2001/2

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    Ultrasonic Approach to Nonivasive Temperature Monitoring During Microwave Thermotherapy
    (Společnost pro radioelektronické inženýrství, 2001-06) Novak, P.; Zuna, I.; Pousek, L.; Vrba, J.
    Microwave thermotherapy (MT) is an oncological treatment. At present the invasive thermometer probes are clinically used for temperature measuring during an MT. Any invasive handling of tumors is of high-risk. A new possible method of noninvasive monitoring of temperature distribution in tissue has been developed. An MT treatment of the experimentally induced pedicle-tumors of the rat was prepared. For 100 rat samples a strong correlation between the mean gray level in the ROIs in the ultrasound pictures and the invasively measured temperature in the range 37-44 °C was found. The correlation coefficient of the mean gray level and the invasively measured temperature is 0.96a0.05. A system for representation of changes of spatial temperature distribution of the whole tumor during MT is presented.
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    Impulse Detectors for Noised Sequences
    (Společnost pro radioelektronické inženýrství, 2001-06) Lukac, R.
    This paper is focused on a problem of impulse detection in the dynamic image environments corrupted by impulse noise. Using a proposed architecture that includes an impulse detector and the median filter, the effective methods can be designed. Thus, the image points are classified into two classes such as a class of noise free samples and a class of noised image points. In the case of impulse detection the estimate is performed by a median filter whereas a noise free sample is passed on the output without the change i.e. system works as an identity filter.
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    Identifying the Deterministic Chaos by Using the Lyapunov Exponents
    (Společnost pro radioelektronické inženýrství, 2001-06) Kvarda, P.
    This paper presents an investigation of deterministic chaos. The modified Colpitts oscillator is used as an example of deterministic chaos in electronic circuits. The most known quality of deterministic chaotic systems the positive Lyapunov exponent is used for investigation the chaotic Colpitts oscillator.
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    Digital Watermarking in Wavelet Transform Domain
    (Společnost pro radioelektronické inženýrství, 2001-06) Candik, M.; Matus, E.; Levicky, D.
    This paper presents a technique for the digital watermarking of still images based on the wavelet transform. The watermark (binary image) is embedded into original image in its wavelet domain. The original unmarked image is required for watermark extraction. The method of embedding of digital watermarks in wavelet transform domain was analyzed and verified on grey scale static images.
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    Two Layer Vector Quantization of Images
    (Společnost pro radioelektronické inženýrství, 2001-06) Mihalik, J.; Gladisova, I.; Michalcin, V.
    This paper deals with spatial scaleable vector quantization of images by using two layers. At the base layer the small dimensional full search vector quantization of an image of block means is carried out. After subtracting it from the input image at the enhancement layer the difference of full spatial resolution is quantized by large dimensional weighted pyramid vector quantizer in transform domain. Experimental results demonstrate acceptable quality of the downscaled image from the output of base layer at very low bit rate and possibility of next increasing its quality by the upscaled difference image from the output of enhancement layer.