Rapid evolution of digital technology has improved the ease of access to digital information enabling reliable, faster and efficient storage, transfer and processing of digital data. It also leads to the consequence of making the illegal production and redistribution of digital media easy and undetectable. Hence, the risk of copyright violation of multimedia data has increased due to the enormous growth of computer networks that provides fast and error free transmission of any unauthorized duplicate and possibly manipulated copy of multimedia information. One possible solution may be to embed a secondary signal or pattern into the image that is not perceivable and is mixed so well with the original digital data that it is inseparable and remains unaffected against any kind of multimedia signal processing. This embedded secondary information is digital watermark which is, in general, a visible or invisible identification code that may contain some information about the intended recipient, the lawful owner or author of the original data, its copyright etc. in the form of textual data or image. In order to be effective for copyright protection, digital watermark must be robust which are difficult to remove from the object in which they are embedded despite a variety of possible attacks. Several types of watermarking algorithms have been developed so far each of which has its own advantages and limitations. Among these, recently Singular Value Decomposition (SVD) based watermarking algorithms have attracted researchers due to its simplicity and some attractive mathematical properties of SVD. Here a number of pure and hybrid SVD based watermarking schemes have been investigated and finally a RST invariant modified SVD and Discrete Cosine Transform (DCT) based algorithm has been developed. A preprocessing step before the watermark extraction has been proposed which makes the algorithm resilient to geometric attack i.e. RST attack. Performance of this watermarking scheme has been analyzed by evaluating the robustness of the algorithm against geometric attack including rotation, scaling, translation (RST) and some other attacks. Experimental results have been compared with existing algorithm which seems to be promising. / Phone number: +88041730212

With the rapid growth of the internet and digital media techniques over the last decade, multimedia data such as images, video and audio can easily be copied, altered and distributed over the internet without any loss in quality. Therefore, protection of ownership of multimedia data has become a very significant and challenging issue. Three novel image watermarking algorithms have been designed and implemented for copyright protection. The first proposed algorithm is based on embedding multiple watermarks in the blue channel of colour images to achieve more robustness against attacks. The second proposed algorithm aims to achieve better trade-offs between imperceptibility and robustness requirements of a digital watermarking system. It embeds a watermark in adaptive manner via classification of DCT blocks with three levels: smooth, edges and texture, implemented in the DCT domain by analyzing the values of AC coefficients. The third algorithm aims to achieve robustness against geometric attacks, which can desynchronize the location of the watermark and hence cause incorrect watermark detection. It uses geometrically invariant feature points and image normalization to overcome the problem of synchronization errors caused by geometric attacks. Experimental results show that the proposed algorithms are robust and outperform related techniques found in literature.

The rapid development of data transfer through internet made it easier to send the data accurate and faster to the destination. There are many transmission media to transfer the data to destination like e-mails; at the same time it is may be easier to modify and misuse the valuable information through hacking. So, in order to transfer the data securely to the destination without any modifications, there are many approaches like cryptography and steganography. This paper deals with the image steganography as well as with the different security issues, general overview of cryptography, steganography and digital watermarking approaches.  The problem of copyright violation of multimedia data has increased due to the enormous growth of computer networks that provides fast and error free transmission of any unauthorized duplicate and possibly manipulated copy of multimedia information. In order to be effective for copyright protection, digital watermark must be robust which are difficult to remove from the object in which they are embedded despite a variety of possible attacks. The message to be send safe and secure, we use watermarking. We use invisible watermarking to embed the message using LSB (Least Significant Bit) steganographic technique. The standard LSB technique embed the message in every pixel, but my contribution for this proposed watermarking, works with the hint for embedding the message only on the image edges alone. If the hacker knows that the system uses LSB technique also, it cannot decrypt correct message. To make my system robust and secure, we added cryptography algorithm as Vigenere square. Whereas the message is transmitted in cipher text and its added advantage to the proposed system. The standard Vigenere square algorithm works with either lower case or upper case. The proposed cryptography algorithm is Vigenere square with extension of numbers also. We can keep the crypto key with combination of characters and numbers. So by using these modifications and updating in this existing algorithm and combination of cryptography and steganography method we develop a secure and strong watermarking method. Performance of this watermarking scheme has been analyzed by evaluating the robustness of the algorithm with PSNR (Peak Signal to Noise Ratio) and MSE (Mean Square Error) against the quality of the image for large amount of data. While coming to see results of the proposed encryption, higher value of 89dB of PSNR with small value of MSE is 0.0017. Then it seems the proposed watermarking system is secure and robust for hiding secure information in any digital system, because this system collect the properties of both steganography and cryptography sciences.

