Enhancing The Performance Of Digital Image Data Hiding Using Reduced Difference Expansion Technique And Constant Base Point

The last few decades have been marked by a rapid growth and significant enhancement of the internet infrastructures, i.e., the internet has become a broad network enabling many enterprises around the world to interact while sharing multimedia data. Nevertheless, this technology has brought many challenges related to securing private and sensitive information which has led to the application of cryptography technique as a mean for securing data by encrypting them. However, since the encrypted data can be seen by active and sophisticated intruders during the transmission, this may lead to its suspicion which can result in unauthorized access. Thereby, data hiding (which is also called information hiding) is another technique for securing commutation via the public network. Data hiding is one of the best and most challenging fields dealing with securing organizational sensitive information due to many factors such as identity theft, information phishing, user privacy, network policy violation, contents and copyright protection. It is performed by utilizing some carriers to conceal private information which is further extracted later to verify and validate the genuineness. Digital steganography has been recognized among the recent and most popular data hiding techniques. Steganography is the practice of concealing confidential information in the codes that make up the digital files. Such digital files can be an image, audio, video, and text. Different from cryptography, however, steganography provides security by disguising the presence of communication. It originates from the concept that if the communication is visible, the suspicion or attack is obvious. Hence, the main goal is to always disguise the presence of the hidden confidential data. Recently, various data iv hiding methods based on digital image steganography have been already suggested by several researchers around the globe. The main goal was to improve the security, embedding capacity and the quality of the stego image. However, research have shown that there is still a challenge to achieve a good visual quality of the stego media while preserving a good embedding capacity. In this direction, this study aims at proposing a new data hiding approach that enhances the quality of the stego image and the embedding capacity. That is, the suggested approach enhances the existing data hiding methods by utilizing pixel block, constant base point for each pixel block and the reduced difference expansion scheme (RDE-scheme) for grayscale digital images. Accordingly, the suggested enhancement is detailed as follows. First, the existing reduced difference expansion scheme (RDE-scheme) for reducing the difference values is enhanced in order to get possible small values to be used while concealing the secret data into the cover image. The main objective behind this enhancement is to allow data to be concealed while preserving the quality of the stego image. Notice that the suggested RDE-scheme does not only enhance the quality but also it solves the problem of underflow and overflow. The underflow is encountered when the pixel value in the stego image is below 0 (Pixel value < 0) while the overflow occurs when it is greater than 255 (Pixel value > 255). Second, the new constant base point for each pixel block is chosen differently for the sake of increasing the visual quality of the stego image. Third, we have adjusted the size of the pixel block which achieves a high embedding capacity while distorting the cover media from quad of quad (4 × 4 ) to quad, block of size 2 by 2 (2 × 2). Besides, the effect of varying the size of the secret data with respect to the quality of the stego image is also investigated throughout this study. Overall, based on the experimental results, good visual quality of the stego image which is evaluated by measuring the peak signal-to-noise ratio (PSNR) and good embedding capacity (measured in bits) are yielded compared to the previous approach, i.e., the proposed method is effective in terms of maintaining