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Dissertations / Theses on the topic 'Watermark'
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1
Lam, Ioi Tun. "Biometric watermark embedding in document images." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2130131.
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Xu, Xin. "Digital watermark technology in security applications." Thesis, University of Plymouth, 2008. http://hdl.handle.net/10026.1/335.
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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.
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Woo, Chaw-Seng. "Digital image watermarking methods for copyright protection and authentication." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16457/1/Chaw-Seng_Woo_Thesis.pdf.
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The ease of digital media modification and dissemination necessitates content protection beyond encryption. Information hidden as digital watermarks in multimedia enables protection mechanism in decrypted contents.
The aims of this research are three-fold: (i) to investigate the strength and limitations of current watermarking schemes, (ii) to design and develop new schemes to overcome the limitations, and (iii) to evaluate the new schemes using application scenarios of copyright protection, tamper detection and authentication. We focus on geometrically robust watermarking and semi-fragile watermarking for digital images. Additionally, hybrid schemes that combine the strength of both robust and semi-fragile watermarks are studied.
Robust watermarks are well suited for copyright protection because they stay intact with the image under various manipulations. We investigated two major approaches of robust watermarking. In the synchronization approach, we employed motion estimation for watermark resynchronization. We also developed a novel watermark resynchronization method that has low computational cost using scale normalization and flowline curvature. In another approach, we firstly analyzed and improved a blind watermark detection method. The new method reduces significantly the computational cost of its watermark embedding. Secondly, we created a geometric invariant domain using a combination of transforms, and adapted the blind watermark detection method that we improved. It totally eliminates the need of resynchronization in watermark detection, which is a very desirable achievement that can hardly be found in existing schemes.
On the other hand, semi-fragile watermarks are good at content authentication because they can differentiate minor image enhancements from major manipulations. New capabilities of semi-fragile watermarks are identified. Then, we developed a semi-fragile watermarking method in wavelet domain that offers content authentication and tamper localization. Unlike others, our scheme overcomes a major challenge called cropping attack and provides approximate content recovery without resorting to an original image.
Hybrid schemes combine robust and semi-fragile watermarks to offer deductive information in digital media forensics. We firstly carried out a pilot study by combining robust and fragile watermarks. Then, we performed a comparative analysis on two implementation methods of a hybrid watermarking scheme. The first method has the robust watermark and the fragile watermark overlapped while the second method uses non-overlapping robust and fragile watermarks. Based on the results of the comparative analysis, we merge our geometric invariant domain with our semi-fragile watermark to produce a hybrid scheme. This hybrid scheme fulfilled the copyright protection, tamper detection, and content authentication objectives when evaluated in an investigation scenario.
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Woo, Chaw-Seng. "Digital image watermarking methods for copyright protection and authentication." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16457/.
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The ease of digital media modification and dissemination necessitates content protection beyond encryption. Information hidden as digital watermarks in multimedia enables protection mechanism in decrypted contents. The aims of this research are three-fold: (i) to investigate the strength and limitations of current watermarking schemes, (ii) to design and develop new schemes to overcome the limitations, and (iii) to evaluate the new schemes using application scenarios of copyright protection, tamper detection and authentication. We focus on geometrically robust watermarking and semi-fragile watermarking for digital images. Additionally, hybrid schemes that combine the strength of both robust and semi-fragile watermarks are studied. Robust watermarks are well suited for copyright protection because they stay intact with the image under various manipulations. We investigated two major approaches of robust watermarking. In the synchronization approach, we employed motion estimation for watermark resynchronization. We also developed a novel watermark resynchronization method that has low computational cost using scale normalization and flowline curvature. In another approach, we firstly analyzed and improved a blind watermark detection method. The new method reduces significantly the computational cost of its watermark embedding. Secondly, we created a geometric invariant domain using a combination of transforms, and adapted the blind watermark detection method that we improved. It totally eliminates the need of resynchronization in watermark detection, which is a very desirable achievement that can hardly be found in existing schemes. On the other hand, semi-fragile watermarks are good at content authentication because they can differentiate minor image enhancements from major manipulations. New capabilities of semi-fragile watermarks are identified. Then, we developed a semi-fragile watermarking method in wavelet domain that offers content authentication and tamper localization. Unlike others, our scheme overcomes a major challenge called cropping attack and provides approximate content recovery without resorting to an original image. Hybrid schemes combine robust and semi-fragile watermarks to offer deductive information in digital media forensics. We firstly carried out a pilot study by combining robust and fragile watermarks. Then, we performed a comparative analysis on two implementation methods of a hybrid watermarking scheme. The first method has the robust watermark and the fragile watermark overlapped while the second method uses non-overlapping robust and fragile watermarks. Based on the results of the comparative analysis, we merge our geometric invariant domain with our semi-fragile watermark to produce a hybrid scheme. This hybrid scheme fulfilled the copyright protection, tamper detection, and content authentication objectives when evaluated in an investigation scenario.
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Jiang, Feng. "Efficient Public-Key Watermark Techniques for Authentication." Thesis, Purdue University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10618833.
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The security of digital media content has received significant attention as the usage of multimediahas increased in today's society. Digital watermarking is widely applied for digital image copyright protection and authentication. The extraction and verification of the watermark can be used for many applications, for example, authenticating the image. In some situations, the authentication should be accessible to all, thus public-key watermarking would be necessary.
In addition, many essential image-embedded documents are kept in a physical format and used widely for authentication purposes. These documents include the personal ID, license, passport, immigration document, commercial ticket with identity information, personal medical report, etc.
A digital watermarking system with high embedding capacity, robust to various attacks, high extraction efficiency is needed for such practical use. A public-key watermarking system is proposed for such applications. The embedded watermark/message can be extracted and verified publicly using a public-key. The watermark extraction process is efficient and blind. The watermark can be only embedded by the document issuer. The watermark embedded is robust against not only common digital signal processing attacks, geometric attacks but also the print-scan process. Differing from existing watermarking approaches, the watermark is embedded according to the result of proposed object weight map detection and automatic object segmentation. Higher watermark robustness and embedding capacity are achieved. Our simulation results demonstrate that the proposed approach is effective and is able to be applied to various applications.
