Spatial and temporal regularization to estimate COVID-19 reproduction number R(t): Promoting piecewise smoothness via convex optimization

P Abry, N Pustelnik, S Roux, P Jensen, P Flandrin… - Plos one, 2020 - journals.plos.org
Among the different indicators that quantify the spread of an epidemic such as the on-going
COVID-19, stands first the reproduction number which measures how many people can be …

A deep primal-dual proximal network for image restoration

M Jiu, N Pustelnik - IEEE Journal of Selected Topics in Signal …, 2021 - ieeexplore.ieee.org
Image restoration remains a challenging task in image processing. Numerous methods
tackle this problem, which is often solved by minimizing a nonsmooth penalized co-log …

Nonsmooth convex optimization to estimate the Covid-19 reproduction number space-time evolution with robustness against low quality data

B Pascal, P Abry, N Pustelnik, S Roux… - IEEE Transactions …, 2022 - ieeexplore.ieee.org
Daily pandemic surveillance, often achieved through the estimation of the reproduction
number, constitutes a critical challenge for national health authorities to design counter …

A variational approach for joint image recovery and feature extraction based on spatially varying generalised Gaussian models

E Chouzenoux, MC Corbineau, JC Pesquet… - Journal of Mathematical …, 2024 - Springer
The joint problem of reconstruction/feature extraction is a challenging task in image
processing. It consists in performing, in a joint manner, the restoration of an image and the …

Risk Estimate under a Nonstationary Autoregressive Model for Data-Driven Reproduction Number Estimation

B Pascal, S Vaiter - arxiv preprint arxiv:2409.14937, 2024 - arxiv.org
COVID-19 pandemic has brought to the fore epidemiological models which, though
describing a rich variety of behaviors, have previously received little attention in the signal …

Parameter-free and fast nonlinear piecewise filtering: application to experimental physics

B Pascal, N Pustelnik, P Abry, JC Géminard… - Annals of …, 2020 - Springer
Numerous fields of nonlinear physics, very different in nature, produce signals and images
that share the common feature of being essentially constituted of piecewise homogeneous …

Hyperparameter selection for discrete Mumford–Shah

CG Lucas, B Pascal, N Pustelnik, P Abry - Signal, Image and Video …, 2023 - Springer
This work focuses on a parameter-free joint piecewise smooth image denoising and contour
detection. Formulated as the minimization of a discrete Mumford–Shah functional and …

Restart strategies enabling automatic differentiation for hyperparameter tuning in inverse problems

L Davy, N Pustelnik, P Abry - 2024 32nd European Signal …, 2024 - ieeexplore.ieee.org
Numerous signal/image processing tasks can be formulated as variational problems, whose
solutions depend, often crucially, on the values of hyperparameters. Their automated …

Spectral Total-variation Processing of Shapes—Theory and Applications

J Brokman, M Burger, G Gilboa - ACM Transactions on Graphics, 2024 - dl.acm.org
We present a comprehensive analysis of total variation (TV) on non-Euclidean domains and
its eigenfunctions. We specifically address parameterized surfaces, a natural representation …

Contributions to stochastic bilevel optimization

M Dagreou - 2024 - theses.hal.science
Bilevel problems are a type of optimization problem characterized by a hierarchical
structure. In these problems, one wants to minimize an outer function under the constraint …