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Several gravitationally lensed quasars are observed with anomalous magnifications in pairs of images that straddle a critical curve. Simple theoretical arguments suggest that the magnification of these images should be approximately…

Astrophysics · Physics 2009-11-13 Nicholas F. Bate , Rachel L. Webster , Stuart Wyithe

Image coaddition is one of the most basic operations that astronomers perform. In Paper~I, we presented the optimal ways to coadd images in order to detect faint sources and to perfrom flux measurements under the assumption that the noise…

Instrumentation and Methods for Astrophysics · Physics 2018-03-28 Barak Zackay , Eran O. Ofek

Procedures based on current methods to detect sources in X-ray images are applied to simulated XMM images. All significant instrumental effects are taken into account, and two kinds of sources are considered -- unresolved sources…

Astrophysics · Physics 2009-11-06 I. Valtchanov , M. Pierre , R. Gastaud

We consider the problem of multivariate density deconvolution when the interest lies in estimating the distribution of a vector-valued random variable but precise measurements of the variable of interest are not available, observations…

Methodology · Statistics 2016-12-06 Abhra Sarkar , Debdeep Pati , Bani K. Mallick , Raymond J. Carroll

Difference image analysis (DIA) is a powerful tool for studying time-variable phenomena, and has been used by many time-domain surveys. Most DIA algorithms involve matching the spatially-varying PSF shape between science and template…

Elongated anisotropic Gaussian filters are used for the orientation estimation of fibers. In cases where computed tomography images are noisy, roughly resolved, and of low contrast, they are the method of choice even if being efficient only…

Image and Video Processing · Electrical Eng. & Systems 2024-10-28 Alex Keilmann , Michael Godehardt , Ali Moghiseh , Claudia Redenbach , Katja Schladitz

In the previous blind deconvolution methods, de-blurred images can be obtained by using the edge or pixel information. However, the existing edge-based methods did not take advantage of edge information in ommi-directions, but only used…

Computer Vision and Pattern Recognition · Computer Science 2019-05-06 Trung Dung Do , Xuenan Cui , Thi Hai Binh Nguyen , Hakil Kim , Van Huan Nguyen

Deblurring is a fundamental inverse problem in bioimaging. It requires modelling the point spread function (PSF), which captures the optical distortions entailed by the image formation process. The PSF limits the spatial resolution…

Image and Video Processing · Electrical Eng. & Systems 2019-03-04 Denis K. Samuylov , Prateek Purwar , Gábor Székely , Grégory Paul

We have developed a method based on wavelets to obtain the true underlying smooth density from a point distribution. The goal has been to reconstruct the density field in an optimal way ensuring that the morphology of the reconstructed…

Astrophysics · Physics 2009-11-13 V. J. Martinez , J. -L. Starck , E. Saar , D. L. Donoho , S. Reynolds , P. de la Cruz , S. Paredes

While automatic detection of point sources in astronomical images has experienced a great degree of success, less effort has been directed towards the detection of extended and low-surface brightness features. At present, existing…

Instrumentation and Methods for Astrophysics · Physics 2012-04-03 Christopher Hollitt , Melanie Johnston-Hollitt

Non-Gaussianities of dynamical origin are disentangled from primordial ones using the formalism of large deviation statistics with spherical collapse dynamics. This is achieved by relying on accurate analytical predictions for the one-point…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-27 Cora Uhlemann , Enrico Pajer , Christophe Pichon , Takahiro Nishimichi , Sandrine Codis , Francis Bernardeau

Radio synthesis imaging is dependent upon deconvolution algorithms to counteract the sparse sampling of the Fourier plane. These deconvolution algorithms find an estimate of the true sky brightness from the necessarily incomplete sampled…

Astrophysics · Physics 2009-11-13 T. J. Cornwell

Fluorescence microscopy is widely used for the study of biological specimens. Deconvolution can significantly improve the resolution and contrast of images produced using fluorescence microscopy; in particular, Bayesian-based methods have…

Methodology · Statistics 2015-02-04 Alexander Wong , Xiao Yu Wang , Maud Gorbet

Lensless microscopy with coherent or partially coherent light sources is a well known imaging technique, commonly referred as digital in-line holographic microscopy. In the established methods, both the spatial and temporal coherence of…

Optics · Physics 2020-11-04 Sanjeev Kumar , Manjunatha Mahadevappa , Pranab Kumar Dutta

Gravitational waves propagate along null geodesics like light rays in the geometrical optics approximation, and they may have a chance to suffer from gravitational lensing by intervening objects, as is the case for electromagnetic waves.…

General Relativity and Quantum Cosmology · Physics 2010-10-12 Yousuke Itoh , Toshifumi Futamase , Makoto Hattori

In the presence of strong clustering, low-resolution surveys measure the summed contributions of groups of sources within the beam. The counts of bright intensity peaks are therefore shifted to higher flux levels compared to the counts of…

In the unified scheme of active galactic nuclei, a dusty torus absorbs and then reprocesses a fraction of the intrinsic luminosity which is emitted at longer wavelengths. Thus, subject to radiative transfer corrections, the fraction of the…

High Energy Astrophysical Phenomena · Physics 2017-11-08 Savithri H. Ezhikode , Poshak Gandhi , Chris Done , Martin Ward , Gulab C. Dewangan , Ranjeev Misra , Ninan Sajeeth Philip

Ptychography involves a sample being illuminated by a coherent, localised probe of illumination. When the probe interacts with the sample, the light is diffracted and a diffraction pattern is detected. Then the probe or sample is shifted…

Numerical Analysis · Mathematics 2023-05-09 Mark Philip Roach

A quality-Bayesian approach, combining the direct sampling method and the Bayesian inversion, is proposed to reconstruct the locations and intensities of the unknown acoustic sources using partial data. First, we extend the direct sampling…

Numerical Analysis · Mathematics 2020-04-10 Zhaoxing Li , Yanfang Liu , Jiguang Sun , Liwei Xu

Most research on astrophysical lensing has been conducted using the geometric optics framework, where there exists a clear concept of lensing images. However, wave optics effects can be important for coherent sources, e.g. pulsars, fast…

Instrumentation and Methods for Astrophysics · Physics 2024-10-29 Xun Shi