Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 163-178). Also available in electronic version. Access restricted to campus users.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2003. / Vita. Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

For digital media, the risk of piracy is aggravated by the ease to copy and distribute the content. Watermarking has become the technology of choice for discouraging people from creating illegal copies of digital content. Watermarking is the practice of imperceptibly altering the media content by embedding a message, which can be used to identify the owner of that content. A watermark message can also be a set of instructions for the display equipment, providing information about the content’s usage restrictions. Several applications are considered and three watermarking solutions are provided. First, applications such as owner identification, proof of ownership, and digital fingerprinting are considered and a fast content-dependent image watermarking method is proposed. The scheme offers a high degree of robustness against distortions, mainly additive noise, scaling, low-pass filtering, and lossy compression. This method also requires a small amount of computations. The method generates a set of evenly distributed codewords that are constructed via an iterative algorithm. Every message bit is represented by one of these codewords and is then embedded in one of the image’s 8 × 8 pixel blocks. The information in that particular block is used in the embedding so as to ensure robustness and image fidelity. Two watermarking schemes designed to prevent theatre camcorder piracy are also presented. In these methods, the video is watermarked so that its display is not permitted if a compliant video player detects the watermark. A watermark that is robust to geometric distortions (rotation, scaling, cropping) and lossy compression is required in order to block access to media content that has been recorded with a camera inside a movie theatre. The proposed algorithms take advantage of the properties of the dual-tree complex wavelet transform (DT CWT). This transform offers the advantages of both the regular and the complex wavelets (perfect reconstruction, approximate shift invariance and good directional selectivity). Our methods use these characteristics to create watermarks that are robust to geometric distortions and lossy compression. The proposed schemes are simple to implement and outperform comparable methods when tested against geometric distortions.

Digital watermarking is the way to solve digital image copyright protection problem. Such a solution is quite new and the need for software, which would ensure image authentication, is huge. Image authentication control area and its relevance are analyzed in this work. Digital watermarking theoretical basics are presented; six algorithms – Cox, Kim, Wang, Xia, Dugad and Zhu – are analyzed. The analysis of similar software was performed; it revealed the predominance of such software products that allows only visible (though transparent) watermarking, and the number of software with a possibility of invisible watermarking is small. The work consists of these main parts: analysis, design, user documentation and experimental research. The main objective of this work was to design and implement image authentication control system. This system has such features: PGM and JPEG format images review, digital watermark generation, embedding, extraction.

Joint source-channel coding (JSCC) has been acknowledged to have superior performance over separate source-channel coding in terms of coding efficiency, delay and complexity. In the first part of this thesis, we study a hybrid digital-analog (HDA) JSCC system to transmit a memoryless Gaussian source over a memoryless Gaussian channel under bandwidth compression. Information-theoretic upper bounds on the asymptotically optimal mean squared error distortion of the system are obtained. An allocation scheme for distributing the channel input power between the analog and the digital signals is derived for the HDA system with mismatched channel conditions. A low-complexity and low-delay version of the system is next designed and implemented. We then propose an image communication application demonstrating the effectiveness of HDA coding. In the second part of this thesis, we consider problems in information hiding. We begin by considering a single-user joint compression and private watermarking (JCPW) problem. For memoryless Gaussian sources and memoryless Gaussian attacks, an exponential upper bound on the probability of error in decoding the watermark is derived. Numerical examples show that the error exponent is positive over a (large) subset of the entire achievable region derived by Karakos and Papamarcou (2003). We then extend the JCPW problem to a multi-user setting. Two encoders independently embed two secret information messages into two correlated host sources subject to a pair of tolerable distortion levels. The (compressed) outputs are subject to multiple access attacks. The tradeoff between the achievable watermarking rates and the compression rates is studied for discrete memoryless host sources and discrete memoryless multiple access channels. We derive an inner bound and an outer bound with single-letter characterization for the achievable compression and watermarking rate region. We next consider a problem where two correlated sources are separately embedded into a common host source. A single-letter sufficient condition is established under which the sources can be successfully embedded into the host source under multiple access attacks. Finally, we investigate a public two-user information hiding problem under multiple access attacks. Inner and outer bounds for the embedding capacity region are obtained with single-letter characterization. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2007-09-28 23:11:21.398

