70 research outputs found
Fast Fragile Watermark Embedding and Iterative Mechanism With High Self-Restoration Performance
This paper presents a new algorithm to reduce significantly the computational cost of one of the best methods with self-recovery capabilities in the fragile watermarking literature. This is achieved by generating two sequences of reference bits associated to the 5 most significant bit-planes (MSBPs) of the image. The reference bits and some authentication bits are then allocated to the 3 least significant bit-planes (LSBPs) of the image. The receiver uses the authentication bits to localise altered pixel-blocks and then executes an iterative restoration mechanism to calculate the original value of the watermarked pixels. Experimental results demonstrate that the embedding method executes significantly faster compared to the state-of-the-art method while achieving a high restoration performance
Application and Theory of Multimedia Signal Processing Using Machine Learning or Advanced Methods
This Special Issue is a book composed by collecting documents published through peer review on the research of various advanced technologies related to applications and theories of signal processing for multimedia systems using ML or advanced methods. Multimedia signals include image, video, audio, character recognition and optimization of communication channels for networks. The specific contents included in this book are data hiding, encryption, object detection, image classification, and character recognition. Academics and colleagues who are interested in these topics will find it interesting to read
Image watermarking, steganography, and morphological processing
With the fast development of computer technology, research in the fields of multimedia security, image processing, and robot vision have recently become popular. Image watermarking, steganogrphic system, morphological processing and shortest path planning are important subjects among them. In this dissertation, the fundamental techniques are reviewed first followed by the presentation of novel algorithms and theorems for these three subjects.
The research on multimedia security consists of two parts, image watermarking and steganographic system. In image watermarking, several algorithms are developed to achieve different goals as shown below. In order to embed more watermarks and to minimize distortion of watermarked images, a novel watermarking technique using combinational spatial and frequency domains is presented. In order to correct rounding errors, a novel technique based on the genetic algorithm (GA) is developed. By separating medical images into Region of Interest (ROI) and non-ROI parts, higher compression rates can be achieved where the ROI is compressed by lossless compression and the non-ROI by lossy compression. The GA-based watermarking technique can also be considered as a fundamental platform for other fragile watermarking techniques. In order to simplify the selection and integrate different watermarking techniques, a novel adjusted-purpose digital watermarking is developed. In order to enlarge the capacity of robust watermarking, a novel robust high-capacity watermarking is developed. In steganographic system, a novel steganographic algorithm is developed by using GA to break the inspection of steganalytic system.
In morphological processing, the GA-based techniques are developed to decompose arbitrary shapes of big binary structuring elements and arbitrary values of big grayscale structuring elements into small ones. The decomposition is suited for a parallel-pipelined architecture. The techniques can speed up the morphological processing and allow full freedom for users to design any type and any size of binary and grayscale structuring elements.
In applications such as shortest path planning, a novel method is first presented to obtaining Euclidean distance transformation (EDT) in just two scans of image. The shortest path can be extracted based on distance maps by tracking minimum values. In order to record the motion path, a new chain-code representation is developed to allow forward and backward movements. By placing the smooth turning-angle constraint, it is possible to mimic realistic motions of cars. By using dynamically rotational morphology, it is not only guarantee collision-free in the shortest path, but also reduce time complexity dramatically. As soon as the distance map of a destination and collision-free codes have been established off-line, shortest paths of cars given any starting location toward the destination can be promptly obtained on-line
Privacy-preserving information hiding and its applications
The phenomenal advances in cloud computing technology have raised concerns about data privacy. Aided by the modern cryptographic techniques such as homomorphic encryption, it has become possible to carry out computations in the encrypted domain and process data without compromising information privacy. In this thesis, we study various classes of privacy-preserving information hiding schemes and their real-world applications for cyber security, cloud computing, Internet of things, etc.
Data breach is recognised as one of the most dreadful cyber security threats in which private data is copied, transmitted, viewed, stolen or used by unauthorised parties. Although encryption can obfuscate private information against unauthorised viewing, it may not stop data from illegitimate exportation. Privacy-preserving Information hiding can serve as a potential solution to this issue in such a manner that a permission code is embedded into the encrypted data and can be detected when transmissions occur.
Digital watermarking is a technique that has been used for a wide range of intriguing applications such as data authentication and ownership identification. However, some of the algorithms are proprietary intellectual properties and thus the availability to the general public is rather limited. A possible solution is to outsource the task of watermarking to an authorised cloud service provider, that has legitimate right to execute the algorithms as well as high computational capacity. Privacypreserving Information hiding is well suited to this scenario since it is operated in the encrypted domain and hence prevents private data from being collected by the cloud.
