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We describe a new instrument that forms the core of a long-term high contrast imaging program at the 200-inch Hale Telescope at Palomar Observatory. The primary scientific thrust is to obtain images and low-resolution spectroscopy of brown…

Context. In the context of direct imaging of exoplanets, coronagraphs are commonly proposed to reach the required very high contrast levels. However, wavefront aberrations induce speckles in their focal plane and limit their performance.…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 Johan Mazoyer , Pierre Baudoz , Raphaël Galicher , Gérard Rousset

Restore lost images due to noise and blurred is a burgeoning subject in image processing and despite the different algorithms on this subject, but the effort to improve is always considered. The definition of fractional derivatives in…

Information Theory · Computer Science 2021-10-29 Reza Parvaz

Recent methods for learning unsupervised visual representations, dubbed contrastive learning, optimize the noise-contrastive estimation (NCE) bound on mutual information between two views of an image. NCE uses randomly sampled negative…

Machine Learning · Computer Science 2020-10-06 Mike Wu , Milan Mosse , Chengxu Zhuang , Daniel Yamins , Noah Goodman

The acquisition of MRI images offers a trade-off in terms of acquisition time, spatial/temporal resolution and signal-to-noise ratio (SNR). Thus, for instance, increasing the time efficiency of MRI often comes at the expense of reduced SNR.…

Computer Vision and Pattern Recognition · Computer Science 2011-10-28 Sudipto Dolui , Alan Kuurstra , Iván C. Salgado Patarroyo , Oleg V. Michailovich

Iodinated contrast media is essential for dual-energy computed tomography (DECT) angiography. Previous studies show that iodinated contrast media may cause side effects, and the interruption of the supply chain in 2022 led to a severe…

Image and Video Processing · Electrical Eng. & Systems 2023-08-28 Qing Lyu , Josh Tan , Megan E. Lipford , Chuang Niu , Micheal E. Zapadka , Christopher M. Lack , Jonathan D. Clemente , Christopher T. Whitlow , Ge Wang

Diffusion models have established new state of the art in a multitude of computer vision tasks, including image restoration. Diffusion-based inverse problem solvers generate reconstructions of exceptional visual quality from heavily…

Image and Video Processing · Electrical Eng. & Systems 2024-08-21 Zalan Fabian , Berk Tinaz , Mahdi Soltanolkotabi

NACO is the famous and versatile diffraction limited NIR imager and spectrograph with which ESO celebrated 10 years of Adaptive Optics at the VLT. Since two years a substantial effort has been put in to understanding and fixing issues that…

Instrumentation and Methods for Astrophysics · Physics 2012-10-12 Julien H. V. Girard , Jared O'Neal , Dimitri Mawet , Markus Kasper , Gérard Zins , Benoît Neichel , Johann Kolb , Valentin Christiaens , Martin Tourneboeuf

Image deblurring is an ill-posed problem with multiple plausible solutions for a given input image. However, most existing methods produce a deterministic estimate of the clean image and are trained to minimize pixel-level distortion. These…

Computer Vision and Pattern Recognition · Computer Science 2021-12-30 Jay Whang , Mauricio Delbracio , Hossein Talebi , Chitwan Saharia , Alexandros G. Dimakis , Peyman Milanfar

For imaging of static object by the means of sequential repeated independent measurements, a theoretical modeling of the behavior of signal-to-noise ratio (SNR) with varying number of measurement is developed, based on the information…

Optics · Physics 2016-03-02 Junhui Li , Bin Luo , Dongyue Yang , Guohua Wu , Longfei Yin , Hong Guo

Long lasting efforts have been made to reduce radiation dose and thus the potential radiation risk to the patient for computed tomography acquisitions without severe deterioration of image quality. To this end, numerous reconstruction and…

Medical Physics · Physics 2024-10-07 Elias Eulig , Björn Ommer , Marc Kachelrieß

Contrastive learning relies on an assumption that positive pairs contain related views, e.g., patches of an image or co-occurring multimodal signals of a video, that share certain underlying information about an instance. But what if this…

Computer Vision and Pattern Recognition · Computer Science 2022-01-13 Ching-Yao Chuang , R Devon Hjelm , Xin Wang , Vibhav Vineet , Neel Joshi , Antonio Torralba , Stefanie Jegelka , Yale Song

The behavior of an adaptive optics (AO) system for ground-based high contrast imaging (HCI) dictates the achievable contrast of the instrument. In conditions where the coherence time of the atmosphere is short compared to the speed of the…

Instrumentation and Methods for Astrophysics · Physics 2021-08-23 Maaike A. M. van Kooten , Rebecca Jensen-Clem , Sylvain Cetre , Sam Ragland , Charlotte Z. Bond , J. Fowler , Peter Wizinowich

The use of CT imaging is important for screening, diagnosis, therapy planning, and prognosis of lung cancers. Unfortunately, due to differences in imaging protocols and scanner models, CT images acquired by different means may show large…

Computer Vision and Pattern Recognition · Computer Science 2026-05-05 Md Shifatul Ahsan Apurba , Md Selim , Jin Chen

The purpose of this study is to investigate a method, using simulations, to improve contrast agent quantification in Dynamic Contrast Enhanced MRI. Bayesian hierarchical models (BHMs) are applied to smaller images ($10\times10\times10$)…

Applications · Statistics 2017-01-24 Jianfeng Wang , Anders Garpebring , Patrik Brynolfsson , Xijia Liu , Jun Yu

CNNs perform remarkably well when the training and test distributions are i.i.d, but unseen image corruptions can cause a surprisingly large drop in performance. In various real scenarios, unexpected distortions, such as random noise,…

Computer Vision and Pattern Recognition · Computer Science 2021-03-31 Tonmoy Saikia , Cordelia Schmid , Thomas Brox

Resolution, usually defined by the Rayleigh criterion or the Full Width at Half Maximum of a Point Spread Function, is a basic property of an image. Here, we present a new statistical definition of image resolution based on the…

Instrumentation and Methods for Astrophysics · Physics 2015-10-29 Jian-Feng Zhou

Computational ghost imaging generally requires a large number of pattern illumination to obtain a high-quality image. The colored noise speckle pattern was recently proposed to substitute the white noise pattern in a variety of noisy…

Optics · Physics 2022-10-11 Xiaoyu Nie , Xingchen Zhao , Tao Peng , Marlan O. Scully

X-ray imaging is the most widely used medical imaging modality. However, in the common practice, inconsistency in the initial presentation of X-ray images is a common complaint by radiologists. Different patient positions, patient habitus…

Image and Video Processing · Electrical Eng. & Systems 2025-01-22 Hongxu Yang , Najib Akram Aboobacker , Xiaomeng Dong , German Gonzalez , Lehel Ferenczi , Gopal Avinash

Estimation of a deterministic quantity observed in non-Gaussian additive noise is explored via order statistics approach. More specifically, we study the estimation problem when measurement noises either have positive supports or follow a…

Signal Processing · Electrical Eng. & Systems 2020-07-15 Kamiar Radnosrati , Gustaf Hendeby , Fredrik Gustafsson