A tecnologia atual não oferece prevenção contra cópia, adulteração ou plágio de uma imagem estática em meio digital sem autorização do verdadeiro autor. Dado que tais mal feitos não podem ser evitados, resta ao criador da obra original lutar a posteriori por seus direitos nos fóruns adequados (no tribunal, por exemplo). Na época da fotografia analógica com filme, o negativo poderia ser utilizado como prova. Hoje este recurso raramente está disponível e se faz necessária uma solução alternativa. A técnica de Marca d´Água é uma das possibilidades criptográficas existentes para apoiar o autor em sua defesa. O principio da Marca d´Água é o encapsulamento de informações relevantes, preferencialmente de forma imperceptível, na imagem a ser protegida. Tais informações, quando extraídas da imagem marcada, devem revelar o verdadeiro autor num processo de disputa. Soluções de Marca d´Água combinada com Criptografia Visual são encontradas na literatura. A principal vantagem deste caminho é a propriedade Imperceptível por segurança perfeita que a Marca d´Água assume quando tratada por Criptografia Visual. O segredo (neste caso, a Marca d´Água) é segmentado via Criptografia Visual em 2 transparências: uma delas é encapsulada na imagem a ser protegida e a outra é mantida pelo verdadeiro autor. Basta a sobreposição de tais transparências para que a Marca d´Água seja revelada. Nesta pesquisa propomos um novo método, denominado MACV, que combina Marca d´Água, Criptografia Visual e um algoritmo de hashing. O MACV apresenta, entre outras, as seguintes propriedades desejáveis de Marca d´Água: imperceptível por segurança perfeita, alta entropia, armazenamento na própria imagem e sem ambiguidade. Veremos em nossa pesquisa bibliográfica que há uma lacuna de soluções que apresentem, simultaneamente, todas estas propriedades. Esta lacuna torna o MACV único em sua categoria. / Current technology does not prevent copy, tamper or plagiarism of a still image in digital media without authorization of the true author. Since such misdeeds can not be avoided, the creator of the original work has to defend his rights a posteriori in the appropriate forum (in court, for example). A negative could be used as evidence in the era of analog photography. Currently this feature is rarely available and an alternative solution is needed. Watermark is one of the existing cryptographic possibilities to support the author in his defense. A Watermark is embedded into the image to be protected, preferably imperceptibly. Such information when extracted from the watermarked image should reveal the true author in a dispute process. Solutions using Watermark with Visual Cryptography are found in the literature. The main advantage of this way is the property Imperceptible by perfect secrecy that the Water- mark assumes when treated by Visual Cryptography. The key (in this case, the Watermark) is partitioned by Visual Cryptography in 2 transparencies: one is embedded in the image to be protected and the other is kept by the true author. The Watermark is revealed by overlapping such transparencies. In this research we propose a new method, called MACV, combining Watermark, Vi- sual Cryptography and a hashing algorithm. The MACV has, among others, the following desirable properties of Watermark: invisible by perfect secrecy, high entropy, stored into the image itself and unambiguously. We will see in our research that there is no solution that presents, simultaneously, all these properties. This fact makes the MACV the first one to show all these properties

Safeguarding creative content in a digital form has become increasingly difficult. It is progressively easier to copy, modify and redistribute digital media, which causes great declines in business profits. For example, the International Federation of the Phonographic Industry estimates that in 2001 the worldwide sales of pirated music CDs were 475 million US dollars. While a large amount of time and money is committed to creating intellectual property, legal means have not proven to be sufficient for the protection of this property. Digital watermarking is a steganographic technique that has been proposed as a possible solution to this problem. A digital watermark hides embedded information about the origin, status, owner and/or destination of the data, often without the knowledge of the viewer or user. This dissertation examines a technique for digital watermarking which utilizes properties of the Discrete Wavelet Transform (DWT). Research has been done in this field, but which wavelet family is superior is not adequately addressed. This dissertation studies the influence of the wavelet family when using a blind, nonvisible watermark in digital media. The digital watermarking algorithm uses a database of multiple images with diverse properties. Various watermarks are embedded. Eight different families of wavelets with dissimilar properties are compared. How effective is each wavelet? To objectively measure the success of the algorithm, the influence of the mother wavelet, the imperceptibility of the embedded watermark and the readability of the extracted watermark, the Peak Signal-to-Noise Ratio and the Image Quality Index for each wavelet family and image are obtained. Two common categories of digital watermarking attacks are removing the watermark and rendering the watermark undetectable. To simulate and examine the effect of attacks on the images, noise is added to the image data. Also, to test the effect of reducing an image in size, each image containing the embedded watermark is compressed. The dissertation asks the questions: “Is the wavelet family chosen to implement the algorithm for a blind, nonvisible watermark in digital images of consequence? If so, which family is superior?” This dissertation conclusively shows that the Haar transform is the best for blind, non-visible digital watermarking.