Internet of things is a promising technology to healthcare industry. A common framework consists of wearable equipments for monitoring the health status of an individual, a local gateway device for aggregating the data, and a cloud server for storing and analysing the data. However, there are risks that an adversary may attempt to eavesdrop the wireless communication, attack the gateway device or even access to the cloud server. Hence, it is desirable to produce and encrypt the data simultaneously and incorporate secret sharing schemes to realise access control. Privacy-preserving secret sharing is a novel research for fulfilling this function.
In summary, this thesis presents novel schemes and algorithms, including:
• two privacy-preserving reversible information hiding schemes based upon symmetric cryptography using arithmetic of quadratic residues and lexicographic permutations, respectively.
• two privacy-preserving reversible information hiding schemes based upon asymmetric cryptography using multiplicative and additive privacy homomorphisms, respectively.
• four predictive models for assisting the removal of distortions inflicted by information hiding based respectively upon projection theorem, image gradient, total variation denoising, and Bayesian inference.
• three privacy-preserving secret sharing algorithms with different levels of generality
Fast image watermarking based on signum of cosine matrix
In the field of image watermarking, the singular value decomposition has good imperceptibility and robustness, but it has high complexity. It divides a host image into matrices of U, S, and V. Singular matrix S has been widely used for embedding and extracting watermark, while orthogonal matrices of U and V are used in decomposition and reconstruction. The proposed signum of cosine matrix method is carried out to eliminate the generation of the three matrices at each block and replace it with a signum of cosine matrix. The proposed signum of cosine matrix is performed faster on the decomposition and reconstruction. The image is transformed into a coefficient matrix C using the signum matrix. The C matrix values are closer to the S value of singular value decomposition which can preserve high quality of the watermarked image. The experimental results show that our method is able to produce similar imperceptibility and robustness level of the watermarked image with less computational time
Optimisation of Tamper Localisation and Recovery Watermarking Techniques
Digital watermarking has found many applications in many fields, such as:
copyright tracking, media authentication, tamper localisation and recovery,
hardware control, and data hiding. The idea of digital watermarking is to embed
arbitrary data inside a multimedia cover without affecting the perceptibility of the
multimedia cover itself. The main advantage of using digital watermarking over
other techniques, such as signature based techniques, is that the watermark is
embedded into the multimedia cover itself and will not be removed even with the
format change.
Image watermarking techniques are categorised according to their robustness
against modification into: fragile, semi-fragile, and robust watermarking. In fragile
watermarking any change to the image will affect the watermark, this makes fragile
watermarking very useful in image authentication applications, as in medical and
forensic fields, where any tampering of the image is: detected, localised, and
possibly recovered. Fragile watermarking techniques are also characterised by a
higher capacity when compared to semi-fragile and robust watermarking. Semifragile
watermarking techniques resist some modifications, such as lossy
compression and low pass filtering. Semi-fragile watermarking can be used in
authentication and copyright validation applications whenever the amount of
embedded information is small and the expected modifications are not severe.
Robust watermarking techniques are supposed to withstand more severe
modifications, such as rotation and geometrical bending. Robust watermarking is
used in copyright validation applications, where copyright information in the image
must remains accessible even after severe modification.
This research focuses on the application of image watermarking in tamper
localisation and recovery and it aims to provide optimisation for some of its
aspects. The optimisation aims to produce watermarking techniques that enhance
one or more of the following aspects: consuming less payload, having better
recovery quality, recovering larger tampered area, requiring less calculations, and
being robust against the different counterfeiting attacks. Through the survey of the main existing techniques, it was found that most of them
are using two separate sets of data for the localisation and the recovery of the
tampered area, which is considered as a redundancy. The main focus in this
research is to investigate employing image filtering techniques in order to use only
one set of data for both purposes, leading to a reduced redundancy in the
watermark embedding and enhanced capacity. Four tamper localisation and
recovery techniques were proposed, three of them use one set of data for
localisation and recovery while the fourth one is designed to be optimised and
gives a better performance even though it uses separate sets of data for
localisation and recovery.
The four techniques were analysed and compared to two recent techniques in the
literature. The performance of the proposed techniques vary from one technique to
another. The fourth technique shows the best results regarding recovery quality
and Probability of False Acceptance (PFA) when compared to the other proposed
techniques and the two techniques in the literature, also, all proposed techniques
show better recovery quality when compared to the two techniques in the
literature
Digital watermark technology in security applications
With the rising emphasis on security and the number of fraud related crimes
around the world, authorities are looking for new technologies to tighten
security of identity. Among many modern electronic technologies, digital
watermarking has unique advantages to enhance the document authenticity.
At the current status of the development, digital watermarking technologies
are not as matured as other competing technologies to support identity authentication
systems. This work presents improvements in performance of
two classes of digital watermarking techniques and investigates the issue of
watermark synchronisation.
