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Shack-Hartmann wavefront sensing relies on accurate spot centre measurement. Several algorithms were developed with this aim, mostly focused on precision, i.e. minimizing random errors. In the solar and extended scene community, the…

Instrumentation and Methods for Astrophysics · Physics 2018-02-07 Narsireddy Anugu , Paulo J. V. Garcia , Carlos M. Correia

In a previous paper we described a method of estimating the single-measurement bias to be expected in astrometric observations of targets in crowded fields with the future Space Interferometry Mission (SIM). That study was based on a…

Astrophysics · Physics 2009-11-13 R. Sridharan , Ronald J. Allen

Direct imaging of exoplanets represents a challenge for astronomical instrumentation due to the high-contrast ratio and small angular separation between the host star and the faint planet. Multi-star systems pose additional challenges for…

Instrumentation and Methods for Astrophysics · Physics 2017-11-15 Dan Sirbu , Sandrine Thomas , Ruslan Belikov , Eduardo Bendek

We proposed a novel approach to coherent imaging of dynamic samples. The inter-frame similarity of the sample's local structures is found to be a powerful constraint in phasing a sequence of diffraction patterns. We devised a new image…

Optics · Physics 2024-07-11 Pengju Sheng , Fucai Zhang

Two sequential camera source identification methods are proposed. Sequential tests implement a log-likelihood ratio test in an incremental way, thus enabling a reliable decision with a minimal number of observations. One of our methods…

Cryptography and Security · Computer Science 2015-10-14 Fernando Pérez-González , Iria González-Iglesias , Miguel Masciopinto , Pedro Comesaña

Compact and low-cost devices are needed for autonomous driving to image and measure distances to objects 360-degree around. We have been developing an omnidirectional stereo camera exploiting two hyperbolic mirrors and a single set of a…

Image and Video Processing · Electrical Eng. & Systems 2021-08-19 Ryota Kawamata , Keiichi Betsui , Kazuyoshi Yamazaki , Rei Sakakibara , Takeshi Shimano

Semantic objects are unevenly distributed over images. In this paper, we study the spatial disequilibrium problem of modern object detectors and propose to quantify this ``spatial bias'' by measuring the detection performance over zones.…

Computer Vision and Pattern Recognition · Computer Science 2023-01-18 Zhaohui Zheng , Yuming Chen , Qibin Hou , Xiang Li , Ming-Ming Cheng

The use of remote vision sensors for autonomous decision-making poses the challenge of transmitting high-volume visual data over resource-constrained channels in real-time. In robotics and control applications, many systems can quickly…

Information Theory · Computer Science 2026-02-04 Ronald Ogden , David Fridovich-Keil , Takashi Tanaka

In this paper, we propose a novel unsupervised color constancy method, called Probabilistic Color Constancy (PCC). We define a framework for estimating the illumination of a scene by weighting the contribution of different image regions…

Computer Vision and Pattern Recognition · Computer Science 2020-12-24 Firas Laakom , Jenni Raitoharju , Alexandros Iosifidis , Uygar Tuna , Jarno Nikkanen , Moncef Gabbouj

Single-photon sources (SPSs) are mainly characterized by the minimum value of their second-order coherence function, viz. their $g^{(2)}$ function. A precise measurement of $g^{(2)}$ may, however, require high time-resolution devices, in…

Quantum Physics · Physics 2009-09-12 E. Bocquillon , C. Couteau , M. Razavi , R. Laflamme , G. Weihs

Missing channels in radio-interferometric visibility data can introduce systematic artifacts into the estimated 21-cm power spectrum. A common workaround is to first estimate the two-frequency correlation $C(\Delta\nu)$ and then…

Instrumentation and Methods for Astrophysics · Physics 2026-03-27 Khandakar Md Asif Elahi

Optical diffraction tomography is an indispensable tool for studying objects in three-dimensions due to its ability to accurately reconstruct scattering objects. Until now this technique has been limited to coherent light because spatial…

Corner detection is a vital operation in numerous computer vision applications. The Chord-to-Point Distance Accumulation (CPDA) detector is recognized as the contour-based corner detector producing the lowest localization error while…

Computer Vision and Pattern Recognition · Computer Science 2017-08-22 Mohammad Asiful Hossain , Abdul Kawsar Tushar , Shofiullah Babor

Stellar coronagraph performance is highly sensitive to optical aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Hari Subedi , Neil T. Zimmerman , N. Jeremy Kasdin , Kathleen Cavanagh , A J Eldorado Riggs

We present the result from a comprehensive laboratory and on-sky characterization of the commercial spectrograph system consisting of a PIXIS 1300BX charge-coupled device (CCD) camera and an IsoPlane 320A spectrograph as part of the…

Instrumentation and Methods for Astrophysics · Physics 2026-03-10 Jiwon Jang , Changsu Choi , Ho Seong Hwang , Haeun Chung , Hyeonguk Bahk , Dongkok Kim , Jae-Woo Kim

Detection and characterization of exoplanets by direct imaging requires a coronagraph designed to deliver high contrast at small angular separation. To achieve this, an accurate control of low order aberrations, such as pointing and focus…

Instrumentation and Methods for Astrophysics · Physics 2015-06-03 Frédéric P. A. Vogt , Frantz Martinache , Olivier Guyon , Takashi Yoshikawa , Kaito Yokochi , Vincent Garrel , Taro Matsuo

Camera calibration is a crucial step in robotics and computer vision. Accurate camera parameters are necessary to achieve robust applications. Nowadays, camera calibration process consists of adjusting a set of data to a pin-hole model,…

Computer Vision and Pattern Recognition · Computer Science 2024-02-08 Carlos Ricolfe-Viala , Alicia Esparza

Object Detection, a fundamental computer vision problem, has paramount importance in smart camera systems. However, a truly reliable camera system could be achieved if and only if the underlying object detection component is robust enough…

Computer Vision and Pattern Recognition · Computer Science 2022-08-23 Ujjal Kr Dutta

We demonstrate optical coherence tomography based on an SU(1,1) nonlinear interferometer with high-gain parametric down-conversion. For imaging and sensing applications, this scheme promises to outperform previous experiments working at low…

Quantum Physics · Physics 2020-08-31 Gerard J. Machado , Gaetano Frascella , Juan P. Torres , Maria V. Chekhova

This work is concerned with optical imaging in strongly diffusive environments. We consider a typical setting in optical coherence tomography where a sample is probed by a collection of wavefields produced by a laser and propagating through…

Optics · Physics 2024-12-10 Randy Bartels , Olivier Pinaud , Maxine Varughese