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Digital Image Steganography
Kolarčík, Tomáš ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor thesis deals with digital image steganography and implements some of the available methods. This thesis describes steganography on a general level, it's history and it's current form. It also shows it's classification according to the type of carrier, the classification of the methods according to the style of hiding data and the influence of the hidden information. The primary subject of this thesis is image steganography, where facts that allow imperceptibly hide data inside image are described. A great part of this thesis is dedicated to the characteristics of the methods, which we observe and to the methods themselves. All of the methods described are implemented in a graphical and console application. The created application provides multiple image formats for hiding. In the last part, testing is performed in terms of capacity, imperceptibility and robustness.
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Digital Steganalysis
Molnár, Ondřej ; Nevoral, Jan (referee) ; Strnadel, Josef (advisor)
Steganalysis is the opposite science discipline of the steganography - which is an art of information hiding . Steganography deals with embedding of secret messages to different types of media. The most commonly used cover media in modern steganography are image files . This bachelor's thesis creates an overview of known steganograpy and steganalysis methods . It also describes practical implementation of application that is able to detect hidden information in image.
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Digital Image Steganography
Mazánek, Antonín ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor's thesis introduces the steganography scientific discipline. It presents its ancient and relative recent history, mentions its current use and outlines the possible directions for steganography future. It introduces steganography into context of hiding information superior domain and highlights differences between other methods in this domain. It describes steganography subdivisions and closer deals with digital image steganography. It presents some known methods and types of digital image data. The thesis also contains more detailed description of image data in PNG format. It describes the implementation of LSB and PVD steganography methods with images in PNG format as cover object and evaluates their key properties, namely: imperceptibility, capacity and robustness. At the end of the thesis, the author's reflection on the results and possibilities of further modifications of the mentioned methods is given.
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Comparison of the Effect of Fingerprint Image Compression Algorithms on the Quality of Matching Algorithms
Varga, Marek ; Kanich, Ondřej (referee) ; Drahanský, Martin (advisor)
Táto práca si kladie za cieľ zhodnotiť vplyv rôznych možností kompresie a techník spracovania obrazu pre rôzne typy snímok odtlačkov prstov. Kvalita kompresných metód sa otestuje pomocou rôznych techník porovnávania odtlačkov prstov na meranie podobnosti medzi spracovaným a pôvodným obrázkom odtlačku prsta. Práca hodnotila výkonnosť kompresií JPEG, PNG a WSQ, ako aj porovnávače založené na markantoch, krížovej korelácií a PSNR. Techniky spracovania odtlačkov prstov zahŕňali normalizáciu obrazu, binarizáciu, zmenu bitovej hĺbky, odstránenie šumu a zmenu veľkosti obrazu. Výsledkom bolo, že kompresia PNG zaznamenala najlepšie priemerné skóre pre všetky typy odtlačkov prstov podľa všetkých testovaných porovnávačov. Okrem toho kompresia JPEG zaznamenala najlepšie priemerné kompresné časy, zatiaľ čo kompresia WSQ priniesla najmenšie komprimované veľkosti súborov. Techniky spracovania snímok odtlačkov prstov nezlepšili skóre zhody, iba ich zhoršili.
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UGE - Import/Export
Kádek, Tibor ; Polášek, Petr (referee) ; Smrčka, Aleš (advisor)
This thesis deals with creating graphs in application UGE (Universal graphic editor) and facilities it offers for plugins programmers. Goal of the thesis is to design UGML (UGE Graph Markup Language) data format, implement plugin for importing/exporting graph, implement SVG graphic format export and export into several bitmap formats. Thesis extends particular parts of application, especially API (application program interface) and manipulating graphical representation of objects.
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High-Quality Visualization of Petri Nets for Publishing Purposes
Bednář, Drahoslav ; Kočí, Radek (referee) ; Janoušek, Vladimír (advisor)
This work is trying to solve the problem of graphical visualization of Petri nets in text publications. The aim of the thesis is to create a tool that will simplify generating of Petri nets and at the same time provide a more aesthetic graphical output than existing tools do. A simplex algorithm was used for automatic network layout. The program has both graphical interface and text mode and can cooperate well with existing tools for working with Petri nets, which the text also mentions. The program is able to load a pnml file and produce a usable image in png, pdf, and svg formats.
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Compression of ECG signals recorded using mobile ECG device
Had, Filip ; Vítek, Martin (referee) ; Němcová, Andrea (advisor)
Signal compression is necessary part for ECG scanning, because of relatively big amount of data, which must be transmitted primarily wirelessly for analysis. Because of the wireless sending it is necessary to minimize the amount of data as much as possible. To minimize the amount of data, lossless or lossy compression algorithms are used. This work describes an algorithm SPITH and newly created experimental method, based on PNG, and their testing. This master’s thesis there is also a bank of ECG signals with parallel sensed accelerometer data. In the last part, modification of SPIHT algorithm, which uses accelerometer data, is described and realized.
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Modern compression formats of digital image
Eder, Radek ; Přinosil, Jiří (referee) ; Číka, Petr (advisor)
This bachelor thesis deals with the problems of digital image compression. There are described basic color models RGB and YCbCr and conversion between them. Described are currently used codecs for digital images. JPEG compression format is discussed in more detail, which currently is still the most widely used format for digital photos. Described is a process of digitizing the image using the JPEG standard, which includes sampling, quantization and coding. Described are also formats JPEG2000, PNG and WebP. End of chapter are described methods for subjective and objective evaluation of the quality of digital image compression. Among the subjective methods include Double Stimulus Impairment Scale (DSIS) and Double Stimulus Continuous Quality Scale (DSCQS), then the objective methods include Mean Squared Error (MSE), Peak Signal to Noise Ratio (PSNR) a Structural Similarity (SSIM). Application was created as part of the work that allows you to compress the source image to the selected formats. It also allows a qualitative evaluation of compression and store the results to the file.
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