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The Event Horizon Telescope (EHT) provides a unique opportunity to probe the physics of supermassive black holes through Very Large Baseline Interferometry (VLBI), such as the existence of the event horizon, the accretion processes as well…

High Energy Astrophysical Phenomena · Physics 2018-12-12 Bidisha Bandyopadhyay , Dominik R. G. Schleicher , Neil Nagar , Fu-Guo Xie , Venkatessh Ramakrishnan

We consider efficient methods for computing solutions to dynamic inverse problems, where both the quantities of interest and the forward operator (measurement process) may change at different time instances but we want to solve for all the…

Numerical Analysis · Mathematics 2021-07-14 Mirjeta Pasha , Arvind K. Saibaba , Silvia Gazzola , Malena I. Espanol , Eric de Sturler

As the realm of spectral imaging applications extends its reach into the domains of mobile technology and augmented reality, the demands for compact yet high-fidelity systems become increasingly pronounced. Conventional methodologies,…

Very long baseline interferometry (VLBI) provides the highest-resolution images in astronomy. The sharpest resolution is nominally achieved at the highest frequencies, but as the observing frequency increases so too does the atmospheric…

Stokes polarimetry (SP) is a powerful technique that enables spatial reconstruction of the state of polarization (SoP) of a light beam using only intensity measurements. A given SoP is reconstructed from a set of four Stokes parameters,…

The hybrid opto-electronic correlator (HOC) architecture has been shown to be able to detect matches in a shift, scale, and rotation invariant (SSRI) manner by incorporating a polar Mellin transform (PMT) pre-processing step. Here we…

Optics · Physics 2022-11-09 Julian Gamboa , Xi Shen , Tabassom Hamidfar , Selim M. Shahriar

A polarization camera has great potential for 3D reconstruction since the angle of polarization (AoP) and the degree of polarization (DoP) of reflected light are related to an object's surface normal. In this paper, we propose a novel 3D…

Computer Vision and Pattern Recognition · Computer Science 2022-12-27 Jinyu Zhao , Yusuke Monno , Masatoshi Okutomi

Many practical imaging systems suffer from uncertainty in acquisition geometry -- such as projection angles in computed tomography or sensor positions in photoacoustic tomography -- leading to nonlinear inverse problems that require joint…

Numerical Analysis · Mathematics 2026-05-08 Toluwani Okunola , Mirjeta Pasha , Misha E. Kilmer , James G. Nagy , Eric de Sturler

We investigate Hermite Gaussian Imaging (HGI) -- a novel passive super-resolution technique -- for complex 2D incoherent objects in the sub-Rayleigh regime. The method consists of measuring the field's spatial mode components in the image…

Optics · Physics 2023-09-20 Jernej Frank , Alexander Duplinskiy , Kaden Bearne , A. I. Lvovsky

Due to numerous hardware shortcomings, medical image acquisition devices are susceptible to producing low-quality (i.e., low contrast, inappropriate brightness, noisy, etc.) images. Regrettably, perceptually degraded images directly impact…

Image and Video Processing · Electrical Eng. & Systems 2025-03-12 S M A Sharif , Rizwan Ali Naqvi , Mithun Biswas , Woong-Kee Loh

We present a novel self-supervised algorithm named MotionHint for monocular visual odometry (VO) that takes motion constraints into account. A key aspect of our approach is to use an appropriate motion model that can help existing…

Computer Vision and Pattern Recognition · Computer Science 2026-02-20 Cong Wang , Yu-Ping Wang , Dinesh Manocha

Homography estimation is erroneous in the case of large-baseline due to the low image overlay and limited receptive field. To address it, we propose a progressive estimation strategy by converting large-baseline homography into multiple…

Computer Vision and Pattern Recognition · Computer Science 2022-12-07 Hai Jiang , Haipeng Li , Yuhang Lu , Songchen Han , Shuaicheng Liu

Interferometers, such as the Event Horizon Telescope (EHT), do not directly observe the images of sources but rather measure their Fourier components at discrete spatial frequencies up to a maximum value set by the longest baseline in the…

High Energy Astrophysical Phenomena · Physics 2020-04-15 Dimitrios Psaltis , Lia Medeiros , Tod R. Lauer , Chi-Kwan Chan , Feryal Ozel

In Evans function computations of the spectra of asymptotically constant-coefficient linear operators, a basic issue is the efficient and numerically stable computation of subspaces evolving according to the associated eigenvalue ODE. For…

Numerical Analysis · Mathematics 2017-06-12 Jeffrey Humpherys , Kevin Zumbrun

A range of nonlinear image reconstruction procedures based on extremizing the generalized Shannon entropy, Kullback-Leibler cross-entropy and Renyi information measures and proposed by the author in early papers is presented. The…

Astrophysics · Physics 2007-05-23 Anisa T. Bajkova

We investigate both the theoretical and algorithmic aspects of likelihood-based methods for recovering a complex-valued signal from multiple sets of measurements, referred to as looks, affected by speckle (multiplicative) noise. Our…

Information Theory · Computer Science 2024-02-27 Xi Chen , Zhewen Hou , Christopher A. Metzler , Arian Maleki , Shirin Jalali

High-frequency very-long-baseline interferometry (VLBI) observations can now resolve the horizon-scale emission from sources in the immediate vicinity of nearby supermassive black holes. Future space-VLBI observations will access highly…

High Energy Astrophysical Phenomena · Physics 2022-12-07 Frederic H. Vincent , Samuel E. Gralla , Alexandru Lupsasca , Maciek Wielgus

Histologic examination plays a crucial role in oncology research and diagnostics. The adoption of digital scanning of whole slide images (WSI) has created an opportunity to leverage deep learning-based image classification methods to…

Computer Vision and Pattern Recognition · Computer Science 2024-01-23 Md Zahangir Alom , Quynh T. Tran , Brent A. Orr

The VLTI Spectro Imager (VSI) was proposed as a second-generation instrument of the Very Large Telescope Interferometer providing the ESO community with spectrally-resolved, near-infrared images at angular resolutions down to 1.1…

We propose the application of multiresolution transforms, such as wavelets (WT) and curvelets (CT), to the reconstruction of images of extended objects that have been acquired with adaptive optics (AO) systems. Such multichannel approaches…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Roberto Baena Gallé , Jorge Núñez , Szymon Gladysz