Search query: real time high resolution

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abstract: Low signal to noise ratio (SNR) measurements, primarily due to the quartic attenuation of intensity with distance, are arguably the fundamental barrier to real time, high resolution, non line of sight (NLoS) imaging at long standoffs. To better model, characterize, and exploit these low SNR measurements, we use spectral estimation theory to derive a noise model for NLoS correlography. We use this model to develop a speckle correlation based technique for recovering occluded objects from indirect reflections. Then, using only synthetic data sampled from the proposed noise model, and without knowledge of the experimental scenes nor their geometry, we train a deep convolutional neural network to solve the noisy phase retrieval problem associated with correlography. We validate that the resulting deep inverse correlography approach is exceptionally robust to noise, far exceeding the capabilities of existing NLoS systems both in terms of spatial resolution achieved and in terms of total capture time. We use the proposed technique to demonstrate NLoS imaging with 300 um resolution at a 1 m standoff, using just two 1/8th {s}$s exposure length images from a standard complementary metal oxide semiconductor detector.
author_names: Christopher A Metzler

Felix Heide

Prasana Rangarajan

Muralidhar Madabhushi Balaji

Aparna I Viswanath

Ashok Veeraraghavan

Richard Baraniuk
title: Deep inverse correlography: towards real time high resolution non line of sight imaging
year: 2020

abstract: The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid infrared spectral domain optical coherence tomography system operating at a central wavelength of 4 um and an axial resolution of 8.6 um is demonstrated. The system produces two dimensional cross sectional images in real time enabled by a high brightness 0.9 to 4.7 um mid infrared supercontinuum source with a pulse repetition rate of 1 MHz for illumination and broadband upconversion of more than 1 um bandwidth from 3.58 4.63 um to 820 865 nm, where a standard 800 nm spectrometer can be used for fast detection. The images produced by the mid infrared system are compared with those delivered by a state of the art ultra high resolution near infrared optical coherence tomography system operating at 1.3 mm, and the potential applications and samples suited for this technology are discussed. In doing so, the first practical mid infrared optical coherence tomography system is demonstrated, with immediate applications in real time non destructive testing for the inspection of defects and thickness measurements in samples that exhibit strong scattering at shorter wavelengths.Optical Coherence Tomography: Longer wavelengths improve imaging in depthUsing longer wavelengths of light in Optical Coherence Tomography (OCT) imaging allows deeper penetration in highly scattering materials, offering possibilities for OCT in non destructive testing and enhanced non invasive biomedical imaging. OCT images are based on interference patterns generated by combining light reflected from the examined object with reference light that does not encounter the object. It is currently most widely used to examine the retina of the eye. Researchers at the Technical University of Denmark, together with co workers in Austria and the UK, overcame several technical challenges to obtain images using mid infrared light to reveal microscopic structures that are not visible using conventional shorter wavelength near infrared light.The team combined broadband supercontinuum light and frequency upconversion to achieve high resolution and real time image acquisition.Promising applications include advances in defect detection and thickness measurements.
author_names: Niels Moller Israelsen

Christian Rosenberg Petersen

Ajanta Barh

Deepak Jain

Mikkel Jensen

Gunther Hannesschlager

Peter Tidemand-Lichtenberg

Christian Pedersen

Adrian Gh Podoleanu

Ole Bang
title: Real time high resolution mid infrared optical coherence tomography
venue: Light, science applications
year: 2019

abstract: We consider image transformation problems, where an input image is transformed into an output image. Recent methods for such problems typically train feed forward convolutional neural networks using a per pixel loss between the output and ground truth images. Parallel work has shown that high quality images can be generated by defining and optimizing perceptual loss functions based on high level features extracted from pretrained networks. We combine the benefits of both approaches, and propose the use of perceptual loss functions for training feed forward networks for image transformation tasks. We show results on image style transfer, where a feed forward network is trained to solve the optimization problem proposed by Gatys et al. in real time. Compared to the optimization based method, our network gives similar qualitative results but is three orders of magnitude faster. We also experiment with single image super resolution, where replacing a per pixel loss with a perceptual loss gives visually pleasing results.
author_names: Justin Johnson

Alexandre Alahi

Li Fei-Fei
title: Perceptual Losses for Real Time Style Transfer and Super Resolution
venue: ECCV
year: 2016

abstract: We introduce a real time, high resolution background replacement technique which operates at 30fps in 4K resolution, and 60fps for HD on a modern GPU. Our technique is based on background matting, where an additional frame of the background is captured and used in recovering the alpha matte and the foreground layer. The main challenge is to compute a high quality alpha matte, preserving strand level hair details, while processing high resolution images in real time. To achieve this goal, we employ two neural networks; a base network computes a low resolution result which is refined by a second network operating at high resolution on selective patches. We introduce two largescale video and image matting datasets: VideoMatte240K and PhotoMatte13K/85. Our approach yields higher quality results compared to the previous state of the art in background matting, while simultaneously yielding a dramatic boost in both speed and resolution.
author_names: Shanchuan Lin

