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Image restoration is typically addressed through non-convex inverse problems, which are often solved using first-order block-wise splitting methods. In this paper, we consider a general type of non-convex optimisation model that captures…

For lossy image compression systems, we develop an algorithm, iterative refinement, to improve the decoder's reconstruction compared to standard decoding techniques. Specifically, we propose a recurrent neural network approach for…

Computer Vision and Pattern Recognition · Computer Science 2018-11-13 Alexander G. Ororbia , Ankur Mali , Jian Wu , Scott O'Connell , David Miller , C. Lee Giles

We consider the problem of blind ptychography, that is the joint estimation of an unknown object and an illumination function from diffraction intensity measurements. In ptychography, diffraction measurements from neighboring regions of the…

Optimization and Control · Mathematics 2016-02-04 Stefano Marchesini , Hau-Tieng Wu

We derive a computable a posteriori error estimator for the $\alpha$-harmonic extension problem, which localizes the fractional powers of elliptic operators supplemented with Dirichlet boundary conditions. Our a posteriori error estimator…

Numerical Analysis · Mathematics 2015-05-20 Long Chen , Ricardo H. Nochetto , Enrique Otárola , Abner J. Salgado

In this article we consider the problem of finding the visibility set from a given point when the obstacles are represented as the level set of a given function. Although the visibility set can be computed efficiently by ray tracing, there…

Analysis of PDEs · Mathematics 2019-08-05 Adam Oberman , Tiago Salvador

Increasing the layer number of on-chip photonic neural networks (PNNs) is essential to improve its model performance. However, the successively cascading of network hidden layers results in larger integrated photonic chip areas. To address…

Machine Learning · Computer Science 2023-02-08 Yun Zhao , Hang Chen , Min Lin , Haiou Zhang , Tao Yan , Xing Lin , Ruqi Huang , Qionghai Dai

We present and mathematically analyze an online adjoint algorithm for the optimization of partial differential equations (PDEs). Traditional adjoint algorithms would typically solve a new adjoint PDE at each optimization iteration, which…

Optimization and Control · Mathematics 2022-01-27 Justin Sirignano , Konstantinos Spiliopoulos

The task of simultaneously reconstructing multiple physical coefficients in partial differential equations (PDEs) from observed data is ubiquitous in applications. In this work, we propose an integrated data-driven and model-based iterative…

Numerical Analysis · Mathematics 2025-07-04 Kui Ren , Lu Zhang

PDE learning is an emerging field that combines physics and machine learning to recover unknown physical systems from experimental data. While deep learning models traditionally require copious amounts of training data, recent PDE learning…

Machine Learning · Computer Science 2023-09-20 Nicolas Boullé , Diana Halikias , Alex Townsend

Dehazing is in the image processing and computer vision communities, the task of enhancing the image taken in foggy conditions. To better understand this type of algorithm, we present in this document a dehazing method which is suitable for…

Computer Vision and Pattern Recognition · Computer Science 2020-06-02 Bangyong Sun , Vincent Whannou de Dravo , Zhe Yu

We study the numerical approximation of a class of degenerate parabolic stochastic partial differential equations on non-compact metric graphs, which naturally arise in the asymptotic analysis of Hamiltonian flows under small noise…

Numerical Analysis · Mathematics 2026-04-14 Jianbo Cui , Mihály Kovács , Derui Sheng

Optical flow is the pattern of apparent motion of objects in a scene. The computation of optical flow is a critical component in numerous computer vision tasks such as object detection, visual object tracking, and activity recognition.…

Signal Processing · Electrical Eng. & Systems 2024-01-15 Muhammad Wasim Nawaz , Abdesselam Bouzerdoum , Muhammad Mahboob Ur Rahman , Ghulam Abbas , Faizan Rashid

Ill-posed linear inverse problems (ILIP), such as restoration and reconstruction, are a core topic of signal/image processing. A standard approach to deal with ILIP uses a constrained optimization problem, where a regularization function is…

Optimization and Control · Mathematics 2016-11-15 Manya V. Afonso , Jose M. Bioucas-Dias , Mario A. T. Figueiredo

The purpose of this paper is to propose a semi-analytical technique convenient for numerical approximation of solutions of the initial value problem for $p$-dimensional delayed and neutral differential systems with constant, proportional…

Classical Analysis and ODEs · Mathematics 2019-01-29 Josef Rebenda , Zdeněk Šmarda

A method of representation of a solution as segments of the series in powers of the step of the independent variable is expanded for solving complex systems of ordinary differential equations (ODE): the Lorenz system and other systems. A…

Numerical Analysis · Computer Science 2014-05-26 Vladimir Aristov , Andrey Stroganov

Nonlocally related partial differential equation (PDE) systems are useful in the analysis of a given PDE system. It is known that each local conservation law of a given PDE system systematically yields a nonlocally related system. In this…

Mathematical Physics · Physics 2015-06-12 George W. Bluman , Zhengzheng Yang

Various research studies indicate that action recognition performance highly depends on the types of motions being extracted and how accurate the human actions are represented. In this paper, we investigate different optical flow, and…

Computer Vision and Pattern Recognition · Computer Science 2023-12-19 Lei Wang , Piotr Koniusz

Stochastic simulation methods can be applied successfully to model exact spatio-temporally resolved reaction-diffusion systems. However, in many cases, these methods can quickly become extremely computationally intensive with increasing…

Quantitative Methods · Quantitative Biology 2016-04-29 Jonathan U. Harrison , Christian A. Yates

We develop a framework for estimating unknown partial differential equations from noisy data, using a deep learning approach. Given noisy samples of a solution to an unknown PDE, our method interpolates the samples using a neural network,…

Machine Learning · Computer Science 2019-10-24 Ali Hasan , João M. Pereira , Robert Ravier , Sina Farsiu , Vahid Tarokh

This paper concerns an optimization algorithm for unconstrained non-convex problems where the objective function has sparse connections between the unknowns. The algorithm is based on applying a dissipation preserving numerical integrator,…

Optimization and Control · Mathematics 2018-09-26 Torbjørn Ringholm , Jasmina Lazić , Carola-Bibiane Schönlieb