both visual quality of the stego image and the embedding capacity. Index terms— Data hiding, information security, reduced difference expansion, digital steganography, cover image, stego image, confidential data =================================================================================================== Beberapa dekade terakhir internet telah menjadi jaringan luas yang memungkinkan banyak perusahaan di seluruh dunia untuk berinteraksi sambil berbagi data multimedia. Ini merupakan tanda bahwa infrastruktur internet telah tumbuh dan berkembang secara signifikan. Namun, teknologi ini memiliki banyak tantangan dalam hal pengamanan informasi yang bersifat sensitif dan pribadi sehingga mendorong penerapan teknik kriptografi untuk mengamankan data dengan cara mengenkripsinya. Teknik kriptografi memiliki kekurangan yaitu hasil enkripsi dapat dilihat oleh penyusup (intruders) selama transmisi sehingga menyebabkan kecurigaan yang berakibat pada tindakan akses yang bersifat ilegal. Untuk mengurangi hal ini, data hiding dapat dimanfaatkan untuk mengamankan informasi tersebut. Data hiding adalah salah satu teknik terbaik untuk mendapatkan data tetapi memiliki banyak tantangan permasalahan seperti pencurian identitas, phising, pelanggaran kebijakan jaringan dan hak cipta. Untuk mendapatkan kemanan data, data hiding memanfaatkan beberapa media untuk menyembunyikan informasi dan dapat diekstrak untuk memverifikasi keasliannya. Salah satu teknik data hiding yang paling terkenal adalah steganografi digital. Teknik ini menyembunyikan informasi rahasia kedalam file digital seperti citra digital, audio, video dan teks. Berbeda dengan kriptografi, steganografi memberikan keamanan informasi dengan menyamarkannya dalam file digital. Penyebab digunakannya tindakan ini adalah jika komunikasi terlihat maka akan mengundang kecurigaan yang mengakibatkan terjadi serangan seperti yang dijelaskan sebelumnya. Oleh karena itu, tujuan utama dari teknik ini adalah menyamarkan informasi rahasia dengan vi menyembunyikannya kedalam file yang digunakan. Akhir-akhir ini, beberapa teknik data hiding dengan menggunakan citra digital telah banyak dikembangkan oleh beberapa peneliti di seluruh dunia. Tujuan utama mereka adalah untuk meningkatkan keamanan, kapasitas penyisipan dan kualitas dari citra stego. Sampai saat ini, banyak penelitian yang menunjukkan bahwa masih menjadi tantangan untuk mendapatkan kualitas media stego yang baik dengan kapasitas penyisipan yang tinggi. Dengan maksud yang sama, penelitian ini mengusulkan konsep pendekatan baru dalam hal data hiding yang dapat meningkatkan kualitas dan kapasitas dari citra stego. Pendekatan tersebut dilakukan dengan cara meningkatkan metode data hiding yang sudah ada dengan memanfaatkan blok piksel, penentuan base point yang konsisten untuk masing-masing blok dan mereduksi difference expansion untuk citra abu-abu. Rincian dari pendekatan tersebut adalah sebagai berikut. Pertama, skema reduksi difference expansion (RDE) ditingkatkan untuk mendapatkan nilai terkecil yang akan digunakan dalam penyembunyian data kedalam citra carrier. Tujuannya adalah memungkinkan data dapat disisipkan dengan tetap menjaga kualitas citra stego tetap baik. Perlu diketahui bahwa usulan skema RDE tidak hanya meningkatkan kualitas tetapi juga menyelesaikan masalah overflow dan underflow. Underfow merupakan kondisi piksel dalam citra stego bernilai kurang dari 0 sedangkan overflow terjadi ketika nilai piksel melebihi 255. Kedua, base-point yang bersifat konstan untuk masing-masing blok piksel akan dipilih secara berbeda untuk dapat meningkatkan kualitas visual dari citra stego. Ketiga, kami mengatur ukuran blok dari quad of quad (4x4) yang memiliki kualitas citra stego kurang baik menjadi 2x2. Hal lain yang kami lakukan adalah mengetahui efek dari besar ukuran data yang digunakan dalam proses penyisipan. Secara keseluruhan, berdasarkan hasil eksperimen, usulan pendekatan ini memiliki kemampuan yang lebih baik dibandingkan dengan penelitian sebelumnya yang ditandai dengan kapasitas penyisipan yang lebih tinggi dan kualitas visual citra stego yang baik yang diukur menggunakan metode signal-to-noise ratio (PSNR)

