Publications

2025

• Elshiaty, Y. and Vanmaele, F. and Petra, S. Information Geometry of Exponentiated Gradient: Convergence beyond l-Smoothness, International Conference on Scale Space and Variational Methods in Computer \dots, 2025. [DOI]
• Elshiaty, Y. and Petra, S. Multilevel Bregman Proximal Gradient Descent, arXiv preprint arXiv:2506., 2025. [DOI]
• Gonzalez-Alvarado, D. and Schlindwein, F. and Cassel, J. and Steingruber, L. and Petra, S. and ... Riemannian Patch Assignment Gradient Flows, International Conference on Scale Space and Variational Methods in Computer \dots, 2025. [DOI]
• Steingruber, L. and Schweiger, F. and Handtke, S. and Schiele, S. and Petra, S. and Krabichler, F. and ... Respiratory Skeletal Muscle Degeneration in Covid-19 Patients, Annals of Anatomy-Anatomischer Anzeiger, 2025. [DOI]
• Vanmaele, F. and Elshiaty, Y. and Petra, S. Multilevel Optimization: Geometric Coarse Models and Convergence Analysis, International Conference on Scale Space and Variational Methods in Computer \dots, 2025. [DOI]

2024

• Boll, B. and Gonzalez-Alvarado, D. and Petra, S. and Schnörr, C. Generative Assignment Flows for Representing and Learning Joint Distributions of Discrete Data, arXiv preprint arXiv:2406., 2024. [DOI]
• Boll, B. and Cassel, J. and Albers, P. and Petra, S. and Schnörr, C. A Geometric Embedding Approach to Multiple Games and Multiple Populations, 2024. [DOI]
• Cassel, J. and Boll, B. and Petra, S. and Albers, P. and Schnörr, C. Sigma Flows for Image and Data Labeling and Learning Structured Prediction, arXiv preprint arXiv:2408., 2024. [DOI]
• Raus, M. and Elshiaty, Y. and Petra, S. Accelerated Bregmann Divergence Optimization with SMART: An Information Geometry Point of View, 2024. [DOI]

2023

• Boll, B. and Schwarz, J. and Gonzalez-Alvarado, D. and Sitenko, D. and Petra, S. and Schnörr, C. Modeling Large-Scale Joint Distributions and Inference by Randomized Assignment, International Conference on Scale Space and Variational Methods in Computer \dots, 2023. [DOI]
• Boll, B. and Zeilmann, A. and Petra, S. and Schnörr, C. Self-certifying Classification by Linearized Deep Assignment, PAMM, 2023. [DOI]
• Kahl, M. and Petra, S. and Schnörr, C. and Steidl, G. and Zisler, M. On the Remarkable Efficiency of SMART, Scale Space and Variational Methods in Computer Vision: 9th International \dots, 2023. [DOI]
• Zeilmann, A. and Petra, S. and Schnörr, C. Learning Linearized Assignment Flows for Image Labeling, Journal of Mathematical Imaging and Vision, 2023. [DOI]

2022

• Müller, S. and Petra, S. and Zisler, M. Multi-Level Geometric Optimization for Regularised Constrained Linear Inverse Problems, arXiv preprint arXiv:2207., 2022. [DOI]
• Plier, J. and Zisler, M. and Furkel, J. and Knoll, M. and Marx, A. and Fischer, A. and Polsterer, K. and ... Learning Features via Transformer Networks for Cardiomyocyte Profiling, Bildverarbeitung für die Medizin 2022: Proceedings, German Workshop on \dots, 2022. [DOI]

2021

• Hühnerbein, R. and Savarino, F. and Petra, S. and Schnörr, C. Learning Adaptive Regularization for Image Labeling Using Geometric Assignment, Journal of Mathematical Imaging and Vision, 2021. [DOI]
• Kiefer, L. and Petra, S. and Storath, M. and Weinmann, A. Multi-Channel Potts-Based Reconstruction for Multi-Spectral Computed Tomography, Inverse Problems, 2021. [DOI]
• Plier, J. and Savarino, F. and Kočvara, M. and Petra, S. First-Order Geometric Multilevel Optimization for Discrete Tomography, International Conference on Scale Space and Variational Methods in Computer \dots, 2021. [DOI]
• Zeilmann, A. and Petra, S. and Schnörr, C. Learning Linear Assignment Flows for Image Labeling via Exponential Integration, International Conference on Scale Space and Variational Methods in Computer \dots, 2021. [DOI]
• Zisler, M. and Zern, A. and Boll, B. and Petra, S. and Schnörr, C. Unsupervised Data Labeling on Graphs by Self-assignment Flows, PAMM, 2021. [DOI]

