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Image watermarking in frequency domain
Štrbíková, Tatiana ; Rajmic, Pavel (referee) ; Číka, Petr (advisor)
This thesis analyze digital watermarking. At first we can read about watermarking in generally. Secondarily, it considers about possibilities of watermarking, therefore about different ways of watermarking. Methods of digital watermarking we can divide into three main categories: spatial domain watermarking, frequency domain watermarking and spread spectrum watermarking. In detail there is described frequency domain watermarking. Two methods are compared. First method, which use DCT (Discrete cosine transformation) and second metohd, which use DWT (Discrete wavelet transformation). Finally we can found out, which method seems to be better.
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Protecting of image data
Nováček, Aleš ; Přinosil, Jiří (referee) ; Číka, Petr (advisor)
Bachelor´s thesis is about protection of digital images, especially about modern watermarking techniques. It consists of three main parts. The first one is the theoretical part, that describes watermarking terminology, techniques of embeding and detection of watermark, watermarking applications and watermarking requirements such as robustness and impercebility. The second and third part compares two methods of watermarking. Both methods are based on the transformation of image to the frequency domain. The first method uses discrete cosine transformation and the second one discrete wavelet transformation. Method using DCT embeds watermark by swaping DCT coefficients. The second method embeds watermark by modifying some coefficients of DWT decomposition according to the equation vi´= vi (1+sxi ), where vi´ is a coefficient of watermarked image, vi is a coefficient of original image, xi is pixel of watermark and s is scale factor, constant, that affects robustness of watermark.
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Invisible watermarking method for images
Trbušek, Pavel ; Říha, Kamil (referee) ; Malý, Jan (advisor)
Bachelor´s thesis deals with embedding of invisible watermark into image. The methods used for reach the main objective of this thesis are given in the first part. I mention three methods: Discrete Cosine Transform method, Discrete Wavelet Transform method and Set Partitioning in Hierarchical Trees method. In the second part I describe implementation of Discrete Wavelet Transform method and Set Partitioning in Hierarchical Trees method in MATLAB setting. The last part deals with the test of the watermark endurance to geometrical attacks. I summarize the results of the watermark endurance test are very satisfactory even by the disruption of the image quality.
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Advanced Methods to Multimedia Data Protection
Mikulčík, Ondřej ; Zukal, Martin (referee) ; Číka, Petr (advisor)
To protect the the copyright of multimedia works have been developed watermarking techniques, that insert an invisible watermark to the original data. The aim of this thesis was to explore modern watermarking techniques, choose three of them and realize them. Also test them, evaluate their properties and possibly improve them. All methods insert a watermark into luminance component of the original image, and work with binary or black and white watermark. All techniques work in the frequency domain using discrete wavelet transform. For the implementation of methods, have been developed software named "Watermarking" that has been programmed in JAVA Version 7. The first chapter describes the types of watermarks, the general process of insertion and extraction, watermarking systems and important feature requests of embedded water- marks. In addition, qualitative methods are mentioned for their comparisons and testing. The chapter also contains a theoretical description of the used transformations and functions. In the second chapter is described the user interface of the software "Water- marking". Chapters three and four contain a theoretical description of the implemented methods and description of implementation of insertion and extraction processes of the watermark. Also there are discussed the exact procedures for testing, the sample data, and the results which are clearly displayed in the tables. The fifth chapter discusses in detail the results obtained in testing the robustness of the watermark, using the software StirMark. In the conclusion are evaluated the advantages and disadvantages of methods and quality parameters.
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Neural networks in audio signal watermarking algorithms
Kaňa, Ondřej ; Smékal, Zdeněk (referee) ; Zezula, Radek (advisor)
Digital watermarking is a technique for digital multimedia copyright protection. The robustness and the imperceptibility are the main requirements of the watermark. This thesis deals with watermarking audio signals using artificial neural networks. There is described audio watermarking method in the DCT domain. Method is based on human psychoacoustic model and the techniques of neural networks.
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Neural networks in audio signal watermarking algorithms
Kaňa, Ondřej ; Smékal, Zdeněk (referee) ; Zezula, Radek (advisor)
Digital watermarking is a technique for digital multimedia copyright protection. The robustness and the imperceptibility are the main requirements of the watermark. This thesis deals with watermarking audio signals using artificial neural networks. There is described audio watermarking method in the DCT domain. Method is based on human psychoacoustic model and the techniques of neural networks.
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Image watermarking
Štágl, Luboš ; Zezula, Radek (referee) ; Číka, Petr (advisor)
This diploma thesis is concerned in static pictures Security problems. That means, additional informations (watermark) are embedded to the original picture in a specific way. This complex picture structure (watermark) should be unremoval by different attacks runing processes. The main goal of this diploma thesis is realize two separated methods digital data watermarking in MATLAB program. For reason of a quite large scale of different watermarking methods are chosen at this time only two of take were choosen. First of the methods is Watermark injection in the spatial domain and the second in the freuquency domain. Both methods are set up in a special way and finish goals of the process. Expected result are, that digital picture user doesn't know about the watermarking technique was aplied on this picture and the watermarking data are the most resistant as possible as can be. These attacks were simulated in Checkmark program.
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VST Plug-IN for audio signal watermarking
Henzl, David ; Schimmel, Jiří (referee) ; Zezula, Radek (advisor)
This thesis deal with digital signal proccessing methods, possibilities their processing and especially audio signal watermarking like possibility safeguard author's rights of audio content. In this thesis are foreshadoweds basic audio watermarking methods and possibilities of watermark detection. To idea generation about watermarking there is described audio watermarking method known as Echo Hiding. This method embed watermarks to audio content in time-domain while watermark detection is made in kepstral-domain by using Fast Fourier Transform and correlation function. Method is implemented like VST plug - in and along with ASIO drivers that minimize signal latency provides audio signal watermarking in real - time. Aim of the first volume of this thesis is introduction of VST technology, ASIO driver and creating VST plug – in‘s. Alternative volume of thesis deal with implementation watermarking methods in conjunction with VST technology.
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Watermarking of digital data
Kupka, Jan ; Přinosil, Jiří (referee) ; Číka, Petr (advisor)
The main aim of this project is to implement two different types of the watermarking algorithm in frequency (transforamtion) domain. Because of the huge amount of the watermarking algorithms is this thesis dedicated to the watermarking methods in the frequency domain. These methods use kind of transformation implemented on the original data, the second step is modification of transformation coeficients. This project is dedicated to the methods which use discrete wavelet transformation. Nowdays the most popular transformation, which meets the best efforts. The aim of every method is to embeed the watermark into the original data so precisly, that none observer can recognize any change between the original and watermarked data. On the contrary, watermarked picture should be as resistant to the attacks as possible. By the term of attack, we understand all the ways, that disable watermark extraction. The watermark method robustness will be tested with the use of Checkmark program.
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Watermarking of static images
Bambuch, Petr ; Burda, Karel (referee) ; Číka, Petr (advisor)
The thesis deals with the security of static images. The main aim is to embed the watermark into the original data so effectively, to avoid removal of the watermark with the use of simple and fast attacks methods. With developing of the watermarking techniques the technique of attacks are improved and developed also. The main aim of the attacks is to remove and devalue the hidden watermark in the image. The goal of the thesis is to check current techniques of static image watermarking and implement two methods of watermarking, which are to be tested for robustness against attacks.
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