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Michaël Unser

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Publications associées (516)

Optical Imaging Using Binary Sensors

Michaël Unser, François Aguet, Aurélien Bourquard

This paper addresses the problem of reconstructing an image from 1-bit-quantized measurements, considering a simple but nonconventional optical acquisition model. Following a compressed-sensing design, a known pseudo-random phase-shifting mask is introduce ...

OSA2010

An Efficient Numerical Method for General

Michaël Unser, Kai Hassler, Jean-Charles Baritaux

Reconstruction algorithms for fluorescence tomography have to address two crucial issues : 1) the ill-posedness of the reconstruction problem, 2) the large scale of numerical problems arising from imaging of 3-D samples. Our contribution is the design and ...

Institute of Electrical and Electronics Engineers2010

On the Shiftability of Dual-Tree Complex Wavelet Transforms

Michaël Unser, Kunal Narayan Chaudhury

The dual-tree complex wavelet transform (DT-ℂWT) is known to exhibit better shift-invariance than the conventional discrete wavelet transform. We propose an amplitude-phase representation of the DT-ℂWT which, among other things, offers a direct explanation ...

IEEE2010

Fractional Brownian Models For Vector Field Data

Michaël Unser, Pouya Dehghani Tafti

In this note we introduce a vector generalization of fractional Brownian motion. Our definition takes into account directional properties of vector fields-such as divergence, rotational behaviour, and interactions with coordinate transformations-that have ...

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

A Priori Guided Reconstruction For Fdot Using Mixed Norms

Michaël Unser, Jean-Charles Baritaux

We propose new soft-prior approach for incorporating structural a priori in FDOT reconstruction. The technique is a non-linear regularization scheme based on the penalization of the (2, 1)-mixed norm. We solve the numerical reconstruction problem with an i ...

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

A method and apparatus for enhanced spatial bandwidth wavefronts reconstructed from digital interferograms or holograms

Christian Depeursinge, Michaël Unser, Nicolas Pavillon, Chandra Sekhar Seelamantula

The present invention discloses a method and an apparatus to compute a complex wavefield, referred to as the object wave o, by means of measuring the intensity signal resulting from the interference of the said object wave with a second wave termed the ref ...

2010

Fast Space-Variant Elliptical Filtering Using Box Splines

Michaël Unser, Kunal Narayan Chaudhury

The efficient realization of linear space-variant (non-convolution) filters is a challenging computational problem in image processing. In this paper, we demonstrate that it is possible to filter an image with a Gaussian-like elliptic window of varying siz ...

IEEE2010

Performance Analysis of Reconstruction Techniques for Frequency-Domain Optical-Coherence Tomography

Michaël Unser, Chandra Sekhar Seelamantula

We address the issue of noise robustness of reconstruction techniques for frequency-domain optical-coherence tomography (FDOCT). We consider three reconstruction techniques: Fourier, iterative phase recovery, and cepstral techniques. We characterize the re ...

Institute of Electrical and Electronics Engineers2010

Regularized Interpolation for Noisy Images

Philippe Thévenaz, Michaël Unser, Sathish Ramani

Interpolation is the means by which a continuously defined model is fit to discrete data samples. When the data samples are exempt of noise, it seems desirable to build the model by fitting them exactly. In medical imaging, where quality is of paramount im ...

Institute of Electrical and Electronics Engineers2010

Accelerated Wavelet-Regularized Deconvolution For 3-D Fluorescence Microcopy

Michaël Unser, Matthieu Guerquin-Kern, Raquel Terrés Cristofani, Ilker Bayram

Modern deconvolution algorithms are often specified as minimization problems involving a non-quadratic regularization functional. When the latter is a wavelet-domain l(1)-norm that favors sparse solutions, the problem can be solved by a simple iterative sh ...

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

Wavelet Steerability and the Higher-Order Riesz Transform

Michaël Unser, Dimitri Nestor Alice Van De Ville

Our main goal in this paper is to set the foundations of a general continuous-domain framework for designing steerable, reversible signal transformations (a.k.a. frames) in multiple dimensions (d ≥ 2). To that end, we introduce a self-reversible, Nth-order ...

Institute of Electrical and Electronics Engineers2010

A software solution for recording circadian oscillator features in time-lapse live cell microscopy

Michaël Unser, Daniel Sage

Background: Fluorescent and bioluminescent time-lapse microscopy approaches have been successfully used to investigate molecular mechanisms underlying the mammalian circadian oscillator at the single cell level. However, most of the available software and ...

BioMed Central Ltd.2010

Model-Based Estimation of Three-Dimensional Stiffness Parameters in Photonic-Force Microscopy

Andrzej Kulik, Philippe Thévenaz, Michaël Unser, Elena Bertseva, Amardeep Singh

We propose a system to characterize the 3-D diffusion properties of the probing bead trapped by a photonic-force microscope. We follow a model-based approach, where the model of the dynamics of the bead is given by the Langevin equation. Our procedure comb ...

Institute of Electrical and Electronics Engineers2010

A Stochastic Minimum-Norm Approach to Image and Texture Interpolation

Michaël Unser, Hagay Kirshner

We introduce an exponential-based consistent approach to image scaling. Our model stems from Sobolev reproducing kernels, motivated by their role in continuous-domain stochastic autoregressive processes. The proposed approach imposes consistency and applie ...

EURASIP2010

Steerable filters for orientation estimation and localization of fluorescent dipoles

Iwan Märki, Michaël Unser, Theo Lasser, François Aguet, Stefan Geissbühler

Fluorescence localization microscopy (i.e., PALM, STORM) has enabled optical imaging at nanometer-scale resolutions. The localization algorithms used in these techniques rely on fitting a 2-D Gaussian to the in-focus image of individual fluorophores. For f ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2009

Suppression of the zero-order in off-axis digital holography through nonlinear filtering

Christian Depeursinge, Michaël Unser, Jonas Kühn, Nicolas Pavillon, Chandra Sekhar Seelamantula

We present experimental validation of a new reconstruction method for off-axis digital holographic microscopy (DHM). This method effectively suppresses the object auto-correlation — namely the zero-order term — from holographic data, thereby improving the ...

2009

See the Brain at Work—Intraoperative Laser Doppler Functional Brain Imaging

Marcel Leutenegger, Michaël Unser, Theo Lasser, Antonio Lopez, Dimitri Nestor Alice Van De Ville, Rainer Leitgeb, Erica Martin-Williams

During open brain surgery we acquire perfusion images non-invasively using laser Doppler imaging. The regions of brain activity show a distinct signal in response to stimulation providing intraoperative functional brain maps of remarkably strong contrast. ...

2009

The Fractional Hilbert Transform And Dual-Tree Gabor-Like Wavelet Analysis

Michaël Unser, Kunal Narayan Chaudhury

We provide an amplitude-phase representation of the dual-tree complex wavelet transform by extending the fixed quadrature relationship of the dual-tree wavelets to arbitrary phase-shifts using the fractional Hilbert transform. (fHT). The fHT is a generaliz ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2009

A Nonlinear Technique for Automatic Twin-Image and Zero-Order Term Suppression in Digital Holographic Microscopy

Christian Depeursinge, Michaël Unser, Nicolas Pavillon, Chandra Sekhar Seelamantula

ITO2009

A bulk modulus dependent linear model for acoustical imaging

Michaël Unser, Thierry Blu

Modeling the acoustical process of soft biological tissue imaging and understanding the consequences of the approximations required by. such modeling are key steps for accurately simulating ultrasonic scanning as well as estimating the scattering coefficie ...

ASA2009

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