114 citations · 188 across the 17 of their papers we have counts for
18 papers
Multimodal Approaches for Visually-Rich Document Type Classification: A Comparative Analysis
Catyana Heyne, Jürgen Frikel, Filippo Riccio
Document type classification in visually rich documents remains challenging, as relevant information is distributed across textual, visual, and layout modalities. To capture this c…
Data-proximal null-space networks for inverse problems
Simon Göppel, Jürgen Frikel, Markus Haltmeier
Inverse problems are inherently ill-posed and therefore require regularization techniques to achieve a stable solution. While traditional variational methods have well-established…
Translation invariant diagonal frame decomposition for the Radon transform
Simon Göppel, Markus Haltmeier, Jürgen Frikel
In this article, we address the challenge of solving the ill-posed reconstruction problem in computed tomography using a translation invariant diagonal frame decomposition (TI-DFD)…
Data-proximal complementary -TV reconstruction for limited data CT
Simon Göppel, Jürgen Frikel, Markus Haltmeier
In a number of tomographic applications, data cannot be fully acquired, resulting in a severely underdetermined image reconstruction. In such cases, conventional methods lead to re…
Translation invariant diagonal frame decomposition of inverse problems and their regularization
Simon Göppel, Jürgen Frikel, Markus Haltmeier
Solving inverse problems is central to a variety of important applications, such as biomedical image reconstruction and non-destructive testing. These problems are characterized by…
Feature reconstruction from incomplete tomographic data without detour
Simon Göppel, Jürgen Frikel, Markus Haltmeier
In this paper, we consider the problem of feature reconstruction from incomplete x-ray CT data. Such problems occurs, e.g., as a result of dose reduction in the context medical ima…
Combining reconstruction and edge detection in computed tomography
Jürgen Frikel, Simon Göppel, Markus Haltmeier
We present two methods that combine image reconstruction and edge detection in computed tomography (CT) scans. Our first method is as an extension of the prominent filtered backpro…
Regularization of Inverse Problems by Filtered Diagonal Frame Decomposition
Andrea Ebner, Jürgen Frikel, Dirk Lorenz +2
The characteristic feature of inverse problems is their instability with respect to data perturbations. In order to stabilize the inversion process, regularization methods have to…
A new 3D model for magnetic particle imaging using realistic magnetic field topologies for algebraic reconstruction
Gaël Bringout, Wolfgang Erb, Jürgen Frikel
We derive a new 3D model for magnetic particle imaging (MPI) that is able to incorporate realistic magnetic fields in the reconstruction process. In real MPI scanners, the generate…
Sparse regularization of inverse problems by operator-adapted frame thresholding
Jürgen Frikel, Markus Haltmeier
We analyze sparse frame based regularization of inverse problems by means of a diagonal frame decomposition (DFD) for the forward operator, which generalizes the SVD. The DFD allow…
Mathematical Analysis of the 1D Model and Reconstruction Schemes for Magnetic Particle Imaging
Wolfgang Erb, Andreas Weinmann, Mandy Ahlborg +10
Magnetic particle imaging (MPI) is a promising new in-vivo medical imaging modality in which distributions of super-paramagnetic nanoparticles are tracked based on their response i…
Analyzing Reconstruction Artifacts from Arbitrary Incomplete X-ray CT Data
Leise Borg, Jurgen Frikel, Jakob Sauer Jorgensen +1
This article provides a mathematical analysis of singular (nonsmooth) artifacts added to reconstructions by filtered backprojection (FBP) type algorithms for X-ray CT with arbitrar…
Efficient regularization with wavelet sparsity constraints in PAT
Jürgen Frikel, Markus Haltmeier
In this paper we consider the reconstruction problem of photoacoustic tomography (PAT) with a flat observation surface. We develop a direct reconstruction method that employs regul…
Limited data problems for the generalized Radon transform in
Jürgen Frikel, Eric Todd Quinto
We consider the generalized Radon transform (defined in terms of smooth weight functions) on hyperplanes in . We analyze general filtered backprojection type reconstr…
On Artifacts in Limited Data Spherical Radon Transform: Curved Observation Surface
Lyudmyla L. Barannyk, Jürgen Frikel, Linh V. Nguyen
In this article, we consider the limited data problem for spherical mean transform. We characterize the generation and strength of the artifacts in a reconstruction formula. In con…
Artifacts in incomplete data tomography - with applications to photoacoustic tomography and sonar
Jürgen Frikel, Eric Todd Quinto
We develop a paradigm using microlocal analysis that allows one to characterize the visible and added singularities in a broad range of incomplete data tomography problems. We give…
Joint Image Reconstruction and Segmentation Using the Potts Model
Martin Storath, Andreas Weinmann, Jürgen Frikel +1
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…
Sparse regularization in limited angle tomography
Jürgen Frikel
We investigate the reconstruction problem of limited angle tomography. Such problems arise naturally in applications like digital breast tomosynthesis, dental tomography, electron…