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Monitoring Trends of Electrical Activity of the Heart Using Time-Frequency Decomposition
Čáp, Martin ; Kozumplík, Jiří (referee) ; Provazník, Ivo (advisor)
Work is aimed at the time-frequency decomposition of a signal application for monitoring the EKG trend progression. Goal is to create algorithm which would watch changes in the ST segment in EKG recording and its realization in the Matlab program. Analyzed is substance of the origin of EKG and its measuring. For trend calculations after reading the signal is necessary to preprocess the signal, it consists of filtration and detection of necessary points of EKG signal. For taking apart, also filtration and measuring the signal is used wavelet transformation. Source of the data is biomedicine database Physionet. As an outcome of the algorithm are drawn ST segment trends for three recordings from three different patients and its comparison with reference method of ST qualification. For qualification of the heart stability, as a system, where designed methods watching differences in position of the maximal value in two-zone spectrum and the Poincare mapping method. Realized method is attached to this thesis.
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Processing of images of early spruce needles scanned by MR technology
Raichl, Jaroslav ; Říha, Kamil (referee) ; Gescheidtová, Eva (advisor)
This semester project deals with filtering of the images detected by use of NMR obtained by NMR application measurement of nuclear magnetic resonance (NMR). This thesis includes the theory of nuclear magnetic resonance, digital filters, basic digital filter banks structures, theory of Wavelet transformation and description of Signal to Noise Ratio calculation. Basic procedure of the MR signal denoising is summarized in the theoretical part of the thesis. The denoising of the images detected by nuclear magnetic resonance is described. In experimental part filtering methods for images denoising are described, which are implemented in program Matlab. These methods are based on Wavelet transformation, digital filter banks with proper thresholding. Effectiveness of filtering methods designed was verified on 2D NMR images. All of these 2D images were measure on MR tomography in the Institute of Scientific Instruments Academy of Science of the Czech Republic in Brno.
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A Wavelet-Based QRS-Complex Detection
Kocian, Ondřej ; Provazník, Ivo (referee) ; Kozumplík, Jiří (advisor)
This project investigates methods of construction the wavelet-based QRS-complex detector. QRS-complex detection is very important, because it helps automatically calculate heart rate and in some cases it is used for compression ECG signal. The design of QRS detector can be made with many methods, in this project were mentioned and consequently tested only a few variants. The principle of designed detector used a wavelet-based decomposition of the original ECG signal to several frequency-coded bands. These bands are consequently transformed to absolute values and with the help of the threshold value are marked positions of assumed QRS complexes. Then are these assumed positions from all bands compared between themselves. If the position is confirmed at least at one nearby band, then is this position marked as true QRS complex. To increase efficiency of designed detector, two modifications were additionally mentioned. The first one, using the envelope of the signal, had rather negative effect on detectors efficiency. The second modification, using combined signal from three pseudoorthogonal leads, had reversely very good effect on detectors efficiency. In the end, the designed detector and all its modifications were tested on signals from CSE library (exactly on leads II, V2 and V6).
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JAVA-based effective implementation of an image compression tool
Průša, Zdeněk ; Rajmic, Pavel (referee) ; Malý, Jan (advisor)
This diploma thesis deals with digital image lossy compression. Lossy compression in general inserts some kind of distorsion to the resulting image. The distorsion should not be interupting or even noticable in the better case. For image analysis there is used process called transformation and for choosing relevant coefficients process called coding. Evaluation of image quallity can be done by objective or subjective method. There is encoder introduced and realized in this work. Encoder utilizes two-dimension wavelet transform and SPIHT algortihm for coefficient coding. It was made use of accelerated method of wavelet transform computation by lifting scheme. Coder can proccess color information of images using modificated original SPIHT algorithm. For implementation the JAVA programming language was employed. The object-oriented design principes was made use of and thus the program is easy to extended. At demonstaration pictures there are shown effectiveness and characteristic way of distorsion of the proposed coder at high compression rates.
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Video compression based on wavelet transform
Kintl, Vojtěch ; Číka, Petr (referee) ; Malý, Jan (advisor)
This diploma thesis focuses on current possibilities concerning the employment of wavelet transformation for video signal compression. One part of the work is devoted to the necessary execution of this task in practise. This deals with video signal and its features description, wavelet transformation and compression methods. The second part concentrates on description of selected compression method. It is the SPIHT (Set Partitioning In Hierarchical Trees) algorithm which is intended for compression of static image data. The algorithm is modified for usage with video signal compression which is specific for its time redundancy. The algorithm is called 3D SPIHT as it works in the spatial and time domain. The algorithm is implemented in the MATLAB programming environment which provides a sophisticated support for wavelet transformation (Wavelet Toolbox). To provide a simple and intuitive encoder control there has been developed an application delivering graphical user interface (GUI). On displayed image previews and measured graphs the user can change encoder parameters and monitor performed changes. There are four image test-sequential modes containing various scenes with different features. The final part of the work is focused on testing of the proposed encoding scheme, various image test-sequential modes and encoder settings. Measured values are graphically displayed and analyzed.
