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Assistant-based reconstruction of believed destroyed shredded documents

 
: Pöhler, D.; Schneider, J.; Nickolay, B.

:

Krüger, Jörg (Hrsg.); Nickolay, Bertram (Hrsg.); Gaycken, Sandro (Hrsg.):
The secure information society : Ethical, legal and political challenges
Guildford, Surrey: Springer London, 2013
ISBN: 978-1-4471-4762-6 (Print)
ISBN: 978-1-4471-4763-3 (Online)
ISBN: 1-4471-4762-6
S.163-185
Englisch
Aufsatz in Buch
Fraunhofer IPK ()

Abstract
This article introduces the assistance system for the virtual reconstruction of shredded documents developed at Fraunhofer IPK. The system enables the user to reconstruct documents, which often could not be reconstructed by hand. By this system the information contained in the documents can be made usable again.
The process of the assistance system is divided into the four phases of Digitalization, Feature-Extraction, Context Matching and Interactive Viewer.
In the first phase the fragile and often twisted strips to be reconstructed have to be separated and straightened. They then need to be scanned double-sided, anechoic, and shadeless as well as with highest colour and geometrical fidelity compared to the originals. In the second phase the strips are segmented pixel by pixel from the raw scans. Foreground from background information is separated and describing content features for a discriminative similarity comparison are extracted from the digitized strips. The third phase works on the basis of these calculated features. At first a search space reduction is carried out. Afterwards a pairwise context matching is executed by using dynamic programming algorithms. Thereby similarity scores of all possible combinations of shredder strip pairs are calculated. On the basis of these scores a semi-automatic reconstruction is performed in the interactive viewer in phase four. By doing so strip-pairs are put together gradually to grow partial reconstructions up to complete reconstructed documents by user interaction.
In the past, numerous enquiries within the framework of tax and murder investigations could be solved successfully by means of this assistance system, enabling the evaluation of procedural relevant documents; which had been destroyed purposely.

: http://publica.fraunhofer.de/dokumente/N-226411.html