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Implementation of Statistical Compression Methods
Beněk, Tomáš ; Polok, Lukáš (referee) ; Bařina, David (advisor)
This thesis deals with the statistical compression methods. This work describes basic theoretical introduction to the data compression and the most important representatives of statistical methods. There is also described compression process based on the Burrows-Wheeler algorithm, which is implemented in the form of portable library in C++ programming language. This work compares effectiveness of each method on suitable data corpus, which contains various data types and according to achieved results discusses suitability of usage of methods and possible improvements.
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ECG Signal Transmission via Ethernet
Bayerová, Zuzana ; Provazník, Ivo (referee) ; Sekora, Jiří (advisor)
The semestral thesis describes ECG signal compression methods designed to modify the data for transmission via communication channels. The thesis contains an introduction to Ethernet and explanation of communication in the network. The transport protocols TCP and UDP are discussed in more detail. In the practical part of the thesis was created two separate applications. The first application in the sender's computer opens a text file with the ECG signal. Loaded ECG signal is filtered by cascade of filters to eliminate interference. The resulting signal is displayed. A part of the application is the R wave detection, calculating the length of RR interval and heart rate. The application also allows to compress an ECG signal. ECG signal is sent via Ethernet network via UDP protocol for individual samples. Applications in the recipient's computer receives signal samples from the network. Recieved compressed data is reconstructed. The resulting ECG signal is displayed and there are again detected R waves, the length of RR intervals and sampling frequency are calculated.
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Uplatnění fraktálů v kompresi dat
Dušák, Petr ; Ivánek, Jiří (advisor) ; Palovský, Radomír (referee)
The mission of the Technology Transfer Programme Office is to increase impact on a society by transferring technologies developed by the European Space Agency. Method and Apparatus for compressing time series is a patented compression algorithm designed to be efficient as its purpose is to run on deep space probes or satellites. The algorithm is inspired by a method for fractal terrain generation, namely the midpoint displacement algorithm. This work introduces fractals, their application and modifying the patented algorithm, in order to achieve greater compression. The modification lies in modifying the displacement mechanism. The modified algorithm is capable of reducing data up to 25 %, compared to the patented algorithm. The modification made the algorithm less efficient. In large-scale test, performed on Rosetta spacecraft telemetry, the modified algorithm achieved around 5 % higher compression.
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Dynamic Texture Modelling and Editing Using Temporal Mixing Coefficients Reduction
Havlíček, Michal
Real world materials often change their appearance over time. If these variations are spatially and temporally homogeneous then the visual appearance can be represented by a dynamic texture which is a natural extension of classic texture concept including the time as an extra dimension. In this article we present possible way to handle multispectral dynamic textures based on a combination of input data eigen analysis and subsequent processing of temporal mixing coefficients. The proposed method exhibits overall good performance, offers extremely fast synthesis which is not restricted in temporal dimension and simultaneously enables to compress significantly the original data and additionally perform texture editing.
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MSAR BTF Model
Havlíček, Michal
The Bidirectional Texture Function (BTF) is the recent most advanced representation of material surface visual properties. BTF specifies the changes of visual appearance due to varying illumination and viewing conditions. Such a function might be represented by thousands of images of surface taken in given illumination and viewing conditions per sample of the material. Resulting BTF size, hundreds of gigabytes, excludes its direct rendering in graphical applications, accordingly some compression of these data is obviously necessary. This paper presents a novel probabilistic model based algorithm for realistic multispectral BTF texture modelling. This complex but efficient method combines several multispectral band limited spatial factors and corresponding range map to produce the required BTF texture. Proposed scheme enables very high BTF texture compression ratio and in addition may be used to reconstruct BTF space i.e. non-measured parts of the BTF space.
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Data compression in ORACLE database system and it's impact on performance
Vacek, Martin ; Macák, Petr (advisor) ; Chlapek, Dušan (referee)
In present day, when magnitude of user generated content rises (web 2.0 technology) and important becomes also the role of multimedial content which is wanted to be stored within DBMS, the space saving turns to be a challenge for back-end developers on the side of providers as well as for database administrators on the side of their clients. How to store, manage and process data effectively led Oracle to research and development of several technologies that are to help DBA in resolving up to date's data distribution requirements for endusers. For instance, let's name clustered tables, partitioned tables, data compression. Each of these technologies comes with different approach to the problem, has it's pros, cons and limitations and sometimes it is possible to combine them at some level. In this thesis I concentrate on the last forenamed and its implementation in database system Oracle 11g Enterprise Edition R1. Basically it consists of two alternatives of data compression application. One of them already implemented in previous version - Oracle 9i EE R2 and the second one -- separately licensed -- newly introduced along with version 11g that consists of compression functions package for various data structures and operations. By means of theoretic analysis of functionality, benchmark definition, running several tests and their interpretation I route this thesis to possible practical use in decision making, when to apply compression, when to avoid it, eventually as a starting point for additional testing within the scope of more extensive theses further unraveling this topic.
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