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Michaël Unser

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Related publications (516)

Back-Propagating the Light of Field Stars to Probe Telescope Mirrors Aberrations

Michaël Unser, Frédéric Courbin, Ferréol Arnaud Marie Soulez

We propose a wavefront-based method to estimate the PSF over the whole field of view. This method estimate the aberrations of all the mirrors of the telescope using only field stars. In this proof of concept paper, we described the method and present some ...

SPIE2016

Variational Phase Imaging Using the Transport-of-Intensity Equation

Michaël Unser, Daniel Sage, Emrah Bostan, Masih Nilchian, Emmanuel Augustin Julien Froustey

We introduce a variational phase retrieval algorithm for the imaging of transparent objects. Our formalism is based on the transport-of-intensity equation (TIE), which relates the phase of an optical field to the variation of its intensity along the direct ...

IEEE2016

Reconstruction From Multiple Poses in Fluorescence Imaging: Proof of Concept

Michaël Unser, Paul Guichard, Ning Chu, Denis Fortun

One disadvantage of all fluorescence imaging modalities is a poor axial resolution. To overcome this issue, we propose a novel approach to reconstruct fluorescence volumes with isotropic high resolution, from images of particle replicates observed at multi ...

Ieee-Inst Electrical Electronics Engineers Inc2016

A Family of Smooth and Interpolatory Basis Functions for Parametric Curve and Surface Representation

Michaël Unser, Daniel Andreas Schmitter, Ricard Delgado Gonzalo

Interpolatory basis functions are helpful to specify parametric curves or surfaces that can be modified by simple user-interaction. Their main advantage is a characterization of the object by a set of control points that lie on the shape itself (i.e., curv ...

2016

Proximity Operators for Phase Retrieval

Michaël Unser, Frédéric Courbin, Ferréol Arnaud Marie Soulez

We present a new formulation of a family of proximity operators that generalize the projector step for phase retrieval. These proximity operators for noisy intensity measurements can replace the classical "noise-free" projection in any projection-based alg ...

OSA2016

On the Continuous Steering of the Scale of Tight Wavelet Frames

Michaël Unser, Daniel Sage, Zsuzsanna Püspöki, John Paul Ward

In analogy with steerable wavelets, we present a general construction of adaptable tight wavelet frames, with an emphasis on scaling operations. In particular, the derived wavelets can be "dilated" by a procedure comparable to the operation of steering ste ...

SIAM2016

SpotCaliper: Fast Wavelet-Based Spot Detection with Accurate Size Estimation

Michaël Unser, Daniel Sage, Zsuzsanna Püspöki, John Paul Ward

Motivation: SpotCaliper is a novel wavelet-based image-analysis software providing a fast automatic detection scheme for circular patterns (spots), combined with the precise estimation of their size. It is implemented as an ImageJ plugin with a friendly us ...

Oxford Journals2016

Smoothly Deformable Spheres: Modeling, Deformation, and Interaction

Michaël Unser, Daniel Andreas Schmitter, Pablo Garcia-Amorena Garcia

Existing shape models with spherical topology are typically designed either in the discrete domain using interpolating polygon meshes or in the continuous domain using smooth but non-interpolating schemes such as NURBS. Polygon models and subdivision metho ...

ACM2016

Fast 3D reconstruction method for differential phase contrast X-ray CT

Michaël Unser, Masih Nilchian, Marco Stampanoni, Michael Thompson McCann

We present a fast algorithm for fully 3D regularized X-ray tomography reconstruction for both traditional and differential phase contrast measurements. In many applications, it is critical to reduce the X-ray dose while producing high-quality reconstructio ...

2016

Local Refinement for 3D Deformable Parametric Surfaces

Michaël Unser, Daniel Andreas Schmitter, Anaïs Laure Marie-Thérèse Badoual

Biomedical image segmentation is an active field of research where deformable models have proved to be efficient. The geometric representation of such models determines their ability to approximate the shape of interest as well as the speed of convergence ...

IEEE2016

Isotropic Resolution in Fluorescence Imaging by Single Particle Reconstruction

Michaël Unser, Paul Guichard, Ning Chu, Denis Fortun

Low axial resolution is a major limitation of fluorescence imaging modalities. We propose a methodology to achieve high isotropic resolution by reconstructing fluorescence volumes from observations of multiple particle replicates with different orientation ...

IEEE2016

MMSE Denoising of Sparse and Non-Gaussian AR(1) Processes

Michaël Unser, Emrah Bostan, Pedram Pad, Pouria Tohidi

We propose two minimum-mean-square-error (MMSE) estimation methods for denoising non-Gaussian first-order autoregressive (AR(1)) processes. The first one is based on the message passing framework and gives the exact theoretic MMSE estimator. The second is ...

IEEE2016

An Inner-Product Calculus for Periodic Functions and Curves

Michaël Unser, Daniel Andreas Schmitter, Anaïs Laure Marie-Thérèse Badoual

Our motivation is the design of efficient algorithms to process closed curves represented by basis functions or wavelets. To that end, we introduce an inner-product calculus to evaluate correlations and

L _{ 2 }

distances between such curves. In partic ...

IEEE Institute of Electrical and Electronics Engineers2016

New Parametric 3D Snake for Medical Segmentation of Structures with Cylindrical Topology

Michaël Unser, Daniel Andreas Schmitter

We propose a new parametric 3D snake with cylindrical topology. Its construction is based on interpolatory basis functions which facilitates user-interaction because the control points of the snake directly lie on the surface of the deformable cylinder. We ...

IEEE2015

Design of Steerable Wavelets to Detect Multifold Junctions

Michaël Unser, Cédric René Jean Vonesch, Virginie Sophie Uhlmann, Zsuzsanna Püspöki

We propose a framework for the detection of junctions in images. Although the detection of edges and key points is a well examined and described area, the multiscale detection of junction centers, especially for odd orders, poses a challenge in pattern ana ...

IEEE2015

Sampling and (Sparse) Stochastic Processes: A Tale of Splines and Innovation

Michaël Unser

The commonality between splines and Gaussian or sparse stochastic processes is that they are ruled by the same type of differential equations. Our purpose here is to demonstrate that this has profound implications for the three primary forms of sampling: u ...

IEEE2015

Optimal Isotropic Wavelets for Localized Tight Frame Representations

Michaël Unser, John Paul Ward, Pedram Pad

In this letter, we aim to identify the optimal isotropic mother wavelet for a given spatial dimension based on a localization criterion. Within the framework of the calculus of variations, we specify an Euler-Lagrange equation for this problem, and we find ...

IEEE Institute of Electrical and Electronics Engineers2015

Structure Tensor Total Variation

Michaël Unser, Stamatios Lefkimmiatis

We introduce a novel generic energy functional that we employ to solve inverse imaging problems within a variational framework. The proposed regularization family, termed as structure tensor total variation (STV), penalizes the eigenvalues of the structure ...

SIAM2015

Joint image reconstruction and segmentation using the Potts model

Michaël Unser, Martin Kurt Storath

We propose a new algorithmic approach to the non-smooth and non-convex Potts problem (also called piecewise-constant Mumford-Shah problem) for inverse imaging problems. We derive a suitable splitting into specific subproblems that can all be solved efficie ...

Institute of Physics2015

Ellipse-Preserving Hermite Interpolation and Subdivision

Michaël Unser

We introduce a family of piecewise-exponential functions that have the Hermite interpolation property. Our design is motivated by the search for an effective scheme for the joint interpolation of points and associated tangents on a curve with the ability t ...

Elsevier2015

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