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Al, Faleh Al Hiary Hazem Ali Abd. "Paper-based watermark extraction with image processing." Thesis, University of Leeds, 2008. http://etheses.whiterose.ac.uk/1355/.
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This thesis presents frameworks for the digitisation, localisation, extraction and graphical representation of paper-based watermark designs embedded in paper texture. There is a growing need for this among librarians and antiquarians to aid with identification, wider accessibility, and providing a further level of document imaging for preservation. The proposed approaches are designed to handle manuscripts with interference such as recto and verso writing, and defects such as non-uniform paper structure, physical damage, etc. A back-lighting scanning technique is used for capturing images of paper, followed by a selection of intelligent image processing operations, rather than alternatives such as radioactive techniques. This technique requires low cost equipment, and produces a fast and safe solution to capturing all details on paper, including watermarks, and laid and chain lines patterns. Two approaches are presented: the first takes a bottom-up approach and deploys image processing operations to enhance, filter, and extract the watermark, and convert it into a graphical representation. These operations determine a suitable configuration of parameters to allow optimal content processing, in addition to the detection and extraction of chain lines. The second approach uses a model of the back-lighting effect to locate a watermark in pages of archaic documents. It removes recto information, and highlights remaining ‘hidden’ data, and then presents a statistical approach to locate watermarks from a known lexicon. Work is further presented on reconstructing features of the paper mould by aggregating the success of the foregoing steps: this permits an analysis of ‘twin’ watermarks. Results are presented from comprehensively scanned eighteenth and nineteenth century manuscripts, including two unusual copies of the Quran, an Islamic Prayer, and various historical documents.
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Davis, Jacqueline M. L. "Occurrence of Erwinia Salicis in cricket-bat willow (Salix alba var caerulea)." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296345.
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Noorkami, Maneli. "Secure and Robust Compressed-Domain Video Watermarking for H.264." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16267.
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The objective of this thesis is to present a robust watermarking algorithm for H.264 and to address challenges in compressed-domain video watermarking. To embed a perceptually invisible watermark in highly compressed H.264 video, we use a human visual model. We extend Watson's human visual model developed for 8x8 DCT block to the 4x4 block used in H.264. In addition, we use P-frames to increase the watermark payload. The challenge in embedding the watermark in P-frames is that the video bit rate can increase significantly. By using the structure of the encoder, we significantly reduce the increase in video bit rate due to watermarking. Our method also exploits both temporal and texture
masking.
We build a theoretical framework for watermark detection using a likelihood ratio test. This framework is used to develop two different video watermark detection algorithms; one detects the watermark only from watermarked coefficients and one detects the watermark from all the ac coefficients in the video. These algorithms can be used in different video watermark detection applications where the detector knows and does not know the precise location of watermarked coefficients. Both watermark detection schemes obtain video watermark detection with controllable detection performance. Furthermore, control of the detector's performance lies completely with the detector and does not place any burden on the watermark embedding system. Therefore, if the video has been attacked, the detector can maintain the same detection performance by using more frames to obtain its detection response. This is not the case with images, since there is a limited number of coefficients that can be watermarked in each image before the watermark is visible.
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Wu, Pianhui. "Research on digital image watermark encryption based on hyperchaos." Thesis, University of Derby, 2013. http://hdl.handle.net/10545/305004.
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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.
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Barr, Mohammad. "Robust logo watermarking." Thesis, De Montfort University, 2018. http://hdl.handle.net/2086/16550.
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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.
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Samuel, Sindhu. "Digital rights management (DRM) : watermark encoding scheme for JPEG images." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-09122008-182920/.
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Brannock, Evelyn. "Using the discrete wavelet transform to Haar'd code a blind digital watermark." Atlanta, Ga. : Georgia State University, 2009. http://digitalarchive.gsu.edu/cs_diss/35/.
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Thesis (Ph. D.)--Georgia State University, 2009.Title from title page (Digital Archive@GSU, viewed July 20, 2010) Michael Weeks, committee chair; Saeid Belkasim, Robert Harrison, Ephraim McLean, committee members. Includes bibliographical references (p. 145-153).
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Brannock, Evelyn R. "Using the Discrete Wavelet Transform to Haar'd Code a Blind Digital Watermark." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/cs_diss/35.
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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.
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Li, Ji-Wei, and 李紀緯. "Authenticated Watermark System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/66313975587556048313.
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碩士國立臺灣海洋大學
資訊工程學系
103
Digital signature is an effective verification tool for validating electronic documents, but it does not work for images since a minor attack on images can result in invalidity of signature verification. In the thesis, a watermarking system is proposed to assist the copyright verification of images by using digital signature. The digital signature is first encoded into a QR code which is then embedded as a watermark in an image. With the help of error correction capability of OR codes, the extracted digital signature can correctly pass the verification process. Experiments of some common attack for images are given, which shows that the proposed system fulfils the desired requirements and can be implemented for practical applications.
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Chu, Hung-Hui, and 朱航輝. "Research of Audio Watermark." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/56722996013061675539.
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碩士大同大學
通訊工程研究所
94
ABSTRACT In the society of digitization now, because the Internet has convenience and speed that enables everybody to search useful information in the network. It brings quite a lot of convenience, but in following problems: it is too easy to obtain information. People may ignore the intellectual property carelessly, and tend to duplicate, revise and destroy digital works without authorization of original author. These problems are serious day by day, so how to protect the original author’s property becomes a very important subject for this research. Presently the majority of digital watermarking is concerned about embedding image or text into picture, audio or video … etc. Few literatures discussed that how to embed audio watermark into these multimedia data. Though the use of audio watermarks requires a large amount data, based on our experiments, in comparison to human’s vision, human’s hearing has better distinguishability for distorted watermark. Our research thus is focused on reducing the amount of required audio watermark data and increasing the system robustness. Specifically, we divide audio watermark data into groups based on their amplitudes to reduce the embedded data, and then embed group indices rather than each detailed data. Furthermore, the hiding data are embedded in low frequency band after the processing of discrete wavelet transform (DWT). Our experiments of attacks include amplitude modification, filtering, noising (additive white noise) and MP3 compression, the results showed that our method does not only reduce the watermark data but also holds the robustness at the same time. It was found from our simulation that in comparison to human’s vision; human’s hearing has better distinguishability for distorted watermark. We expect to apply the technology of digital watermarking to related problems of law in the future.
