332 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
New Digital Audio Watermarking Algorithms for Copyright Protection
This thesis investigates the development of digital audio watermarking in addressing issues such as copyright protection. Over the past two decades, many digital watermarking algorithms have been developed, each with its own advantages and disadvantages. The main aim of this thesis was to develop a new watermarking algorithm within an existing Fast Fourier Transform framework. This resulted in the development of a Complex Spectrum Phase Evolution based watermarking algorithm. In this new implementation, the embedding positions were generated dynamically thereby rendering it more difficult for an attacker to remove, and watermark information was embedded by manipulation of the spectral components in the time domain thereby reducing any audible distortion. Further improvements were attained when the embedding criteria was based on bin location comparison instead of magnitude, thereby rendering it more robust against those attacks that interfere with the spectral magnitudes.
However, it was discovered that this new audio watermarking algorithm has some disadvantages such as a relatively low capacity and a non-consistent robustness for different audio files. Therefore, a further aim of this thesis was to improve the algorithm from a different perspective.
Improvements were investigated using an Singular Value Decomposition framework wherein a novel observation was discovered. Furthermore, a psychoacoustic model was incorporated to suppress any audible distortion. This resulted in a watermarking algorithm which achieved a higher capacity and a more consistent robustness.
The overall result was that two new digital audio watermarking algorithms were developed which were complementary in their performance thereby opening more opportunities for further research
Watermarking via zero assigned filter banks
Cataloged from PDF version of article.In order to identify the owner and distributor of digital data, a watermarking scheme in
frequency domain for multimedia files is proposed. The scheme satisfies the
imperceptibility and persistence requirements and it is robust against additive noise.
It consists of a few stages of wavelet decomposition of several subblocks of the original
signal using special zero assigned filter banks. By assigning zeros to filters on the high
frequency portion of the spectrum, filter banks with frequency selective response are
obtained. The information is then inserted in the wavelet-decomposed and compressed
signal. Several robustness tests are performed on male voice, female voice, and music
files, color and gray level images. The algorithm is tested under white Gaussian noise
and against JPEG compression and it is observed to be robust even when exposed to high
levels of corruption.
& 2009 Elsevier B.V. All rights reserve
Hardware Implementations of Video Watermarking
Various digital watermarking (WM) techniques for still imaging have been studied in the last several
years. Recently, many new WM schemes have been proposed for other types of digital multimedia data, such as
text, audio and video. This paper presents a brief overview of existing digital video WM. We classify WM
techniques and discuss the properties of video WM. Since each WM application has its own specific
requirements, WM design must take the intended application into consideration. Video WM applications are also
discussed in the paper. The features of video WM implementations in software and hardware and their
differences are presented through the description of four examples of existing work
Perceptual model-based information hiding in audio signals
Audio data hiding is the process of embedding information into an audio signal so that the embedded information is inseparable from
it and imperceptible to the listener. Information hiding is a multi- disciplinary area that combines signal processing with cryptography,
communication theory, coding theory, information theory and the theory of human auditory and visual systems where information is
hided within a host signal. A data hiding system should be robust, meaning that the embedded data could be decoded from the
combined signal, even if it is distorted or attacked. This paper examines information hiding in speech signals. A perceptual modelbased
information hiding in speech signal is developed
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