Prof. Hintermüller entwickelt mathematische Optimierungs- und Steuerungsmethoden für komplexe physikalische und technische Systeme. Sein aktueller Fokus liegt auf der Lösung von Variationsungleichungen und quasi-variationalen Problemen mit Anwendungen in der optimalen Steuerung, sowie auf skalierbaren numerischen Verfahren für große Systeme — etwa in der Quantensimulation, der Bildrekonstruktion (MRT) und der Multiskalensimulation. Diese Methoden ermöglichen es Unternehmen und Forschungseinrichtungen, komplexe Optimierungsprobleme in Materialwissenschaften, Energiemärkten, Mikrofluidiksystemen und Quantentechnologien effizient zu lösen und dabei Rechenzeit und Ressourcen zu sparen.
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Prof. Dr. Michael Hintermüller
HU-FIS-Profil ↗EXC 2046/2: Berlin Mathematics Research Center (MATH+)
university
EXC 2046/2: Berlin Mathematics Research Center (MATH+)
university
EXC 2046/2: Berlin Mathematics Research Center (MATH+)
other
Förderer: DFG sonstige Programme Zeitraum: 10/2008 - 05/2010 Projektleitung: Prof. Dr. Michael Hintermüller
Förderer: DFG Sachbeihilfe Zeitraum: 10/2009 - 12/2014 Projektleitung: Prof. Dr. Michael Hintermüller
Förderer: Wirtschaftsunternehmen / gewerbliche Wirtschaft Zeitraum: 05/2011 - 09/2011 Projektleitung: Prof. Dr. Michael Hintermüller
SIAM Journal on Optimization · DOI
International audience
SIAM Journal on Scientific Computing · DOI
In this paper, a primal-dual algorithm for total bounded variation (TV)--type image restoration is analyzed and tested. Analytically it turns out that employing a global $\boldsymbol{L}^s$-regularization, with $1 < s \leq 2$, in the dual problem results in a local smoothing of the TV-regularization term in the primal problem. The local smoothing can alternatively be obtained as the infimal convolution of the $\ell_r$-norm, with $r^{-1} + s^{-1} = 1$, and a smooth function. In the case $r = s = 2$, this results in Gauss-TV--type image restoration. The globalized primal-dual algorithm introduced in this paper works with generalized derivatives, converges locally at a superlinear rate, and is stable with respect to noise in the data. In addition, it utilizes a projection technique which reduces the size of the linear system that has to be solved per iteration. A comprehensive numerical study ends the paper.
SIAM Journal on Applied Mathematics
It is demonstrated that the predual for problems with total bounded variation regularization terms can be expressed as a bilaterally constrained optimization problem. Existence of a Lagrange multiplier and an optimality system are established. This allows us to utilize efficient optimization methods developed for problems with box constraints in the context of bounded variation formulations. Here, in particular, the primal-dual active set method, considered as a semismooth Newton method, is analyzed, and superlinear convergence is proved. As a by-product we obtain that the Lagrange multiplier associated with the box constraints acts as an edge detector. Numerical results for image denoising and zooming/resizing show the efficiency of the new approach.