Andrey Ryabtsev

Soumyadip Sengupta

Brian Curless

Steven M Seitz

Ira Kemelmacher-Shlizerman
title: Real Time High Resolution Background Matting
venue: CVPR
year: 2021

abstract: Fluorescence Imaging technology combined with a thin, linear response fluorescent plate and a camera was developed for real time 2D beam profiling of a raw beam of a high power laser in the wavelength range from blue to near infrared. The input laser beam was slightly absorbed on the fluorescent plate in front top of the profiler body and generated 2D fluorescence image, that was precise reproduction of the laser beam profile at the place, was reimaged by a camera at the back side of the profiler. The laser beam that transferred the fluorescent plate was separated by a dichroic mirror and outputted from the body. >99% energy of the input laser beam transferred the fluorescent plate, then the heat generation in the fluorescent plate was very low. This made long time, stable measurement of the high power, raw laser beam profile possible. >2MW/cm2 damage threshold of the fluorescent plate and the efficient heat management made direct measurement of >100W laser beam profiles possible without any attenuators and any computer aided image reconstructions. Speckle free and interference fringe free, high resolution images were also successfully obtained by the incoherent fluorescence reimaging.
author_names: Masaki Tsunekane

K Sato

Takehiro Takahashi

S Yoshino

N Yoshimori

J Ohno
title: Direct, real time, high resolution beam profiler for high power laser
venue: LASE
year: 2020

author_names: Florian Friess

Christoph Muller

Thomas Ertl
title: Real time High resolution Visualisation
venue: VMV
year: 2020

abstract: The recent appearance of augmented reality headsets, such as the Microsoft HoloLens, is a marked move from traditional 2D screen to 3D hologram like interfaces. Striving to be completely portable, these devices unfortunately suffer multiple limitations, such as the lack of real time, high quality depth data, which severely restricts their use as research tools. To mitigate this restriction, we provide a simple method to augment a HoloLens headset with much higher resolution depth data. To do so, we calibrate an external depth sensor connected to a computer stick that communicates with the HoloLens headset in real time. To show how this system could be useful to the research community, we present an implementation of small object detection on HoloLens device.
author_names: Mathieu Garon

Pierre-Olivier Boulet

Jean-Philippe Doironz

Luc Beaulieu

Jean-Francois Lalonde
title: Real Time High Resolution 3D Data on the HoloLens
venue: 2016 IEEE International Symposium on Mixed and Augmented Reality (ISMAR Adjunct)
year: 2016

abstract: Forensic hair evidence can be used to obtain retrospective timelines of drug use by analysis of hair segments. However, this is a laborious and time consuming process, and mass spectrometric (MS) imaging techniques, which show great potential for single hair targeted analysis, are less useful due to differences in hair growth rate between individual hairs. As an alternative, a fast untargeted analysis method was developed that uses direct analysis in real time high resolution mass spectrometry (DART HRMS) to longitudinally scan intact locks of hair without extensive sample preparation or segmentation. The hair scan method was validated for cocaine against an accredited liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. The detection limit for cocaine in hair was found to comply with the cutoff value of 0.5 ng/mg recommended by the Society of Hair Testing; that is, the DART hair scan method is amenable to forensic cases. Under DART conditions, no significant thermal degradation of cocaine occurred. The standard DART spot size of 5.1 1.1 mm could be improved to 3.3 1.0 mm, corresponding to approximately 10 days of hair growth, by using a high spatial resolution exit cone. By use of data dependent product ion scans, multiple drugs of abuse could be detected in a single drug user hair scan with confirmation of identity by both exact mass and MS/HRMS fragmentation patterns. Furthermore, full scan high resolution data were retrospectively interrogated versus a list of more than 100 compounds and revealed additional hits and temporal profiles in good correlation with reported drug use.
author_names: Wilco F Duvivier

Marc R van Putten

Teris A van Beek

Michel W F Nielen
title: (Un)targeted Scanning of Locks of Hair for Drugs of Abuse by Direct Analysis in Real Time High Resolution Mass Spectrometry.
venue: Analytical chemistry
year: 2016

abstract: Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio temporal intensity measurements that allows the characterisation of such complex sources. Fast, round trip resolved spectral dynamics of cavity based systems in real time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated) We also show how under certain conditions for quasi continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach.
author_names: Srikanth Sugavanam

Simon J Fabbri

Son Thai Le

Ivan A Lobach

Sergey I Kablukov

Serge Khorev

Dmitry V Churkin
title: Real time high resolution heterodyne based measurements of spectral dynamics in fibre lasers
venue: Scientific reports
year: 2016

abstract: We present a system for real time, high resolution, sparse voxelization of an image based surface model. Our approach consists of a coarse to fine voxel representation and a collection of parallel processing steps. Voxels are stored as a list of unsigned integer triples. An oracle kernel decides, for each voxel in parallel, whether to keep or cull its voxel from the list based on an image consistency criterion of its projection across cameras. After a prefix sum scan, kept voxels are subdivided and the process repeats until projected voxels are pixel size. These voxels are drawn to a render target and shaded as a weighted combination of their projections into a set of calibrated RGB images. We apply this technique to the problem of smooth visual hull reconstruction of human subjects based on a set of live image streams. We demonstrate that human upper body shapes can be reconstructed to giga voxel resolution at greater than 30 fps on modern graphics hardware.
author_names: Charles T Loop

Cha Zhang

Zhengyou Zhang
title: Real time high resolution sparse voxelization with application to image based modeling
venue: HPG '13
year: 2013