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We reconstruct late-time cosmology using the technique of Principal Component Analysis (PCA). In particular, we focus on the reconstruction of the dark energy equation of state from two different observational data-sets, Supernovae type Ia…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-07 Ranbir Sharma , Ankan Mukherjee , H. K. Jassal

We develop a method for sparse image reconstruction from polychromatic computed tomography (CT) measurements under the blind scenario where the material of the inspected object and the incident-energy spectrum are unknown. We obtain a…

Methodology · Statistics 2016-05-17 Renliang Gu , Aleksandar Dogandžić

We explore the reconstruction of the gravitational lensing field of the cosmic microwave background in real space showing that very little statistical information is lost when estimators of short range on the celestial sphere are used in…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Martin Bucher , Carla Sofia Carvalho , Kavilan Moodley , Mathieu Remazeilles

We demonstrate the use of an eigenbasis that is derived from principal component analysis (PCA) applied on an ensemble of random-noise images that have a "red" power spectrum; i.e., a spectrum that decreases smoothly from large to small…

Instrumentation and Methods for Astrophysics · Physics 2022-03-14 Pravita Hallur , Lia Medeiros , Tod R. Lauer

We investigate implicit regularization schemes for gradient descent methods applied to unpenalized least squares regression to solve the problem of reconstructing a sparse signal from an underdetermined system of linear measurements under…

Machine Learning · Statistics 2019-09-12 Tomas Vaškevičius , Varun Kanade , Patrick Rebeschini

Image deblurring is relevant in many fields of science and engineering. To solve this problem, many different approaches have been proposed and among the various methods, variational ones are extremely popular. These approaches are…

Numerical Analysis · Mathematics 2021-02-23 Davide Bianchi , Alessandro Buccini , Marco Donatelli , Emma Randazzo

In the past decade, sparsity-driven regularization has led to advancement of image reconstruction algorithms. Traditionally, such regularizers rely on analytical models of sparsity (e.g. total variation (TV)). However, more recent methods…

Computer Vision and Pattern Recognition · Computer Science 2018-07-04 Emrah Bostan , Ulugbek S. Kamilov , Laura Waller

Magnetic Resonance Imaging (MRI) is a powerful technique employed for non-invasive in vivo visualization of internal structures. Sparsity is often deployed to accelerate the signal acquisition or overcome the presence of motion artifacts,…

Image and Video Processing · Electrical Eng. & Systems 2025-05-27 Gianluca Giacchi , Isidoros Iakovidis , Bastien Milani , Micah Murray , Benedetta Franceschiello

We apply two sparse reconstruction techniques, the least absolute shrinkage and selection operator (LASSO) and the sparse exponential mode analysis (SEMA), to two-dimensional (2D) spectroscopy. The algorithms are first tested on model data,…

Signal Processing · Electrical Eng. & Systems 2020-07-01 Zhengjun Wang , Shiwen Lei , Khadga Jung Karki , Andreas Jakobsson , Tönu Pullerits

The tomographic Alcock-Paczynski (AP) method can result in tight cosmological constraints by using small and intermediate clustering scales of the large scale structure (LSS) of the galaxy distribution. By focusing on the redshift…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-26 Zhenyu Zhang , Gan Gu , Xiaoma Wang , Yun-He Li , Cristiano G. Sabiu , Hyunbae Park , Haitao Miao , Xiaolin Luo , Feng Fang , Xiao-Dong Li

When the 2dF QSO Redshift Survey (2QZ) is complete, a powerful geometric test for the cosmological constant will be available. By comparing the clustering along and across the line of sight and modelling the effects of peculiar velocities…

Astrophysics · Physics 2009-11-06 P. J. Outram , Fiona Hoyle , T. Shanks , B. J. Boyle , S. M. Croom , N. S. Loaring , L. Miller , R. J. Smith

Based on realistic simulations, we propose an hybrid method to reconstruct the lensing potential power spectrum, directly on PLANCK-like CMB frequency maps. It implies using a large galactic mask and dealing with a strong inhomogeneous…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 S. Plaszczynski , A. Lavabre , L. Perotto , J. -L. Starck

Images acquired with a telescope are blurred and corrupted by noise. The blurring is usually modeled by a convolution with the Point Spread Function and the noise by Additive Gaussian Noise. Recovering the observed image is an ill-posed…

Instrumentation and Methods for Astrophysics · Physics 2021-11-03 Fadi Nammour , Morgan A. Schmitz , Fred Maurice Ngolè Mboula , Jean-Luc Starck , Julien N. Girard

This work addresses the robust reconstruction problem of a sparse signal from compressed measurements. We propose a robust formulation for sparse reconstruction which employs the $\ell_1$-norm as the loss function for the residual error and…

Information Theory · Computer Science 2017-03-30 Fei Wen , Yuan Yang , Ling Pei , Wenxian Yu , Peilin Liu

We analyze an Iteratively Re-weighted Least Squares (IRLS) algorithm for promoting l1-minimization in sparse and compressible vector recovery. We prove its convergence and we estimate its local rate. We show how the algorithm can be…

Numerical Analysis · Mathematics 2008-07-04 Ingrid Daubechies , Ronald DeVore , Massimo Fornasier , C. Sinan Gunturk

Galaxies whose images overlap in the focal plane of a telescope, commonly referred to as blends, are often located at different redshifts. Blending introduces a challenge to weak-lensing cosmology probes since such blends are subject to…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-18 Zekang Zhang , Daniel Gruen , Luca Tortorelli , Shun-Sheng Li , Jamie McCullough

In current seismic acquisition practice, there is an increasing drive for sparsely (in space) acquired data, often in irregular geometry. These surveys can trade off subsurface information for efficiency/cost - creating a problem of…

Geophysics · Physics 2021-01-26 Dieuwertje Kuijpers , Ivan Vasconcelos , Patrick Putzky

This paper presents a semantic planar SLAM system that improves pose estimation and mapping using cues from an instance planar segmentation network. While the mainstream approaches are using RGB-D sensors, employing a monocular camera with…

Computer Vision and Pattern Recognition · Computer Science 2022-06-23 Fangwen Shu , Yaxu Xie , Jason Rambach , Alain Pagani , Didier Stricker

Ptychography has risen as a reference X-ray imaging technique: it achieves resolutions of one billionth of a meter, macroscopic field of view, or the capability to retrieve chemical or magnetic contrast, among other features. A…

Optimization and Control · Mathematics 2019-06-10 Huibin Chang , Pable Enfedaque , Stefano Marchesini

Interloper contamination due to line misidentification is an important issue in the future low-resolution spectroscopic surveys. We realize that the algorithm previously used for photometric redshift self-calibration, with minor…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-28 Hui Peng , Yu Yu