Johannes Ueberberg

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Digital watermarking is the enabling technology to prove ownership on copyrighted material, detect originators of illegally made copies, monitor the usage of the copyrighted multimedia data and analyze the spread spectrum of the data over networks and servers. Embedding of unique customer identification as a watermark into data is called fingerprinting to(More)
We investigate geometric structures fulfilling certain symmetry conditions. Examples for such symmetry conditions are: • Require the existence of a non-trivial automorphism. • Require the existence of an automorphism of given order, for example of order 2. • Require the existence of an automorphism with a given structure of fixed points, for example a(More)
In PG(2, q), q a prime power, we study the set T of Baer subplanes that contain a fixed triangle PQR. To construct a linear rank 2–geometry over T , we determine the dihedral groups, their orders and possible extensions that are generated by the involutions of two Baer subplanes of T . If q+1 is an odd prime, the (q+1)2 Baer subplanes through the triangle(More)