Publications de Martin Vetterli

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Conventional sampling focuses on encoding and decoding bandlimited signals by recording signal amplitudes at known time points. Alternately, sampling can be approached using biologically-inspired schemes. Among these are integrate-and-fire time encoding ma ...

This paper presents a signal processing tool for analyzing and manipulating digitized acoustic wave fields, based on a spatio-temporal extension of the time-frequency representation space. The emphasis is on wave fields acquired with a 1-D linear array of ...

The rate distortion behavior of sparse memoryless sources is studied. These serve as models of sparse signal representations and facilitate the performance analysis of "sparsifying" transforms like the wavelet transform and nonlinear approximation schemes. ...

By replacing the lens with a thin optical element, lensless imaging enables new applications and solutions beyond those supported by traditional camera design and post-processing, e.g. compact and lightweight form factors and visual privacy. The latter arises from the highly multiplexed measurements of lensless cameras, which require knowledge of the imaging system to recover a recognizable image. In this work, we exploit this unique multiplexing property: casting the optics as an encoder that produces lear

The sampling and interpolation of a sound field in two and three dimensions along a circle is discussed. The Fourier domain representation of the sound field is used, and an angular sampling theorem is developed for the sampling of the sound field along a ...

The relation between sensor resolution and the optics of a digital camera is determined by the Nyquist sampling theorem: the sampling frequency should be larger than twice the maximum frequency of the image content coming out of the optical system. If a lower resolution is used, the output is aliased. Aliasing in digital images is often considered as a nuisance and (both optical and digital) filters are designed to avoid aliasing in digital cameras. However, aliasing also contains extra high-frequency infor

The first part of this paper proposes an adaptive, data-driven threshold for image denoising via wavelet soft-thresh- olding. The threshold is derived in a Bayesian framework, and the prior used on the wavelet coefficients is the generalized Gaussian distribution (GGD) widely used in image processing applications. The proposed threshold is simple and closed-form, and it is adap- tive to each subband because it depends on data-driven estimates of the parameters. Experimental results show that the proposed me

We study a new image sensor that is reminiscent of traditional photographic film. Each pixel in the sensor has a binary response, giving only a one-bit quantized measurement of the local light intensity. To analyze its performance, we formulate the oversampled binary sensing scheme as a parameter estimation problem based on quantized Poisson statistics. We show that, with a single-photon quantization threshold and large oversampling factors, the Cramér-Rao lower bound (CRLB) of the estimation variance appro

It is a classic problem to estimate continuous-time sparse signals, like point sources in a direction-of-arrival problem, or pulses in a time-of-flight measurement. The earliest occurrence is the estimation of sinusoids in time series using Prony's method. ...

In the context of environmental monitoring, outdoor wireless cameras are vulnerable to natural hazards. To benefit from the inexpensive imaging sensors, we introduce a multi-camera monitoring system to share the physical risk. With multiple cameras focusin ...

For low bit-rate compression applications, segmentation-based coding methods provide, in general, high compression ratios when compared with traditional (e.g., transform and subband) coding approaches. In this paper, we present a new segmentation-based image coding method that divides the desired image using binary space partitioning (BSP). The BSP approach partitions the desired image recursively by arbitrarily oriented lines in a hierarchical manner. This recursive partitioning generates a binary tree, wh

We investigate the interactionof congestion control with the partitioning of source information into components of varying importance for variable bit-rate packet voice and packet video. High-priority transport for the more important signal components results in substantially increased objective service quality. Using a Markov chain voice source model with simple PCM speech encoding and a priority queue, simulation results show a signal-to=noise ratio improvement of 45 dB with two priorities over unprioriti

We derive a formula for the product of two Toeplitz matrices that is similar to the Trench formula for the inverse of a Toeplitz matrix. We then derive upper and lower bounds for number of multiplications required to compute the inverse or the product of Toeplitz matrices and consider several special cases, e.g., symmetry, as well. The lower bounds for the general cases are in agreement with earlier results, but the specialized lower bounds and all the upper bounds are new. Both upper and lower bounds are O

Elevated in-stream temperature has led to a surge in the occurrence of parasitic intrusion proliferative kidney disease and has resulted in fish kills throughout Switzerland's waterways. Data from distributed temperature sensing (DTS) in-stream measurement ...

This paper reports on our experience with the implementation, deployment, and operation of SensorScope, an indoor environmental monitoring network. Nodes run on standard TinyOS components and use B-MAC for the MAC layer implementation. The main component o ...

We have studied a camera with a very large number of binary pixels referred to as the gigavision camera or the gigapixel digital film camera. Potential advantages of this new camera design include improved dynamic range, thanks to its logarithmic sensor response curve, and reduced exposure time in low light conditions, due to its highly sensitive photon detection mechanism. We use maximum likelihood estimator (MLE) to reconstruct a high quality conventional image from the binary sensor measurements of the g

A computer-implemented method for determining the Walsh-Hadamard transform of N samples of a signal, comprises electing a plurality of hashing C matrices Σ1, . . . ΣC, computing C hashes of a particular length based at least on a hashing front end and the ...

Routing in large-scale mobile ad hoc networks is challenging because all the nodes are potentially moving. Geographic routing can partially alleviate this problem, as nodes can make local routing decisions based solely on the destinations' geographic coordinates. However, geographic routing still requires an efficient {\em location service}, i.e., a distributed database recording the location of every destination node. Devising efficient, scalable, and robust location services has received considerable atte

In spite of the success of the standard wavelet transform (WT) in image processing in recent years, the efficiency of its representation is limited by the spatial isotropy of its basis functions built in the horizontal and vertical directions. One-dimensio ...

Sampling information using timing is an approach that has received renewed attention in sampling theory. The question is how to map amplitude information into the timing domain. One such encoder, called time encoding machine, was introduced by Lazar and To ...

Martin Vetterli

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Encoding And Decoding Mixed Bandlimited Signals Using Spiking Integrate-And-Fire Neurons

Applications of short space-time Fourier analysis in digital acoustics

Rate Distortion Behavior of Sparse Sources

Learning rich optical embeddings for privacy-preserving lensless image classification

Sound Field Analysis Along a Circle and its Application to HRTF Interpolation

Registration for Super-Resolution: Theory, Algorithms, and Applications in Image and Mobile Video Enhancement

Adaptive wavelet thresholding for image denoising and compression

Bits from Photons: Oversampled Image Acquisition Using Binary Poisson Statistics

Towards Generalized FRI Sampling with an Application to Source Resolution in Radioastronomy

Share Risk and Energy: Sampling and Communication Strategies for Multi-Camera Wireless Monitoring Networks

Image Compression Using Binary Space Partitioning Trees

Joint source/channel coding of statistically multiplexed real-time services on packet networks

Structure and arithmetic complexity of products and inverses of Toeplitz matrices

Stream Temperature Response to Three Riparian Vegetation Scenarios by Use of a Distributed Temperature Validated Model

SensorScope: Experiences with a Wireless Building Monitoring Sensor Network

An Optimal Algorithm for Reconstructing Images from Binary Measurements

Method for determining the walsh-hadamard transform of n samples of a signal and apparatus for performing the same

Locating Nodes with EASE: Mobility Diffusion of Last Encounters in Ad Hoc Networks

Directionlets: Anisotropic Multidirectional representation with separable filtering

Sampling based on timing: Time encoding machines on shift-invariant subspaces