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Michaël Unser

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Publications associées (516)

Fast O(1) Bilateral Filtering Using Trigonometric Range Kernels

Michaël Unser, Daniel Sage, Kunal Narayan Chaudhury

It is well known that spatial averaging can be realized (in space or frequency domain) using algorithms whose complexity does not scale with the size or shape of the filter. These fast algorithms are generally referred to as constant-time or O(1) algorithm ...

IEEE2011

A Sampling Theory Approach for Continuous ARMA Identification

Michaël Unser, Simona Maggio, Hagay Kirshner

The problem of estimating continuous-domain autoregressive moving-average processes from sampled data is considered. The proposed approach incorporates the sampling process into the problem formulation while introducing exponential models for both the cont ...

IEEE2011

A New Hybrid Bayesian-Variational Particle Filter With Application To Mitotic Cell Tracking

Michaël Unser, Ricard Delgado Gonzalo

Tracking algorithms are traditionally based on either a variational approach or a Bayesian one. In the variational case, a cost function is established between two consecutive frames and minimized by standard optimization algorithms. In the Bayesian case, ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

Learning Steerable Wavelet Frames

Michaël Unser

SampTA2011

Trends in Bioimaging and Signal Processing

Michaël Unser

This is the second in a series of three columns summarizing the "Trends" expert sessions organized by the Signal Processing Society Technical Committees during ICASSP 2011 in Prague, Czech Republic. Readers have an opportunity to access these Trends sessio ...

IEEE2011

Activelets: Wavelets for sparse representation of hemodynamic responses

Michaël Unser, Dimitri Nestor Alice Van De Ville, François Lazeyras, Ildar Khalidov

We propose a new framework to extract the activity-related component in the BOLD functional magnetic resonance imaging (fMRI) signal. As opposed to traditional fMRI signal analysis techniques, we do not impose any prior knowledge of the event timing. Inste ...

Elsevier2011

A Second-Order Extension Of Tv Regularization For Image Deblurring

Michaël Unser, Aurélien Bourquard, Zafer Dogan, Stamatios Lefkimmiatis

In this paper, we propose a novel second-order regularizer based on the maximum response of the second-order directional derivative, assuming that the image under consideration belongs to the class of piecewise-linear signals. Compared to total-variation r ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

Analytical Footprints: Compact Representation of Elementary Singularities in Wavelet Bases

Michaël Unser, Thierry Blu, Dimitri Nestor Alice Van De Ville

We introduce a family of elementary singularities that are point-Holder alpha-regular. These singularities are self-similar and are the Green functions of fractional derivative operators; i.e., by suitable fractional differentiation, one retrieves a Dirac ...

Institute of Electrical and Electronics Engineers2010

Fractional Brownian Vector Fields

Michaël Unser, Pouya Dehghani Tafti

This work puts forward an extended definition of vector fractional Brownian motion (fBm) using a distribution theoretic formulation in the spirit of Gel′fand and Vilenkin's stochastic analysis. We introduce random vector fields that share the statistical i ...

SIAM2010

A Time-Domain Wavelet-Based Approach for Fluorescence Diffuse Optical Tomography

Michaël Unser, Chandra Sekhar Seelamantula

Purpose: In the context of fluorescence diffuse optical tomography, determining the optimal way to exploit the time-resolved information has been receiving much attention and different features of the time-resolved signals have been introduced. In this art ...

AAPM2010

Fast Interscale Wavelet Denoising of Poisson-Corrupted Images

Michaël Unser, Thierry Blu, Florian Luisier, Cédric René Jean Vonesch

We present a fast algorithm for image restoration in the presence of Poisson noise. Our approach is based on (1) the minimization of an unbiased estimate of the MSE for Poisson noise, (2) a linear parametrization of the denoising process and (3) the preser ...

Elsevier2010

Analytical Form of Shepp-Logan Phantom for Parallel MRI

Michaël Unser, Dimitri Nestor Alice Van De Ville, Matthieu Guerquin-Kern

We present an analytical form of ground-truth k-space data for the 2-D Shepp-Logan brain phantom in the presence of multiple and non-homogeneous receiving coils. The analytical form allows us to conduct realistic simulations and validations of reconstructi ...

IEEE2010

Multi-Target Tracking Of Packed Yeast Cells

Michaël Unser, Nicolas Dénervaud, Sebastian Maerkl, Ricard Delgado Gonzalo

The tracking of cell populations in time-lapse microscopy images enables high-throughput spatiotemporal measurements of cell dynamics. In this paper, we present a new algorithm to simultaneously track many cells in crowded areas. The algorithm runs in real ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010

Fractal Modelling And Analysis Of Flow-Field Images

Michaël Unser, Pouya Dehghani Tafti, Ricard Delgado Gonzalo

We introduce stochastic models for flow fields with parameters that dictate the scale-dependent (self-similar) character of the field and control the balance between its rotational vs compressive behaviour. The development of our models is motivated by the ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010

Fast Detection of Cells Using a Continuously Scalable Mexican-Hat-Like Template

Michaël Unser, Daniel Sage, Kunal Narayan Chaudhury, Zsuzsanna Püspöki

We propose a fast algorithm for the detection of cells in fluorescence images. The algorithm, which estimates the number of cells and their respective centers and radii, relies on the fast computation of intensity-based correlations between the cells and a ...

IEEE2010

A Box Spline Calculus for Computed Tomography

Michaël Unser

B-splines are attractive basis functions for the continuous-domain representation of biomedical images and volumes. In this paper, we prove that the extended family of box splines are closed under the Radon transform and derive explicit formulae for their ...

IEEE2010

Continuous-Time AR Model Identification: Does Sampling Rate Really Matter?

Michaël Unser, Simona Maggio, Hagay Kirshner

We address the problem of identifying continuous-time auto regressive (CAR) models from sampled data. The exponential nature of CAR autocorrelation functions is taken into account by means of exponential B-splines modelling, allowing one to associate the a ...

EURASIP2010

Low-Bond Axisymmetric Drop Shape Analysis for Surface Tension and Contact Angle Measurements of Sessile Drops

Michaël Unser, Daniel Sage, Thierry Blu, Michael Müller

A new method based on the Young-Laplace equation for measuring contact angles and surface tensions is presented. In this approach, a first-order perturbation technique helps to analytically solve the Young-Laplace equation according to photographic images ...

Elsevier2010

SURE-LET for Orthonormal Wavelet-Domain Video Denoising

Michaël Unser, Thierry Blu, Florian Luisier

We propose an efficient orthonormal wavelet-domain video denoising algorithm based on an appropriate integration of motion compensation into an adapted version of our recently devised Stein's unbiased risk estimator-linear expansion of thresholds (SURE-LET ...

IEEE2010

Undecimated Haar Thresholding For Poisson Intensity Estimation

Michaël Unser, Thierry Blu, Florian Luisier

We propose a novel algorithm for denoising Poisson-corrupted images, that performs a signal-adaptive thresholding of the undecimated Haar wavelet coefficients. A Poisson's unbiased MSE estimate is devised and adapted to arbitrary transform-domain pointwise ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010

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