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Generative models based on flow matching have attracted significant attention for their simplicity and superior performance in high-resolution image synthesis. By leveraging the instantaneous change-of-variables formula, one can directly…

Computer Vision and Pattern Recognition · Computer Science 2025-01-06 Yasi Zhang , Peiyu Yu , Yaxuan Zhu , Yingshan Chang , Feng Gao , Ying Nian Wu , Oscar Leong

In this paper, we address the inverse problem of fast, stable, and high-quality wavefront reconstruction from pyramid wavefront sensor data for Adaptive Optics systems on Extremely Large Telescopes. For solving the indicated problem we…

Instrumentation and Methods for Astrophysics · Physics 2019-05-01 Victoria Hutterer , Ronny Ramlau , Iuliia Shatokhina

This work studies the inverse problem of photoacoustic tomography (more precisely, the acoustic subproblem) as the identification of a space-dependent source parameter. The model consists of a wave equation involving a time-fractional…

Numerical Analysis · Mathematics 2025-04-29 Phuoc-Truong Huynh , Barbara Kaltenbacher

Correlated photon pairs, carrying strong quantum correlations, have been harnessed to bring quantum advantages to various fields from biological imaging to range finding. Such inherent non-classical properties support extracting more valid…

Quantum Physics · Physics 2020-06-18 Zhan-Ming Li , Shi-Bao Wu , Jun Gao , Heng Zhou , Zeng-Quan Yan , Ruo-Jing Ren , Si-Yuan Yin , Xian-Min Jin

In ultrasound tomography, the speed of sound inside an object is estimated based on acoustic measurements carried out by sensors surrounding the object. An accurate forward model is a prominent factor for high-quality image reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2021-11-24 Janne Koponen , Timo Lähivaara , Jari Kaipio , Marko Vauhkonen

Iterative image reconstruction algorithms for optoacoustic tomography (OAT), also known as photoacoustic tomography, have the ability to improve image quality over analytic algorithms due to their ability to incorporate accurate models of…

Analysis of PDEs · Mathematics 2015-06-05 Kun wang , Richard Su , Alexander A. Oraevsky , Mark A. Anastasio

The standard approach for photoacoustic imaging with variable speed of sound is time reversal, which consists in solving a well-posed final-boundary value problem for the wave equation backwards in time. This paper investigates the…

Optimization and Control · Mathematics 2016-03-17 Zakaria Belhachmi , Thomas Glatz , Otmar Scherzer

Photoacoustic computed tomography (PACT) is an emerging imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the photoacoustically induced initial pressure distribution within tissue. The…

The eikonal equation is instrumental in many applications in several fields ranging from computer vision to geoscience. This equation can be efficiently solved using the iterative Fast Sweeping (FS) methods and the direct Fast Marching (FM)…

Computational Engineering, Finance, and Science · Computer Science 2016-08-30 Eran Treister , Eldad Haber

The integral image, an intermediate image representation, has found extensive use in multi-scale local feature detection algorithms, such as Speeded-Up Robust Features (SURF), allowing fast computation of rectangular features at constant…

Computer Vision and Pattern Recognition · Computer Science 2015-10-20 Shoaib Ehsan , Adrian F. Clark , Naveed ur Rehman , Klaus D. McDonald-Maier

Photoacoustic tomography is a hybrid imaging technique that combines high optical tissue contrast with high ultrasound resolution. Direct reconstruction methods such as filtered backprojection, time reversal and least squares suffer from…

Iterative methods for tomographic image reconstruction have great potential for enabling high quality imaging from low-dose projection data. The computational burden of iterative reconstruction algorithms, however, has been an impediment in…

Image and Video Processing · Electrical Eng. & Systems 2019-07-25 Kai Zhang , Alireza Entezari

Many application domains, spanning from computational photography to medical imaging, require recovery of high-fidelity images from noisy, incomplete or partial/compressed measurements. State of the art methods for solving these inverse…

Image and Video Processing · Electrical Eng. & Systems 2022-07-13 Xinyi Wei , Hans van Gorp , Lizeth Gonzalez Carabarin , Daniel Freedman , Yonina C. Eldar , Ruud J. G. van Sloun

Photoacoustic tomography seeks to reconstruct an acoustic initial pressure distribution from the measurement of the ultrasound waveforms. Conventional methods assume a-prior knowledge of the sound speed distribution, which practically is…

Image and Video Processing · Electrical Eng. & Systems 2019-09-16 Hongming Shan , Christopher Wiedeman , Ge Wang , Yang Yang

We propose an extended primal-dual algorithm framework for solving a general nonconvex optimization model. This work is motivated by image reconstruction problems in a class of nonlinear imaging, where the forward operator can be formulated…

Optimization and Control · Mathematics 2024-08-28 Yu Gao , Xiaochuan Pan , Chong Chen

Fourier reconstruction algorithms significantly outperform conventional back-projection algorithms in terms of computation time. In photoacoustic imaging, these methods require interpolation in the Fourier space domain, which creates…

Numerical Analysis · Mathematics 2016-11-17 M. Haltmeier , O. Scherzer , G. Zangerl

We investigate the inverse source problem for the wave equation, arising in photo- and thermoacoustic tomography. There exist quite a few theoretically exact inversion formulas explicitly expressing solution of this problem in terms of the…

Analysis of PDEs · Mathematics 2018-08-01 Ngoc Do , Leonid Kunyansky

Orbital tomography has recently been established as a technique to reconstruct molecular orbitals directly from photoemission data using iterative phase retrieval algorithms. In this work, we present a detailed description of steps for…

In optoacoustic (photoacoustic) tomography, several parameters related to tissue and detector features are needed for image formation, but they may not be known a priori. An autofocus (AF) algorithm is generally used to estimate these…

Medical Physics · Physics 2022-03-14 Ludwig Englert , Lucas Riobo , Christine Schonemann , Vasilis Ntziachristos , Juan Aguirre

In this article, we are concerned with a nonlinear inverse problem with a forward operator involving an unknown function. The problem arises in diverse applications and is challenging in the presence of an unknown function, which makes it…

Numerical Analysis · Mathematics 2023-02-07 Gyeongha Hwang , Gihyeon Jeon , Sunghwan Moon