The advances in recording, editing and broadcasting multimedia content in digital form motivate the protection of digital information against illegal use, manipulation and distribution. This thesis work focuses on one aspect of digital rights management (DRM), namely digital watermarking. Specifically, we study its use in copy protection, tamper detection and information hiding. We introduce three application-specific digital watermarking techniques. The first two algorithms, based on embedding film grain like noise and signal dependent watermarks, respectively, are designed for authentication applications. The advantage is that they are able to detect malicious tampering while being robust against content-preserving processes such as compression, filtering and additive noise. The third method, a reversible watermarking technique, is designed so that sensitive personal information can be embedded in medical images. Simulation results show that our proposed method outperforms other approaches in the available literature in terms of image quality and computational complexity.

The advances in recording, editing and broadcasting multimedia content in digital form motivate the protection of digital information against illegal use, manipulation and distribution. This thesis work focuses on one aspect of digital rights management (DRM), namely digital watermarking. Specifically, we study its use in copy protection, tamper detection and information hiding. We introduce three application-specific digital watermarking techniques. The first two algorithms, based on embedding film grain like noise and signal dependent watermarks, respectively, are designed for authentication applications. The advantage is that they are able to detect malicious tampering while being robust against content-preserving processes such as compression, filtering and additive noise. The third method, a reversible watermarking technique, is designed so that sensitive personal information can be embedded in medical images. Simulation results show that our proposed method outperforms other approaches in the available literature in terms of image quality and computational complexity.

Digital watermarking of multimedia content has been proposed as a method for different applications such as copyright protection, content authentication, transaction tracking and data hiding. In this thesis, we propose a lossless watermarking approach based on Discrete Cosine Transform (DCT) for a new application of watermarking. A depth map obtained from a stereoscopic image pair is embedded into one of the two images using a reversible watermarking algorithm. Different from existing approaches which hide depth map in spatial domain, the depth information is hidden in the quantized DCT domain of the stereo image in our method. This modification makes the watermarking algorithm compatible with JPEG and MPEG-2 compression. After the investigation of the quantized DCT coefficients distribution of the compressed image and video, The bit-shift operation is utilized to embed the depth map into its associated 2D image reversibly for the purpose of achieving high compression efficiency of the watermarked image and/or video and high visual quality of stereo image and/or video after the depth map is extracted. We implement the proposed method to analyze its performance. The experimental results show that a very high payload of watermark (e.g. depth map) can be embedded into the JPEG compressed image and MPEG-2 video. The compression efficiency is only slightly reduced after the watermark embedding and the quality of the original image or video can be restored completely at the decoder side.

For digital media, the risk of piracy is aggravated by the ease to copy and distribute the content. Watermarking has become the technology of choice for discouraging people from creating illegal copies of digital content. Watermarking is the practice of imperceptibly altering the media content by embedding a message, which can be used to identify the owner of that content. A watermark message can also be a set of instructions for the display equipment, providing information about the content’s usage restrictions. Several applications are considered and three watermarking solutions are provided. First, applications such as owner identification, proof of ownership, and digital fingerprinting are considered and a fast content-dependent image watermarking method is proposed. The scheme offers a high degree of robustness against distortions, mainly additive noise, scaling, low-pass filtering, and lossy compression. This method also requires a small amount of computations. The method generates a set of evenly distributed codewords that are constructed via an iterative algorithm. Every message bit is represented by one of these codewords and is then embedded in one of the image’s 8 × 8 pixel blocks. The information in that particular block is used in the embedding so as to ensure robustness and image fidelity. Two watermarking schemes designed to prevent theatre camcorder piracy are also presented. In these methods, the video is watermarked so that its display is not permitted if a compliant video player detects the watermark. A watermark that is robust to geometric distortions (rotation, scaling, cropping) and lossy compression is required in order to block access to media content that has been recorded with a camera inside a movie theatre. The proposed algorithms take advantage of the properties of the dual-tree complex wavelet transform (DT CWT). This transform offers the advantages of both the regular and the complex wavelets (perfect reconstruction, approximate shift invariance and good directional selectivity). Our methods use these characteristics to create watermarks that are robust to geometric distortions and lossy compression. The proposed schemes are simple to implement and outperform comparable methods when tested against geometric distortions.

Thesis (PhDElectronicEngineering)--University of South Australia, 2005.