525 research outputs found
Spread spectrum-based video watermarking algorithms for copyright protection
Merged with duplicate record 10026.1/2263 on 14.03.2017 by CS (TIS)Digital technologies know an unprecedented expansion in the last years. The consumer can
now benefit from hardware and software which was considered state-of-the-art several years
ago. The advantages offered by the digital technologies are major but the same digital
technology opens the door for unlimited piracy. Copying an analogue VCR tape was certainly
possible and relatively easy, in spite of various forms of protection, but due to the analogue
environment, the subsequent copies had an inherent loss in quality. This was a natural way of
limiting the multiple copying of a video material. With digital technology, this barrier
disappears, being possible to make as many copies as desired, without any loss in quality
whatsoever. Digital watermarking is one of the best available tools for fighting this threat.
The aim of the present work was to develop a digital watermarking system compliant with the
recommendations drawn by the EBU, for video broadcast monitoring. Since the watermark
can be inserted in either spatial domain or transform domain, this aspect was investigated and
led to the conclusion that wavelet transform is one of the best solutions available. Since
watermarking is not an easy task, especially considering the robustness under various attacks
several techniques were employed in order to increase the capacity/robustness of the system:
spread-spectrum and modulation techniques to cast the watermark, powerful error correction
to protect the mark, human visual models to insert a robust mark and to ensure its invisibility.
The combination of these methods led to a major improvement, but yet the system wasn't
robust to several important geometrical attacks. In order to achieve this last milestone, the
system uses two distinct watermarks: a spatial domain reference watermark and the main
watermark embedded in the wavelet domain. By using this reference watermark and techniques
specific to image registration, the system is able to determine the parameters of the attack and
revert it. Once the attack was reverted, the main watermark is recovered. The final result is a
high capacity, blind DWr-based video watermarking system, robust to a wide range of attacks.BBC Research & Developmen
Detection and robustness of digital image watermarking signals : a communication theory approach
The detection and robustness of the watermark signal is studied from a communications point of view. The contributions of this dissertation are presented in two parts. The first part, which covers the detection aspect, introduces a new digital image watermarking approach that embeds meaningful information in a copyright protection watermark signal; demonstrates the need to approach the watermark signal as a power-constrained signal; studies the relationship between the watermark signal dimension and the image capacity to the signal; explains the similarities and differences between detecting the watermark signal and detecting a signal over a spread-spectrum communication channel; and analyzes the application of sequence detection techniques (MAPSD and MLSD) to the watermark signal. The second part, which covers the robustness aspect, introduces a novel multidimensional interleaving algorithm that increases the signal\u27s robustness against burst errors; presents, analyzes, and compares two techniques for implementing the algorithm (a sliding window technique and a successive partitioning technique); and demonstrates the increase in watermark signal robustness as a result of applying this multidimensional interleaving. This increase of the signal\u27s robustness is shown in the 2-D case by applying the 2-D version of the interleaving algorithm to watermark signals embedded in still images (where the signal layout is in 2-D), and in the 3-D case by applying the 3-D version of the interleaving algorithm to watermark signals embedded in video sequences (where the signal layout is in 3-D)
Watermarking for multimedia security using complex wavelets
This paper investigates the application of complex wavelet transforms to the field of digital data hiding. Complex wavelets offer improved directional selectivity and shift invariance over their discretely sampled counterparts allowing for better adaptation of watermark distortions to the host media. Two methods of deriving visual models for the watermarking system are adapted to the complex wavelet transforms and their performances are compared. To produce improved capacity a spread transform embedding algorithm is devised, this combines the robustness of spread spectrum methods with the high capacity of quantization based methods. Using established information theoretic methods, limits of watermark capacity are derived that demonstrate the superiority of complex wavelets over discretely sampled wavelets. Finally results for the algorithm against commonly used attacks demonstrate its robustness and the improved performance offered by complex wavelet transforms
Simplification Resilient LDPC-Coded Sparse-QIM Watermarking for 3D-Meshes
We propose a blind watermarking scheme for 3-D meshes which combines sparse
quantization index modulation (QIM) with deletion correction codes. The QIM
operates on the vertices in rough concave regions of the surface thus ensuring
impeccability, while the deletion correction code recovers the data hidden in
the vertices which is removed by mesh optimization and/or simplification. The
proposed scheme offers two orders of magnitude better performance in terms of
recovered watermark bit error rate compared to the existing schemes of similar
payloads and fidelity constraints.Comment: Submitted, revised and Copyright transfered to IEEE Transactions on
Multimedia, October 9th 201
Micro protocol engineering for unstructured carriers: On the embedding of steganographic control protocols into audio transmissions
Network steganography conceals the transfer of sensitive information within
unobtrusive data in computer networks. So-called micro protocols are
communication protocols placed within the payload of a network steganographic
transfer. They enrich this transfer with features such as reliability, dynamic
overlay routing, or performance optimization --- just to mention a few. We
present different design approaches for the embedding of hidden channels with
micro protocols in digitized audio signals under consideration of different
requirements. On the basis of experimental results, our design approaches are
compared, and introduced into a protocol engineering approach for micro
protocols.Comment: 20 pages, 7 figures, 4 table
DIGITAL WATERMARKING FOR COMPACT DISCS AND THEIR EFFECT ON THE ERROR CORRECTION SYSTEM
A new technique, based on current compact disc technology, to image the transparent
surface of a compact disc, or additionally the reflective information layer, has been
designed, implemented and evaluated. This technique (image capture technique) has
been tested and successfully applied to the detection of mechanically introduced compact
disc watermarks and biometrical information with a resolution of 1.6um x l4um.
Software has been written which, when used with the image capture technique,
recognises a compact disc based on its error distribution. The software detects digital
watermarks which cause either laser signal distortions or decoding error events.
Watermarks serve as secure media identifiers.
The complete channel coding of a Compact Disc Audio system including EFM
modulation, error-correction and interleaving have been implemented in software. The
performance of the error correction system of the compact disc has been assessed using
this simulation model. An embedded data channel holding watermark data has been
investigated. The covert channel is implemented by means of the error-correction
ability of the Compact Disc system and was realised by aforementioned techniques like
engraving the reflective layer or the polysubstrate layer. Computer simulations show
that watermarking schemes, composed of regularly distributed single errors, impose a
minimum effect on the error correction system.
Error rates increase by a factor of ten if regular single-symbol errors per frame are
introduced - all other patterns further increase the overall error rates. Results show
that background signal noise has to be reduced by a factor of 60% to account for the
additional burden of this optimal watermark pattern.
Two decoding strategies, usually employed in modern CD decoders, have been
examined. Simulations take emulated bursty background noise as it appears in user-handled
discs into account. Variations in output error rates, depending on the decoder
and the type of background noise became apparant. At low error rates {r < 0.003)
the output symbol error rate for a bursty background differs by 20% depending on the
decoder. Differences between a typical burst error distribution caused by user-handling
and a non-burst error distribution has been found to be approximately 1% with the
higher performing decoder.
Simulation results show that the drop of the error-correction rates due to the presence
of a watermark pattern quantitatively depends on the characteristic type of the
background noise. A four times smaller change to the overall error rate was observed
when adding a regular watermark pattern to a characteristic background noise, as
caused by user-handling, compared to a non-bursty background
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