Auflistung nach Autor:in "Stein, Chris"
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- KonferenzbeitragEignung von Smartphone-Kameras zur Fingerabdruckerkennung und Methoden zur Verbesserung der Qualität der Fingerbilder(BIOSIG 2011 – Proceedings of the Biometrics Special Interest Group, 2011) Stein, Chris; Nickel, ClaudiaDiese Arbeit befasst sich mit der Untersuchung auf die Eignung von Smartphone-Kameras für eine Fingerabdruckerkennung. Es werden unter Alltagsbedingungen Fingerfotos mit den Kameras von verschiedenen Smartphones mit mehreren Personen gemacht und ausgewertet. Vier der fünf untersuchten Geräte stellen sich bei der Aufnahme von Fingerfotos als untauglich dar. Die Aufnahmen des tauglichen Gerätes werden weiter auf ihre Qualität untersucht und mit welchen Methoden diese erhöht werden kann, um die Erkennungsleistung zu verbessern.
- KonferenzbeitragFingerphoto recognition with smartphone cameras(BIOSIG 2012, 2012) Stein, Chris; Nickel, Claudia; Busch, ChristophThis paper is concerned with the authentication of people on smartphones using fingerphoto recognition. In this work, fingerphotos are captured with the built-in camera of the smartphone. The proposed authentication method is analyzed for feasibility and implemented in a prototype as application for the Android operating system. Algorithms for the capture process are developed to ensure a minimum of quality of the captured photos to enable a reliable fingerphoto recognition. Several methods for preprocessing of the captured samples are analyzed and performant solutions to evaluate the photos are developed to enhance the recognition rates. This is achieved by evaluating a wide range of different parameters and configurations of the algorithms as well as various combinations of preprocessing chains for the captured samples. The operations for preprocessing are selected with respect to their computational effort to guarantee that they can be executed on a smartphone with limited computation and memory capacity. The developed prototype is evaluated in user tests with two different smartphones. Additionally, a biometric database containing photos of the two test devices from 41 test subjects is created. These fingerphotos are used to evaluate and optimize the procedures.
- KonferenzbeitragVideo-based fingerphoto recognition with anti-spoofing techniques with smartphone cameras(BIOSIG 2013, 2013) Stein, Chris; Bouatou, Vincent; Busch, ChristophThis work is concerned with the acquisition of fingerprints samples on smartphones with the built-in smartphone camera. A novel approach to capture multiple fingerphotos in a videostream with a smartphone camera and the processing of the photos for the finger recognition is discussed in this paper. The proposed technique offers a convenient and efficient way to capture multiple samples of a biometric instance in a short time frame. Due the fact that fingerphotos can be easily replicated with low effort (e.g. print outs with an ordinary printer) and thus are vulnerable to presentation attacks, anti-spoofing algorithms were developed to detect such spoof attempts. The algorithms for the detection and segmentation of the finger as well the preprocessing of the photo with graphical operations and anti-spoofing were implemented in a prototype as application for the Android operating system. User tests are performed to evaluate the usability and to create a database of biometric samples for offline evaluation of the recognition performance. Further tests are done with diverse artefacts such as printed finger images, fake fingers of gelatin, gummy and silicon as well finger replay videos to measure the resistance of the developed solution against presentation attacks.