Σκοπός της συγκεκριμένης εργασίας είναι η παρουσίαση των σημαντικότερων τεχνικών υδατογράφησης (watermarking techniques) ψηφιακών εικόνων με ανθεκτικότητα σε γεωμετρικούς μετασχηματισμούς και η περιγραφή και υλοποίηση ενός τέτοιου συστήματος. Οι γεωμετρικοί μετασχηματισμοί, στους οποίους δόθηκε περισσότερη έμφαση κατά την υλοποίηση του συστήματος υδατογράφησης ψηφιακών εικόνων που θα παρουσιαστεί παρακάτω, έχουν να κάνουν με την κλιμάκωση (scaling), την περιστροφή (rotation) και τον μετασχηματισμό συντεταγμένων (translation) μιας εικόνας καθώς επίσης και με συνδυασμούς αυτών. Παρόλα αυτά όμως το σύστημα που περιγράφεται αντιμετωπίζει σε ικανοποιητικό βαθμό και άλλες γεωμετρικές επιθέσεις (όπως shearing,aspect ratio change, projective, template remove κ.α.).Η ανθεκτικότητα ενός συστήματος υδατογράφησης σε αυτούς τους μετασχηματισμούς έχει να κάνει με την διατήρηση του υδατογραφήματος και την ικανοποιητική ανίχνευση του σε εικόνες που έχουν υποστεί τέτοιου είδους μετασχηματισμούς. Στην εργασία, αρχικά γίνεται μια εκτενής αναφορά στην τεχνική της υδατογράφησης και τις εφαρμογές της και έπειτα τονίζονται τα σημαντικότερα χαρακτηριστικά των συστημάτων υδατογράφησης ψηφιακού υλικού. Στη συνέχεια, ορίζονται οι γεωμετρικές επιθέσεις σε εικόνες και παρουσιάζονται οι σημαντικότερες μέθοδοι υδατογράφησης ψηφιακών εικόνων, που υπάρχουν στην βιβλιογραφία, με ανθεκτικότητα στις επιθέσεις αυτές. Στην εργασία αυτή υλοποιήθηκε μία από αυτές τις μεθόδους και έγινε προσπάθεια για επέκταση και βελτίωση της σε ορισμένα σημεία που υστερούσε. Η αρχική και βελτιωμένη μέθοδος περιγράφονται αναλυτικά. Στο τέλος ένας αριθμός πειραματικών αποτελεσμάτων αποδεικνύουν την ανθεκτικότητα του νέου βελτιωμένου συστήματος που υλοποιήθηκε σε ένα μεγάλο πλήθος γεωμετρικών επιθέσεων. / The aim of this work is the presentation of the most important watermarking techniques for digital images with robustness to geometric transformations and the description and implementation of such a system. The geometric transformations, to which was given more emphasis at the implementation of the digital images watermarking system, that will be presented below, are the scaling, the rotation and the transformation of coordinates (translation) of an image as well as the combinations of these. Nevertheless, the system that is described faces in satisfactory degree and the other geometric attacks (as the shearing, the aspect ratio change, the projective, the template remove etc.). The robustness of a watermarking system to these transformations it is simply translated as the maintenance of the watermark and its satisfactory detection in images that have existed such type of transformations. In this work, it initially becomes a extensive report to the watermark technique and to its applications and then the more important characteristics of digital material watermarking systems are highlighted. Afterwards, the geometric attacks of digit images are determined and the most important watermarking methods of digital images with robustness to these attacks, that exist in the bibliography, are presented. In this work, one of these methods was implemented and it became some effort for its extension and its improvement in certain points that disadvantages. The initial and improved methods are analytically described. At the end, a number of experimental results are presented, that they prove the robustness of the new improved system to a large number of geometric attacks.