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Chuang, Shoou-Shean, and 莊守顯. "OBJECT-BASED WATERMARK TECHNIQUE." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/80378857117833821876.
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碩士國立東華大學
電機工程研究所
89
Owing to rapid development in network and multimedia technologies, standards in text, audio, image and video are expected to provide support in lots of applications. Digital watermark technology puts emphasis on copyright protection against pirating and various applications. In this thesis, in addition to investigating the data hiding technologies, we also focus on the object-based issue. The wavelet packet method is a generalization of wavelet decomposition that offers a richer range of possibilities for signal analysis. Instead of the traditional pyramid wavelet, we use wavelet packet transform to increase the robustness, non-removable, and more significant coefficient capability. We use the human visual system(HVS) to select the significant coefficients to embed watermark that will satisfy imperceptible property. If we use the automatic mechanism to decompose expected subbands, we can get more significant coefficients. We use the criterion that the two subbands among four subbands with larger energies are chosen for further wavelet packet decomposition. Shape erosion can reduce the distortion of wavelet coefficients near the object boundary inside shape before extracting watermark. After counting the number of the significant coefficients, the suitable watermark can be found by multi-resolution operation. Before embedded into the wavelet coefficients, the watermark image is pre-processed by chaotic transformation implemented by toral automorphisms. This way will raise the security of watermark. The experimental results show that the proposed methods result almost imperceptible difference between the watermarked data and original data, and are also robust to common image manipulation and processing operations: noise adding, JPEG, JPEG2000, MPEG-4 and SPIHT with ROI compression, etc. Our proposed scheme also can tolerate Stirmak attacks. With this proposed technique, the Intelligent Property Right(IPR) can be more securely protected and the legal issue for the ownership and copyright of digital data can be technically solved.
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Chen, Yong-Cong, and 陳詠琮. "The New Encrypted Watermark Technique." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/19635431019725218831.
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碩士國立清華大學
資訊工程學系
88
In recent years, digital watermark is important for academic research and industry application. It can be applied in multimedia data such as digital music, images and videos etc. Watermarking technology adds a watermark ,visible or invisible,on the these signals for copyright protection. In order that to ensure watermark’s robustness, it will effect to the image quality.On the other hand, if you want to have good image quality, it will affect the watermark’s validity. It is a trade-off between watermark robustness and image quality. There are two domain researches on watermark technology.One is the spatial domain technique, and the other is frequency domain Technique. Recently, wavelet transform has been adopted in JPEG 2000 and MPEG 4. It is very important for image coding. Encryption algorithm is one of the cipher security. In1977, American government released the DES encryption algorithm in public. However, the 56 bits key’s DES algorithm is almost over. Therefore, in 1997, American government asked for developing the advanced encryption algorithm fothe next generation.
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Chan, Lee Yung, and 李泳展. "Video Watermark System with ECC." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/88996542950711340991.
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碩士長榮大學
經營管理研究所
93
Digital videos become more and more popular, meanwhile, the illegal usages and distribution also grow as well. It also arise another problems such as users can copy vast amount of digital data at will. Watermark is a logo belongs to the owner and watermarking is the technique which is created for protecting the copyright. The watermark can be embedded and hidden into the video products. Because the owner can prove his ownership by extracting the watermark such that the watermarked videos can be distributed via the public channel, and the unauthorized copying may be discouraged. On the basis of applying to digital monitoring system, this thesis describes in detail the design of an innovative digital video surveillance watermark embedding and error control system. The proposed approach includes two sub-modules, one is watermark embedding and the other is Error Detection and Correction. By these embedding and error control schemes, the locations where was attacked in video would be detected and corrected such that the integrity of the embedded watermark can be maintained and the attempts of manipulation of video contents can be discouraged. This thesis includes two kinds of error correction codes which are Hamming Code and Golay Code.
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Lee, Ming-Harng, and 李明航. "Study on Robust Watermark Technology." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/48183957080257616622.
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碩士樹德科技大學
資訊工程學系
95
In this thesis, a spatial-domain and a frequency-domain watermarking techniques are proposed to improve the robustness of watermark hidden in images against the attacks including compression, cutting, and pepper-salt noise. In the spatial domain approach, the technique of hamming code is employed to protect the watermark spread-hiding in images. This hybrid scheme can effectively maintain the integrity of hidden watermark, even corrupted in either transmission corrupt or malicious attack. Besides, in frequency-domain watermark technology, the DC component of the frequency conversion of an image has the feature of robustness. Thus, a DC-component based watermarking is proposed to overcome the watermark distortion caused by image compression. To evaluate the performance of the proposed schemes, we use the standard image database to conduct a series of experiments to compare and to analyze the spatial domain and frequency domain schemes. The experimental results depict that (1) the spatial-based scheme has a better robustness than the frequency-based scheme in case of random noise (2) the frequency-based scheme has a better robustness than the spatial-based scheme in cases of cutting and compression attacks. Besides, comparing to the previous related works, the proposed schemes have a higher similarity of the recovered watermarks than before. Thus, the improvement of watermark robustness is properly verified.
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Lu, Chang-Cheng, and 呂章誠. "Personalized Stamps with Infrared Watermark." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/10675893425144081389.
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碩士國立臺灣師範大學
圖文傳播學系
98
In the recent years, because digital copiers improved rapidly, there are more and more unauthorized counterfeit and copy. Security document sometimes use watermark to improve its effective in protecting documents. Personalized Stamps is a valuable papers that people can participate the stamp design. The objective of this paper is to embed infrared watermark in the personalized stamp. The infrared watermark is composed of cyan, magenta, yellow, and black halftone dots. The carbon material in black ink can absorb the infrared light and the watermark could be detected under infrared detection. A calibration chart is designed to obtain the best parameters to hide the watermark in the personalized stamp. In addition, this research combine the method of dot shift used to hide figurative pattern. The result shows that the infrared watermark could be successfully hidden in a personalized stamp. This method would provide the stamp with not only encoded data but also the aesthetic appearance.
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Atherfold, Joanna. "Watermark: a short story cycle." Thesis, 2015. http://hdl.handle.net/1959.13/1309822.
