1,887 research outputs found
A robust digital image watermarking using repetition codes against common attacks
Digital watermarking is hiding the information inside a digital media to protect for
such documents against malicious intentions to change such documents or even
claim the rights of such documents. Currently the capability of repetition codes on
various attacks in not sufficiently studied. In this project, a robust frequency domain
watermarking scheme has been implemented using Discrete Cosine Transform
(DCT). The idea of this scheme is to embed an encoded watermark using repetition
code (3, 1) inside the cover image pixels based on Discrete Cosine Transform (DCT)
embedding technique. The proposed methods have undergone several simulation
attacks tests in order to check up and compare their robustness against various
attacks, like salt and pepper, speckle, compress, Gaussian, image contrast, resizing
and cropping attack. The robustness of the watermarking scheme has been calculated
using Peak Signal-To-Noise Ratio (PSNR), Mean Squared Error (MSE) and
Normalized Correlations (NC). In our experiments, the results show that the
robustness of a watermark with repetition codes is much better than without
repetition code
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
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