Publications by Martin Vetterli

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This chapter focuses on the development of a new \true" two- dimensional representation for images that can capture the intrinsic geo- metrical structure of pictorial information. Our emphasis is on the discrete framework that can lead to algorithmic implementations. We propose a double filter bank structure, named the pyramidal directional filter bank, by combining the Laplacian pyramid with a directional filter bank. The result is called the contourlet transform, which provides a flexible multiresolution,

Building acoustic beamformers is a problem whose solution is hindered by the wide-band nature of audible sound. In order to achieve a consistent directional response over a wide range of frequencies, a conventional acoustic beamformer needs a high number of discrete loudspeakers and be large enough to achieve a desired low-frequency performance. The acoustic beamformer design described in this paper uses measurement-based optimized beamforming for loudspeakers mounted on a rigid cylindrical baffle. Super-di

We design distributed and quantized average consensus algorithms on arbitrary connected networks. By construction, quantized algorithms cannot produce a real, analog average. Instead, our algorithm reaches consensus on the quantized interval that contains ...

We study the use and impact of a dictionary in a tomographic reconstruction setup. First, we build two different dictionaries: one using a set of bases functions (Discrete Cosine Transform), and the other that is learned using patches extracted from training images, similar to the image that we would like to reconstruct. We use K-SVD as the learning algorithm. These dictionaries being local, we convert them to global dictionaries, ready to be applied on whole images, by generating all possible shifts of eac

We propose a novel algorithm for sparse system identification in the frequency domain. Key to our result is the observation that the Fourier transform of the sparse impulse response is a simple sum of complex exponentials, whose parameters can be efficient ...

We consider the problem of super-resolution from unregistered aliased images with unknown spatial scaling factors and shifts. Due to the limitation of pixel size in the image sensor, the sampling rate for each image is lower than the Nyquist rate of the sc ...

Have you ever tried to reproduce the results presented in a research paper? For many of our current publications, this would unfortunately be a challenging task. For a computational algorithm, details such as the exact data set, initialization or terminati ...

A general framework is presented for constructing transforms in the field of the input which have a convolution-like property. The construction is carried out over finite fields, but is shown to be valid over the real and complex fields as well. It is shown that these basefield transforms can be viewed as “projections” of the discrete Fourier transform (DFT) and that they exist for all lengths N for which the DFT is defined. The convolution property of the basefield transforms is derived and a condition for

System comprising at least one sensor configured to take a set of images from different viewpoints of a scene; a processor configured to identifying a point source represented in the images of a set of images; computing for each image of the set of images ...

A fast rate-distortion (R-D) optimal scheme for coding adaptive trees whose individual nodes spawn descendents forming a disjoint and complete basis cover for the space spanned by their parent nodes is presented. The scheme guarantees operation on the convex hull of the operational R-D curve and uses a fast dynamic programing pruning algorithm to markedly reduce computational complexity. Applications for this coding technique include R. Coefman et al.'s (Yale Univ., 1990) generalized multiresolution wavelet

Recently a sampling theorem for a certain class of signals with finite rate of innovation (which includes for example stream of Diracs) has been developed. In essence, such non band-limited signals can be sampled at or above the rate of innovation. In the present paper, we consider the case of such signals when noise is present. Clearly, the finite rate of innovation property is lost, but if the signal-to-noise ratio (SNR) is sufficient, several methods are possible to reconstruct the signal while sampling

The system and method for estimating impulse response of a wideband communication channel represented as linear combination of L time-shifted pulsed P1 (t) with propagation coefficients a1, comprising functionalities or steps for obtaining an ultrawideband signal (y(t) of Fig. 1) received over the channel, filtered (h (1) of Fig. 1) with low pass/bandpass filter and sampled uniformly at a sub-Nyquist rate a functionality for determining discrete-Fourier-transforin coefficients Yj and Sj (FFT of Figure 1) fr

Identification of defective members of large populations has been widely studied in the statistics community under the name of group testing. It involves grouping subsets of items into different pools and detecting defective members based on the set of tes ...