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Research Doctorate - Doctor of Philosophy (PhD)Watermark is a short story cycle exploring intergenerational and personal relationships in coastal communities. The stories observe the complexity of characters drawn together, but also separated, by family, topography and circumstance. Written to reflect experiences from the 1960s through to present times, the stories reveal individuals responding to the uncertainty and disorder of life-changing events and unexpected revelations. Located in a quintessentially Australian landscape, the characters transgress physical and metaphorical boundaries and experience pivotal moments of transformation, even if – and, as it will be argued, because – those times are fleeting or unsustainable. The stories oscillate between their autonomous status and their interconnection within the broader narrative framework of the short story cycle. This structural aesthetic enables continuity through recurring characters, settings and themes. Paradoxically, these elements combine to reflect fractured relationships and unstable characters against a backdrop that is constantly changing. The exegesis draws on the notion of liminality to explore the generic and thematic concerns that emerged during the composition of the stories, particularly in relation to the oppositions and paradoxes evinced above. It looks at the complexities and challenges of the short story cycle with close reference to three short story cycles with coastal settings – The Bodysurfers by Robert Drewe, The Turning by Tim Winton and Having Cried Wolf by Gretchen Shirm. These texts reveal that Australian short story writers regard the coastline as more than simply a setting; it is a place of transition and a viable site to explore character development and transformation.
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Lai, Shih-Hsiung, and 賴世雄. "A Genetic Algorithm For Image Watermark." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/wr5n57.
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碩士銘傳大學
資訊工程學系碩士班
96
In this paper, a digital image watermark scheme based on the directional filter banks and discrete wavelet decomposition technique is proposed. To embed a mark, we systematically find out the locations from the low frequency of the directional images by the genetic algorithm. Moreover, to extract the embedded mark, we only need to know the locations of the embedded mark and one threshold value instead of the original image and mark. Several simulation examples are provided to illustrate practicability of this proposed image watermark technique which promotes the BER and preserves the quality of embedded image.
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Chang, Ting-Jung, and 張庭榕. "Document Watermark Based on Secret Sharing." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/8hf4zz.
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碩士靜宜大學
資訊管理學系研究所
92
The rapid technological advances of computers and the Internet have been directly influencing people’s lives. The endless possibilities of the Internet can be attained for a much lower price than the past. This causes issues of ownership as digital information can be easily duplicated without degradation. Digital watermark, which is to hide the owner’ s secret information or the logo, were thus developed to provide a means to a proof of ownership. Most watermark researches have focused on multi-media files taking advantage of their coding can withstand slight modification without being audio-visually noticed. There has been little research on watermark as applied to document files because one runs the risk of damaging the document’s structure when applying multi-media based watermarking techniques to a document file. In this thesis, we devise a secret-sharing based watermark model for document files and implement a system for RTF files. We randomly select n letter-segments and convert these segments into small 2-color image files for embedding the n unique “shadows” of the main secret, which are created from the (n, t) secret sharing scheme. In this way, the system preserves the document style while taking advantage of applying data hiding technique of 2-color images. Meanwhile, spreading the secret shadows into the entire document provides the system with the capability of proving the ownership for partial copying. Our system is secure as the following two mechanisms complicate the analysis: (a), It embeds n unique shadows instead of embedding the same secret n times. (b), Each shadow information is embedded into different non-uniform sections determined by a sequence-key only known to the owner or the authorized user.
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Cheng-Ming, Chou, and 周振民. "Watermark in Three-Dimensional Holographic Images." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/22052001037787578038.
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碩士國立臺灣師範大學
圖文傳播學系
95
The objective of this research is to propose a suitable watermarking method for the dot matrix hologram to display 3D image. Error diffusion and pseudo random number are used to embed watermark into halftone image, and then watermarked image is integrated into a 3D holographic image. After outputting the encoded hologram, this holographic image is captured and the watermark is extracted by digital image processing. The result shows that it is feasible to embed watermark in the 3D holographic image. Watermarked 3D-hologram possesses both artistic quality, and anti-counterfeit function.
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Wang, Liang-Feng, and 王亮丰. "Genetic Watermark Embedding Based on Wavelet." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/10260987185993461891.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
92
Because the rapid development of Internet, digitized content can be accessed, duplicated and altered easily, therefore intellectual property (IP) of Internet became more and more important. Digital watermarking is one kind of methods for protecting intelligence proprietary security. In this thesis, a watermarking system based on Discrete Wavelet Transform (DWT) is proposed. To begin with, we transform the original image (Cover image) and the watermark image (Logo image) from the spatial domain to the frequency domain by using 1-scale and 2-scale equal band DWT respectively. After the transformation, we use SVD to choose the feature of watermark, which is referred to as the watermark element (feature). The watermark feature is then quantized and encoded ((7,4) Hamming code) to form a watermark code. Each watermark code is then spreaded by 5 bits PN code to form a watermark PN sequence. To combine (7,4) Hamming code and PN code, our scheme has ability of double error correction. For security, we rearrange blocks of the original image to break down the relationship of the coefficients in each subband, and take absolute value, sort and divide into 7 parts in each block. Finally, we used the genetic algorithm to choose a fine group coefficients of the original image adaptively for embedding the watermark. Experimental results show that the proposed scheme can obtain good quality extracted watermarks under various attacks. The PSNR values of the watermarked image of Lena and Texture are more than 25dB.
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Cheung, Ning-Chung, and 張寧中. "visible digital watermark system designand analysis." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/34194839191423070848.
Full textAbstract:
碩士中原大學
電機工程研究所
89
ABSTRACT Digital watermarking is a technology that embeds signals into multi-media content in visible or invisible approach.By visible approach it indicates that the signal is visible,and invisible approach indicates that the signal is invisible.Visible watermark is mainly applied to protect unauthorized data,and invisible watermark is applied to protect authorized data.Existing visible watermarking technology is based on the visual property of contrast sensitivity to apply watermark into content.While not defacing the image content is the main concern of these technologies,this also limits the visibility of watermarkand prevents from instantaneous burglar-proof functionality.Thesis suggests the approach to apply the local and image-adaptive contrast adjustment into watermark can be visible to provide instaneous burglar-prof functionality without too much defacing the image.
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Huang, Shao-Da, and 黃少達. "Provable Watermark-Based Copyright Protection Scheme." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/01359852403731985259.