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Detection of the nerve fibres in ophthalmologic images
Urbánek, Dušan ; Harabiš, Vratislav (referee) ; Kolář, Radim (advisor)
This thesis deals with detection of the retinal nerve fiber layer in gray level retinal images taken by fundus camera. The first part describes a physiology of human eye and glaucoma disease. Then, the use of wavelet transform and algorithm of texture analysis applied for texture analysis. Next chapters describe theory of texture analysis named „Gray level run length matrices“ and its application for detection of the nerve fiber layer. Applications of this method are described for three types of retinal tissues and for whole image. The last chapter describes gray levels around optic disc and results obtained from parameters from GLRL matrices.
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Dynamic time warping in biosignal processing
Novobilský, Petr ; Provazník, Ivo (referee) ; Kolářová, Jana (advisor)
The thesis deals with one of the non-linear methods for signal processing - dynamic time warping (DTW). The method observes shape changes, which should be used in biomedical signals processing. The thesis involves the method description and consecution for finding DTW optimal way. The method is applied on the number series in the edutainment program, on the group of simulated signals and real electrocardiograms (ECG). ECG recordings were gained by performing experiments on the Masaryk University and their aim was clarifying the influence of voltage-sensitive dye on the heart tissue. One-lead ECG was described in time domain, frequency domain, time-frequency domain and subsequently remitted to DTW algorithm. The method outcomes evaluates the diversity rate of ECG signals obtained in each experiment stages. During the data evaluation were followed up the changes in process of the tension-sensible paint application and the stage of scouring toward control. The difference of elaborating signals group was verified in the time domain (37,5 %), in the frequency domain (75 %) and in the time-frequency domain (25 %). However, due to the small data group was not possible to explicitly approve the activity of voltage-sensitive dye on the heart tissue and to determinate limiting value of minimum algorithm way DTW for each heart round electrocardiogram classification. In the more data group analysis it is supposed to manifest the trend of growth heart round ECG differences in the stage of staining toward the stage of scouring.
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ECG Signal Compression Based on Wavelet Transform
Ondra, Josef ; Hrubeš, Jan (referee) ; Kozumplík, Jiří (advisor)
Signal compression is daily-used tool for memory capacities reduction and for fast data communication. Methods based on wavelet transform seem to be very effective nowadays. Signal decomposition with a suitable bank filters following with coefficients quantization represents one of the available technique. After packing quantized coefficients into one sequence, run length coding together with Huffman coding are implemented. This thesis focuses on compression effectiveness for the different wavelet transform and quantization settings.
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A Detections and Measurements in ECG Signals
Toušek, Vojtěch ; Vítek, Martin (referee) ; Kozumplík, Jiří (advisor)
Automatic detection and delineation of ECG characteristic points is a basic procedure of any analyze of ECG using computer. This detection is a necessary step to simplify the work of cardiologists to evaluate long ECG records. In this thesis is proposed and evaluate a method of detection and delineation in a single-lead ECG using dyadic wavelet transform followed by correction in pseudo-orthogonal lead system taken from standard 12-lead system. The method uses information about position of positive maximum – negative minimum pair to detect ECG characteristic waves. At first the QRS complex is detected and than its morphology (waves Q and S) and the onset and end of the complex. After that the T-wave is detected and delineated within a searching window dependent on QRS position. And last the P-wave is detected and delineated. There are used two types of wavelets in developed method, “haar” and “quadratic spline”. The developed method was evaluated on CSE database. When haar wavelet was used the QRS detector sensitivity was 99.14%. In the work is also evaluated the accuracy of delineation characteristic points. As the P-wave and QRS complex delineation produced quite good results the T-wave end delineator produced relatively big deviations. All deviations are presented in histograms.
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Filtering methods for MR images processing
Pláněk, Jiří ; Smékal, Zdeněk (referee) ; Gescheidtová, Eva (advisor)
This master´s thesis deals with wavelet transformation and its signal and image noise reduction application method. Significant parameters problems as a wavelet type, a threshold technique selection, a threshold level and a level analysis selection for successful signal and noise image filtering are described. A relation between wavelet transformation and digital bank filter is used by anti-noise and sub-bandwidth filtration. A part of the master´s thesis is focused on nuclear magnetic resonation, where jaw-joint image is processed. Jaw joint image noise reduction filtration methods are used in experimental part of the master´s thesis. Consequently, filtration methods improve a jaw joint image quality, which helps a doctor with patient health state condition. Different types of wavelets were tested and in different application methods order. Filtration methods results were visually compared; therefore any conclusion comparison has subjective matter. Accordingly, only doctor is able to resolve which filtration method is convenient to use to determine patient health state.
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