2020

• Zeilmann, A. and Savarino, F. and Petra, S. and Schnörr, C. Geometric Numerical Integration of the Assignment Flow, Inverse Problems, 2020. [DOI]
• Zern, A. and Zisler, M. and Petra, S. and Schnörr, C. Unsupervised Assignment Flow: Label Learning on Feature Manifolds by Spatially Regularized Geometric Assignment, Journal of Mathematical Imaging and Vision, 2020. [DOI]
• Zisler, M. and Zern, A. and Petra, S. and Schnörr, C. Self-Assignment Flows for Unsupervised Data Labeling on Graphs, SIAM Journal on Imaging Sciences, 2020. [DOI]

2019

• Censor, Y. and Petra, S. and Schnörr, C. Superiorization vs. Accelerated Convex Optimization: The Superiorized/Regularized Least-Squares Case, arXiv preprint arXiv:1911., 2019. [DOI]
• Kiefer, L. and Petra, S. and Storath, M. and Weinmann, A. Direct MRI Segmentation from K-Space Data by Iterative Potts Minimization, Scale Space and Variational Methods in Computer Vision: 7th International \dots, 2019. [DOI]
• Kuske, J. and Petra, S. Performance Bounds for Co-/Sparse Box Constrained Signal Recovery, Analele ̧stiin\ţifice ale Universit ̆a\ci̧i" Ovidius" Constan\c, 2019. [DOI]
• Zeilmann, A. and Savarino, F. and Petra, S. and Schnörr, C. Exponential Integration of the Linear Assignment Flow, PAMM, 2019. [DOI]
• Zern, A. and Zisler, M. and Petra, S. and Schnörr, C. Spatially Regularized Geometric Assignment for Unsupervised Label Learning on Manifolds, PAMM, 2019. [DOI]
• Zern, A. and Zisler, M. and Åström, F. and Petra, S. and Schnörr, C. Unsupervised Label Learning on Manifolds by Spatially Regularized Geometric Assignment, Pattern Recognition: 40th German Conference, GCPR 2018, Stuttgart, Germany \dots, 2019. [DOI]
• Zisler, M. and Zern, A. and Petra, S. and Schnörr, C. Unsupervised Labeling by Geometric and Spatially Regularized Self-Assignment, Scale Space and Variational Methods in Computer Vision: 7th International \dots, 2019. [DOI]

2018

• Gibali, A. and Petra, S. DC-programming versus $\ell$-Superiorization for Discrete Tomography, Analele ̧stiin\ţifice ale Universit ̆a\ci̧i" Ovidius" Constan\c, 2018. [DOI]

2017

• Åström, F. and Petra, S. and Schmitzer, B. and Schnörr, C. Image Labeling by Assignment, Journal of Mathematical Imaging and Vision, 2017. [DOI]
• Bodnariuc, E. and Petra, S. and Schnörr, C. and Voorneveld, J. A Local Spatio-Temporal Approach to Plane Wave Ultrasound Particle Image Velocimetry, Pattern Recognition: 39th German Conference, GCPR 2017, Basel, Switzerland \dots, 2017. [DOI]
• Dalitz, R. and Petra, S. and Schnörr, C. Compressed Motion Sensing, Scale Space and Variational Methods in Computer Vision: 6th International \dots, 2017. [DOI]
• Kiefer, L. and Petra, S. Performance Bounds for Cosparse Multichannel Signal Recovery via Collaborative-TV, Scale Space and Variational Methods in Computer Vision: 6th International \dots, 2017. [DOI]
• Kuske, J. and Swoboda, P. and Petra, S. A Novel Convex Relaxation for Non-Binary Discrete Tomography, International Conference on Scale Space and Variational Methods in Computer \dots, 2017. [DOI]
• Petra, S. and Popa, C. Erratum to: Single Projection Kaczmarz Extended Algorithms., Numer. Algorithms, 2017. [DOI]
• Trajkovska, V. and Swoboda, P. and Åström, F. and Petra, S. Graphical Model Parameter Learning by Inverse Linear Programming, Scale Space and Variational Methods in Computer Vision: 6th International \dots, 2017. [DOI]
• Zisler, M. and Savarino, F. and Petra, S. and Schnörr, C. Gradient Flows on a Riemannian Submanifold for Discrete Tomography, Pattern Recognition: 39th German Conference, GCPR 2017, Basel, Switzerland \dots, 2017. [DOI]
• Zisler, M. and Åström, F. and Petra, S. and Schnörr, C. Image Reconstruction by Multilabel Propagation, Scale Space and Variational Methods in Computer Vision: 6th International \dots, 2017. [DOI]

