
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Acquisition of touchless fingerprinting is a remote sensing technology for capturing the ridge-valley pattern that offers vital identification data. Several methods have been indicated for the touchless fingerprint recognition scheme.
(Y. Song. C. Lee, 2004) proposed a preprocessing technique that comprised of low pass filtering, segmentation, and Gabor enhancement for their own-designed touch-less sensor.
(C. Lee, 2006) resolved the 3D to 2D image mapping problem that was introduced by (Y. Song. C. Lee, 2004) by a robust view difference image rejection method. Preprocessing of the fingerprint images captured with a mobile camera has been proposed by (C. Lee. S. Lee, 2006)]. Application of the fingerprint verification technology to mobile handsets is discussed by (Thornton, 2005) and a novel method for the fingerprint enhancement has been developed for that particular design by (T. Nakanuira, 2004). Most recently, (Diaz-Santana, 2006) introduced a new touch-less device - The Surround Imager, which can acquire 3D rolled- equivalent fingerprints. To make 3D touch-less fingerprints interoperable with the current AFIS system. (Y. Chen. G. Parziale. E. Diaz—Sanlana, 2006) proposed an unwrapping algorithm that unfolds the 3D touch-less fingerprint images into a 2D representation that is comparable with the legacy rolled fingerprints. (Elnighammer, 2002) developed a touchless fingerprint sensor using a camera. They used a polarizer filter and a band-pass filter (N.Vyas, 2011) in order to acquire the right quality image.