Publications by Martin Vetterli

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

In this work, we consider the problem of channel estimation by using the recently developed theory for sampling of signals with a finite rate of innovation [1]. We show a framework which allows for lower than Nyquist rate sampling applicable for timing and channel estimation of both narrowband and wideband channels. In certain cases we demonstrate performance exceeding that of algorithms using Nyquist rate sampling while working at lower sampling rates, thus saving power and computational complexity.

In 1983, Burt and Adelson introduced the Laplacian pyramid (LP) as a multiresolution representation for images. We study the LP using the frame theory, and this reveals that the usual reconstruction is suboptimal. We show that the LP with orthogonal filters is a tight frame, and thus, the optimal linear reconstruction using the dual frame operator has a simple structure that is sym- metric with the forward transform. In more general cases, we pro- pose an efficient filterbank (FB) for the reconstruction of

We propose a novel edge detection algorithm with sub-pixel accuracy based on annihilation of signals with finite rate of innovation. We show that the Fourier domain annihilation equations can be interpreted as spatial domain multiplications. From this new ...

Results are presented on 2-D FIR (two-dimensional finite-impulse-response) filter banks for multirate applications. The theory is valid for all sampling lattices; conditions for alias-free and perfect signal reconstruction are derived. Synthesis structures for paraunitary and nonparaunitary polynomial matrices are derived, which yield perfect reconstruction filter banks. The degrees of freedom are given for these systems. Linear phase conditions are posed on the polyphase form of filter banks. which is used

Digital camera sensors are inherently sensitive to the near-infrared (NIR) part of the light spectrum. In this paper, we propose a general design for color filter arrays that allow the joint capture of visible/NIR images using a single sensor. We pose the ...

The present invention relates to a device (10) for determining a bidirectional reflectance distribution function of a subject (S) comprising: a light source (LS) for producing an incident light (li) and directing said incident light (li) onto a subject (S) ...

The sampling of the soundfield using circular microphone arrays is studied. We give a new representation of the soundfield sampled on such an array using the two-dimensional Fourier transform. We then show how we can reconstruct the soundfield at all possible po- sitions on the array from a finite number of measurements. We give the necessary azimuthal angular sampling frequency necessary to reconstruct the data up to some temporal frequency. This new tech- nique is applied to interpolate Head Related Trans

Spatial sampling is traditionally studied in a static setting where static sensors scattered around space take measurements of the spatial field at their locations. In this paper we study the emerging paradigm of sampling and reconstructing spatial fields ...

In this paper, we consider classes of not bandlimited signals, namely, streams of Diracs and piecewise polynomial signals, and show that these signals can be sampled and perfectly reconstructed using wavelets as sampling kernel. Due to the multiresolution structure of the wavelet transform, these new sampling theorems naturally lead to the development of a new resolution enhancement algo- rithm based on wavelet footprints [2]. Preliminary results show the potentiality of this algorithm.

subband decompisition of HDTV signlas is important both for representation purpose (to create compatible subchannels) and fro coding (several proposed compression schemes include some subband division). We first review perfect reconstruction filter banks in multiple dimensions in the contest of arbitrary sampling patterns. Then we concentrate on the special case of quincunx substampling and derive filter banks to go from processing to interlaced scanning (with a highpass which contains deinterlacing informa

A simple, nonrigorous, synthetic view of wavelet theory is presented for both review and tutorial purposes. The discussion includes nonstationary signal analysis, scale versus frequency, wavelet analysis and synthesis, scalograms, wavelet frames and orthonormal bases, the discrete-time case, and applications of wavelets in signal processing. The main definitions and properties of wavelet transforms are covered, and connections among the various fields where results have been developed are shown

An acoustic processing method for M acoustic receivers comprising the steps of: Determining a beamforming weight vector with M weights for the M acoustic receivers based on at least one the steering vector of at least one real acoustic source, on steering ...

While wireless sensor networks have been extensively studied in the past few years, most results are of theoretical nature and were obtained outside of a practical context. This can be problematic for real applications, especially in the area of environmen ...

Lensless imaging can drastically relax traditional camera constraints by replacing lenses with optical masks, enabling lighter, cheaper, and thinner systems. However, unlike lenses, there is a lack of clear criteria for optical mask design. Most approaches ...

This study focuses on the spatial variability of meteorological parameters in an alpine watersehd in the Swiss Alps, where a wireless sensor network has been deployed. We present some results from the previous summer campaigns, sharing experiences and challenges on the use of a wireless network in a complex environment.

The theory and practice of digital communication during the past 50 years has been strongly influenced by Shannon's separation theorem. While it is conceptually and practically appealing to separate source from channel coding, either step requires infinite delay in general for optimal performance. On the other extreme is uncoded transmission, which has no delay but is suboptimal in general. In this paper, necessary and sufficient conditions for the optimality of uncoded transmission are shown. These conditi

We describe a spatially adaptive algorithm for image interpolation. The algorithm uses a wavelet transform to extract information about sharp variations in the low-resolution image and then implicitly applies interpolation which adapts to the image local s ...

Reconstruction method for reconstructing a first signal (x(t)) regularly sampled at a sub-Nyquist rate, comprising the step of retrieving from the regularly spaced sampled values (ys[n], y(nT)) a set of weights (cn, cnr, ck) and shifts (tn, tk) with which said first signal (x(t) can be reconstructed. The reconstructed signal (x(t) can be represented as a sequence of known functions ( gamma (t) weighted by the weights (ck) and shifted by the shifts (tk). The sampling rate is at least equal to the rate of inn

Consumer-grade plenoptic camera Lytro draws a lot of interest from both academic and industrial world. However its low resolution in both spatial and angular domain prevents it from being used for ﬁne and detailed light ﬁeld acquisition. This paper propose ...

A computerized method for annotating at least one feature of an image of a view, comprising the steps of: obtaining the image with an image sensor of a portable device retrieving at least one condition based on the at least one condition, automatically sel ...

Martin Vetterli

Chat with Graph Search

Sampling With Finite Rate of Innovation: Channel and Timing Estimation for UWB and GPS

Framing pyramids

Annihilation-driven Localised Image Edge Models

Theory of two-dimensional multirate filter banks

Designing color filter arrays for the joint capture of visible and near-infrared images

Device for Determining a Bidirectional Reflectance Distribution Function of a Subject

The plenacoustic function on the circle with application to HRTF interpolation

Sampling and Reconstruction of Spatial Fields using Mobile Sensors

Wavelet and footprint sampling of signals with a finite rate of innovation

Perfect reconstruction filter banks for HDTV representation and coding

Wavelets and signal processing

Optimal acoustic rake receiver

Wireless Sensor Networks for Environmental Monitoring: The SensorScope Experience

Hardware-in-the-loop training for lensless imaging with a programmable mask

Application of a meteorological wireless sensor network to a small alpine watershed

To code or not to code

Locally Adaptive Wavelet-Based Image Interpolation

Sampling method, reconstruction method, and device for sampling and/or reconstructing signals

Light ﬁeld panorama by a plenoptic camera

Computerized method and device for annotating at least one feature of an image of a view