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Plethysmography for retinal video processing
Plavcová, Daniela ; Valterová, Eva (referee) ; Kolář, Radim (advisor)
Sight is one of the five human senses and is very important for exploring near and far surroundings. However, this is prevented by various eye defects, which may be related to the vascular system of the retina and the pulsations that are observable on it. This work deals with the study of the relationship between the mentioned pulsations and glaucoma. To search for connections between these two aspects, video recordings from the retina are used, the pulsation of which is further worked in the form of a 1D signal, especially in the spectral region.
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Detection of delay between arterial and venous pulse signal from videoophthalmoscope
Pejskar, Michael ; Mézl, Martin (referee) ; Valterová, Eva (advisor)
The goal of this bachelor´s work is to measure a time difference between arterial and venous pulses on a retina from video sequences obtained from a binocular videoopthalmoscope. Theoretical part contains a description of the eye and its structures, description of the imaging devices used to display ocular background and research of methods used to measure and calculate the delay between pulses. Practical part describes the processing and adjustments of the videosequences and the measurement of time differences using foot-to-foot and phase difference method.
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Processing of high-resolution retinal images
Vraňáková, Sofia ; Chmelík, Jiří (referee) ; Valterová, Eva (advisor)
Diplomová práca je zameraná na spracovávanie obrazov sietnice s vysokým rozlíšením. Cieľom práce je zlepšiť výslednú kvalitu výsledných snímkov sietnice získaných zo sekvencie snímkov nižšej kvality. Jednotlivé snímky sú najskôr spracované pomocou bilaterálnej filtrácie a zlepšenia kontrastu. v ďalšom kroku sú odstránené rozmazané snímky a snímky zobrazujúce iné časti sietnice. Posun medzi jednotlivými snímkami v sekvencii sa odhaduje pomocou fázovej korelácie, a tieto obrazy sú potom fúzované do výsledného snímku s vysokým rozlíšením pomocou priemerovania a využitia superrozlišovacej techniky, presnejšie regularizácie pomocou bilaterálneho celkového rozptylu. Výsledné mediánové hodnoty skóre kvality získaných obrazov sú PIQUE 0.2600, NIQE 0.0701, a BRISQUE 0.3936 pre techniku priemerovania, a PIQUE 0.1063, NIQE 0.0507, and BRISQUE 0.1570 pre superrozlišovaciu techniku.
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Blood vessel segmentation in high resolution retinal images
Svobodová, Sabina ; Odstrčilík, Jan (referee) ; Valterová, Eva (advisor)
This thesis focuses on implementation of an algorithm for retinal vessel segmentation in high resolution retinal images.A neural network with two hidden layers was used as the method. A total of 7 features were obtained from matched filtering based on vessel thickness, texture analysis and individual pixels brightness. Within the thesis, the whole database was manually annotated for the implementation of the algorithm and the results. The achieved mean sensitivity reached 80%, specificity 70% and Dice coefficient is 59%.
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Time Delay Estimation Between Retinal Arteries And Veins Pulsations Using Instantaneous Phase
Valterova, Eva
The eye fundus suffers from many diseases such as glaucoma, central retinal venous occlusion or intracranial pressure rise. The fundus examination by video-ophthalmoscope can diagnose and reveal the assumption of these diseases, for example, from dynamic changes in the vascular system. This paper focuses on the determination of time delay between signals extracted from vein and artery pulsations obtained by experimental video-ophthalmoscope. The signal is further processed and the instantaneous frequency is utilized for time delay estimation. The observed time delay is in the range of 0 to 233 ms, which is in accordance with published results.
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Radiation damage of samples in low-voltage transmission electron microscopy
Vykydal, Václav ; Valterová, Eva (referee) ; Kolář, Radim (advisor)
This thesis is focused on Radiation damage of samples in low-voltage transmission electron microscopy. In thesis is general description of transmission electron microscopy and their important parts. There is described how samples are damaged by primary electron beam and how samples for transmission electron microscopy are prepared and which degradation occurs from the point of view materials of sample and time dose of electrons from primary electron beam.
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Blind Image Deconvolution in STEM mode of Electron Microscope
Valterová, Eva ; Walek, Petr (referee) ; Potočňák, Tomáš (advisor)
Slepá dekonvoluce je metoda, při které je rozptylová funkce a skutečný obraz rekonstruován zároveň. Cílem této práce je představit různé metody slepé dekonvoluce a najít optimální metodu rekonstrukce původního obrazu a rozptylové funkce. Jako nejvhodnější metoda slepé dekonvoluce byl zvolen algoritmus střídavé minimalizace, který byl upraven a testován. Vlastnosti navrženého algoritmu byly testovány na uměle degradovaných datech a na reálných datech pořízených skenovacím transmisním elektronovým mikroskopem. Účinnost algoritmu byla hodnocena hned několika hodnotícími kritérii. Byla zjištěna omezení algoritmu a tím specifikováno jeho využití.
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