Digital Image Watermarking Algorithm Based on Texture Masking Model

The trade-off between invisibility and robustness in image watermarking algorithms is considered as one of the major issues in designing watermark-based copyright protection systems. Accordingly, different models had been proposed in the literature to obtain robust watermarked images while maintaining the perceptual quality. However, most of these studies are involved with complex algorithms as using multiple signal transformation tools within hybrid systems. In this paper, a low complexity texture-masking model based on Lifting Wavelet Transform (LWT) is utilized to find the blocks with the highest texture and choose them for watermark embedding. Choosing highly textured places helps to insert the watermark with a further intensity that leads to higher robustness and at the same time the Human Visual System (HVS) is less sensitive to changes in these areas. As a result, high quality watermarked images were produced in terms of objective and subjective evaluations, as the structural similarity value (SSIM) for tested images was larger than 0.99

Robust Logo Watermarking

Digital image watermarking is used to protect the copyright of digital images. In this thesis, a novel blind logo image watermarking technique for RGB images is proposed. The proposed technique exploits the error correction capabilities of the Human Visual System (HVS). It embeds two different watermarks in the wavelet/multiwavelet domains. The two watermarks are embedded in different sub-bands, are orthogonal, and serve different purposes. One is a high capacity multi-bit watermark used to embed the logo, and the other is a 1-bit watermark which is used for the detection and reversal of geometrical attacks. The two watermarks are both embedded using a spread spectrum approach, based on a pseudo-random noise (PN) sequence and a unique secret key. Robustness against geometric attacks such as Rotation, Scaling, and Translation (RST) is achieved by embedding the 1-bit watermark in the Wavelet Transform Modulus Maxima (WTMM) coefficients of the wavelet transform. Unlike normal wavelet coefficients, WTMM coefficients are shift invariant, and this important property is used to facilitate the detection and reversal of RST attacks. The experimental results show that the proposed watermarking technique has better distortion parameter detection capabilities, and compares favourably against existing techniques in terms of robustness against geometrical attacks such as rotation, scaling, and translation

Recent Advances in Signal Processing

The signal processing task is a very critical issue in the majority of new technological inventions and challenges in a variety of applications in both science and engineering fields. Classical signal processing techniques have largely worked with mathematical models that are linear, local, stationary, and Gaussian. They have always favored closed-form tractability over real-world accuracy. These constraints were imposed by the lack of powerful computing tools. During the last few decades, signal processing theories, developments, and applications have matured rapidly and now include tools from many areas of mathematics, computer science, physics, and engineering. This book is targeted primarily toward both students and researchers who want to be exposed to a wide variety of signal processing techniques and algorithms. It includes 27 chapters that can be categorized into five different areas depending on the application at hand. These five categories are ordered to address image processing, speech processing, communication systems, time-series analysis, and educational packages respectively. The book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity

Esquemas de watermarking semifrágil para la protección de imágenes de obtención remota

La flexibilidad de la transmisión de la información y los reducidos precios de los dispositivos digitales hacen posible que la gran mayoría de personas tengan acceso a reproducir, editar e intercambiar todo tipo de contenidos multimedia. La Red permite que los contenidos se puedan transmitir sin ningún problema y la redistribución se realiza sin pérdida de calidad alguna. La facilidad con la que se puede modificar un contenido y la distribución sin permiso de este han contribuido a que la protección del contenido y la prevención de las manipulaciones se hayan convertido en una importante área de investigación. Esto hace que las técnicas de protección de contenidos digitales y, entre ellas, las técnicas de watermarking sean de gran importancia para proteger los derechos de autor o para autenticar el contenido.The flexibility of content transmission and the low prices of digital players make it possible for that vast majority of people to play, edit and exchange all kinds of multimedia contents. The Internet allows that all these contents are transmitted without effort and redistribution can be performed without any kind of quality loss. The easiness to modify contents and the unauthorised distribution of them have contributed to the development of content protection and tampering prevention as relevant research topics. Because of this, digital content protection techniques and, among them, watermarking systems have become suitable strategies for copyright protection and content authentication.La flexibilitat de la transmissió de la informació i els preus reduïts dels dispositius digitals fan possible que la gran majoria de persones tinguin accés a reproduir, editar i intercanviar tot tipus de continguts multimèdia. La Xarxa permet que els continguts es puguin transmetre sense cap problema i la redistribució es realitza sense cap pèrdua de qualitat. La facilitat amb què es pot modificar un contingut i la distribució sense permís d'aquest han contribuït a fer que la protecció del contingut i la prevenció de les manipulacions s'hagin convertit en una important àrea de recerca. Això fa que les tècniques de protecció de continguts digitals i, entre elles, les tècniques de watermarking siguin de gran importància per protegir els drets d’autor o per autenticar el contingut.Societat de la informació i el coneixemen