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Iterative ptychographic reconstruction algorithms are widely used for coherent diffractive imaging but can exhibit slow convergence under realistic experimental conditions. We propose a machine learning-augmented approach that accelerates…

Ptychography is a popular technique to achieve diffraction limited resolution images of a two or three dimensional sample using high frame rate detectors. We introduce a relaxation of common projection algorithms to account for…

Although originally designed and analyzed for convex problems, the alternating direction method of multipliers (ADMM) and its close relatives, Douglas-Rachford splitting (DRS) and Peaceman-Rachford splitting (PRS), have been observed to…

Optimization and Control · Mathematics 2020-02-25 Andreas Themelis , Panagiotis Patrinos

In this work we focus on the convex feasibility problem (CFP) in Hilbert space. A specific method in this area that has gained a lot of interest in recent years is the Douglas-Rachford (DR) algorithm. This algorithm was originally…

Optimization and Control · Mathematics 2022-11-08 Kay Barshad , Aviv Gibali , Simeon Reich

Force-directed approach is one of the most widely used methods in graph drawing research. There are two main problems with the traditional force-directed algorithms. First, there is no mature theory to ensure the convergence of iteration…

Computational Geometry · Computer Science 2018-03-12 Yong-Xian Wang , Zheng-Hua Wang

The circumcentered Douglas--Rachford method (C--DRM), introduced by Behling, Bello Cruz and Santos, is an acceleration of the well-known Douglas-Rachford method (DRM) for finding the best approximation onto the intersection of finitely many…

Optimization and Control · Mathematics 2020-06-16 Heinz H. Bauschke , Hui Ouyang , Xianfu Wang

We adapt the Douglas-Rachford (DR) splitting method to solve nonconvex feasibility problems by studying this method for a class of nonconvex optimization problem. While the convergence properties of the method for convex problems have been…

Optimization and Control · Mathematics 2015-11-17 Guoyin Li , Ting Kei Pong

Maximum a posteriori (MAP) inference over discrete Markov random fields is a fundamental task spanning a wide spectrum of real-world applications, which is known to be NP-hard for general graphs. In this paper, we propose a novel…

Machine Learning · Computer Science 2015-01-06 Qixing Huang , Yuxin Chen , Leonidas Guibas

Low Dose Computed Tomography suffers from a high amount of noise and/or undersampling artefacts in the reconstructed image. In the current article, a Deep Learning technique is exploited as a regularization term for the iterative…

Image and Video Processing · Electrical Eng. & Systems 2019-06-04 Shabab Bazrafkan , Vincent Van Nieuwenhove , Joris Soons , Jan De Beenhouwer , Jan Sijbers

Magnetorelaxometry imaging is a novel tool for quantitative determination of the spatial distribution of magnetic nanoparticle inside an organism. The use of multiple excitation patterns has been demonstrated to significantly improve…

Numerical Analysis · Mathematics 2019-03-20 Markus Haltmeier , Gerhard Zangerl , Peter Schier , Daniel Baumgarten

The problem of finding a vector with the fewest nonzero elements that satisfies an underdetermined system of linear equations is an NP-complete problem that is typically solved numerically via convex heuristics or nicely-behaved nonconvex…

Optimization and Control · Mathematics 2018-02-07 Robert Hesse , D. Russell Luke , Patrick Neumann

We are interested in restoring images having values in a symmetric Hadamard manifold by minimizing a functional with a quadratic data term and a total variation like regularizing term. To solve the convex minimization problem, we extend the…

Numerical Analysis · Mathematics 2018-12-10 Ronny Bergmann , Johannes Persch , Gabriele Steidl

We provide here a framework to analyze the phase transition phenomenon of slice inverse regression (SIR), a supervised dimension reduction technique introduced by \cite{Li:1991}. Under mild conditions, the asymptotic ratio $\rho= \lim p/n$…

Statistics Theory · Mathematics 2016-11-22 Qian Lin , Zhigen Zhao , Jun S. Liu

Ptychography is a popular imaging technique that combines diffractive imaging with scanning microscopy. The technique consists of a coherent beam that is scanned across an object in a series of overlapping positions, leading to reliable and…

Numerical Analysis · Mathematics 2019-02-20 Samy Wu Fung , Zichao Di

Splitting schemes are a class of powerful algorithms that solve complicated monotone inclusion and convex optimization problems that are built from many simpler pieces. They give rise to algorithms in which the simple pieces of the…

Optimization and Control · Mathematics 2015-05-04 Damek Davis , Wotao Yin

The Douglas-Rachford algorithm is a simple yet effective method for solving convex feasibility problems. However, if the underlying constraints are inconsistent, then the convergence theory is incomplete. We provide convergence results when…

Optimization and Control · Mathematics 2020-04-14 Heinz H. Bauschke , Minh N. Dao , Walaa M. Moursi

The Semi-Implicit Root solver (SIR) is an iterative method for globally convergent solution of systems of nonlinear equations. Since publication, SIR has proven robustness for a great variety of problems. We here present MATLAB and MAPLE…

Computational Physics · Physics 2017-04-14 Jan Scheffel , Kristoffer Lindvall

In application of tomography imaging, limited-angle problem is a quite practical and important issue. In this paper, an iterative reprojection-reconstruction (IRR) algorithm using a modified Papoulis-Gerchberg (PG) iterative scheme is…

Computer Vision and Pattern Recognition · Computer Science 2019-05-01 Yuli Sun , Jinxu Tao , Conggui Liu

The Douglas--Rachford algorithm is a classical and very successful splitting method for finding the zeros of the sums of monotone operators. When the underlying operators are normal cone operators, the algorithm solves a convex feasibility…

Optimization and Control · Mathematics 2015-04-16 Heinz H. Bauschke , Walaa M. Moursi

Ptychography is a popular imaging technique that combines diffractive imaging with scanning microscopy. The technique consists of a coherent beam that is scanned across an object in a series of overlapping positions, leading to reliable and…

Numerical Analysis · Mathematics 2024-08-08 Ricardo Parada , Samy Wu Fung , Stanley Osher