Universität Stuttgart
Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1
Browse
3 results
Search Results
Item Open Access Optical detection of random features for high security applications(1998) Haist, Tobias; Tiziani, Hans J.Optical detection of random features in combination with digital signatures based on public key codes in order to recognise counterfeit objects will be discussed. Without applying expensive production techniques objects are protected against counterfeiting. Verification is done offline by optical means without a central authority. The method is applied for protecting banknotes. Experimental results for this application are presented. The method is also applicable for identity verification of a credit- or chip-card holder.Item Open Access Positioning of noncooperative objects using joint transform correlation combined with fringe projection(1998) Haist, Tobias; Schönleber, Martin; Tiziani, Hans J.Automated assembly and quality control require reliable systems for the detection of the position and orientation of complicated objects. Correlation methods are well suited, but they are affected by structured backgrounds, varying illumination conditions, and textured or dirty object surfaces. Using fringe projection to exploit the three-dimensional topography of objects, we improve the performance of a nonlinear joint transform correlator. Positioning of noncooperative objects with subpixel accuracy is demonstrated. Additionally, the tilt angle of an arbitrarily shaped object is measured by projecting object-adapted fringes that produce a homogeneous fringe pattern in the image plane. An accuracy of better than one degree is achieved.Item Open Access Iterative nonlinear joint transform correlation for the detection of objects in cluttered scenes(1999) Haist, Tobias; Tiziani, Hans J.An iterative correlation technique with digital image processing in the feedback loop for the detection of small objects in cluttered scenes is proposed. A scanning aperture is combined with the method in order to improve the immunity against noise and clutter. Multiple reference objects or different views of one object are processed in parallel. We demonstrate the method by detecting a noisy and distorted face in a crowd with a nonlinear joint transform correlator.