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We present an imaging technique that allows the recovery of the transparency profile of wavelength-scale objects with deep subwavelength resolution based on far-field intensity measurements. The approach, interscale mixing microscopy (IMM),…

Optics · Physics 2017-03-21 Sandeep Inampudi , Nicholas Kuhta , Viktor A. Podolskiy

We demonstrate an imageless method of concealed contraband detection using a real-time 75 GHz rotationally dynamic antenna array. The array measures information in the two-dimensional Fourier domain and captures a set of samples that is…

Signal Processing · Electrical Eng. & Systems 2024-10-23 Daniel Chen , Anton Schlegel , Jeffrey A. Nanzer

Medical image segmentation is a crucial method for assisting professionals in diagnosing various diseases through medical imaging. However, various factors such as noise, blurriness, and low contrast often hinder the accurate diagnosis of…

Computer Vision and Pattern Recognition · Computer Science 2025-09-09 Jeonghyun Noh , Wangsu Jeon , Jinsun Park

Scalar diffraction calculations such as the angular spectrum method (ASM) and Fresnel diffraction, are widely used in the research fields of optics, X-rays, electron beams, and ultrasonics. It is possible to accelerate the calculation using…

The frequency-diverse array (FDA) offers a time-varying beamforming capability without the use of phase shifters. The autoscanning property is achieved by applying a frequency offset between the antennas. This paper analyzes the performance…

Signal Processing · Electrical Eng. & Systems 2025-02-13 Marcin Wachowiak , André Bourdoux , Sofie Pollin

Diffusion models have become a leading paradigm for image super-resolution (SR), but existing methods struggle to guarantee both the high-frequency perceptual quality and the low-frequency structural fidelity of generated images. Although…

Computer Vision and Pattern Recognition · Computer Science 2026-04-14 Hexin Zhang , Dong Li , Jie Huang , Bingzhou Wang , Xueyang Fu , Zhengjun Zha

Spatial resolution of most imaging devices is fundamentally restricted by diffraction. This limitation is manifested in the loss of high spatial frequency information contained in evanescent waves. As a result, conventional far-field optics…

Optics · Physics 2010-03-16 Leonid Alekseyev , Evgenii Narimanov , Jacob Khurgin

In this paper, we extend our method [1] for FMCW radar mutual interference mitigation (IM) based on the discrete fractional Fourier transform (DFrFT). Firstly, we propose a radar signal processing chain including our DFrFT-based IM for…

Signal Processing · Electrical Eng. & Systems 2026-05-01 Christian Oswald , Josef Kulmer , Franz Pernkopf

Fourier Ptychography (FP) is a recently proposed technique for large field of view and high resolution imaging. Specifically, FP captures a set of low resolution images under angularly varying illuminations and stitches them together in…

Optics · Physics 2014-11-25 Liheng Bian , Jinli Suo , Guohai Situ , Guoan Zheng , Feng Chen , Qionghai Dai

Previous unsupervised domain adaptation methods did not handle the cross-domain problem from the perspective of frequency for computer vision. The images or feature maps of different domains can be decomposed into the low-frequency…

Computer Vision and Pattern Recognition · Computer Science 2022-09-01 Zhaowen Li , Xu Zhao , Chaoyang Zhao , Ming Tang , Jinqiao Wang

Dispersive Fourier transformation is a powerful technique in which spectral information is mapped into the time domain using chromatic dispersion. It replaces a spectrometer with an electronic digitizer, and enables real-time spectroscopy.…

Optics · Physics 2009-11-13 J. Chou , D. R. Solli , B. Jalali

This paper, addressing the integration requirements of radar imaging and communication for High-Altitude Platform Stations (HAPs) platforms, designs a waveform based on linear frequency modulated (LFM) frequency-hopping signals that…

Signal Processing · Electrical Eng. & Systems 2024-12-24 Bang Huang , Sajid Ahmed , Mohamed-Slim Alouini

Existing single-image denoising algorithms often struggle to restore details when dealing with complex noisy images. The introduction of near-infrared (NIR) images offers new possibilities for RGB image denoising. However, due to the…

Computer Vision and Pattern Recognition · Computer Science 2025-03-25 Yuchen Wang , Hongyuan Wang , Lizhi Wang , Xin Wang , Lin Zhu , Wanxuan Lu , Hua Huang

The event camera, benefiting from its high dynamic range and low latency, provides performance gain for low-light image enhancement. Unlike frame-based cameras, it records intensity changes with extremely high temporal resolution, capturing…

Computer Vision and Pattern Recognition · Computer Science 2025-08-04 Chunyan She , Fujun Han , Chengyu Fang , Shukai Duan , Lidan Wang

In the phased-array radar (PAR) signals from each antenna are transmitted at the same carrier frequency, which yields narrowly focused only angle dependent beampattern. In contrast, in the frequency-diverse-array (FDA) radar signals from…

Signal Processing · Electrical Eng. & Systems 2020-06-24 Muhammad Zubair , Sajid Ahmed , Mohamed-Slim Alouini

Reconfigurable intelligent surfaces (RISs) have emerged as a promising auxiliary technology for radio frequency imaging. However, existing works face challenges of faint and intricate back-scattered waves and the restricted field-of-view…

Signal Processing · Electrical Eng. & Systems 2024-07-23 Fuhai Wang , Yunlong Huang , Zhanbo Feng , Rujing Xiong , Zhe Li , Chun Wang , Tiebin Mi , Robert Caiming Qiu , Zenan Ling

Next-generation radio interferometers, such as the Square Kilometre Array (SKA), will revolutionise our understanding of the universe through their unprecedented sensitivity and resolution. However, to realise these goals significant…

Instrumentation and Methods for Astrophysics · Physics 2017-11-20 Luke Pratley , Jason D. McEwen , Mayeul d'Avezac , Rafael E. Carrillo , Alexandru Onose , Yves Wiaux

Radio interferometry invariably suffers from an incomplete coverage of the spatial Fourier space, which leads to imaging artifacts. The current state-of-the-art technique is to create an image by Fourier-transforming the incomplete…

Instrumentation and Methods for Astrophysics · Physics 2024-12-19 F. Geyer , K. Schmidt , J. Kummer , M. Brüggen , H. W. Edler , D. Elsässer , F. Griese , A. Poggenpohl , L. Rustige , W. Rhode

The emergence of large foundation models has propelled significant advances in various domains. The Segment Anything Model (SAM), a leading model for image segmentation, exemplifies these advances, outperforming traditional methods.…

Computer Vision and Pattern Recognition · Computer Science 2025-07-29 Saurabh Yadav , Avi Gupta , Koteswar Rao Jerripothula

The research community has witnessed the powerful potential of self-supervised Masked Image Modeling (MIM), which enables the models capable of learning visual representation from unlabeled data. In this paper, to incorporate both the…

Computer Vision and Pattern Recognition · Computer Science 2023-12-01 Wenxuan Wang , Jing Wang , Chen Chen , Jianbo Jiao , Yuanxiu Cai , Shanshan Song , Jiangyun Li