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    Trigonometric Approximation in Fractal Image Coding
    (Společnost pro radioelektronické inženýrství, 2001-04) Candik, M.
    In this paper is presented a new approach in fractal image coding based on trigonometric approximation. The least square approximation method is used for approximation of blocks in standard fractal image compression algorithm. In the paper is shown that it is possible to use also trigonometric approximation for describing of blocks in fractal image coding. This approximation was implemented and analyzed from point of view of quality of reconstructed images. The experimental results of this method were tested on static grayscale images.
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    Extension of Impulse Detectors to Spatial Dimension and their Utilization as Switch in the LMS L-SD Filter
    (Společnost pro radioelektronické inženýrství, 2001-04) Hudec, R.; Marchevsky, S.
    In this paper, one kind of adaptive LMS filters based on order statistics is used for two-dimensional filtration of noisy greyscale images degraded by mixed noise. The signal-dependent adaptive LMS L-filter (L-SD) consists of two normalized constrained adaptive LMS L-filters, because they have better convergence properties than simple LMS algorithm. Moreover, first filter suppresses the noise in homogeneous regions and second filter preserves the high components of filtered image. Some versions of spatial order statistic detectors were developed from the impulse detectors and were employed as switch between output these filters.
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    Adaptive Order-Statistic LMS Filters
    (Společnost pro radioelektronické inženýrství, 2001-04) Hudec, R.; Marchevsky, S.
    The LMS-based adaptive order-statistic filters are presented in this paper. The adaptive Ll-filters as extension of the adaptive L-filter for two-dimensional filtering of noisy greyscale images is studied too. Their adaptation properties are studied by three types of noise, the additive white Gaussian noise, the impulsive noise or both, respectively. Moreover, the impulsive noise has the fixed noise value (Salt & Pepper noise). The problem of pixel value multiplicity and determination its position in the ordered input vector for adaptive Ll-filter is shown in this article. The two types of images with different of image complexity are used to demonstration of the power of time-spatial ordering.
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    Measuring of Track Velocity and Drift Angle
    (Společnost pro radioelektronické inženýrství, 2001-04) Hanousek, K.
    The fundamental problem of air navigation in real meteorological conditions is the fact that the aircraft is all the flight time under the action of wind causing its drifting and changing its velocity. Detailed exploration of possibilities of drifting and velocity changes measuring is not the intention of this article. The article is just pointing out the possible use of a space filtration method for this purpose.
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    Maximally Flat Waveforms Operation of Class-F Power Amplifiers
    (Společnost pro radioelektronické inženýrství, 2001-04) Rudiakova, A.; Krizhanovski, V.
    The requirements to output network's impedance on higher harmonic components and appropriate input driving for formation maximally flat waveforms of drain current and voltage were presented. Using such waveforms allows obtaining maximal efficiency and output power capability of class-F power amplifiers.