# June 2001, Volume 10, Number 2

**L. Andras, J. Chmurny**
[references] [full-text]

Image Compression by Gabor Expansion

Transform-based coding methods are popular in data compression. In the paper, an easily implemented method is proposed for the weighting factors of the Gabor decomposition. The method is based on the least-mean- squares error (LMSE) approach. The solution of the LMSE problem shows that the weighting factors can be extracted by simple multiplication between a matrix and the vector of data. If the set Gabor functions are chosen to be independent of the test images, this matrix is constant. Images are reconstructed by multiplying the matrix of Gabor functions and the vector of weighting factors. The choise of Gabor functions in the decomposition allows that the resulting decomposition has a pyramidal structure. In the paper is proposed simple codec system for pyramidal Gabor expansion for image compression.

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**R. Lukac**
[references] [full-text]

Impulse Detectors for Noised Sequences

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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- LUKAC, R., STUPAK, CS., MARCHEVSKY, S., MACEKOVA, L. Order-Statistic Filters in Dynamic Image Sequences. Radioengineering, vol. 9, no. 3, September 2000, pp. 8-14.
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- MACEKOVA, L., MARCHEVSKY, S. Noisy Dynamic Image Sequences Filtering Based on Order Statistic Filters. In: Pro-ceedings of DSP '97 3rd International Conference on Digital Signal Processing, Herzany (Slovakia), 1997, pp. 274-278.
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- STUPAK, CS. Digital Image Filtration Based on Local Statis-tics. 3rd International Scientific Conference Elektro '99, Zilina, May 25-26 1999, pp.106-111.
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- STUPAK, CS., LUKAC, R. Impulse Detection in Grayscale Images. In: Proceedings of the 4th International Conference DIGITAL SIGNAL PROCESSING '99, Technical University of Kosice (Slovakia), 1999, pp. 96-99.
- STUPAK, CS., LUKAC, R., MARCHEVSKY, S. Utilization of the Impulse Detectors in the Grayscale Image Filtering. Jour-nal of Electrical Engineering, vol. 51, no. 7-8, 2000, pp. 173-181.
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**J. Valsa**
[references] [full-text]

The Modified Node Voltage Method as Tool for Calculation of Network
Functions and Sensitivities

The paper deals with the well-known modified node voltage method that is generally used for formulation of system equations in universal network simulation programs. It shows very efficient ways if utilizing this type of equation formulation for evaluation of network transfer functions and their sensitivities to variations of element parameters. The described procedures can be used very effectively namely in connection with some matrix oriented mathematical program like for instance MATLAB. Several illustrative examples support the explanation of the methods described in the paper.

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**M. Candik, E. Matus, D. Levicky**
[references] [full-text]

Digital Watermarking in Wavelet Transform Domain

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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- LUKAC, R. An Adaptive Control of LUM Smoother. Radio-engineering, vol. 9, no. 1, April 2000, pp.9-12.
- LUKAC, R., MARCHEVSKY, S. Adaptive LUM Smoother Controlled by Adaptive Threshold System. Journal of Electrical Engineering, no. 3-4, vol. 51, 2000, pp.100-104.

**V. Ricny**
[references] [full-text]

Contactless Opto-electronic Area and Their Attainable Measuring
Accuracy

This paper deals with the problems of the contactless area measurement on the principle of video signal processing. This video signal generates TV camera, which scans the measured object. Basic principle of these meters is explained and attainable measurement accuracy and factors influencing this accuracy are analyzed.

- RICNY, V. Properties and Applications of the Light-sensitive Sensors CCD (in Czech). Editorship: Technical University of Brno, Brno 1992.
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**J. Mihalik, I. Gladisova, V. Michalcin**
[references] [full-text]

Two Layer Vector Quantization of Images

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.

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**P. Novak, I. Zuna, L. Pousek, J. Vrba**
[references] [full-text]

Ultrasonic Approach to Nonivasive Temperature Monitoring During
Microwave Thermotherapy

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.

- NOVAK, P., ZUNA, I., POUSEK, L., PESCHKE, P., VRBA, J., SCHREIB, P. Noninvasive Temperature Monitoring in the Microwave Heated Rat Pedicle Tumors Using Ultrasound Tissue Characterization Method. EMBEC99, Medical&Biological En-gineering & Computing, Journal of the International Federation for Medical & Biological Engineering, Vol. 37 Suppl. 2, Vienna, 1999, ISSN 01400118, pp. 1032-1033, 1668
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- P.NOVAK, L.POUSEK, I.ZUNA, P.PESCHKE, A.LORENZ, J.VRBA, P.SCHREIB: "Nichtinvasive Bestimmung der Temperaturverteilung im Zielbereich der Hyperthermie durch diagnostischen Ultraschall", Ultraschall 99 Berlin, Ultraschall in der Medizin, Suppl.1, 1999, Georg Thieme Verlag Stuttgart, ISSN 0172-4614, pp. 132, 150
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**P. Kvarda**
[references] [full-text]

Identifying the Deterministic Chaos by Using the Lyapunov Exponents

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.

- KENNEDY, P., Chaos in the Colpitts Oscillator. IEEE Trans. Circuits Syst., vol. 41, no. 11, p. 771-774, 1994
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