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Most advanced unsupervised anomaly detection (UAD) methods rely on modeling feature representations of frozen encoder networks pre-trained on large-scale datasets, e.g. ImageNet. However, the features extracted from the encoders that are…

Computer Vision and Pattern Recognition · Computer Science 2023-10-25 Jia Guo , Shuai Lu , Lize Jia , Weihang Zhang , Huiqi Li

X-ray imaging is a fast, precise and non-invasive method of imaging which, when combined with computed tomography, provides detailed 3D rendering of samples. Incorporating propagation-based phase contrast can vastly improve data quality for…

Classical phase retrieval problem is the recovery of a constrained image from the magnitude of its Fourier transform. Although there are several well-known phase retrieval algorithms including the hybrid input-output (HIO) method, the…

Image and Video Processing · Electrical Eng. & Systems 2019-08-20 Çağatay Işıl , Figen S. Oktem , Aykut Koç

Practical applications of thermoacoustic tomography require numerical inversion of the spherical mean Radon transform with the centers of integration spheres occupying an open surface. Solution of this problem is needed (both in 2-D and…

Analysis of PDEs · Mathematics 2009-11-13 Leonid Kunyansky

This paper is concerned with a nonlinear imaging problem, which aims to reconstruct a locally perturbed, perfectly reflecting, infinite plane from intensity-only (or phaseless) far-field or near-field data. A recursive Newton iteration…

Numerical Analysis · Mathematics 2017-06-06 Bo Zhang , Haiwen Zhang

Diffuse optical tomography (DOT) has been investigated as an alternative imaging modality for breast cancer detection thanks to its excellent contrast to hemoglobin oxidization level. However, due to the complicated non-linear photon…

Computer Vision and Pattern Recognition · Computer Science 2019-09-10 Jaejun Yoo , Sohail Sabir , Duchang Heo , Kee Hyun Kim , Abdul Wahab , Yoonseok Choi , Seul-I Lee , Eun Young Chae , Hak Hee Kim , Young Min Bae , Young-wook Choi , Seungryong Cho , Jong Chul Ye

We study an approach to solving the phase retrieval problem as it arises in a phase-less imaging modality known as ptychography. In ptychography, small overlapping sections of an unknown sample (or signal, say $x_0\in \mathbb{C}^d$) are…

Numerical Analysis · Mathematics 2019-10-09 Brian Preskitt , Rayan Saab

Recovering an unknown signal from quadratic measurements has gained popularity due to its wide range of applications, including phase retrieval, fusion frame phase retrieval, and positive operator-valued measures. In this paper, we employ a…

Optimization and Control · Mathematics 2024-09-02 Jun Fan , Jie Sun , Ailing Yan , Shenglong Zhou

The realm of classical phase retrieval concerns itself with the arduous task of recovering a signal from its Fourier magnitude measurements, which are fraught with inherent ambiguities. A single-exposure intensity measurement is commonly…

Computer Vision and Pattern Recognition · Computer Science 2023-11-21 Yixiao Yang , Ran Tao , Kaixuan Wei , Jun Shi

Inspired by the multiple-exposure fusion approach in computational photography, recently, several practitioners have explored the idea of high dynamic range (HDR) X-ray imaging and tomography. While establishing promising results, these…

Numerical Analysis · Mathematics 2024-04-10 Matthias Beckmann , Ayush Bhandari , Meira Iske

The problem of phase retrieval is a classic one in optics and arises when one is interested in recovering an unknown signal from the magnitude (intensity) of its Fourier transform. While there have existed quite a few approaches to phase…

Information Theory · Computer Science 2015-10-28 Kishore Jaganathan , Yonina C. Eldar , Babak Hassibi

Imaging 3D nano-structures at very high resolution is crucial in a variety of scientific fields. However, due to fundamental limitations of light propagation we can only measure the object indirectly via 2D intensity measurements of the 3D…

Image and Video Processing · Electrical Eng. & Systems 2020-02-28 Zalan Fabian , Justin Haldar , Richard Leahy , Mahdi Soltanolkotabi

By profiting from recent developments in detector technologies, making it possible to access a stream of detection events with few-ns time resolutions, a new ptychographic workflow is established. This methodological framework, referred to…

Applied Physics · Physics 2026-03-27 Hoelen L. Lalandec Robert , Arno Annys , Tamazouzt Chennit , Jo Verbeeck

In a variety of fields, in particular those involving imaging and optics, we often measure signals whose phase is missing or has been irremediably distorted. Phase retrieval attempts to recover the phase information of a signal from the…

Information Theory · Computer Science 2019-10-02 Gilles Baechler , Miranda Kreković , Juri Ranieri , Amina Chebira , Yue M. Lu , Martin Vetterli

This paper considers the question of recovering the phase of an object from intensity-only measurements, a problem which naturally appears in X-ray crystallography and related disciplines. We study a physically realistic setup where one can…

Information Theory · Computer Science 2013-11-08 Emmanuel Candes , Xiaodong Li , Mahdi Soltanolkotabi

Deformable image registration is a standard engineering problem used to determine the distortion experienced by a body by comparing two images of it in different states. This study introduces two new DIR methods designed to capture…

Computer Vision and Pattern Recognition · Computer Science 2024-09-04 Daniel E. Hurtado , Axel Osses , Rodrigo Quezada

The problem of phase retrieval, i.e., the problem of recovering a function from the magnitudes of its Fourier transform, naturally arises in various fields of physics, such as astronomy, radar, speech recognition, quantum mechanics and,…

Functional Analysis · Mathematics 2020-02-17 Philipp Grohs , Sarah Koppensteiner , Martin Rathmair

In this manuscript we demonstrate a method to reconstruct the wavefront of focused beams from a measured diffraction pattern behind a diffracting mask in real-time. The phase problem is solved by means of a neural network, which is trained…

Image and Video Processing · Electrical Eng. & Systems 2021-04-07 Jonathon White , Sici Wang , Wilhelm Eschen , Jan Rothhardt

The Radon cumulative distribution transform (R-CDT) exploits one-dimensional Wasserstein transport and the Radon transform to represent prominent features in images. It is closely related to the sliced Wasserstein distance and facilitates…

Numerical Analysis · Mathematics 2026-02-02 Matthias Beckmann , Robert Beinert , Jonas Bresch

Differential phase contrast interior tomography allows for reconstruction of a refractive index distribution over a region of interest (ROI) for visualization and analysis of internal structures inside a large biological specimen. In this…

Medical Physics · Physics 2015-05-30 Wenxiang Cong , Ge Wang