Generalized PVO‐based dynamic block reversible data hiding for secure transmission using firefly algorithm

In this paper, we proposed a novel generalized pixel value ordering–based reversible data hiding using firefly algorithm (GPVOFA). The sequence of minimum and maximum number pixels value has been used to embed the secret data while prediction and modification are held on minimum, and the maximum number of pixel blocks is used to embed the secret data into multiple bits. The host image is divided into the size of noncoinciding dynamic blocks on the basis of firefly quadtree partition, whereas rough blocks are divided into a larger size; moreover, providing more embedding capacity used small flat blocks size and optimal location in the block to write the information. Our proposed method becomes able to embed large data into a host image with low distortion. The rich experimental results are better, as compared with related preceding arts

Fragile watermarking for image authentication using dyadic walsh ordering

A digital image is subjected to the most manipulation. This is driven by the easy manipulating process through image editing software which is growing rapidly. These problems can be solved through the watermarking model as an active authentication system for the image. One of the most popular methods is Singular Value Decomposition (SVD) which has good imperceptibility and detection capabilities. Nevertheless, SVD has high complexity and can only utilize one singular matrix S, and ignore two orthogonal matrices. This paper proposes the use of the Walsh matrix with dyadic ordering to generate a new S matrix without the orthogonal matrices. The experimental results showed that the proposed method was able to reduce computational time by 22% and 13% compared to the SVD-based method and similar methods based on the Hadamard matrix respectively. This research can be used as a reference to speed up the computing time of the watermarking methods without compromising the level of imperceptibility and authentication

Progressive transmission and display of static images

Progressive image transmission has been studied for some time in association with image displays connected to remote image sources, by communications channels of insufficient data rate to give subjectively near instantaneous transmission. Part of the work presented in this thesis addresses the progressive transmission problem constrained that the final displayed image is exactly identical to the source image with no redundant data transmitted. The remainder of the work presented is concerned with producing the subjectively best image for display from the information transmitted throughout the progression. Quad-tree and binary-tree based progressive transmission techniques are reviewed, especially an exactly invertible table based binary-tree technique. An algorithm is presented that replaces the table look-up in this technique, typically reducing implementation cost, and results are presented for the subjective improvement using interpolation of the display images. The relevance of the interpolation technique to focusing the progressive sequence on some part of the image is also discussed. Some aspects of transform coding for progressive transmission are reviewed, intermediate image resolution and most importantly problems associated with the coding being exactly invertible. Starting with the two-dimensional case, an algorithm is developed, that judged by the progressive display image can mimic the behaviour of a linear transform while also being exactly invertible (no quantisation). This leads to a mean/difference transform similar to the binary-tree technique. The mimic algorithm is developed to operate on n-dimensions and used to mimic an eight-dimensional cosine transform. Photographic and numerical results of the application of this algorithm to image data are presented. An area transform, interpolation to disguise block boundaries and bit allocation to coefficients, based on the cosine mimic transform are developed and results presented

DCT Implementation on GPU

There has been a great progress in the field of graphics processors. Since, there is no rise in the speed of the normal CPU processors; Designers are coming up with multi-core, parallel processors. Because of their popularity in parallel processing, GPUs are becoming more and more attractive for many applications. With the increasing demand in utilizing GPUs, there is a great need to develop operating systems that handle the GPU to full capacity. GPUs offer a very efficient environment for many image processing applications. This thesis explores the processing power of GPUs for digital image compression using Discrete cosine transform

Reversible and imperceptible watermarking approach for ensuring the integrity and authenticity of brain MR images

The digital medical workflow has many circumstances in which the image data can be manipulated both within the secured Hospital Information Systems (HIS) and outside, as images are viewed, extracted and exchanged. This potentially grows ethical and legal concerns regarding modifying images details that are crucial in medical examinations. Digital watermarking is recognised as a robust technique for enhancing trust within medical imaging by detecting alterations applied to medical images. Despite its efficiency, digital watermarking has not been widely used in medical imaging. Existing watermarking approaches often suffer from validation of their appropriateness to medical domains. Particularly, several research gaps have been identified: (i) essential requirements for the watermarking of medical images are not well defined; (ii) no standard approach can be found in the literature to evaluate the imperceptibility of watermarked images; and (iii) no study has been conducted before to test digital watermarking in a medical imaging workflow. This research aims to investigate digital watermarking to designing, analysing and applying it to medical images to confirm manipulations can be detected and tracked. In addressing these gaps, a number of original contributions have been presented. A new reversible and imperceptible watermarking approach is presented to detect manipulations of brain Magnetic Resonance (MR) images based on Difference Expansion (DE) technique. Experimental results show that the proposed method, whilst fully reversible, can also realise a watermarked image with low degradation for reasonable and controllable embedding capacity. This is fulfilled by encoding the data into smooth regions (blocks that have least differences between their pixels values) inside the Region of Interest (ROI) part of medical images and also through the elimination of the large location map (location of pixels used for encoding the data) required at extraction to retrieve the encoded data. This compares favourably to outcomes reported under current state-of-art techniques in terms of visual image quality of watermarked images. This was also evaluated through conducting a novel visual assessment based on relative Visual Grading Analysis (relative VGA) to define a perceptual threshold in which modifications become noticeable to radiographers. The proposed approach is then integrated into medical systems to verify its validity and applicability in a real application scenario of medical imaging where medical images are generated, exchanged and archived. This enhanced security measure, therefore, enables the detection of image manipulations, by an imperceptible and reversible watermarking approach, that may establish increased trust in the digital medical imaging workflow

