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Phase retrieval is a nonlinear inverse problem that arises in a wide range of imaging modalities, from electron microscopy to Fourier ptychography. In particular, the reconstruction is facilitated when the sensing matrix is i.i.d. random,…

Extracting parametric edge curves from point clouds is a fundamental problem in 3D vision and geometry processing. Existing approaches mainly rely on keypoint detection, a challenging procedure that tends to generate noisy output, making…

Computer Vision and Pattern Recognition · Computer Science 2023-03-30 Xiangyu Zhu , Dong Du , Weikai Chen , Zhiyou Zhao , Yinyu Nie , Xiaoguang Han

Purpose: Inter-scan motion is a substantial source of error in $R_1$ estimation, and can be expected to increase at 7T where $B_1$ fields are more inhomogeneous. The established correction scheme does not translate to 7T since it requires a…

Image and Video Processing · Electrical Eng. & Systems 2021-12-09 Yaël Balbastre , Ali Aghaeifar , Nadège Corbin , Mikael Brudfors , John Ashburner , Martina F. Callaghan

Like many other advanced imaging methods, x-ray phase contrast imaging and tomography require mathematical inversion of the observed data to obtain real-space information. While an accurate forward model describing the generally nonlinear…

Numerical Analysis · Mathematics 2016-04-07 Simon Maretzke , Matthias Bartels , Martin Krenkel , Tim Salditt , Thorsten Hohage

Full Stokes filter-polarimeters are key instruments for investigating the rapid evolution of magnetic structures on the solar surface. To this end, the image quality is routinely improved using a-posteriori image reconstruction methods. We…

Solar and Stellar Astrophysics · Physics 2015-06-03 A. Asensio Ramos , M. J. Martinez Gonzalez , E. Khomenko , V. Martinez Pillet

Perspective-n-Point-and-Line (P$n$PL) algorithms aim at fast, accurate, and robust camera localization with respect to a 3D model from 2D-3D feature correspondences, being a major part of modern robotic and AR/VR systems. Current…

Computer Vision and Pattern Recognition · Computer Science 2021-07-09 Alexander Vakhitov , Luis Ferraz Colomina , Antonio Agudo , Francesc Moreno-Noguer

Non-line-of-sight (NLOS) imaging aims to reconstruct the three-dimensional hidden scenes from the data measured in the line-of-sight, which uses photon time-of-flight information encoded in light after multiple diffuse reflections. The…

Computer Vision and Pattern Recognition · Computer Science 2024-03-07 Rui Ding , Juntian Ye , Qifeng Gao , Feihu Xu , Yuping Duan

This work presents a new constructive uniqueness proof for Calder\'on's inverse problem of electrical impedance tomography, subject to local Cauchy data, for a large class of piecewise constant conductivities that we call "piecewise…

Analysis of PDEs · Mathematics 2020-08-18 Henrik Garde

The image blurring process is generally modelled as the convolution of a blur kernel with a latent image. Therefore, the estimation of the blur kernel is essentially important for blind image deblurring. Unlike existing approaches which…

Computer Vision and Pattern Recognition · Computer Science 2019-04-18 Liyuan Pan , Richard Hartley , Miaomiao Liu , Yuchao Dai

A phase retrieval technique using a spatial light modulator (SLM) and a phase diffuser for a fast reconstruction of smooth wave fronts is demonstrated experimentally. Diffuse illumination of a smooth test object with the aid of a phase…

Optics · Physics 2015-06-11 Mostafa Agour , Percival F. Almoro , Claas Falldorf

Purpose: To develop a general phase regularized image reconstruction method, with applications to partial Fourier imaging, water-fat imaging and flow imaging. Theory and Methods: The problem of enforcing phase constraints in reconstruction…

Computer Vision and Pattern Recognition · Computer Science 2017-09-26 Frank Ong , Joseph Cheng , Michael Lustig

This paper develops uniqueness theory for 3D phase retrieval with finite, discrete measurement data for strong phase objects and weak phase objects, including: (i) {\em Unique determination of (phase) projections from diffraction patterns}…

Information Theory · Computer Science 2023-12-05 Albert Fannjiang

Phase retrieval algorithms have become an important component in many modern computational imaging systems. For instance, in the context of ptychography and speckle correlation imaging, they enable imaging past the diffraction limit and…

Machine Learning · Statistics 2018-07-03 Christopher A. Metzler , Philip Schniter , Ashok Veeraraghavan , Richard G. Baraniuk

Phase unwrapping is a key problem in many coherent imaging systems, such as synthetic aperture radar (SAR) interferometry. A general formulation for redundant integration of finite differences for phase unwrapping (Costantini et al., 2010)…

Other Computer Science · Computer Science 2018-05-04 Ravi Lanka

Parallel imaging is ubiquitous in MRI, enabling diverse applications such as ultra-high-resolution functional and quantitative imaging with greater temporal resolution or reduced scan times respectively. Successful unfolding is contingent…

Surface reconstruction from a set of scattered points, or a point cloud, has many applications ranging from computer graphics to remote sensing. We present a new method for this task that produces an implicit surface (zero-level set)…

Numerical Analysis · Mathematics 2022-07-22 Kathryn P. Drake , Edward J. Fuselier , Grady B. Wright

We consider the problem of reconstructing signals and images from periodic nonlinearities. For such problems, we design a measurement scheme that supports efficient reconstruction; moreover, our method can be adapted to extend to…

Machine Learning · Statistics 2017-10-03 Viraj Shah , Mohammadreza Soltani , Chinmay Hegde

We address the problem of signal reconstruction from intensity measurements with respect to a measurement frame. This non-convex inverse problem is known as phase retrieval. The case considered in this paper concerns phaseless measurements…

Functional Analysis · Mathematics 2019-02-13 Goetz E. Pfander , Palina Salanevich

Unoriented surface reconstruction is an important task in computer graphics and has extensive applications. Based on the compact support of wavelet and orthogonality properties, classic wavelet surface reconstruction achieves good and fast…

Computational Geometry · Computer Science 2025-06-23 Yueji Ma , Yanzun Meng , Dong Xiao , Zuoqiang Shi , Bin Wang

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