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Atmospheric Turbulence (AT) correction is a challenging restoration task as it consists of two distortions: geometric distortion and spatially variant blur. Diffusion models have shown impressive accomplishments in photo-realistic image…

Computer Vision and Pattern Recognition · Computer Science 2023-07-28 Xijun Wang , Santiago López-Tapia , Aggelos K. Katsaggelos

An iterative algorithm is adopted to construct approximate representations of matrices describing the scattering properties of arbitrary objects. The method is based on the implicit evaluation of scattering responses from iteratively…

Computational Physics · Physics 2023-04-19 Johan Lundgren , Kurt Schab , Miloslav Capek , Mats Gustafsson , Lukas Jelinek

In the ELTs era, where the need for versatile and innovative solutions to produce very high spatial resolution images has become a major issue, the search of synergies with other science fields seems a logic step. One of the considered…

Instrumentation and Methods for Astrophysics · Physics 2018-11-15 E. Quevedo , S. Velasco , C. Colodro-Conde , G. Rodríguez-Coira , A. Oscoz , R. L. López , J. Font , J. H. Brito , O. Llinas , S. Robaina , G. M. Callico , R. Sarmiento , R. Rebolo

We find that the EPE evaluation metrics of RAFT-stereo converge inconsistently in the low and high frequency regions, resulting high frequency degradation (e.g., edges and thin objects) during the iterative process. The underlying reason…

Computer Vision and Pattern Recognition · Computer Science 2025-05-26 Xiaobao Wei , Jiawei Liu , Dongbo Yang , Junda Cheng , Changyong Shu , Wei Wang

Deep learning-based image enhancement methods face a fundamental trade-off between computational efficiency and representational capacity. For example, although a conventional three-dimensional Look-Up Table (3D LUT) can process a degraded…

Computer Vision and Pattern Recognition · Computer Science 2025-09-30 Liubing Hu , Chen Wu , Anrui Wang , Dianjie Lu , Guijuan Zhang , Zhuoran Zheng

Adaptive optics systems are essential on all large telescopes where image quality is important. These are complex systems with many design parameters requiring optimisation before good performance can be achieved. The simulation of adaptive…

Astrophysics · Physics 2007-05-23 Alastair Basden , Timothy Butterley , Richard Myers , Richard Wilson

Iterative projection algorithms are successfully being used as a substitute of lenses to recombine, numerically rather than optically, light scattered by illuminated objects. Images obtained computationally allow aberration-free…

Optics · Physics 2007-05-23 S. Marchesini

The efficiency of the management of top-class ground-based astronomical facilities supported by Adaptive Optics (AO) relies on our ability to forecast the optical turbulence (OT) and a set of relevant atmospheric parameters. Indeed, in…

Instrumentation and Methods for Astrophysics · Physics 2020-06-14 E. Masciadri , G. Martelloni , A. Turchi

Several Wide Field of view Adaptive Optics (WFAO) concepts like Multi-Conjugate AO (MCAO), Multi-Object AO (MOAO) or Ground-Layer AO (GLAO) are currently studied for the next generation of Extremely Large Telescopes (ELTs). All these…

Astrophysics · Physics 2009-11-13 B. Neichel , T. Fusco , J. -M. Conan

We introduce a new efficient algorithm for Helmholtz problems in perforated domains with the design of the scheme allowing for possibly large wavenumbers. Our method is based upon the Wavelet-based Edge Multiscale Finite Element Method…

Numerical Analysis · Mathematics 2019-06-21 Shubin Fu , Guanglian Li , Richard Craster , Sebastien Guenneau

Restoring images distorted by atmospheric turbulence is a ubiquitous problem in long-range imaging applications. While existing deep-learning-based methods have demonstrated promising results in specific testing conditions, they suffer from…

Image and Video Processing · Electrical Eng. & Systems 2023-12-12 Xingguang Zhang , Zhiyuan Mao , Nicholas Chimitt , Stanley H. Chan

Electrical capacitance tomography (ECT) has been investigated in many fields due to its advantages of being non-invasive and low cost. Sparse algorithms with l1-norm regularization are used to reduce the smoothing effect and obtain sharp…

Signal Processing · Electrical Eng. & Systems 2017-11-08 Jiaoxuan Chen , Maomao Zhang , Yi Li

This paper describes a new method for mitigating the effects of atmospheric distortion on observed sequences that include large moving objects. In order to provide accurate detail from objects behind the distorting layer, we solve the…

Computer Vision and Pattern Recognition · Computer Science 2018-08-13 N. Anantrasirichai , Alin Achim , David Bull

To derive the convergence field from the gravitational shear (gamma) of the background galaxy images, the classical methods require a convolution of the shear to be performed over the entire sky, usually expressed thanks to the Fast Fourier…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 E. Deriaz , J. -L. Starck , S. Pires

We describe an important addition to the parallel implementation of our generalized NLTE stellar atmosphere and radiative transfer computer program PHOENIX. In a previous paper in this series we described data and task parallel algorithms…

Astrophysics · Physics 2009-10-30 E. Baron , Peter H. Hauschildt

An extremely fast time-harmonic finite element solver developed for the transmission analysis of photonic crystals was applied to mask simulation problems. The applicability was proven by examining a set of typical problems and by a…

Optics · Physics 2009-05-28 S. Burger , R. Köhle , L. Zschiedrich , W. Gao , F. Schmidt , R. März , C. Nölscher

This paper presents a detailed evaluation of the envelope-tracking adaptive integral method (ET-AIM), an FFT-accelerated algorithm for analyzing electromagnetic scattering. ET-AIM is used to solve progressively more complex benchmark…

Computational Physics · Physics 2014-09-01 Guneet Kaur , Ali E. Yilmaz

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working at an extremely high resolution (larger than 150x150). We use focal-plane images collected…

Instrumentation and Methods for Astrophysics · Physics 2015-06-22 Visa Korkiakoski , Christoph U. Keller , Niek Doelman , Matthew Kenworthy , Gilles Otten , Michel Verhaegen

Accurate characterization of free-space optical (FSO) channels requires joint estimation of transmitter pointing errors, receiver angle-of-arrival (AoA) fluctuations, and turbulence-induced fading. However, existing literature addresses…

Signal Processing · Electrical Eng. & Systems 2025-12-16 Mohammad Taghi Dabiri , Meysam Ghanbari , Rula Ammuri , Mazen Hasna , Khalid Qaraqe

We develop efficient and high-order accurate solvers for the Helmholtz equation on complex geometry. The schemes are based on the WaveHoltz algorithm which computes solutions of the Helmholtz equation by time-filtering solutions of the wave…

Numerical Analysis · Mathematics 2025-04-07 Daniel Appelo , Jeffrey W. Banks , William D. Henshaw , Donald W. Schwendeman