2016

• Astrom, F. and Petra, S. and Schmitzer, B. and Schnorr, C. The Assignment Manifold: A Smooth Model for Image Labeling, Proceedings of the IEEE Conference on Computer Vision and Pattern \dots, 2016. [DOI]
• Åström, F. and Petra, S. and Schmitzer, B. and Schnörr, C. A Geometric Approach to Image Labeling, Computer Vision--ECCV 2016: 14th European Conference, Amsterdam, The \dots, 2016. [DOI]
• Bodnariuc, E. and Petra, S. and Poelma, C. and Schnörr, C. Parametric Dictionary-Based Velocimetry for Echo PIV, Pattern Recognition: 38th German Conference, GCPR 2016, Hannover, Germany \dots, 2016. [DOI]
• Bodnariuc, E. and Schiffner, M. and Petra, S. and Schnörr, C. Plane Wave Acoustic Superposition for Fast Ultrasound Imaging, 2016 IEEE International Ultrasonics Symposium (IUS), 2016. [DOI]
• Dalitz, R. and Bodnariuc, E. and Petra, S. and Schnorr, C. Compressed Motion Sensing for Tomographical Particle Image Velocimetry, 2016.
• Petra, S. and Popa, C. Single Projection Kaczmarz Extended Algorithms, Numerical Algorithms, 2016. [DOI]
• Zisler, M. and Petra, S. and Schnörr, C. and Schnörr, C. Discrete Tomography by Continuous Multilabeling Subject to Projection Constraints, Pattern Recognition: 38th German Conference, GCPR 2016, Hannover, Germany \dots, 2016. [DOI]
• Zisler, M. and Petra, S. and Schnörr, C. and Schnörr, C. Discrete Tomography by Continuous Multilabeling Subject to Projection Constraints Supplementary Material, 2016.
• Zisler, M. and Kappes, J. H. and Schnörr, C. and Petra, S. and Schnörr, C. Non-Binary Discrete Tomography by Continuous Non-Convex Optimization, IEEE Transactions on Computational Imaging, 2016. [DOI]

2015

• Becker, F. and Petra, S. and Schnörr, C. Optical Flow, Handbook of Mathematical Methods in Imaging, 2015. [DOI]
• Bodnariuc, E. and Gurung, A. and Petra, S. and Schnörr, C. Adaptive Dictionary-Based Spatio-Temporal Flow Estimation for Echo PIV, Energy Minimization Methods in Computer Vision and Pattern Recognition: 10th \dots, 2015. [DOI]
• Kappes, J. H. and Petra, S. and Schnörr, C. and Zisler, M. TomoGC: Binary Tomography by Constrained Graphcuts, Pattern Recognition: 37th German Conference, GCPR 2015, Aachen, Germany \dots, 2015. [DOI]
• Kappes, J. H. and Petra, S. and Schnörr, C. and Zisler, M. TomoGC: Binary Tomography by Constrained GraphCuts Supplementary Material, 2015.
• Lenzen, F. and Lellmann, J. and Becker, F. and Petra, S. and Schnörr, C. Adaptive Total Variation Regularization, Book of Abstracts-Extract, 2015.
• Petra, S. Randomized Sparse Block Kaczmarz as Randomized Dual Block-Coordinate Descent, Analele Universitatii" Ovidius" Constanta-Seria Matematica, 2015. [DOI]

2014

• Deniţiu, A. and Petra, S. and Schnörr, C. and Schnörr, C. An Entropic Perturbation Approach to TV-minimization for Limited-Data Tomography, Discrete Geometry for Computer Imagery: 18th IAPR International Conference \dots, 2014. [DOI]
• Deniţiu, A. and Petra, S. and Schnörr, C. and Schnörr, C. Phase Transitions and Cosparse Tomographic Recovery of Compound Solid Bodies from Few Projections, Fundamenta Informaticae 135 (1-2), 2014. [DOI]
• Petra, S. and Schnörr, C. Average Case Recovery Analysis of Tomographic Compressive Sensing, Linear Algebra and its Applications, 2014. [DOI]