Entropy in Image Analysis II

Image analysis is a fundamental task for any application where extracting information from images is required. The analysis requires highly sophisticated numerical and analytical methods, particularly for those applications in medicine, security, and other fields where the results of the processing consist of data of vital importance. This fact is evident from all the articles composing the Special Issue "Entropy in Image Analysis II", in which the authors used widely tested methods to verify their results. In the process of reading the present volume, the reader will appreciate the richness of their methods and applications, in particular for medical imaging and image security, and a remarkable cross-fertilization among the proposed research areas

Improved Encoding for Compressed Textures

For the past few decades, graphics hardware has supported mapping a two dimensional image, or texture, onto a three dimensional surface to add detail during rendering. The complexity of modern applications using interactive graphics hardware have created an explosion of the amount of data needed to represent these images. In order to alleviate the amount of memory required to store and transmit textures, graphics hardware manufacturers have introduced hardware decompression units into the texturing pipeline. Textures may now be stored as compressed in memory and decoded at run-time in order to access the pixel data. In order to encode images to be used with these hardware features, many compression algorithms are run offline as a preprocessing step, often times the most time-consuming step in the asset preparation pipeline. This research presents several techniques to quickly serve compressed texture data. With the goal of interactive compression rates while maintaining compression quality, three algorithms are presented in the class of endpoint compression formats. The first uses intensity dilation to estimate compression parameters for low-frequency signal-modulated compressed textures and offers up to a 3X improvement in compression speed. The second, FasTC, shows that by estimating the final compression parameters, partition-based formats can choose an approximate partitioning and offer orders of magnitude faster encoding speed. The third, SegTC, shows additional improvement over selecting a partitioning by using a global segmentation to find the boundaries between image features. This segmentation offers an additional 2X improvement over FasTC while maintaining similar compressed quality. Also presented is a case study in using texture compression to benefit two dimensional concave path rendering. Compressing pixel coverage textures used for compositing yields both an increase in rendering speed and a decrease in storage overhead. Additionally an algorithm is presented that uses a single layer of indirection to adaptively select the block size compressed for each texture, giving a 2X increase in compression ratio for textures of mixed detail. Finally, a texture storage representation that is decoded at runtime on the GPU is presented. The decoded texture is still compressed for graphics hardware but uses 2X fewer bytes for storage and network bandwidth.Doctor of Philosoph

Design of a secure architecture for the exchange of biomedical information in m-Health scenarios

