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Total variation (TV) denoising is a nonparametric smoothing method that has good properties for preserving sharp edges and contours in objects with spatial structures like natural images. The estimate is sparse in the sense that TV…

Methodology · Statistics 2016-05-06 Sylvain Sardy , Hatef Monajemi

Total Generalized Variation (TGV) regularization in image reconstruction relies on an infimal convolution type combination of generalized first- and second-order derivatives. This helps to avoid the staircasing effect of Total Variation…

Optimization and Control · Mathematics 2022-05-09 Michael Hintermüller , Kostas Papafitsoros , Carlos N. Rautenberg , Hongpeng Sun

In this paper, we study a practical space-time video super-resolution (STVSR) problem which aims at generating a high-framerate high-resolution sharp video from a low-framerate low-resolution blurry video. Such problem often occurs when…

Computer Vision and Pattern Recognition · Computer Science 2022-07-25 Jiezhang Cao , Jingyun Liang , Kai Zhang , Wenguan Wang , Qin Wang , Yulun Zhang , Hao Tang , Luc Van Gool

Two critical aspects of radio interferometric imaging analysis are data calibration and deconvolution of the point spread function (PSF) structure. Both of these are particularly important for high-frequency observations using a VLBI…

Instrumentation and Methods for Astrophysics · Physics 2024-09-27 Makoto Miyoshi , Yoshiaki Kato , Junichiro Makino

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

We propose that the ring structure found by the Event Horizon Telescope Collaboration (EHTC) as the black hole shadow of Sgr A*is an artifact by the bumpy PSF (Point Spread Function) of the EHT2017. The imaging using sparse u-v data…

High Energy Astrophysical Phenomena · Physics 2024-10-31 Makoto Miyoshi , Yoshiaki Kato , Junichiro Makino

This paper introduces a novel variational approach for image compression motivated by recent PDE-based approaches combining edge detection and Laplacian inpainting. The essential feature is to encode the image via a sparse vector field,…

Optimization and Control · Mathematics 2015-03-09 Eva-Maria Brinkmann , Martin Burger , Joana Grah

Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of…

Total variation (TV) regularization is a popular reconstruction method for ill-posed imaging problems, and particularly useful for applications with piecewise constant targets. However, using TV for medical cone-beam computed X-ray…

Medical Physics · Physics 2024-12-11 Alexander Meaney , Mikael A. K. Brix , Miika T. Nieminen , Samuli Siltanen

The spatio-spectral total variation (SSTV) model has been widely used as an effective regularization of hyperspectral images (HSI) for various applications such as mixed noise removal. However, since SSTV computes local spatial differences…

Image and Video Processing · Electrical Eng. & Systems 2022-10-05 Shingo Takemoto , Kazuki Naganuma , Shunsuke Ono

Total variation (TV) minimization is one of the most important techniques in modern signal/image processing, and has wide range of applications. While there are numerous recent works on the restoration guarantee of the TV minimization in…

Analysis of PDEs · Mathematics 2022-07-18 Jian-Feng Cai , Jae Kyu Choi , Ke Wei

This paper focuses on the development of a space-variant regularization model for solving an under-determined linear inverse problem. The case study is a medical image reconstruction from few-view tomographic noisy data. The primary…

Image and Video Processing · Electrical Eng. & Systems 2024-04-29 Elena Morotti , Davide Evangelista , Andrea Sebastiani , Elena Loli Piccolomini

Many imaging technologies rely on tomographic reconstruction, which requires solving a multidimensional inverse problem given a finite number of projections. Backprojection is a popular class of algorithm for tomographic reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2020-06-03 Xueqing Liu , Paul Sajda

This paper proposes a simple, accurate, and robust approach to single image nonparametric blind Super-Resolution (SR). This task is formulated as a functional to be minimized with respect to both an intermediate super-resolved image and a…

Computer Vision and Pattern Recognition · Computer Science 2015-03-17 Wen-Ze Shao , Michael Elad

Regularization plays a crucial role in reliably utilizing imaging systems for scientific and medical investigations. It helps to stabilize the process of computationally undoing any degradation caused by physical limitations of the imaging…

Image and Video Processing · Electrical Eng. & Systems 2021-05-26 Manu Ghulyani , Deepak G Skariah , Muthuvel Arigovindan

Hyperspectral image (HSI) denoising aims to restore clean HSI from the noise-contaminated one. Noise contamination can often be caused during data acquisition and conversion. In this paper, we propose a novel spatial-spectral total…

Image and Video Processing · Electrical Eng. & Systems 2021-04-07 Haijin Zeng , Xiaozhen Xie , Jifeng Ning

Flash X-ray computed tomography (CT) is an important imaging modality for characterization of high-speed dynamic events, such as Kolsky bar impact experiments for the study of mechanical properties of materials subjected to impulsive…

Image and Video Processing · Electrical Eng. & Systems 2024-06-27 Maliha Hossain , Charles A. Bouman , Brendt Wohlberg

The Event Horizon Telescope (EHT), a global 230 GHz VLBI array, achieves an angular resolution of ${\approx} 20\,\mu{\rm as}$, sufficient to resolve the supermassive black hole Sagittarius A* (Sgr A*). This resolution may soon enable…

Instrumentation and Methods for Astrophysics · Physics 2019-01-09 Ziyan Zhu , Michael D. Johnson , Ramesh Narayan

This work presents a new super-resolution imaging approach by using subwavelength hole resonances. We employ a subwavelength structure in which an array of tiny holes are etched in a metallic slab with the neighboring distance $\ell$ that…

Optics · Physics 2020-10-07 Junshan Lin , Hai Zhang

The use of ray projections to reconstruct images is a common technique in medical imaging. Dealing with incomplete data is particularly important when a patient is vulnerable to potentially damaging radiation or is unable to cope with the…

Neural and Evolutionary Computing · Computer Science 2024-06-04 Mohammad Majid al-Rifaie , Tim Blackwell