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A Comparative Study of Various Edge Detection Techniques for Underwater Images

Awalludin Ezmahamrul Afreen, Arsad Tengku Noorfarahana T., Yussof Wan Nural Jawahir Hj Wan, Bachok Zainudin, Hitam Muhammad Suzuri

Journal of Telecommunications and Information Technology

2022

nr 1

23--33

Nowadays, underwater image identification is a challenging task for many researchers focusing on various ap plications, such as tracking fish species, monitoring coral reef species, and counting marine species. Because underwater im ages frequently suffer from distortion and light attenuation, pre-processing steps are required in order to enhance their quality. In this paper, we used multiple edge detection techniques to determine the edges of the underwater images. The pictures were pre-processed with the use of specific techniques, such as enhancement processing, Wiener filtering, median filtering and thresholding. Coral reef pictures were used as a dataset of underwater images to test the efficiency of each edge detection method used in the experiment. All coral reef image datasets were captured using an underwater GoPro camera. The performance of each edge detection technique was evaluated using mean square error (MSE) and peak signal to noise ratio (PSNR). The lowest MSE value and the highest PSNR value represent the best quality of underwater images. The results of the experiment showed that the Canny edge detection technique outperformed other approaches used in the course of the project.

Wiener Filtering Applied to Conducted EMI Estimation in Soft Switching Inverter

Musznicki P., Chrzan P. J., Mandrek S.

Electrical Power Quality and Utilisation. Journal

2008

Vol. 14, iss. 2

25--28

This paper presents an estimation method of the conducted electromagnetic interference EMI emissions in soft switching inverters. Estimation process is carried out by a number of Wiener filters, which represent different operation conditions as reflected through subsequent power converter states determined by initial commutation event conditions and propagation paths layout. Filters are fed by a semiconductor power switch voltage or current waveforms regarded as sources of perturbation. The EMI emissions are measured on the line impedance stabilization network LISN terminals. Optimal filter adaptation is effected in the frequency domain by measuring input and cross power signal spectra. Analysis of parallel quasi resonant dc link voltage inverter PQRDCLI is outlined to distinguish filters assigned for inverter operation and those for an external DC/DC converter interaction. Experimental results are given to illustrate the Wiener filtering estimation quality. Possibility of detailed decomposition of the LISN-EMI waveforms is depicted in both time and frequency domain. Comparative analysis of frequency responses for PQRDCLI link voltage changes is given.