Recherche

Afficher tous les résultats pour

Accueil

Personne

Michaël Unser

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (516)

Monte-Carlo SURE: A Black-Box Optimization of Regularization Parameters for General Denoising Algorithms

Michaël Unser, Thierry Blu, Sathish Ramani

We consider the problem of optimizing the parameters of a given denoising algorithm for restoration of a signal corrupted by white Gaussian noise. To achieve this, we propose to minimize Stein's unbiased risk estimate (SURE) which provides a means of asses ...

IEEE2008

Controlled Exchange of Chromosomal Arms Reveals Principles Driving Telomere Interactions in Yeast

Michaël Unser, Daniel Sage

The 32 telomeres in the budding yeast genome cluster in three to seven perinuclear foci. Although individual telomeres and telomeric foci are in constant motion, preferential juxtaposition of some telomeres has been scored. To examine the principles that g ...

Cold Spring Harbor Laboratory Press2008

Spontaneous $ Na ^{ + } $ Transients in Individual Mitochondria of Intact Astrocytes

Michaël Unser, Dimitri Nestor Alice Van De Ville, Jean-Yves Chatton

Mitochondria in intact cells maintain low

Na ^{ + }

levels despite the large electrochemical gradient favoring cation influx into the matrix. In addition, they display individual spontaneous transient depolarizations. We report here that individual mit ...

Wiley-Liss2008

The Marr Wavelet Pyramid and Multiscale Directional Image Analysis

Michaël Unser, Daniel Sage, Dimitri Nestor Alice Van De Ville, Katarina Balac

The “Marr wavelet pyramid” is a wavelet decomposition that implements a multiscale version of the complex gradient-Laplace operator. It is closely linked to a multiresolution analysis of

L _{ 2 }

(\mathbb{R} ^{ 2 }

) and it has a fast filterbank im ...

EURASIP2008

Quantitative Morphometrical Characterization of Human Pronuclear Zygotes

Philippe Thévenaz, Michaël Unser

BACKGROUND: Identification of embryos with high implantation potential remains a challenge in in vitro fertilization (IVF). Subjective pronuclear (PN) zygote scoring systems have been developed for that purpose. The aim of this work was to provide a softwa ...

Oxford University Press2008

Model-Based 2.5-D Deconvolution for Extended Depth of Field in Brightfield Microscopy

Michaël Unser, François Aguet, Dimitri Nestor Alice Van De Ville

Due to the limited depth of field of brightfield microscopes, it is usually impossible to image thick specimens entirely in focus. By optically sectioning the specimen, the in-focus information at the specimen's surface can be acquired over a range of imag ...

IEEE2008

Blind optimization of algorithm parameters for signal denoising by Monte-Carlo sure

Michaël Unser, Thierry Blu, Sathish Ramani

We consider the problem of optimizing the parameters of an arbitrary denoising algorithm by minimizing Stein's Unbiased Risk Estimate (SURE) which provides a means of assessing the true mean-squared-error (MSE) purely from the measured data assuming that i ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Parametric B-Spline Snakes on Distance Maps—Application to Segmentation of Histology Images

Philippe Thévenaz, Michaël Unser, François Aguet, Chandra Sekhar Seelamantula

We construct parametric active contours (snakes) for outlining cells in histology images. These snakes are defined in terms of cubic B-spline basis functions. We use a steerable ridge detector for obtaining a reliable map of the cell boundaries. Using the ...

EURASIP2008

Variational B-Spline Level-Set Method for Fast Image Segmentation

Philippe Thévenaz, Michaël Unser

In the field of image segmentation, most of level-set-based active contour approaches are based on a discrete representation of the associated implicit function. We present in this paper a different formulation where the level-set is modelled as a continuo ...

IEEE2008

Theoretical analysis of complex-conjugate-ambiguity suppression in frequency-domain optical-coherence tomography

Michaël Unser, Roland Michaely, Rainer Leitgeb

New phase-shifting techniques have recently been proposed to suppress the complex-conjugate ambiguity in frequency-domain optical-coherence tomography. A phase shift is introduced, in an elegant fashion, by incorporating a small beam offset at the scanning ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Snakuscules

Philippe Thévenaz, Michaël Unser

A snakuscule (a minuscule snake) is the simplest active contour that we were able to design while keeping the quintessence of traditional snakes: an energy term governed by the data, and a regularization term. Our construction is an area-based snake, as op ...

IEEE2008

Effect of Ageing on Elastin Functionality in Human Cerebral Arteries

Nikolaos Stergiopoulos, Jean Fasel, Michaël Unser, Daniel Sage, Edouard Fonck

ASME2008

Coupled tomography and distinct-element-method approach to exploring the granular media microstructure in a jamming hourglass

Michel Tsukahara, Thomas Liebling, Giorgio Margaritondo, Michaël Unser, Daniel Sage, Lionel Pournin, Marco Ramaioli, Vincent Gajdosik, Slobodan Mitrovic

We describe an approach for exploring microscopic properties of granular media that couples x-ray microtomography and distinct-element-method (DEM) simulations through image analysis. We illustrate it via the study of the intriguing phenomenon of instant a ...

APS2008

Construction of Hilbert transform pairs of wavelet bases and optimal time-frequency localization

Michaël Unser, Kunal Narayan Chaudhury

We propose a novel method of constructing exact Hilbert transform (HT) pairs of wavelet bases using fractional B-splines and state necessary and sufficient conditions for generating such wavelet pairs. In particular, we demonstrate how HT pairs of biorthog ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

The Pairing of a Wavelet Basis With a Mildly Redundant Analysis via Subband Regression

Michaël Unser, Dimitri Nestor Alice Van De Ville

A distinction is usually made between wavelet bases and wavelet frames. The former are associated with a one-to-one representation of signals, which is somewhat constrained but most efficient computationally. The latter are over-complete, but they offer ad ...

Institute of Electrical and Electronics Engineers2008

Innovation modelling and wavelet analysis of fractal processes in bio-imaging

Michaël Unser, Dimitri Nestor Alice Van De Ville, Pouya Dehghani Tafti

Growth and form in biology are often associated with some level of fractality. Fractal characteristics have also been noted in a number of imaging modalities. These observations make fractal modelling relevant in the context of bio-imaging. ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Short basis functions for constant-variance interpolation

Philippe Thévenaz, Michaël Unser, Thierry Blu

An interpolation model is a necessary ingredient of intensity-based registration methods. The properties of such a model depend entirely on its basis function, which has been traditionally characterized by features such as its order of approximation and it ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2008

Fast Computation of Polyharmonic B-Spline Autocorrelation Filters

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

A fast computational method is given for the Fourier transform of the polyharmonic B-spline autocorrelation sequence in d dimensions. The approximation error is exponentially decaying with the number of terms taken into account. The algorithm improves spee ...

IEEE Institute of Electrical and Electronics Engineers2008

Exact and Efficient Signal Reconstruction in Frequency-Domain Optical-Coherence Tomography

Michaël Unser, Rainer Leitgeb, Chandra Sekhar Seelamantula

We address the problem of tomogram reconstruction in frequency-domain optical-coherence tomography. We propose a new technique for suppressing the autocorrelation artifacts that are commonly encountered with the conventional Fourier-transform-based approac ...

OSA2008

Dynamic PET Reconstruction Using Wavelet Regularization with Adapted Basis Functions

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

Tomographic reconstruction from positron emission tomography (PET) data is an ill-posed problem that requires regularization. An attractive approach is to impose an

\ell_{ 1 }

-regularization constraint, which favors sparse solutions in the wavelet dom ...

Institute of Electrical and Electronics Engineers2008

Page 22 sur 26