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碩士國立臺灣海洋大學
資訊工程學系
103
Watermark-based copyright protection techniques have been investigated for more than two decades in the signal processing and the digital rights management communities. In this paper, following the previous works, we discuss the requirements of a watermark scheme for providing proof of ownerships, and build our scheme based on previous well developed signal processing techniques but focus on how to employ unpredictable signature-seeded pseudorandom bit sequence to not only establish the unique relation between the watermark, the identity of true owner, and the original cover work, but also make the false positive watermark detection rate computationally negligible. We formally prove that if a valid watermark can be found in a disputed image, the probability that this image is not derived from the true owner’s published image is computationally negligible.
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Kuo, Ya-Hui, and 郭雅惠. "Image-switching Watermark by Digital Halftoning." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/86573879026796615480.
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Tsai, Kai-Shiang, and 蔡凱翔. "A grayscale watermark for copyright protection." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/25847458866908396598.
Full textAbstract:
碩士國立中正大學
資訊管理所
95
We propose a new algorithm of watermark for grayscale images in this paper. For this purpose, We obtain the main feature of the watermark via Haar Discrete Wavelet Transform (HDWT) and consider the secondary characteristic of the original image as the secret key for later watermark extraction. The mid-frequency pixels of transformed image which derived from Discrete Cosine Transform are choose to hide the bits of watermark. We then compute original pixels by using the secret key and stego-information. Experimental results are promising with our proposed algorithm.
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Fang, Bo-siang, and 方柏翔. "Watermark Research Based On Error Expansion." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/aa25b4.
Full textAbstract:
碩士國立虎尾科技大學
航空與電子科技研究所
99
Digital data can be transmitted easily nowadays due to the rapid development of multimedia technology and the dramatic expansion of the Internet. However, the issue of copyrights and security of digital data is thus important. Nowadays, many techniques are developed to protect digital data. Still, the issues about reproducing illegally exist. It may arouse social problems and copyrights controversy, etc. Therefore, ensuring the security of data transmissions on the Internet is an important topic. In some applications, such as medical, military and legal domains, the data hiding techniques not only retain the properties of recovery the watermark image after the secret data are extracted but also provide the application about secret communication and image identify. This kind of data hiding techniques is termed as reversible data hiding techniques. There are two categories of reversible data hiding techniques. The first category is the histogram techniques. Its particularity is that the algorithms are simple and the image quality is fine. The second category is difference expansion techniques. The neighboring pixel is a pixel-pair then expanded with the differences to embed the secret data. The capacity of this technique is fine, However, the working of such algorithms is usually time-consuming. In this research, two reversible data hiding schemes based on prediction errors were proposed. The first scheme, an overflow/underflow shift operation was proposed to make non-expandable prediction errors expandable. This scheme improved the algorithm of Thodi et al.’s PE2 to effectively increase the maximum true payload capacity. The second scheme, used the above overflow/underflow shift operation to improve Hu’s algorithm but with modification. The experimental results proved that the maximum true capacity of the first proposed scheme is larger than Thodi et al.’s PE2 algorithm. Compared with Hu’s algorithm, the second proposed scheme has larger maximum true capacity and better visual quality.
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Luo, Chih-Ping, and 羅治平. "A study of the robustness of watermark." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/85653753744115203312.
Full textAbstract:
碩士淡江大學
電機工程學系
89
The rapid development of Internet makes the multimedia data can be conveyed fast and unlimitedly through the Internet. But it also introduces several security issues such as the intellectual property (IP). Everyone can easily duplicates and distributes the multimedia data in the digital world. But the unauthorized duplication and distribution can violate the rights of the rightful owner. Digital watermarking is a commonly used technique to protect the legal use of the multimedia data. Robustness is an important requirement in digital watermarking. In order to obtain a digital watermarking system with high robustness, we use the concept of spread spectrum to spread the watermark over subbands, except the lowest frequency band LL. First calculate the energy of each subband and then distribute the watermark among these subbands according to the magnitude of the energy of each subband. If the energy of the subband is large (small), we embed more (less) watermarks. The watermark is embedded into the most significant wavelet coefficients. The inserting strength of watermark is proportional to the wavelet coefficient and then is adaptive. As a result, we can embed the watermark as strong as possible and obtain better image quality. The watermark is simultaneously embedded using two different ways that play complementary roles in resisting various kinds of attacks. No matter what kind of attacks it suffers, there is always one watermark can survive. We also use Error-Correcting Code (ECC) to detect and correct the error part of the extracted watermarks. In this paper, we propose two methods to embed two types of watermark. The first method can embed a bipolar watermark and the second method can embed a binary image. A binary image consists of black and white pixels and can only contain less information. We use the dithering to convert a gray-level image into binary image. Such procedure can reduce the quantity of the data but still can hold most information. We have considered several attacks including general image processing, JPEG compression, StirMark, Jitter and many image editing accomplished by the PhotoShop tools, totally 29 attacks. Experiment results show that the proposed two methods indeed can provide high robustness performance.
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Shi, Jones, and 徐上崢. "Fragile watermark technique embedded in JPEG2000 compression." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/88580529929059153993.
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吳業寬. "A study of the digital image watermark." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/10131646721149702423.
Full textAbstract:
碩士淡江大學
電機工程學系
90
Digital watermarking has been proposed as a way to claim protection. In this paper, we try to use the adaptive multi-frequency of wavelet transformation, and the human visual system to improve the traditional watermarking. We propose a blind watermarking technique by embedding watermark in all sub-bands. Watermark must have two most important properties: transparency and robustness. In our method, the host image can be disregarded in the procedure of the watermark extraction. Comparing with the traditional methods that have been proposed, we propose the adaptive quantization table by using the HVS (Human Visual System) model. According to the characteristics of the wavelet transform and the JND model, we embed the watermarking into the host image with different length according to the different frequency repeated. We also propose the duplicate quantization model and adopt the cocktail watermarking model to improve the robustness. In our experiments, the results show that the robustness in this watermark method can protect from wide-range of common attacks.
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Tseng, Woan-Jing, and 曾婉菁. "Multiple Spectrum Watermark in 2D Bar code." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/86756346506360996508.