Safeguarding creative content in a digital form has become increasingly difficult. It is progressively easier to copy, modify and redistribute digital media, which causes great declines in business profits. For example, the International Federation of the Phonographic Industry estimates that in 2001 the worldwide sales of pirated music CDs were 475 million US dollars. While a large amount of time and money is committed to creating intellectual property, legal means have not proven to be sufficient for the protection of this property. Digital watermarking is a steganographic technique that has been proposed as a possible solution to this problem. A digital watermark hides embedded information about the origin, status, owner and/or destination of the data, often without the knowledge of the viewer or user. This dissertation examines a technique for digital watermarking which utilizes properties of the Discrete Wavelet Transform (DWT). Research has been done in this field, but which wavelet family is superior is not adequately addressed. This dissertation studies the influence of the wavelet family when using a blind, nonvisible watermark in digital media. The digital watermarking algorithm uses a database of multiple images with diverse properties. Various watermarks are embedded. Eight different families of wavelets with dissimilar properties are compared. How effective is each wavelet? To objectively measure the success of the algorithm, the influence of the mother wavelet, the imperceptibility of the embedded watermark and the readability of the extracted watermark, the Peak Signal-to-Noise Ratio and the Image Quality Index for each wavelet family and image are obtained. Two common categories of digital watermarking attacks are removing the watermark and rendering the watermark undetectable. To simulate and examine the effect of attacks on the images, noise is added to the image data. Also, to test the effect of reducing an image in size, each image containing the embedded watermark is compressed. The dissertation asks the questions: “Is the wavelet family chosen to implement the algorithm for a blind, nonvisible watermark in digital images of consequence? If so, which family is superior?” This dissertation conclusively shows that the Haar transform is the best for blind, non-visible digital watermarking.

A tecnologia atual não oferece prevenção contra cópia, adulteração ou plágio de uma imagem estática em meio digital sem autorização do verdadeiro autor. Dado que tais mal feitos não podem ser evitados, resta ao criador da obra original lutar a posteriori por seus direitos nos fóruns adequados (no tribunal, por exemplo). Na época da fotografia analógica com filme, o negativo poderia ser utilizado como prova. Hoje este recurso raramente está disponível e se faz necessária uma solução alternativa. A técnica de Marca d´Água é uma das possibilidades criptográficas existentes para apoiar o autor em sua defesa. O principio da Marca d´Água é o encapsulamento de informações relevantes, preferencialmente de forma imperceptível, na imagem a ser protegida. Tais informações, quando extraídas da imagem marcada, devem revelar o verdadeiro autor num processo de disputa. Soluções de Marca d´Água combinada com Criptografia Visual são encontradas na literatura. A principal vantagem deste caminho é a propriedade Imperceptível por segurança perfeita que a Marca d´Água assume quando tratada por Criptografia Visual. O segredo (neste caso, a Marca d´Água) é segmentado via Criptografia Visual em 2 transparências: uma delas é encapsulada na imagem a ser protegida e a outra é mantida pelo verdadeiro autor. Basta a sobreposição de tais transparências para que a Marca d´Água seja revelada. Nesta pesquisa propomos um novo método, denominado MACV, que combina Marca d´Água, Criptografia Visual e um algoritmo de hashing. O MACV apresenta, entre outras, as seguintes propriedades desejáveis de Marca d´Água: imperceptível por segurança perfeita, alta entropia, armazenamento na própria imagem e sem ambiguidade. Veremos em nossa pesquisa bibliográfica que há uma lacuna de soluções que apresentem, simultaneamente, todas estas propriedades. Esta lacuna torna o MACV único em sua categoria. / Current technology does not prevent copy, tamper or plagiarism of a still image in digital media without authorization of the true author. Since such misdeeds can not be avoided, the creator of the original work has to defend his rights a posteriori in the appropriate forum (in court, for example). A negative could be used as evidence in the era of analog photography. Currently this feature is rarely available and an alternative solution is needed. Watermark is one of the existing cryptographic possibilities to support the author in his defense. A Watermark is embedded into the image to be protected, preferably imperceptibly. Such information when extracted from the watermarked image should reveal the true author in a dispute process. Solutions using Watermark with Visual Cryptography are found in the literature. The main advantage of this way is the property Imperceptible by perfect secrecy that the Water- mark assumes when treated by Visual Cryptography. The key (in this case, the Watermark) is partitioned by Visual Cryptography in 2 transparencies: one is embedded in the image to be protected and the other is kept by the true author. The Watermark is revealed by overlapping such transparencies. In this research we propose a new method, called MACV, combining Watermark, Vi- sual Cryptography and a hashing algorithm. The MACV has, among others, the following desirable properties of Watermark: invisible by perfect secrecy, high entropy, stored into the image itself and unambiguously. We will see in our research that there is no solution that presents, simultaneously, all these properties. This fact makes the MACV the first one to show all these properties