2013

• Lenzen, F. and Becker, F. and Lellmann, J. and Petra, S. and Schnörr, C. A Class of Quasi-Variational Inequalities for Adaptive Image Denoising and Decomposition, Computational Optimization and Applications, 2013. [DOI]
• Petra, S. and Schnörr, C. and Becker, F. and Lenzen, F. B-SMART: Bregman-based First-Order Algorithms for Non-Negative Compressed Sensing Problems, Scale Space and Variational Methods in Computer Vision: 4th International \dots, 2013. [DOI]
• Petra, S. and Schnörr, C. and Schröder, A. Critical Parameter Values and Reconstruction Properties of Discrete Tomography: Application to Experimental Fluid Dynamics, Fundamenta Informaticae 125 (3-4), 2013. [DOI]

2012

• Becker, F. and Wieneke, B. and Petra, S. and Schroder, A. and Schnorr, C. Corrections to ``Variational Adaptive Correlation Method for Flow Estimation'', IEEE Transactions on Image Processing, 2012. [DOI]
• Becker, F. and Wieneke, B. and Petra, S. and Schroder, A. and Schnorr, C. Variational Adaptive Correlation Method for Flow Estimation, IEEE Transactions on Image Processing, 2012. [DOI]
• Becker, F. and Wieneke, B. and Petra, S. and Schroeder, A. and Schnoerr, C. Variational Adaptive Correlation Method for Flow Estimation (Vol 21, Pg 3053, 2012), IEEE TRANSACTIONS ON IMAGE PROCESSING, 2012. [DOI]
• Lenzen, F. and Becker, F. and Lellmann, J. and Petra, S. and Schnörr, C. Variational Image Denoising with Adaptive Constraint Sets, Scale Space and Variational Methods in Computer Vision: Third International \dots, 2012.
• Nicola, A. and Petra, S. and Popa, C. and Schnörr, C. A General Extending and Constraining Procedure for Linear Iterative Methods, International Journal of Computer Mathematics, 2012. [DOI]

2011

• Petra, S. and Schnörr, C. and Schröder, A. Reconstruction Properties of Sensing Matrices in Tomographic Particle Imaging Velocimetry, 2011.

2010

• Gesemann, S. and Schanz, D. and Schröder, A. and Petra, S. and Schnörr, C. Recasting Tomo-PIV Reconstruction as Constrained and L1-regularized Non-Linear Least Squares Problem, Symp, 2010.
• Petra, S. and Schnörr, C. TomoPIV Meets Compressed Sensing, AIP Conference Proceedings, 2010. [DOI]

2009

• Petra, S. and Schröder, A. and Schnörr, C. 3D Tomography from Few Projections in Experimental Fluid Dynamics, Imaging Measurement Methods for Flow Analysis, 2009. [DOI]
• Petra, S. and Popa, C. and Schnörr, C. Accelerating Constrained Sirtwith Applications in Tomographic Particle Image Reconstruction, 2009.

2008

• Petra, S. and Popa, C. and Schnörr, C. Enhancing Sparsity by Constraining Strategies: Constrained SIRT versus Spectral Projected Gradient Methods, 7 th Workshop on Modelling of Environmental and Life Sciences Problems (WMM \dots), 2008.
• Petra, S. and Popa, C. and Schnoerr, C. Extended and Constrained Cimmino-Type Algorithms with Applications in Tomographic Image Reconstruction, 2008.
• Petra, S. and Schröder, A. and Wieneke, B. and Schnörr, C. On Sparsity Maximization in Tomographic Particle Image Reconstruction, Joint Pattern Recognition Symposium, 2008. [DOI]

2007

• Kanzow, C. and Petra, S. Projected Filter Trust Region Methods for a Semismooth Least Squares Formulation of Mixed Complementarity Problems, Optimisation Methods and Software, 2007. [DOI]
• Petra, S. and Schnörr, C. and Schröder, A. and Wieneke, B. Tomographic Image Reconstruction in Experimental Fluid Dynamics: Synopsis and Problems, Mathematical Modelling of Environmental and Life Sciences Problems, 2007.

2006

• Petra, S. Semismooth Least Squares Methods for Complementarity Problems, Universität Ẅ̊zburg, 2006.

2005

• Kanzow, C. and Petra, S. LMMCP: A Levenberg-Maquardt Type MATLAB Solver for Mixed Complementarity Problems, 2005.

2004

• Kanzow, C. and Petra, S. On a Semismooth Least Squares Formulation of Complementarity Problems with Gap Reduction, Optimization Methods and Software, 2004. [DOI]