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Wu, Chih-Chien, and 吳志堅. "The Study of Blind Digital Watermark Technology." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17769364875448397218.
Full textAbstract:
博士國防大學理工學院
國防科學研究所
101
A digital watermark is a pattern of bits inserted into a digital signal such as image file, that identifies the data's copyright or ownership information. Comparing with the traditional non-blind watermarking schemes, the proposed digital watermark schemes in this dissertation are all blind, which means that they require neither the original imagery nor any side information in the watermark recovery procedure. Firstly, we present a novel secret text hiding technique, where the secret text is embedded into the low frequency sub-band of the saturation component of a color image via redundant discrete wavelet transform (RDWT), while the color image's intensity and hue components are preserved with direct saturation adjustment, and the hidden secret text can be extracted from the watermarked image based on independent component analysis (ICA) without referring to the original cover image. The next one we proposed is a remote-sensing imagery web watermarking scheme, which equipped with dual functions of temper detection and ownership declaration. With the pre-defined watermark strength and statistical information of every image tile, not only multiple watermarks can be adaptive embedded into image tiles utilizing the discrete wavelet transform (DWT), but also significantly reduce the secret keys depository problems. The third scheme is alos a blind digital watermark, by utilize the scale-invariant feature transform (SIFT) and discrete wavelet transform, the watermarks can be adaptive embedded into selected blocks and to resist rotation and common compression attacks. In view of the mobile telecommunications and cloud applications have become the mainstream of information applications, we planning to integrate graphic procssing units (GPUs) and watermarking scheme, via cloud computing to fulfill the requirement of near real-time watermark encryption and decryption, and utilize the basic computing power of mobile devices in the watermark verification.
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Kuo, We-Shen, and 郭偉晟. "Robust two-domain for digital image watermark." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/13237969733211052958.
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碩士國立宜蘭大學
電子工程學系碩士班
96
As many current image watermarking technologies have difficulty to cope with general and geometric attacks at the same time, the motive of this thesis is thus to integrate a variety of technologies to allow the watermark to survive under various malicious attacks. In actual practice, a dual-domain watermark embedding scheme is developed for such a purpose. In our study, the dual-domain watermarking employs the Discrete Wavelet Transform (DWT) and Discrete Fourier Transform (DFT). The DWT has multi-band resolution properties so that the watermark can be embedded in the low-frequency band that is less susceptible to damages. On the other hand, the DFT has the invariant geometric properties that can withstand geometric attacks. Our scheme is to embed a trial template in the amplitude DFT for judging the possibility of geometric distortion during the process of watermark extraction. In addition, in order to enhance the obscurity and security of the watermarks, we have used the spread spectrum technique along with chaos theory. The experiment results show that our dual-domain watermark frame is superior to many others. Not only its PSNR can reach 45 dB, but it can effectively shield against general attacks (e.g. salt and pepper noise, Gaussian noise, JPEG compression, etc.) as well as geometric attacks (e.g. rotating, zooming, cropping, etc.). This study will prove that our scheme constitutes a very effective and robust watermarking algorithm
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Chen, Yi-Chih, and 陳羿志. "Code Division Multiple Access for Digital Watermark." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/97150957998901733858.
Full textAbstract:
碩士國立高雄應用科技大學
電子與資訊工程研究所碩士班
95
Thesis proposed a novel CDMA technique for multiple watermarking applied on digital images. Because the owner of the digital image can apply his private modulation code sequence to embed his watermark into an image, regardless of any others, each user can independently retrieve his watermark from the watermarked image as his secret code (private modulation code sequence) is given. The experimental results show the proposed method is reliable enough protect against the JPEG compression and cropping.
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Chiang, Yu-Hwa, and 蔣毓華. "Resisting Segmental Attack by the Watermark Technology." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/44694311600779321170.
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碩士國防大學中正理工學院
電子工程研究所
90
As the development of World Wide Web, the data distribution is becoming faster, and requiring less effort to make copies. One of the major challenges is that of discouraging unauthorized copying and distributing electronic documents. Digital watermarking is seen as a viable solution to authentication of multimedia data in a networked environment. In the pass decades, the study in digital watermarking has been presented as a solution to the copyright protection. Because of the development of this technique, private data can be transmitted by network to the full and achieve its concealment. In this thesis, a novel robust watermark technique is proposed to prevent the copyright of electronic document or image file been attacked from pirates in the network transmission. The aim of the proposed method is to resist cropping attack. First, the original image is segmented into four sub-images, and then makes them chaotic to change relative position with each pixel. Second, a binary logo is selected to act as the digital watermark and then make it to chaotic watermark. The embedding process is based on Discrete Cosine Transform (DCT) to embed the chaotic watermark into the original sub-image individual in the transform domain. The experimental results shown that the proposed watermarking scheme is robust to against cropping attack and JPEG compression.
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Lin, Li-Ming, and 林禮銘. "Digital Image Halftoning Techniques and Watermark Hiding." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/91941885198917056387.
Full textAbstract:
碩士中原大學
電機工程研究所
99
Most black and white printers use screentone technology to simulate the gray color. In fact, it composes of a large number of two-toned black and white dots. Since the human eyes can not scrutinize these dots, after the human eye it will produce the illusion of gray, which is the so-called halftone technique. Examples include inkjet printers, fax machines, newspapers, magazines, and comic books printing. Most of them use halftone images as outputs. This thesis first reviews order dither, error diffusion, dot diffusion and other existing halftoning techniques. We will explore techniques to convert the gray-scale image into a halftone image and compare their advantages and disadvantages. Information encryption is often discussed in this network age. A technology to hide watermark in an image to transmit the secrete watermark information is also an information encryption method. Because the information amount is less for halftone images than for grayscale and color images, transmission of halftone images can reduce the time required. Chapter 3 will explore the use of stochastic error diffusion, noise-balanced error diffusion, and other methods to hide the watermark in the error diffused halftone pictures. Finally, we propose new methods to hide watermarks in two halftone images. Specifically, we propose to use threshold changes to hide watermarks in order dither halftone images. We also propose to change error diffusing orders of the dot diffusion halftoning technique to hide the watermarks.
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Wang, Jang-Meng, and 王彰盟. "On the noise sensitivity of optical watermark system." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/72899244720521846955.
