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Multiphysics problems such as multicomponent diffusion, phase transformations in multiphase systems and alloy solidification involve numerical solution of a coupled system of nonlinear partial differential equations (PDEs). Numerical…

Materials Science · Physics 2022-11-24 Vir Karan , A. Maruthi Indresh , Saswata Bhattacharyya

This paper reported a general noninterferometric high-accuracy quantitative phase imaging (QPI) method for arbitrary complex valued objects. Given by a typical 4f optical configuration as the imaging system, three frames of small-window…

Image and Video Processing · Electrical Eng. & Systems 2021-05-05 Jianhui Huang , An Pan , Huiliang Jin , Guoxiang Meng , Qian Ye

Moving horizon estimation (MHE) is a widely studied state estimation approach in several practical applications. In the MHE problem, the state estimates are obtained via the solution of an approximated nonlinear optimization problem.…

Optimization and Control · Mathematics 2023-06-26 Tianchen Liu , Kushal Chakrabarti , Nikhil Chopra

Phase retrieval is the problem of reconstructing images from magnitude-only measurements. In many real-world applications the problem is underdetermined. When training data is available, generative models allow optimization in a…

Machine Learning · Computer Science 2023-01-20 Tobias Uelwer , Sebastian Konietzny , Stefan Harmeling

We study an approach to solving the phase retrieval problem as it arises in a phase-less imaging modality known as ptychography. In ptychography, small overlapping sections of an unknown sample (or signal, say $x_0\in \mathbb{C}^d$) are…

Numerical Analysis · Mathematics 2019-10-09 Brian Preskitt , Rayan Saab

Diffusion models have shown remarkable flexibility for solving inverse problems without task-specific retraining. However, existing approaches such as Manifold Preserving Guided Diffusion (MPGD) apply only a single gradient update per…

Computer Vision and Pattern Recognition · Computer Science 2025-06-10 Aditya Chakravarty

Iterative algorithms with feedback are amongst the most powerful and versatile optimization methods for phase retrieval. Among these, the hybrid input-output algorithm has demonstrated practical solutions to giga-element nonlinear phase…

Optics · Physics 2007-11-13 S. Marchesini

Ptychography is a promising phase retrieval technique for label-free quantitative phase imaging. Recent advances in phase retrieval algorithms witnessed the development of spectral methods, in order to accelerate gradient descent…

Optics · Physics 2021-04-07 Lorenzo Valzania , Jonathan Dong , Sylvain Gigan

Ptychography, a special case of the phase retrieval problem, is a popular method in modern imaging. Its measurements are based on the shifts of a locally supported window function. In general, direct recovery of an object from such…

Numerical Analysis · Mathematics 2020-10-28 Anton Forstner , Felix Krahmer , Oleh Melnyk , Nada Sissouno

Multislice electron ptychography (MEP) is an inverse imaging technique that computationally reconstructs the highest-resolution images of atomic crystal structures from diffraction patterns. Available algorithms often solve this inverse…

Image and Video Processing · Electrical Eng. & Systems 2025-07-28 Christian K. Belardi , Chia-Hao Lee , Yingheng Wang , Justin Lovelace , Kilian Q. Weinberger , David A. Muller , Carla P. Gomes

High-quality panoramic images with a Field of View (FoV) of 360{\deg} are essential for contemporary panoramic computer vision tasks. However, conventional imaging systems come with sophisticated lens designs and heavy optical components.…

Computer Vision and Pattern Recognition · Computer Science 2024-07-08 Qi Jiang , Shaohua Gao , Yao Gao , Kailun Yang , Zhonghua Yi , Hao Shi , Lei Sun , Kaiwei Wang

Modeling physical phenomena like heat transport and diffusion is crucially dependent on the numerical solution of partial differential equations (PDEs). A PDE solver finds the solution given coefficients and a boundary condition, whereas an…

Graphics · Computer Science 2022-08-04 Ekrem Fatih Yılmazer , Delio Vicini , Wenzel Jakob

Image segmentation is an important median level vision topic. Accurate and efficient multiphase segmentation for images with intensity inhomogeneity is still a great challenge. We present a new two-stage multiphase segmentation method…

Optimization and Control · Mathematics 2020-09-15 Xueyan Guo , Yunhua Xue , Chunlin Wu

We propose a path cover adaptive algebraic multigrid (PC-$\alpha$AMG) method for solving linear systems of weighted graph Laplacians and can also be applied to discretized second order elliptic partial differential equations. The…

Numerical Analysis · Mathematics 2018-06-20 Xiaozhe Hu , Junyuan Lin , Ludmil T. Zikatanov

In this work, we develop algebraic solvers for linear systems arising from the discretization of second-order elliptic partial differential equations by saddle-point mixed finite element methods of arbitrary polynomial degree $p \ge 0$ on…

Numerical Analysis · Mathematics 2026-02-03 Ani Miraçi , Jan Papež , Martin Vohralík , Ivan Yotov

Standard gradient-based iteration algorithms for optimization, such as gradient descent and its various proximal-based extensions to nonsmooth problems, are known to converge slowly for ill-conditioned problems, sometimes requiring many…

Numerical Analysis · Mathematics 2026-03-24 G. H. M. Araújo , O. A. Krzysik , H. De Sterck

Model-based learned iterative reconstruction methods have recently been shown to outperform classical reconstruction algorithms. Applicability of these methods to large scale inverse problems is however limited by the available memory for…

Image and Video Processing · Electrical Eng. & Systems 2020-04-21 Andreas Hauptmann , Jonas Adler , Simon Arridge , Ozan Öktem

We present a simple but efficient and robust reconstruction algorithm for Fourier ptychographic microscopy, termed error-laxity Fourier ptychographic iterative engine (Elfpie), that is simultaneously robust to (1) noise signal (including…

Complex Variables · Mathematics 2022-09-30 Shuhe Zhang , Tos T. J. M. Berendschot , Jinhua Zhou

Ptychography is an emerging imaging technique that is able to provide wavelength-limited spatial resolution from specimen with extended lateral dimensions. As a scanning microscopy method, a typical two-dimensional image requires a number…

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