This paper studies the interaction between the communication costs in a sensor network and the structure of the data that it measures. We formulate an optimization problem definition for power efficient data gathering and assess its computational difficulty. In particular, we show that the problem is NP-complete. We propose some scalable, distributed and efficient heuristic algorithms for solving this problem and show by numerical simulations that the power consumption can be significantly improved over dir

We consider the problem of low-complexity channel estimation and timing in digital ultra-wideband receivers. We extend some of our recent results on sampling of certain classes of parametric non-bandlimited signals and develop a frequency domain framework that yields high-resolution estimates of all relevant channel parameters by sampling a received signal below the traditional Nyquist rate. In particular, we show that the minimum required sampling rate in an UWB receiver is determined by the so-called {\em

Consider a diffusion field induced by a finite number of localized and instantaneous sources. In this paper, we study the problem of estimating these sources (including their intensities, spatial locations, and activation time) from the spatiotemporal samp ...

Cosine modulated filter banks are filter banks whose impulse responses are obtained by modulating a window with cosines. Among their applications are video and audio compression and multitone modulation. Their continuous time counterpart is known as local cosine bases. While there is an extended literature on the discrete time case, both for single and multiple overlapping, the continuous time case has received less attention and only the single overlapping case has been solved. This work gives a solution t

We address the question of how to characterize the outliers that may appear when matching two views of the same scene. The match is performed by comparing the difference of the two views at a pixel level, aiming at a better registration of the images. When using digital photographs as input, we notice that an outlier is often a region that has been occluded, an object that suddenly appears in one of the images, or a region that undergoes an unexpected motion. By assuming that the error in pixel intensity le

We propose FResher Encounter SearcH (FRESH), a simple algorithm for efficient route discovery in mobile ad hoc networks. Nodes keep a record of their most recent encounter times with all other nodes. Instead of searching for the destination, the source node searches for any intermediate node that encountered the destination {\em more recently than did the source node itself}. The intermediate node then searches for a node that encountered the destination yet more recently, and the procedure iterates until t

We present a new statistical model for characterizing texture images based on wavelet-domain hidden Markov models. With a small number of parameters, the new model captures both the subband marginal distributions and the dependencies across scales and orientations of the wavelet descriptors. Applying to the steerable pyramid, once it is trained for an input texture image, the model can be easily steered to characterize that texture at any other orientation. Furthermore, after a diagonalization operation, we

Martin Vetterli

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Contourlets

Design of a Compact Cylindrical Loudspeaker Array for Spatial Sound Reproduction

Interval consensus: from quantized gossip to voting

Use of Learned Dictionaries in Tomographic Reconstruction

Learning Sparse Systems at Sub-Nyquist Rates: A Frequency-Domain Approach

Super-resolution from unregistered aliased images with unknown scalings and shifts

Reproducible Research in Signal Processing - What, why, and how

Hartley transforms over Finite Fields

Point and sensor estimation from images

Best wavelet packet bases in a rate-distortion sense

Sampling signals with finite rate of innovation: the noisy case

Synchronization and channel estimation with sub-nyquist sampling in ultra-wideband communication systems

Group Testing with Probabilistic Tests: Theory, Design and Application

Power Efficient Gathering of Correlated Data: Optimization, NP-Completeness and Heuristics

Channel Estimation and Synchronization with Sub-Nyquist Sampling and Application to Ultra-Wideband Systems

Localization of Diffusive Sources Using Spatiotemporal Measurements

Discrete and Continuous Time Local Cosine Bases with Multiple Overlapping

Outlier modeling in image matching

Age Matters: Efficient Route Discovery in Mobile Ad Hoc Networks Using Encounter Ages

Rotation invariant texture characterization and retrieval using steerable wavelet-domain hidden Markov models