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碩士逢甲大學
通訊工程所
93
This paper is to discuss the effect of noise and analyze nonlinearity of the optical correlator on detection procedure of the optical watermark system (OWS). In the digital holographic watermarking scheme, the watermark is constructed by an optically holography architecture, and the watermarked hologram is embedded into a cover image. For the Detection, the optical correlator is used to detect the embedded watermark based on the correlation of the watermarked image and the authorized mark pattern. Given a sharp correlation, one can claim that the watermarked image has a correct mark. Conversely, the mark is absence. This thesis consists of two purposes: one is to discuss the noise effect of the optical watermark system and the second is to consider the influence of the nonlinear device of the system. When the watermarked image interrupted by various type of noises such as additive white noise、occlusion of one part of the image and quantization, we develop an statistical model for analyzing the output correlation under the noise environment. Furthermore, since the watermarked image is a wide range gray-level image, the nonlinear SLM effect should consider under this structure. Thus, we derive the nonlinear relationship for the input and output of the SLM and use it to consider output correlation under the nonlinear environment. Experimental results is demonstrated the performance of the optical watermark system under the noise corruption and the nonlinear effect of the optical device in the system.
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Yang, Hao Jen, and 楊浩任. "A Color Digital Watermark Based on Spatial Domain." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/67151348969827077443.
Full textAbstract:
碩士臺中健康暨管理學院
資訊工程學系碩士班
93
Abstract Today, technology is at a tremendous pace, the software and hardware prices are acceptable, and the popularization of Internet, the color images can be obtained easily. It is a difficult problem for affirming copyrights, and digital watermark is a well known technology to judge the copyright dispute. But the most watermark technology embed the binary watermark in gray-scale image, in the multimedia world, such solution is insufficient. This thesis proposes a method can use less calculation to embed the color watermark in color image, and does not need the original image to extract the embedded color watermark. First, this study counts the most 24 colors of color watermark that we want to embed, and use these colors as the representative of color watermark. Then uses a pseudo random number generator to scramble the represented color watermark, and saves the random seed as the secret key. This proposed method embeds the color watermark in B-channel of the RGB color space. We can utilize adjoin pixel relation of similar gray-scale level, with the different permutation order according to pixel values of 2x2 block, to represent 24 kinds of different color, and can emphasize the distance among pixels with a parameter d to increase the robustness of the watermark. While extracting the embedded watermark, only need scan the permutation order of 2x2 block for the disputant image, and need not compare the original image. The experiment results prove the method proposed by this thesis is finer than methods have been proposed in the literatures.
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Shu-O, Chang, and 張素娥. "STUDIES OF AUDIO WATERMARK USING HUMAN MASKING EFFECT." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/13295727004794411700.
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碩士大同工學院
電機工程研究所
87
According to the widely use of the Internet communication, we can transmit and download the digital data more easily and frequently. However, the copyright of the original publication has been ignored. We can use the watermark to protect the copyright of publication and claim the ownership. This thesis is based on the watermarking techniques. The digital data transmitted on the Internet has several forms; such as text, image, audio and video. This thesis is focus on discussion of the audio watermarking. The key concept is using the masking effect of the human audio system to embed the audio watermarks, which can protect the copyrights. The proposed approach embeds the watermark into the second peaks in the Kaiser window. The simulation shows that the extracted watermark can survive under CELP and MP3 attacks.
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Li, Yu-Ting, and 李昱廷. "A DCT Watermark Embedding Algorithm with Image Normalization." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/17496644124272934612.
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碩士國立宜蘭大學
電子工程學系碩士班
98
Abstract Many current image watermarking technologies emphasize the resistibility against either general or geometric attacks, but seldom take full consideration of both concurrently. Therefore, the motive of this thesis is to integrate a variety of technologies to resist most malicious attacks and ameliorate existing shortcomings of previously developed technologies. This thesis proposes a composite algorithm executing two major procedures. First, a two-dimension Gaussian window (2-D GW) acting as a mask is placed a specific region. The center of this particular region, which is presumably the salient point of the image, can be identified using Harris corner detection. Image normalization (IN) is then employed to acquire geometric invariant features. The IN together with the 2-D GW can shield the watermark from geometric distortion such as rotation and whirlpool attacks. During the IN processing, we further apply the quantification method to withstand noise attacks. While in the second procedure, the original image is initially converted into discrete cosine transform (DCT) coefficients. Some of the AC coefficients are altered in accordance to the relation between the embedded bits and the chosen coefficients. Moreover, we use the Arnold transform to scramble the watermark so that the stealth and completeness of the intended watermark can be better preserved. In summary, this thesis has integrated the IN, 2-D GW, Harris corner detection and quantification techniques. Experiment results prove that the proposed algorithm can sustain general attacks (e.g. salt and pepper, Gaussian noise and JPEG compression) as well as geometric attacks (e.g. rotating, zooming and cropping).
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Wang, Wei-Tsung, and 王偉璁. "An Implementation of Watermark Based on Operating System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/19919277842431673725.
Full textAbstract:
碩士逢甲大學
資訊電機工程碩士在職專班
98
It is much easier to convey digital contents due to file digitization and the rapid development in the Internet, so those contents will face serious threat of illegal access if they lack a sound protection mechanism. To protect the important files from using without permissions, digital rights management systems have been highly valued among digital content suppliers. Even thought digital rights management system can limit user’s permission to files such as reading, editing, printing, sending, it can’t prevent legal user from using the method of print screen or camera remaking to copy files. This thesis uses the mechanism of picture-shark to prevent print screen or camera remaking. The framework of this article can break the limitation in file formats and further embed user information into all files directly. The framework can be used in the deterrence and the investigation of tracing back the origin of illegal copied files, so it is beneficial to the development to digital content industries.
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Ma, Sheng-wen, and 馬盛文. "Watermark Embedding in Minimum Difference of Wavelet Tree." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/25898807106695001925.
