Nikola Zaric

Learn More
A watermarking approach based on multidimensional time-frequency analysis is proposed. It represents a unified concept that can be used for different types of data such as audio, speech signals, images or video. Time-frequency analysis is employed for speech signals, while space/spatial-frequency analysis is used for images. Their combination is applied for(More)
Analysis of quantization effects on watermarked coefficients and watermark is considered. A criterion for selection of coefficients suitable for watermarking in the presence of quantization is derived. The effects of quantization are further analyzed in terms of the probability of detectable watermark and the probability of zero-quantized watermarked(More)
– An analog-digital system for implementation of the robust time-frequency distributions is proposed. It provides an efficient real-time analysis of nonstationary signals corrupted by heavy-tailed noise. The most important part of this system is the realization of the L-estimate short-time Fourier transform that requires sorting operation. The proposed(More)
An approach to speech watermarking based on the time-frequency signal analysis is proposed. As a time-frequency representation suitable for speech analysis, the S-method is used. The time-frequency characteristics of watermark are modeled by using speech components in the selected region. The modeling procedure is based on the concept of time-varying(More)
A hardware implementation of the Nth order complex-lag time-frequency distribution is proposed. The considered distribution provides an arbitrary high concentration for multicomponent signals with fast varying instantaneous frequency. Although the distribution form is quite complex, the proposed realization is very efficient and provides high-speed(More)
An application of two-dimensional time-frequency analysis and corresponding two-dimensional eigenvalue decomposition for image watermarking purpose is proposed. The eigenvalue decomposition is used to provide a criterion for watermarking coefficients selection. It is primarily used to select pixels suitable for watermarking that belong to busy image(More)
An approach to multiwindow time-frequency analysis that provides robust performance in noisy environment is proposed. The concept of robust estimates of instantaneous frequency is used to define the optimal weighting coefficients for the multiwindow spectrogram. The proposed form of multiwindow spectrogram provides improved instantaneous frequency(More)
The robust time-frequency distributions with complex-lag argument are proposed. They can provide an accurate estimation of fast varying instantaneous frequency in the presence of noise with heavy-tailed probability density function. The L-estimate form of this distribution is defined and it includes the L-estimate form of Wigner distribution as a special(More)
A new procedure for watermarking in the 8 ϫ 8 block-based discrete cosine transform (DCT) domain (used for JPEG compression) is proposed. The influence of JPEG quantization on watermarked coefficients and on watermark is considered. The criterion for coefficients selection is derived, providing robustness for an arbitrary quantization degree. The modified(More)
– A procedure for logo watermark-ing of speech signals is proposed. In order to take full advantage of both time and frequency domain, we have used joint time-frequency representation of speech signal, which provides a more comprehensive information compared to each domain individually. Time-frequency based selection of the Discrete Fourier Transform (DFT)(More)