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Reconstruction of endoscopic scenes is an important asset for various medical applications, from post-surgery analysis to educational training. Neural rendering has recently shown promising results in endoscopic reconstruction with…

Computer Vision and Pattern Recognition · Computer Science 2024-03-20 Florian Philipp Stilz , Mert Asim Karaoglu , Felix Tristram , Nassir Navab , Benjamin Busam , Alexander Ladikos

Consider the task of estimating a 3-order $n \times n \times n$ tensor from noisy observations of randomly chosen entries in the sparse regime. We introduce a similarity based collaborative filtering algorithm for estimating a tensor from…

Machine Learning · Computer Science 2023-01-18 Devavrat Shah , Christina Lee Yu

Density reconstruction from X-ray projections is an important problem in radiography with key applications in scientific and industrial X-ray computed tomography (CT). Often, such projections are corrupted by unknown sources of noise and…

Image and Video Processing · Electrical Eng. & Systems 2026-02-26 Siddhant Gautam , Marc L. Klasky , Balasubramanya T. Nadiga , Trevor Wilcox , Gary Salazar , Saiprasad Ravishankar

Phase retrieval algorithms have become an important component in many modern computational imaging systems. For instance, in the context of ptychography and speckle correlation imaging, they enable imaging past the diffraction limit and…

Machine Learning · Statistics 2018-07-03 Christopher A. Metzler , Philip Schniter , Ashok Veeraraghavan , Richard G. Baraniuk

We study a regularization framework that combines a convex fidelity term with multiple $\ell_1$-based regularizers, each linked to a distinct linear transform. This multi-penalty model enhances flexibility in promoting structured sparsity.…

Numerical Analysis · Mathematics 2026-02-02 Qianru Liu , Rui Wang , Yuesheng Xu

In this paper we present a general convex optimization approach for solving high-dimensional multiple response tensor regression problems under low-dimensional structural assumptions. We consider using convex and weakly decomposable…

Statistics Theory · Mathematics 2017-04-17 Garvesh Raskutti , Ming Yuan , Han Chen

In this work, we propose a new paradigm of iterative model-based reconstruction algorithms for providing real-time solution for zooming-in and refining a region of interest in medical and clinical tomographic images. This algorithmic…

Image and Video Processing · Electrical Eng. & Systems 2025-12-01 Junqi Tang , Guixian Xu , Jinglai Li

In this letter, we address sparse signal recovery using spike and slab priors. In particular, we focus on a Bayesian framework where sparsity is enforced on reconstruction coefficients via probabilistic priors. The optimization resulting…

Machine Learning · Statistics 2015-05-28 Hojjat S. Mousavi , Vishal Monga , Trac D. Tran

X-ray Ptychography is an advanced computational microscopy technique which is delivering exceptionally detailed quantitative imaging of biological and nanotechnology specimens. However coarse parametrisation in propagation distance,…

Image and Video Processing · Electrical Eng. & Systems 2021-10-20 Francesco Guzzi , George Kourousias , Fulvio Billè , Roberto Pugliese , Alessandra Gianoncelli , Sergio Carrato

Flexible sparsity regularization means stably approximating sparse solutions of operator equations by using coefficient-dependent penalizations. We propose and analyse a general nonconvex approach in this respect, from both theoretical and…

Optimization and Control · Mathematics 2021-11-12 Daria Ghilli , Dirk A. Lorenz , Elena Resmerita

The need for fast sparse optimization is emerging, e.g., to deal with large-dimensional data-driven problems and to track time-varying systems. In the framework of linear sparse optimization, the iterative shrinkage-thresholding algorithm…

Optimization and Control · Mathematics 2025-01-22 Vito Cerone , Sophie M. Fosson , Diego Regruto

In this paper we develop proximal methods for statistical learning. Proximal point algorithms are useful in statistics and machine learning for obtaining optimization solutions for composite functions. Our approach exploits closed-form…

Machine Learning · Statistics 2015-06-02 Nicholas G. Polson , James G. Scott , Brandon T. Willard

Total variation (TV) regularization is a popular reconstruction method for ill-posed imaging problems, and particularly useful for applications with piecewise constant targets. However, using TV for medical cone-beam computed X-ray…

Medical Physics · Physics 2024-12-11 Alexander Meaney , Mikael A. K. Brix , Miika T. Nieminen , Samuli Siltanen

Sparse coding and dictionary learning are popular techniques for linear inverse problems such as denoising or inpainting. However in many cases, the measurement process is nonlinear, for example for clipped, quantized or 1-bit measurements.…

Signal Processing · Electrical Eng. & Systems 2020-01-08 Lucas Rencker , Francis Bach , Wenwu Wang , Mark D. Plumbley

In ground based infrared imaging a well-known technique to reduce the influence of thermal and background noise is chopping and nodding, where four different signals of the same object are recorded from which the object is reconstructed…

Astrophysics · Physics 2009-11-11 Frank Lenzen , Otmar Scherzer , Sabine Schindler

Convolutional Neural Networks (CNN) based image reconstruction methods have been intensely used for X-ray computed tomography (CT) reconstruction applications. Despite great success, good performance of this data-based approach critically…

Computer Vision and Pattern Recognition · Computer Science 2019-01-31 Ziling Wu , Abdulaziz Alorf , Ting Yang , Ling Li , Yunhui Zhu

Image reconstruction in X-ray tomography is an ill-posed inverse problem, particularly with limited available data. Regularization is thus essential, but its effectiveness hinges on the choice of a regularization parameter that balances…

Computer Vision and Pattern Recognition · Computer Science 2026-02-11 Chuyang Wu , Samuli Siltanen

The earlier works in the context of low-rank-sparse-decomposition (LRSD)-driven stationary synthetic aperture radar (SAR) imaging have shown significant improvement in the reconstruction-decomposition process. Neither of the proposed…

Image and Video Processing · Electrical Eng. & Systems 2025-12-12 Hamid Reza Hashempour , Majid Moradikia , Hamed Bastami , Ahmed Abdelhadi , Mojtaba Soltanalian

Electron ptychography enables dose-efficient atomic-resolution imaging, but conventional reconstruction algorithms suffer from noise sensitivity, slow convergence, and extensive manual hyperparameter tuning for regularization, especially in…

Image and Video Processing · Electrical Eng. & Systems 2025-11-12 Arthur R. C. McCray , Stephanie M. Ribet , Georgios Varnavides , Colin Ophus

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…