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ABSTRACT: Phase shifting structured light illumination for range sensing involves projecting a set of grating patterns where accuracy is determined, in part, by the number of stripes. However, high pattern frequencies introduce ambiguities during phase unwrapping. This paper proposes a process for embedding a period cue into the projected pattern set without reducing the signal-to-noise ratio. As a result, each period of the high frequency signal can be identified. The proposed method can unwrap high frequency phase and achieve high measurement precision without increasing the pattern number. Therefore, the proposed method can significantly benefit real-time applications. The method is verified by theoretical and experimental analysis using prototype system built to achieve 120 fps at 640 × 480 resolution.
IEEE Transactions on Image Processing 12/2011; · 3.04 Impact Factor
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ABSTRACT: To solve the problems associated with conventional 2-D fingerprint scanners such as skin deformation and print smearing, in this paper we introduce a noncontact fingerprint scanner employing structured light illumination to generate high-resolution albedo images as well as 3-D ridge scans. The question to be answered in this research is whether or not ridge depth information improves the quality and matching capability of acquired fingerprints? For evaluation of this question, we use the National Institute of Standards and Technology fingerprint image quality metrics. These metrics require the 3-D prints to be flattened. We present a complete and detailed flattening algorithm based upon unfolding an elastic tube fit to the peaks and valleys of ridges identified within the scan. Further improvement of the flattened print is achieved through the incorporation of ridge information extracted from the albedo image with the depth and albedo ridge information fused together according to local scan quality. Our study compares image quality between the flattened 3-D prints and ink rolled prints. Most significantly, the matching performance of 3-D flattened to 3-D flattened prints is evaluated based on ridge depth only, albedo only, and depth with albedo fusion.
IEEE Transactions on Information Forensics and Security 01/2011; · 1.34 Impact Factor
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ABSTRACT: For many years, fingerprints have been captured by pressing a finger against a paper or hard surface. This touch-based fingerprint acquisition introduces some problems such as distortions and deformations in the acquired images, which arise due to the contact of the fingerprint surface with the sensor platen, and degrades the recognition performance. A new touch-less fingerprint technology has been recently introduced to the market, which can address the problems with the contact-based fingerprint systems. In this paper, we propose a new algorithm for unwrapping the acquired 3-D scan of the subject's finger into a 2-D rolled equivalent image. Therefore, The resulting image can be matched with the conventional 2-D scans; it also can be used for matching unwrapped 3-D fingerprints among themselves with the 2-D fingerprint matching algorithms. The algorithm is based on curvature analysis of the 3-D surface. The quality of the resulting image is evaluated and analyzed using NIST fingerprint image software.
Biometrics: Theory, Applications, and Systems, 2009. BTAS '09. IEEE 3rd International Conference on; 10/2009
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ABSTRACT: This paper introduces a new technology of non-contact 3D fingerprint capture and processing for higher quality fingerprint data acquisition. The system relies on a real-time 3D sensor using structured light illumination (SLI), which generates both texture and detailed ridge depth information. The high resolution 3D scans are then converted into flat equivalent images. As a result, many limitations imposed upon conventional fingerprint capture and processing can be reduced by the unobtrusiveness of this approach and the extra depth information acquired. The image quality is evaluated and analyzed using NIST fingerprint image software. A comparison is performed between the unraveled 3D fingerprints and their 2D plain counterparts in terms of fingerprint quality.
Biometrics, Identity and Security (BIdS), 2009 International Conference on; 10/2009
