Petros Maragos

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This paper reports the results of a study of multiscale shape description, smoothing and representation. Multiscale nonlinear smoothing filters are first developed by using morphological openings and closings. These filters smooth signals while preserving their edges, and use a definition of scale that agrees with the spatial size of image objects. Matheron(More)
This paper presents the results of a study on the use of morphological set operations to represent and encode a discrete binary image by parts of its skeleton, a thinned version of the image containing complete information about its shape and size. Using morphological erosions and openings, a finite image can be uniquely decomposed into a finite number of(More)
Amplitude-modulation (AM) and frequency-moddation (FM) systems are widely applicable to the modeling and transmission of information in signals. In this paper it is shown that the nonlinear energy-tracking signal operator P (x) = (i)' xx and its discrete-time counterpart can estimate the AM and FM modulating signals. Specifically, Y can approximately(More)
This paper examines the set-theoretic interpretation of morphological filters in the framework of mathematical morphology and introduces the representation of classical linear filters in terms of morphological correlations, which involve supremumlinfimum operations and additions. Binary signals are classified as sets, and multilevel signals as functions.(More)
The dynamics of airflow during speech production may often result in some small or large degree of turbulence. In this paper, the geometry of speech turbulence as reflected in the fragmentation of the time signal is quantified by using fractal models. An efficient algorithm for estimating the short-time fractal dimension of speech signals based on(More)
This paper extends the theory of median, order-statistic (OS), and stack filters by using mathematical morphology to analyze them and by relating them to those morphological erosions, dilations, openings, closings, and open-closings that commute with thresholding. The max-min representation of OS filters is introduced by showing that any median or other OS(More)
Parametric models of shape and texture such as active appearance models (AAMs) are diverse tools for deformable object appearance modeling and have found important applications in both image synthesis and analysis problems. Among the numerous algorithms that have been proposed for AAM fitting, those based on the inverse-compositional image alignment(More)
In this paper, the amplitude and frequency AM–FM modulation model and a multiband demodulation analysis scheme are applied to formant frequency and bandwidth tracking of speech signals. Filtering by a bank of Gabor bandpass filters is performed to isolate each speech resonance in the signal. Next, the amplitude envelope AM and instantaneous frequency FM are(More)
Fractals can model many classes of time-series data. The fractal dimension is an important characteristic of fractals that contains information about their geometrical structure at multiple scales. The covering methods are a class of efficient approaches to measure the fractal dimension of an arbitrary fractal signal by creating multiscale covers around the(More)