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We investigate iterative methods with randomized preconditioners for solving overdetermined least-squares problems, where the preconditioners are based on a random embedding of the data matrix. We consider two distinct approaches: the…

Numerical Analysis · Mathematics 2021-04-15 Jonathan Lacotte , Mert Pilanci

Reverse engineering 3D computer-aided design (CAD) models from images is an important task for many downstream applications including interactive editing, manufacturing, architecture, robotics, etc. The difficulty of the task lies in vast…

Computer Vision and Pattern Recognition · Computer Science 2025-09-22 Yang You , Mikaela Angelina Uy , Jiaqi Han , Rahul Thomas , Haotong Zhang , Yi Du , Hansheng Chen , Francis Engelmann , Suya You , Leonidas Guibas

Most existing learning-based methods for solving imaging inverse problems can be roughly divided into two classes: iterative algorithms, such as plug-and-play and diffusion methods leveraging pretrained denoisers, and unrolled architectures…

Image and Video Processing · Electrical Eng. & Systems 2026-03-31 Matthieu Terris , Samuel Hurault , Maxime Song , Julian Tachella

Phase retrieval, a nonlinear problem prevalent in imaging applications, has been extensively studied using random models, some of which with i.i.d. sensing matrix components. While these models offer robust reconstruction guarantees, they…

Optics · Physics 2024-09-10 Zhiyuan Hu , Julián Tachella , Michael Unser , Jonathan Dong

Constructing fast samplers for unconditional diffusion and flow-matching models has received much attention recently; however, existing methods for solving inverse problems, such as super-resolution, inpainting, or deblurring, still require…

Computer Vision and Pattern Recognition · Computer Science 2024-11-04 Kushagra Pandey , Ruihan Yang , Stephan Mandt

This paper introduces the Nystr\"om PCG algorithm for solving a symmetric positive-definite linear system. The algorithm applies the randomized Nystr\"om method to form a low-rank approximation of the matrix, which leads to an efficient…

Numerical Analysis · Mathematics 2021-12-20 Zachary Frangella , Joel A. Tropp , Madeleine Udell

Pre-conditioning is a well-known concept that can significantly improve the convergence of optimization algorithms. For noise-free problems, where good pre-conditioners are not known a priori, iterative linear algebra methods offer one way…

Machine Learning · Computer Science 2019-02-21 Filip de Roos , Philipp Hennig

In ultrasound tomography, the speed of sound inside an object is estimated based on acoustic measurements carried out by sensors surrounding the object. An accurate forward model is a prominent factor for high-quality image reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2021-11-24 Janne Koponen , Timo Lähivaara , Jari Kaipio , Marko Vauhkonen

Performing magnetic resonance imaging (MRI) reconstruction from under-sampled k-space data can accelerate the procedure to acquire MRI scans and reduce patients' discomfort. The reconstruction problem is usually formulated as a denoising…

Image and Video Processing · Electrical Eng. & Systems 2023-12-11 Tianqi Xiang , Wenjun Yue , Yiqun Lin , Jiewen Yang , Zhenkun Wang , Xiaomeng Li

We present a method that accelerates reconstruction of 3D scenes and objects, aiming to enable instant reconstruction on edge devices such as mobile phones and AR/VR headsets. While recent works have accelerated scene reconstruction…

Computer Vision and Pattern Recognition · Computer Science 2025-03-31 Chaojian Li , Bichen Wu , Albert Pumarola , Peizhao Zhang , Yingyan Celine Lin , Peter Vajda

We consider the minimization problem with the truncated quadratic regularization with gradient operator, which is a nonsmooth and nonconvex problem. We cooperated the classical preconditioned iterations for linear equations into the…

Optimization and Control · Mathematics 2021-05-04 Shengxiang Deng , Hongpeng Sun

In recent years, diffusion models have gained popularity for their ability to generate higher-quality images in comparison to GAN models. However, like any other large generative models, these models require a huge amount of data,…

Computer Vision and Pattern Recognition · Computer Science 2023-12-21 Rajesh Shrestha , Bowen Xie

This paper presents a GPU-accelerated computational framework for reconstructing high resolution (HR) LF images under a mixed Gaussian-Impulse noise condition. The main focus is on developing a high-performance approach considering…

Image and Video Processing · Electrical Eng. & Systems 2022-06-13 Trung-Hieu Tran , Kaicong Sun , Sven Simon

We present a new approach for nonlocal image denoising, based around the application of an unnormalized extended Gaussian ANOVA kernel within a bilevel optimization algorithm. A critical bottleneck when solving such problems for…

Numerical Analysis · Mathematics 2025-05-14 Andrés Miniguano-Trujillo , John W. Pearson , Benjamin D. Goddard

We describe and examine an algorithm for tomographic image reconstruction where prior knowledge about the solution is available in the form of training images. We first construct a nonnegative dictionary based on prototype elements from the…

Computer Vision and Pattern Recognition · Computer Science 2015-08-18 Sara Soltani , Martin S. Andersen , Per Christian Hansen

Large denoising diffusion models, such as Stable Diffusion, have been trained on billions of image-caption pairs to perform text-conditioned image generation. As a byproduct of this training, these models have acquired general knowledge…

Computer Vision and Pattern Recognition · Computer Science 2025-10-07 Alexandros Graikos , Nebojsa Jojic , Dimitris Samaras

Image Super-Resolution (ISR) has seen significant progress with the introduction of remarkable generative models. However, challenges such as the trade-off issues between fidelity and realism, as well as computational complexity, have also…

Computer Vision and Pattern Recognition · Computer Science 2025-02-03 Yunpeng Qu , Kun Yuan , Jinhua Hao , Kai Zhao , Qizhi Xie , Ming Sun , Chao Zhou

In this paper, we address the efficient numerical solution of linear and quadratic programming problems, often of large scale. With this aim, we devise an infeasible interior point method, blended with the proximal method of multipliers,…

Numerical Analysis · Mathematics 2021-01-18 Luca Bergamaschi , Jacek Gondzio , Ángeles Martínez , John W. Pearson , Spyridon Pougkakiotis

The integration of surface normals for the purpose of computing the shape of a surface in 3D space is a classic problem in computer vision. However, even nowadays it is still a challenging task to devise a method that combines the…

Numerical Analysis · Computer Science 2016-10-20 Martin Bähr , Michael Breuß , Yvain Quéau , Ali Sharifi Boroujerdi , Jean-Denis Durou

In this paper, we further investigate and refine the subspace-constrained preconditioning technique to enhance the theoretical and numerical convergence properties of randomized iterative methods for solving linear systems. In particular,…

Numerical Analysis · Mathematics 2026-05-29 Yonghan Sun , Hou-Duo Qi , Deren Han , Jiaxin Xie