Hans-Georg Schaathun (University of Surrey)

will speak on

Deletion-Insertion Correcting Codes and Robust Watermarking

Time: 4:00PM
Date: Mon 25th February 2008
Location: Mathematical Sciences Seminar Room [map]

Further information

Abstract: Robust watermarking aims to embed a message in a host file
such as an image, in such a way that an attacker cannot
remove the message without also destroying the host.
Applications have been suggested in copyright protection.

Some of the most difficult attacks to counter are local
geometric distortion, which (for instance) occur during
printing and scanning. The classic stirmark attack mimicks the effect of print and scan. The visual effect of these attacks appear as insertions and deletions of pixels, shifting segments of the image by one (or more) pixel(s).

The problem is similar to synchronisation in classical communications system, and deletion-insertion correcting codes have been suggested to solve it. Many interesting open problems, in different fields, appear when we try to realise such a system.

The talk will present the background of the problem, as well
as new results on deletion-insertion correcting codes based
on an inner code due to Davey and MacKay, and outer non-binary turbo codes.

(This talk is part of the Algebra and Number Theory series.)

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