El paradigma de m-Salud (salud móvil) aboga por la integración masiva de las más avanzadas tecnologías de comunicación, red móvil y sensores en aplicaciones y sistemas de salud, para fomentar el despliegue de un nuevo modelo de atención clínica centrada en el usuario/paciente. Este modelo tiene por objetivos el empoderamiento de los usuarios en la gestión de su propia salud (p.ej. aumentando sus conocimientos, promocionando estilos de vida saludable y previniendo enfermedades), la prestación de una mejor tele-asistencia sanitaria en el hogar para ancianos y pacientes crónicos y una notable disminución del gasto de los Sistemas de Salud gracias a la reducción del número y la duración de las hospitalizaciones. No obstante, estas ventajas, atribuidas a las aplicaciones de m-Salud, suelen venir acompañadas del requisito de un alto grado de disponibilidad de la información biomédica de sus usuarios para garantizar una alta calidad de servicio, p.ej. fusionar varias señales de un usuario para obtener un diagnóstico más preciso. La consecuencia negativa de cumplir esta demanda es el aumento directo de las superficies potencialmente vulnerables a ataques, lo que sitúa a la seguridad (y a la privacidad) del modelo de m-Salud como factor crítico para su éxito. Como requisito no funcional de las aplicaciones de m-Salud, la seguridad ha recibido menos atención que otros requisitos técnicos que eran más urgentes en etapas de desarrollo previas, tales como la robustez, la eficiencia, la interoperabilidad o la usabilidad. Otro factor importante que ha contribuido a retrasar la implementación de políticas de seguridad sólidas es que garantizar un determinado nivel de seguridad implica unos costes que pueden ser muy relevantes en varias dimensiones, en especial en la económica (p.ej. sobrecostes por la inclusión de hardware extra para la autenticación de usuarios), en el rendimiento (p.ej. reducción de la eficiencia y de la interoperabilidad debido a la integración de elementos de seguridad) y en la usabilidad (p.ej. configuración más complicada de dispositivos y aplicaciones de salud debido a las nuevas opciones de seguridad). Por tanto, las soluciones de seguridad que persigan satisfacer a todos los actores del contexto de m-Salud (usuarios, pacientes, personal médico, personal técnico, legisladores, fabricantes de dispositivos y equipos, etc.) deben ser robustas y al mismo tiempo minimizar sus costes asociados. Esta Tesis detalla una propuesta de seguridad, compuesta por cuatro grandes bloques interconectados, para dotar de seguridad a las arquitecturas de m-Salud con unos costes reducidos. El primer bloque define un esquema global que proporciona unos niveles de seguridad e interoperabilidad acordes con las características de las distintas aplicaciones de m-Salud. Este esquema está compuesto por tres capas diferenciadas, diseñadas a la medidas de los dominios de m-Salud y de sus restricciones, incluyendo medidas de seguridad adecuadas para la defensa contra las amenazas asociadas a sus aplicaciones de m-Salud. El segundo bloque establece la extensión de seguridad de aquellos protocolos estándar que permiten la adquisición, el intercambio y/o la administración de información biomédica -- por tanto, usados por muchas aplicaciones de m-Salud -- pero no reúnen los niveles de seguridad detallados en el esquema previo. Estas extensiones se concretan para los estándares biomédicos ISO/IEEE 11073 PHD y SCP-ECG. El tercer bloque propone nuevas formas de fortalecer la seguridad de los tests biomédicos, que constituyen el elemento esencial de muchas aplicaciones de m-Salud de carácter clínico, mediante codificaciones novedosas. Finalmente el cuarto bloque, que se sitúa en paralelo a los anteriores, selecciona herramientas genéricas de seguridad (elementos de autenticación y criptográficos) cuya integración en los otros bloques resulta idónea, y desarrolla nuevas herramientas de seguridad, basadas en señal -- embedding y keytagging --, para reforzar la protección de los test biomédicos.The paradigm of m-Health (mobile health) advocates for the massive integration of advanced mobile communications, network and sensor technologies in healthcare applications and systems to foster the deployment of a new, user/patient-centered healthcare model enabling the empowerment of users in the management of their health (e.g. by increasing their health literacy, promoting healthy lifestyles and the prevention of diseases), a better home-based healthcare delivery for elderly and chronic patients and important savings for healthcare systems due to the reduction of hospitalizations in number and duration. It is a fact that many m-Health applications demand high availability of biomedical information from their users (for further accurate analysis, e.g. by fusion of various signals) to guarantee high quality of service, which on the other hand entails increasing the potential surfaces for attacks. Therefore, it is not surprising that security (and privacy) is commonly included among the most important barriers for the success of m-Health. As a non-functional requirement for m-Health applications, security has received less attention than other technical issues that were more pressing at earlier development stages, such as reliability, eficiency, interoperability or usability. Another fact that has contributed to delaying the enforcement of robust security policies is that guaranteeing a certain security level implies costs that can be very relevant and that span along diferent dimensions. These include budgeting (e.g. the