Publications de Luciano Sbaiz | EPFL Graph Search

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We study the spatialization of the sound field in a room, in particular the evolution of room impulse responses as a function of their spatial positions. We observe that the multidimensional spectrum of the solution of the wave equation has an almost bandlimited character. Therefore sampling and interpolation can easily be applied using signals on an array. The decay of the spectrum is studied on both temporal and spatial frequency axes. We study how this decay influences the performance of the interpolatio

In many applications, the sampling frequency is limited by the physical characteristics of the components: the pixel pitch, the rate of the A/D converter, etc. A low-pass filter is then often applied before the sampling operation to avoid aliasing. However, when multiple copies are available, it is possible to use the information that is inherently present in the aliasing to reconstruct a higher resolution signal. If the different copies have unknown relative offsets, this is a non-linear problem in the off

Sound or acoustic tomography is a type of inverse problem. The idea of estimating physical quantities that influence sound propagation by measuring the parameters of sound propagation has proven to be successful in several practical domains, including medicine, seismology, oceanography. The use of acoustic tomography for estimating temperature and wind fields in the atmosphere has been shown to be possible as well and, moreover, its potentials have been demonstrated in field experiments. However, in most of

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

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

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

The spatialization of the sound field in a room is studied, in particular the evolution of room impulse responses as a function of their spatial positions. It was observed that the multidimensional spectrum of the solution of the wave equation has an almost bandlimited character. Therefore, sampling and interpolation can easily be applied using signals on an array. The decay of the spectrum is studied on both temporal and spatial frequency axes. The influence of the decay on the performance of the interpola

Videos representing flames, water, smoke, etc. are often defined as dynamic textures: "textures" because they are characterized by redundant repetition of a pattern and "dynamic" because this repetition is also in time and not only in space. Dynamic textur ...

In signal processing systems, aliasing is normally treated as a disturbing signal. That motivates the need for effective analog, optical and digital anti-aliasing filters. However, aliasing conveys also valuable information on the signal above the Nyquist frequency. Hence, an effective processing of the samples, based on a model of the input signal, would allow to virtually increase the sampling frequency using slower and cheaper converters. In this paper, we present such an algorithm for bandlimited signal

Dynamic textures are sequences of images showing temporal regularity; they can be found in videos representing smoke, flames, flowing water, or moving grass, for instance. Recently, one method based on linear dynamic system theory was proposed to synthesize dynamic textures. Textures are represented as the output of a linear dynamic system and synthesis is reduced to matrix multiplication operations. In this report, we study the problem of implementing this method using fixed-point arithmetic, as required i

We present a new method for signal reconstruction from multiple sets of samples with unknown offsets. We rewrite the reconstruction problem as a set of polynomial equations in the unknown signal parameters and the offsets between the sets of samples. Then, ...

We study a new image device called gigavision camera or the gigapixel digital film camera. The main differences between a conventional and a gigavision camera are that the pixels of the latter are binary and orders of magnitude smaller. A gigavision camera can be built using standard memory chip technology, where each memory bit is designed to be light sensitive. A conventional gray level image can be obtained from the binary gigavision image by low-pass filtering and sampling. The main advantage of the gig

We propose a new image device called gigavision camera. The main differences between a conventional and a gigavision camera are that the pixels of the gigavision camera are binary and orders of magnitude smaller. A gigavision camera can be built using stan ...

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

Acoustic tomography is a type of inverse problem. The idea of estimating physical quantities that influence sound propagation by measuring the parameters of propagation has proven to be successful in many practical domains, including temperature and wind e ...

In this paper, we model a spatially varying channel where a source is moving along a random trajectory with respect to a fixed re- ceiver. The aim is to compute the power spectral density corre- sponding to the channel impulse response as a function of tem ...

Recently, we have proposed a new image device called gigavision camera whose most important characteristic is that pixels have binary response. The response function of a gigavision sensor is non-linear and similar to a logarithmic function, which makes the camera suitable for high dynamic range imaging. One important parameter in the gigavision camera is the threshold for generating binary pixels. Threshold T relates to the number of photo-electrons necessary for the pixel output to switch from "0" to "1".

Luciano Sbaiz

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The Plenacoustic Function and its Sampling

Aliasing is Good for You: Joint Registration and Reconstruction for Super-Resolution

Acoustic tomography for scalar and vector fields: theory and application to temperature and wind estimation

Super-Resolution from Unregistered and Totally Aliased Signals Using Subspace Methods

Bits from Photons: Oversampled Image Acquisition Using Binary Poisson Statistics

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

Bits from Photons: Oversampled Image Acquisition Using Binary Poisson Statistics

An Optimal Algorithm for Reconstructing Images from Binary Measurements

The Plenacoustic Function and its Sampling

Higher Order SVD Analysis for Dynamic Texture Synthesis

How to take advantage of aliasing in bandlimited signals

Dynamic Texture on Fixed-Point Architectures

Signal Reconstruction from Multiple Unregistered Sets of Samples using Groebner Bases

The Gigavision Camera

The Gigavision Camera

Outlier modeling in image matching

Acoustic tomography for scalar and vector fields: theory and application to temperature and wind estimation

On a stochastic version of the plenacoustic function

On Pixel Detection Threshold in the Gigavision Camera