Optimal performance can be obtained if the spreading sequences are designed
to be orthogonal to the cover vector. In this thesis, two classes of
orthogonalisation methods that generate binary sequences quasi-orthogonal
to the cover vector are presented. One method, namely "Sorting and Cancelling"
generates sequences that have a high level of orthogonality to the
cover vector. The Hadamard Matrix based orthogonalisation method, namely
"Hadamard Matrix Search" is able to realise overlapped embedding, thus the
watermarking capacity and image fidelity can be improved compared to using
short watermark sequences. The results are compared with traditional
pseudo-randomly generated binary sequences. The advantages of both classes
of orthogonalisation inethods are significant.
Another watermarking method that is introduced in the thesis is based
on writing-on-dirty-paper theory. The method is presented with biorthogonal
codes that have the best robustness. The advantage and trade-offs of
using biorthogonal codes with this watermark coding methods are analysed
comprehensively. The comparisons between orthogonal and non-orthogonal
codes that are used in this watermarking method are also made. It is found
that fidelity and robustness are contradictory and it is not possible to optimise
them simultaneously.
Comparisons are also made between all proposed methods. The comparisons
are focused on three major performance criteria, fidelity, capacity and
robustness. aom two different viewpoints, conclusions are not the same. For
fidelity-centric viewpoint, the dirty-paper coding methods using biorthogonal
codes has very strong advantage to preserve image fidelity and the advantage
of capacity performance is also significant. However, from the power
ratio point of view, the orthogonalisation methods demonstrate significant
advantage on capacity and robustness. The conclusions are contradictory
but together, they summarise the performance generated by different design
considerations.
The synchronisation of watermark is firstly provided by high contrast
frames around the watermarked image. The edge detection filters are used
to detect the high contrast borders of the captured image. By scanning
the pixels from the border to the centre, the locations of detected edges
are stored. The optimal linear regression algorithm is used to estimate the
watermarked image frames. Estimation of the regression function provides
rotation angle as the slope of the rotated frames. The scaling is corrected by
re-sampling the upright image to the original size. A theoretically studied
method that is able to synchronise captured image to sub-pixel level accuracy
is also presented. By using invariant transforms and the "symmetric
phase only matched filter" the captured image can be corrected accurately
to original geometric size. The method uses repeating watermarks to form an
array in the spatial domain of the watermarked image and the the array that
the locations of its elements can reveal information of rotation, translation
and scaling with two filtering processes
Fractal-based models for internet traffic and their application to secure data transmission
This thesis studies the application of fractal geometry to the application of
covert communications systems. This involves the process of hiding information
in background noise; the information being encrypted or otherwise.
Models and methods are considered with regard to two communications systems: (i) wireless communications; (ii) internet communications.
In practice, of course, communication through the Internet cannot be disassociated
from wireless communications as Internet traffic is 'piped' through a
network that can include wireless communications (e.g. satellite telecommunications).
However, in terms of developing models and methods for covert communications
in general, points (i) and (ii) above require different approaches
and access to different technologies. With regard to (i) above, we develop
two methods based on fractal modulation and multi-fractal modulation. With
regard to (ii), we implement a practical method and associated software for
covert transmission of file attachments based on an analysis of Internet traffic
noise. In both cases, however, two fractal models are considered; the first is
the standard Random Scaling Fractal model and the second is a generalisation
of this model that incorporates a greater range of spectral properties than the
first—a Generalised Random Scaling Fractal Model. [Continues.
ИНТЕЛЛЕКТУАЛЬНЫЙ числовым программным ДЛЯ MIMD-компьютер
For most scientific and engineering problems simulated on computers the solving of problems of the computational mathematics with approximately given initial data constitutes an intermediate or a final stage. Basic problems of the computational mathematics include the investigating and solving of linear algebraic systems, evaluating of eigenvalues and eigenvectors of matrices, the solving of systems of non-linear equations, numerical integration of initial- value problems for systems of ordinary differential equations.Для більшості наукових та інженерних задач моделювання на ЕОМ рішення задач обчислювальної математики з наближено заданими вихідними даними складає проміжний або остаточний етап. Основні проблеми обчислювальної математики відносяться дослідження і рішення лінійних алгебраїчних систем оцінки власних значень і власних векторів матриць, рішення систем нелінійних рівнянь, чисельного інтегрування початково задач для систем звичайних диференціальних рівнянь.Для большинства научных и инженерных задач моделирования на ЭВМ решение задач вычислительной математики с приближенно заданным исходным данным составляет промежуточный или окончательный этап. Основные проблемы вычислительной математики относятся исследования и решения линейных алгебраических систем оценки собственных значений и собственных векторов матриц, решение систем нелинейных уравнений, численного интегрирования начально задач для систем обыкновенных дифференциальных уравнений
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