Oldřich Ondráček

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This paper deals with the study of dependence of subpixel accuracy of edge detection in 1-D images on number of used samples. Our study includes four methods for edge detection with sub-pixel accuracy in 1-D images: method based on approximation of real image function with erf function, moment-based edge operator, technique using spatial moments of the(More)
Dispersion in spectral domain optical coherence tomography (SD OCT) system cause a degradation of point spread function (peak broadening) after FFT of the spectrum with the increase of the optical path distance between an object and reference arm. Different sources of dispersion and methods for the compensation are shown. 1 INTRODUCTION Optical coherence(More)
This paper presents a differential phase detector circuit, whose phase-to-voltage characteristic has an extremum when its two input signals are exactly in phase. In this condition all its digital signals are of 50% duty cycle so that the circuit characteristic does not have a dead zone. This feature allows a precise indication of the zero-phase condition,(More)
Edge detection is often used procedure in digital image processing. For some practical applications is desirable to detect edges with sub-pixel accuracy. In this paper we present comparison of four methods for edge detection with sub-pixel accuracy in 1-D images: method based on approximation of real image function with erf function, moment-based edge(More)
Ability of humans to maintain balance in an upright stance and during movement activities is one of the most natural skills affecting everyday life. This ability progressively deteriorates with increasing age, and balance impairment, often aggravated by age-related diseases, can result in falls that adversely impact the quality of life. Falls represent(More)
Contour detection is often utilized algorithm in picture processing. Sometimes is useful to localize edges with sub-pixel accuracy. In this paper we discuss about precise position of edge which is moving during the exposure time. To localize moving edge we define accumulative function and then we use three edge detection algorithms with sub-pixel accuracy(More)
Spectral analysis of heart rate variability (HRV) signals is widely used method for assessment of autonomous nervous system modulation with attempt to determine contribution of sympathetic and parasympathetic branches. Since primary goal is to estimate neural drive to sinus node noninvasively, signal processing methods have been developed to handle beat(More)
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