With the rapid growth of the internet and digital media techniques over the last decade, multimedia data such as images, video and audio can easily be copied, altered and distributed over the internet without any loss in quality. Therefore, protection of ownership of multimedia data has become a very significant and challenging issue. Three novel image watermarking algorithms have been designed and implemented for copyright protection. The first proposed algorithm is based on embedding multiple watermarks in the blue channel of colour images to achieve more robustness against attacks. The second proposed algorithm aims to achieve better trade-offs between imperceptibility and robustness requirements of a digital watermarking system. It embeds a watermark in adaptive manner via classification of DCT blocks with three levels: smooth, edges and texture, implemented in the DCT domain by analyzing the values of AC coefficients. The third algorithm aims to achieve robustness against geometric attacks, which can desynchronize the location of the watermark and hence cause incorrect watermark detection. It uses geometrically invariant feature points and image normalization to overcome the problem of synchronization errors caused by geometric attacks. Experimental results show that the proposed algorithms are robust and outperform related techniques found in literature.

Dans de nombreuses applications dont celles du domaine médical et de l’embarqué, l’authentification des images nécessite de prendre en compte les contraintes temporelles, le taux d’insertion, la qualité visuelle et la robustesse contre différentes attaques. Le tatouage a été proposé comme approche complémentaire à la cryptographie pour l’amélioration de la sécurité des images. Il peut être effectué soit dans le domaine spatial sur les pixels de l’image, soit dans le domaine fréquentiel sur les coefficients de sa transformée. Dans cette thèse, le but est de proposer des approches de tatouage permettant d’assurer un niveau élevé d’imperceptibilité et de robustesse, tout en maintenant un niveau de complexité répondant aux exigences d’applications soumises à des contraintes temporelles. La démarche adoptée a consisté, d’une part, à s’appuyer sur les bénéfices du zéro-tatouage (zero-watermarking) qui ne change pas la qualité perceptuelle de l’image et qui a une faible complexité computationnelle, et d’autre part, à analyser les caractéristiques visuelles de l’image afin de détecter les zones les plus adaptées pour insérer la marque avec un bon niveau d’imperceptibilité et une bonne robustesse. Une approche de zéro-tatouage a ainsi été proposée dans cette thèse, ainsi que plusieurs approches de tatouage basées sur l’analyse de caractéristiques visuelles de l’image et sur des techniques d’intelligence artificielles ou connexes.Les solutions proposées ont été analysées du point de vue de l’imperceptibilité, de la robustesse et de la performance temporelle et les résultats d’analyses ont montré qu’elles apportent des améliorations significatives par rapport aux approches existantes. / In numerous applications such as those of medical and embedded domains, images authentication requires taking into account time constraints, embedding rate, perceptual quality and robustness against various attacks. Watermarking has been proposed as a complementary approach to cryptography, for improving the security of digital images. Watermarking can be applied either in the spatial domain on the pixels of the image, or in the frequency domain on the coefficient of its transform.In this thesis, the goal is to propose image watermarking approaches that make it possible to ensure high level of imperceptibility and robustness while maintaining a level of computational complexity fitting the requirements of time-constrained applications. The method adopted in this thesis has consisted, on the one hand, to rely on the benefit of zero-watermarking that does not degrade the perceptual quality of image data and has low computational complexity, and on the other hand, to analyze visual characteristics of digital image (characteristics that are correlated to the Human Visual System - HVS) in order to identify the locations the most adapted for embedding the watermark with good level of imperceptibility and robustness. A zero-watermarking has therefore been proposed in this thesis, as well as several watermarking approaches based on the analysis of visual characteristics of image and on artificial intelligence or related techniques. The proposed solutions have been analyzed with respect to imperceptibility, robustness and temporal performance and the results have shown significant improvements in comparison to existing approaches.