Full textAbstract:
碩士國立臺灣科技大學
資訊工程系
98
In recent years, the information bursts out on the Internet. It is more convenient to spread the data through the Internet. But it causes a serious problem. That is copyright violation. Although those images are not really touchable, the values are unpredictable. When we retrieve an image or a text file from the Internet, how can we confirm the copyright of it? These media information are easily copied, reused, and spread. Copyright violation is quite common to be seen on the Internet. The proposed research is to protect the copyright on the Internet. To find a better way for the watermark embedding, we embed the watermark information on the DWT domain. And we use the pseudo-random number generator to generate a key, which is used to select the wavelet tree for embed. We embed the watermark information at the minimum difference of the wavelet tree. And apply the IDWT for the image. In order to improve the watermark correctness, we apply the BCH code which is a kind of error correction code. BCH code uses the character of the algebra which can use the extra redundant information to correct the errors. And finally we use the Human Visual System to find the better threshold between the quality of the watermarked image and the robustness of the watermark logo.
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Fan, Jia-Rong, and 范家榮. "Digital Audio Watermark Based on Subspace Watermarking Method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/19787993844423906428.
Full textAbstract:
碩士國立交通大學
資訊工程系所
93
In recent years, due to the widespread use of Internet and great progress of the computer technologies, the proliferation of digital multimedia or documents is more and more important and can not be disregarded. To protect the intellectual property of the digital data, there has been significant interest in watermarking in recent days. We proposed a watermarking strategy from in which the watermark of a host audio data is selected from the robust features of the estimated forged audios of the host. In this thesis, the robust features will be selected from the coefficients of the low frequency part of DCT coefficients after the DCT transformation. The forged audios are obtained from some software, such as LAME compression encoder and Stirmark Benchmark for Audio (SMBA). They perform potential pirate attacks on the host audio. We apply SVD technique on the features of the forged audios and obtain two orthogonal spaces. One of them characterizes most of the variations in the modifications of the host. We embed our watermark in the other space that most potential pirate attacks don’t touch. Thus, the embedded watermark is robust. According to the result of some experiments, it shows that our watermarking method can reach the goal of both of high detection probability and low false-alarm probability.
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楊秀山. "Using Wavelet to Combine Watermark and Image Transmission." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/62455333481641615991.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
91
The main objective of this thesis is to construct a real time image transmission system with a digital watermark. We use discrete wavelet transform to decompose a image to different frequency band. Associated with the quantization and entropy coding to reduce the amount of data. As a result of reducing the amount of data, we can reduce the transmission time and usage of internet bandwidth at the same time. Furthermore, we embed a binary image’s watermark during our encoding process to be a certification for the person who transmit. This watermark also can be the image authentication data. We can extract the watermark to determine whether an image has been altered or not and locate any alteration made on the image when we doubt a image may be altered. In the network part, we use WinSock API to connect two computers and use TCP/IP communication transmission control protocol to transfer image data from a server to a client. Finally, we develop an application program to combine image encoding and internet transmission, then design a simple operating interface to achieve the purpose of real time image transmission and image authentication.
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Hsu, Te-Cheng, and 徐德成. "Watermark-removal method based on Eigen-image energy." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51205574887161894062.
Full textAbstract:
博士國立中山大學
資訊工程學系研究所
100
Most watermark-removal methods treat watermarks as noise and apply denoising approaches to remove them. However, denoising methods remove not only this watermark energy, but also some of the energy of the original image. A trade-off therefore exists: if not enough of the watermark energy is removed, then the watermark will still be detected, but if too much is removed, the image quality will be noticeably poor. To solve this problem, the relationship among the energies of the original image, the watermark and the watermarked image is initially determined using stochastic models. Then, the energy of the watermark is estimated using just-noticeable-distortion (JND). Finally, the watermark energy is removed from the watermarked image based on the energy distribution of its Eigen-images. The experimental results show that the proposed approach yields a mean peak signal-to-noise ratio (PSNR) of the predicted images that is 2.2dB higher than that obtained using the adaptive Wiener filter, and a mean normalized correlation (NC) value of the extracted watermarks that is 0.27 lower than that obtained using the adaptive Wiener filter. In removing watermark energy from 100 randomly selected watermarked images in which watermarks were embedded using the ‘Broken Arrows (BA)’ algorithm proposed for the second Breaking Our Watermarking System (BOWS-2) contest, the mean PSNR of 100 predicted images is 24.1dB and the proposed approach successfully removed watermarks from 90 of these images. This result exceeds the minimum requirement of PSNR 20dB for the BOWS-2 contest. Clearly, the proposed approach is a very effective watermark-removal approach for removing watermarks.
49
Tsou, Pei-Ying, and 鄒佩瑩. "A study of the synchronization problem of audio watermark." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/26794137828754186677.
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碩士淡江大學
電機工程學系
91
The published digital medias in Internet become commercial and valuable is a trend in recent years. The trend increased the requirements of copyright protection. The digital watermark proposes a solution to solve the copyright problem. This paper focuses on the audio watermarking, which embeds the copyright information into the audio signal without the degrading the quality. The robustness is a condition of digital watermark. The watermarking process in this research is based on cepstrum domain. The SMM (Statistical-Mean Manipulation) technique is used to embed the watermark, which is able to resist the general signal processing attacks. During the detecting process, the watermark can be extracted without the original audio signal. With the popularization of audio editing software and the commercial applications of digital watermark, various attacks should be considered. For example, the illegal user may cut a part of music without permission. The watermark detection may fail without the original audio signal. This attack could be classified into the synchronization problem. The synchronization problem refers to the condition that losing the location of watermarked frame when doing the watermark detection. This paper combines the method based on energy features to decide the location of embed frames. The simulation results verified that the method improved the robustness resisting the attacks such as MP3 compression, time scaling, pitch shifting and cutting samples.
50
Hsieh, Yi-Ta, and 謝易達. "DCT-BASED WATERMARK EXTRACTION WITHOUT ORIGINAL VIDEO AND IMAGE." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/86478368739879191470.
Full textAbstract:
碩士大同大學
電機工程研究所
91
Digital watermarking schemes have been discussed to solve the problem associated with the copyright enforcement. In this thesis, we present a watermarking method that applies to the JPEG images and MPEG videos. The proposed method applies the inter-block correlation of DCT coefficients. It has the features that the embedded watermark can be extracted without the original image nor the parameters used in embedding process, and that amount of modification, which is the strength of embedded watermark, depends on the local feature of an image. Watermark robustness to JPEG compression, low pass filter, image cropping, and reduced attacks is studied for the proposed system.