Abstract
The use of digital watermarking in real applications is impeded by
the weakness of current available algorithms against signal
processing manipulations leading to the desynchronization of the
watermark embedder and detector. For this reason, the problem of
watermarking under geometric attacks has received considerable
attention throughout recent years. Despite their importance, only
few classes of geometric attacks are considered in the literature,
most of which consist of global geometric attacks. The random
bending attack contained in the Stirmark benchmark software is the
most popular example of a local geometric transformation. In this
paper, we introduce two new classes of local desynchronization
attacks (DAs). The effectiveness of the new classes of DAs is
evaluated from different perspectives including perceptual
intrusiveness and desynchronization efficacy. This can be seen as
an initial effort towards the characterization of the whole class of
perceptually admissible DAs, a necessary step for the theoretical
analysis of the ultimate performance reachable in the presence of
watermark desynchronization and for the development of a new class
of watermarking algorithms that can efficiently cope with them.