demand of extra hardware for user authentication), performance (e.g. lower eficiency and interoperability due to the addition of security elements) and usability (e.g. cumbersome configuration of devices and applications due to security options). Therefore, security solutions that aim to satisfy all the stakeholders in the m-Health context (users/patients, medical staff, technical staff, systems and devices manufacturers, regulators, etc.) shall be robust and, at the same time, minimize their associated costs. This Thesis details a proposal, composed of four interrelated blocks, to integrate appropriate levels of security in m-Health architectures in a cost-efcient manner. The first block designes a global scheme that provides different security and interoperability levels accordingto how critical are the m-Health applications to be implemented. This consists ofthree layers tailored to the m-Health domains and their constraints, whose security countermeasures defend against the threats of their associated m-Health applications. Next, the second block addresses the security extension of those standard protocols that enable the acquisition, exchange and/or management of biomedical information | thus, used by many m-Health applications | but do not meet the security levels described in the former scheme. These extensions are materialized for the biomedical standards ISO/IEEE 11073 PHD and SCP-ECG. Then, the third block proposes new ways of enhancing the security of biomedical standards, which are the centerpiece of many clinical m-Health applications, by means of novel codings. Finally the fourth block, with is parallel to the others, selects generic security methods (for user authentication and cryptographic protection) whose integration in the other blocks results optimal, and also develops novel signal-based methods (embedding and keytagging) for strengthening the security of biomedical tests. The layer-based extensions of the standards ISO/IEEE 11073 PHD and SCP-ECG can be considered as robust, cost-eficient and respectful with their original features and contents. The former adds no attributes to its data information model, four new frames to the service model |and extends four with new sub-frames|, and only one new sub-state to the communication model. Furthermore, a lightweight architecture consisting of a personal health device mounting a 9 MHz processor and an aggregator mounting a 1 GHz processor is enough to transmit a 3-lead electrocardiogram in real-time implementing the top security layer. The extra requirements associated to this extension are an initial configuration of the health device and the aggregator, tokens for identification/authentication of users if these devices are to be shared and the implementation of certain IHE profiles in the aggregator to enable the integration of measurements in healthcare systems. As regards to the extension of SCP-ECG, it only adds a new section with selected security elements and syntax in order to protect the rest of file contents and provide proper role-based access control. The overhead introduced in the protected SCP-ECG is typically 2{13 % of the regular file size, and the extra delays to protect a newly generated SCP-ECG file and to access it for interpretation are respectively a 2{10 % and a 5 % of the regular delays. As regards to the signal-based security techniques developed, the embedding method is the basis for the proposal of a generic coding for tests composed of biomedical signals, periodic measurements and contextual information. This has been adjusted and evaluated with electrocardiogram and electroencephalogram-based tests, proving the objective clinical quality of the coded tests, the capacity of the coding-access system to operate in real-time (overall delays of 2 s for electrocardiograms and 3.3 s for electroencephalograms) and its high usability. Despite of the embedding of security and metadata to enable m-Health services, the compression ratios obtained by this coding range from ' 3 in real-time transmission to ' 5 in offline operation. Complementarily, keytagging permits associating information to images (and other signals) by means of keys in a secure and non-distorting fashion, which has been availed to implement security measures such as image authentication, integrity control and location of tampered areas, private captioning with role-based access control, traceability and copyright protection. The tests conducted indicate a remarkable robustness-capacity tradeoff that permits implementing all this measures simultaneously, and the compatibility of keytagging with JPEG2000 compression, maintaining this tradeoff while setting the overall keytagging delay in only ' 120 ms for any image size | evidencing the scalability of this technique. As a general conclusion, it has been demonstrated and illustrated with examples that there are various, complementary and structured manners to contribute in the implementation of suitable security levels for m-Health architectures with a moderate cost in budget, performance, interoperability and usability. The m-Health landscape is evolving permanently along all their dimensions, and this Thesis aims to do so with its security. Furthermore, the lessons learned herein may offer further guidance for the elaboration of more comprehensive and updated security schemes, for the extension of other biomedical standards featuring low emphasis on security or privacy, and for the improvement of the state of the art regarding signal-based protection methods and applications