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In recent investigations, the problem of detecting edges given non-uniform Fourier data was reformulated as a sparse signal recovery problem with an l1-regularized least squares cost function. This result can also be derived by employing a…

Signal Processing · Electrical Eng. & Systems 2018-11-30 Victor Churchill , Anne Gelb

This article gives a procedure to convert a frame which is not a tight frame into a Parseval frame for the same space, with the requirement that each element in the resulting Parseval frame can be explicitly written as a linear combination…

Functional Analysis · Mathematics 2013-08-26 Enrico Au-Yeung , Somantika Datta

Fourier-based wavefront sensors, such as the Pyramid Wavefront Sensor (PWFS), are the current preference for high contrast imaging due to their high sensitivity. However, these wavefront sensors have intrinsic nonlinearities that constrain…

Instrumentation and Methods for Astrophysics · Physics 2020-05-22 Rico Landman , Sebastiaan Haffert

We present a novel method to provide efficient and highly detailed reconstructions. Inspired by wavelets, we learn a neural field that decompose the signal both spatially and frequency-wise. We follow the recent grid-based paradigm for…

Computer Vision and Pattern Recognition · Computer Science 2023-08-25 Zhijie Wu , Yuhe Jin , Kwang Moo Yi

We demonstrate Fourier single-pixel imaging in the terahertz regime. The experimental system is implemented with a photo-induced coded aperture setup, where a monolayer graphene on a high-resistance silicon substrate illuminated by a coded…

Applied Physics · Physics 2019-07-24 Rongbin She , Wenquan Liu , Yuanfu Lu , Zhisheng Zhou , Guangyuan Li

We analyze sparse frame based regularization of inverse problems by means of a diagonal frame decomposition (DFD) for the forward operator, which generalizes the SVD. The DFD allows to define a non-iterative (direct) operator-adapted frame…

Numerical Analysis · Mathematics 2019-12-13 Jürgen Frikel , Markus Haltmeier

Deep learning-based image reconstruction methods have achieved remarkable success in phase recovery and holographic imaging. However, the generalization of their image reconstruction performance to new types of samples never seen by the…

Computer Vision and Pattern Recognition · Computer Science 2022-08-17 Hanlong Chen , Luzhe Huang , Tairan Liu , Aydogan Ozcan

Image reconstruction plays a critical role in the implementation of all contemporary imaging modalities across the physical and life sciences including optical, MRI, CT, PET, and radio astronomy. During an image acquisition, the sensor…

Computer Vision and Pattern Recognition · Computer Science 2018-04-18 Bo Zhu , Jeremiah Z. Liu , Bruce R. Rosen , Matthew S. Rosen

Purpose: Cross-term spatiotemporal encoding-xSPEN-is a single-shot imaging approach with exceptional resilience to field heterogeneities: its images do not require a priori information nor use post-acquisition corrections, to deliver…

Medical Physics · Physics 2017-05-29 Zhiyong Zhang , Lucio Frydman

This paper proposes a model order reduction method for a class of parametric dynamical systems. Using a temporal Fourier transform, we reformulate these systems into complex-valued elliptic equations in the frequency domain, containing…

Numerical Analysis · Mathematics 2026-02-10 Yuming Ba , Liang Chen , Yaru Chen , Qiuqi Li

In this study, we introduce a Fourier series-based trainable filter for computed tomography (CT) reconstruction within the filtered backprojection (FBP) framework. This method overcomes the limitation in noise reduction by optimizing…

Image and Video Processing · Electrical Eng. & Systems 2024-10-28 Yipeng Sun , Linda-Sophie Schneider , Fuxin Fan , Mareike Thies , Mingxuan Gu , Siyuan Mei , Yuzhong Zhou , Siming Bayer , Andreas Maier

Accelerated magnetic resonance imaging resorts to either Fourier-domain subsampling or better reconstruction algorithms to deal with fewer measurements while still generating medical images of high quality. Determining the optimal sampling…

Machine Learning · Computer Science 2023-08-30 Zhishen Huang

Light field cameras provide intriguing possibilities, such as post-capture refocus or the ability to synthesize images from novel viewpoints. This comes, however, at the price of significant storage requirements. Compression techniques can…

Graphics · Computer Science 2019-10-14 Christian Lessig

We introduce a fast algorithm for computing sparse Fourier transforms supported on smooth curves or surfaces. This problem appear naturally in several important problems in wave scattering and reflection seismology. The main observation is…

Numerical Analysis · Mathematics 2008-01-11 Lexing Ying

High resolution images can be acquired using a non-regular sampling sensor which consists of an underlying low resolution sensor that is covered with a non-regular sampling mask. The reconstructed high resolution image is then obtained…

Image and Video Processing · Electrical Eng. & Systems 2022-04-08 Markus Jonscher , Karina Jaskolka , Jürgen Seiler , André Kaup

Deep learning methods for accelerated MRI achieve state-of-the-art results but largely ignore additional speedups possible with noncartesian sampling trajectories. To address this gap, we created a generative diffusion model-based…

Artificial Intelligence · Computer Science 2024-10-02 Trevor J. Chan , Chamith S. Rajapakse

Image signals typically are defined on a rectangular two-dimensional grid. However, there exist scenarios where this is not fulfilled and where the image information only is available for a non-regular subset of pixel position. For…

Image and Video Processing · Electrical Eng. & Systems 2022-07-15 Jürgen Seiler , André Kaup

It is shown here that precision is gained by analyzing the interferometric spectra directly from the interferograms, with no previous Fourier transformation to put them in the standard frequency domain. The method is based on the…

Instrumentation and Detectors · Physics 2018-04-20 Miguel Lagos , Rodrigo Paredes , Cesar Retamal

U-Net style networks are commonly utilized in unsupervised image registration to predict dense displacement fields, which for high-resolution volumetric image data is a resource-intensive and time-consuming task. To tackle this challenge,…

Image and Video Processing · Electrical Eng. & Systems 2023-07-07 Xi Jia , Alexander Thorley , Alberto Gomez , Wenqi Lu , Dipak Kotecha , Jinming Duan

Interferometric Synthetic Aperture Radar (InSAR) Imaging methods are usually based on algorithms of match-filtering type, without considering the scene's characteristic, which causes limited imaging quality. Besides, post-processing steps…

Signal Processing · Electrical Eng. & Systems 2022-10-07 Xu Zhan , Xiaoling Zhang , Shunjun Wei , Jun Shi
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