887 research outputs found

    Partition clustering for GIS map data protection

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    Reversible Fragile Watermarking based on Difference Expansion Using Manhattan Distances for 2D Vector Map

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    AbstractThe need for publishing maps in secure digital format, especially guarantees data integrity which motivated us to propose a scheme that detects and locates modification data with high accuracy while ensuring exact recovery of the original content. In particular, using fragile watermarking algorithm based on reversible manner to embed hidden data in 2D vector map for each spatial features. In this paper, a reversible data-hiding scheme is explored based on the idea of difference expansion with Manhattan distances. A set of invertible integer mappings is defined to extract Manhattan distances from coordinates and the hidden data are embedded by modifying the differences between the adjacent distances. Experiments results show that the proposed scheme has good performance in term invisibility and tamper modification ability. The scheme could detect modification data such addition and deletion some features, and exactly recovery the original content of the 2D vector map

    Models and Algorithms for Graph Watermarking

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    We introduce models and algorithmic foundations for graph watermarking. Our frameworks include security definitions and proofs, as well as characterizations when graph watermarking is algorithmically feasible, in spite of the fact that the general problem is NP-complete by simple reductions from the subgraph isomorphism or graph edit distance problems. In the digital watermarking of many types of files, an implicit step in the recovery of a watermark is the mapping of individual pieces of data, such as image pixels or movie frames, from one object to another. In graphs, this step corresponds to approximately matching vertices of one graph to another based on graph invariants such as vertex degree. Our approach is based on characterizing the feasibility of graph watermarking in terms of keygen, marking, and identification functions defined over graph families with known distributions. We demonstrate the strength of this approach with exemplary watermarking schemes for two random graph models, the classic Erd\H{o}s-R\'{e}nyi model and a random power-law graph model, both of which are used to model real-world networks

    Research on digital image watermark encryption based on hyperchaos

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    The digital watermarking technique embeds meaningful information into one or more watermark images hidden in one image, in which it is known as a secret carrier. It is difficult for a hacker to extract or remove any hidden watermark from an image, and especially to crack so called digital watermark. The combination of digital watermarking technique and traditional image encryption technique is able to greatly improve anti-hacking capability, which suggests it is a good method for keeping the integrity of the original image. The research works contained in this thesis include: (1)A literature review the hyperchaotic watermarking technique is relatively more advantageous, and becomes the main subject in this programme. (2)The theoretical foundation of watermarking technologies, including the human visual system (HVS), the colour space transform, discrete wavelet transform (DWT), the main watermark embedding algorithms, and the mainstream methods for improving watermark robustness and for evaluating watermark embedding performance. (3) The devised hyperchaotic scrambling technique it has been applied to colour image watermark that helps to improve the image encryption and anti-cracking capabilities. The experiments in this research prove the robustness and some other advantages of the invented technique. This thesis focuses on combining the chaotic scrambling and wavelet watermark embedding to achieve a hyperchaotic digital watermark to encrypt digital products, with the human visual system (HVS) and other factors taken into account. This research is of significant importance and has industrial application value

    Global motion compensated visual attention-based video watermarking

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    Imperceptibility and robustness are two key but complementary requirements of any watermarking algorithm. Low-strength watermarking yields high imperceptibility but exhibits poor robustness. High-strength watermarking schemes achieve good robustness but often suffer from embedding distortions resulting in poor visual quality in host media. This paper proposes a unique video watermarking algorithm that offers a fine balance between imperceptibility and robustness using motion compensated wavelet-based visual attention model (VAM). The proposed VAM includes spatial cues for visual saliency as well as temporal cues. The spatial modeling uses the spatial wavelet coefficients while the temporal modeling accounts for both local and global motion to arrive at the spatiotemporal VAM for video. The model is then used to develop a video watermarking algorithm, where a two-level watermarking weighting parameter map is generated from the VAM saliency maps using the saliency model and data are embedded into the host image according to the visual attentiveness of each region. By avoiding higher strength watermarking in the visually attentive region, the resulting watermarked video achieves high perceived visual quality while preserving high robustness. The proposed VAM outperforms the state-of-the-art video visual attention methods in joint saliency detection and low computational complexity performance. For the same embedding distortion, the proposed visual attention-based watermarking achieves up to 39% (nonblind) and 22% (blind) improvement in robustness against H.264/AVC compression, compared to existing watermarking methodology that does not use the VAM. The proposed visual attention-based video watermarking results in visual quality similar to that of low-strength watermarking and a robustness similar to those of high-strength watermarking

    A Non-Blind Image Watermarking Method for Copyright Protection

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       في هذا البحث ، تم تقديم طريقة العلامة المائية غير العمياء لحماية حقوق النشر الخاصة بالصور الرقمية الملونة. تعتمد هذه الطريقة على مجموعة من التحويلات الرقمية (DWT ، DCT) في مجال التردد. تعتمد عملية التضمين في هذه الطريقة على تقسيم الصورة المضيفة إلى كتل غير متراكبة 16 × 16 واستخدام مقياس إنتروبيا الحافة لاختيار الكتل المناسبة لعملية التضمين لزيادة عدم الإدراك في النظام المقترح. أما بالنسبة لعملية الاستخراج ، فهي تتم بطريقة تتطلب وجود الصورة الأصلية ولكنها تتبع نفس بروتوكول التضمين لاستخراج العلامة المائية المشفرة المضمنة . و لرفع مستوى الأمان ، تم تطبيق طريقة تشفير هجينة باستخدام الخريطة الفوضوية وترميز الحمض النووي لتشفير العلامة المائية قبل تضمينها. تظهر النتائج التجريبية أن الاختلافات بين الصورة ذات العلامة المائية والصورة الأصلية لا يمكن تمييزها. الطريقة المقترحة قاومت بشكل فعال هجمات معالجة الصور الشائعة.    In this paper, a non-blind watermarking method for protecting the copyright of digital color images is introduced. This method based on the combination of digital transforms (DWT, DCT) in the frequency domain. The embedding process in this method depends on the partition of the host image into 16×16 non-overlapped blocks and the use of edge entropy metric to choose the appropriate blocks for the insertion process for the purpose of increasing the imperceptibility of the proposed system. As for the extraction process, it is carried out in a way that requires the presence of the original image but rather follows the same embedding protocol to extract the embedded encrypted watermark. To raise the security level, a hybrid encryption method using the chaotic map and DNA coding has been applied for encrypting the watermark before embedding it. Experimental results demonstrate that the differences between the watermarked image and the original image are indistinguishable. The proposed method is effectively resisted common image processing attacks
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