- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - A Co-occurrence Background Model with Hypothesis on Degradation Modification for Object Detection in Strong Background Changes
摘要： Object detection has become an indispensable part of video processing and current background models are sensitive to background changes. In this paper, we propose a novel background model using an algorithm called Co-occurrence Pixel-block Pairs (CPB) against background changes, such as illumination changes and background motion. We utilize the co-occurrence “pixel to block” structure to extract the spatial-temporal information of each pixel to build background model, and then employ an efficient evaluation strategy to identify the current state of each pixel, which is named as correlation dependent decision function. Furthermore, we also introduce a Hypothesis on Degradation Modification (HoD) into CPB structure to reinforce the robustness of CPB. Experimental results obtained from the dataset of the PETS2001, AIST-Indoor, SBMnet and CDW-2012 databases show that our model can detect objects robustly in strong background changes.
关键词： co-occurrence pixel-block pairs,background model,Object detection,hypothesis on degradation modification
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rome, Italy (2018.6.11-2018.6.13)] 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Feasibility of Photoplethysmography Imaging of the Sole of the Foot
摘要： In photoplethysmography imaging the blood volume pulse is extracted from subtle skin color variations recorded with a camera. In most works, the camera is oriented towards the face or the palm of the hand. Recently, it has been shown that applying contact force to the skin, e.g. through contact with a glass plate, increases signal strength. However, this approach is prohibitive for the face and there are applications where the hands are not accessible. In this paper, we address this issue by applying photoplethysmography imaging to the sole of the foot, which is placed on a glass plate and exposed to controlled illumination. We investigate (1) whether this setup acquires signals with an adequate signal-to-noise ratio and (2) whether the feet can be used as a replacement for the more commonly used hands. Additionally, we analyze (3) whether using a carefully selected pixel subset instead of all pixels improves signal-to-noise ratio. We report on experimental data from N=21 healthy subjects that we make publicly available1. We applied photoplethysmography imaging to the sole of the foot and the palm of the hand and used a commercial ?nger photoplethysmography unit as ground truth. It is problematic that there is no established best practice for signal-to-noise estimation in PPGi research; hence we use ?ve different metrics with three from literature. Additionally, we compare the agreement of these metrics using the experimental data. Our results show that (1) the proposed setup acquires signals with an adequate signal-to-noise ratio, (2) using all pixels from foot videos results in slightly inferior performance compared to the hand, but (3) using pixel subsets improves signal quality at the foot to the level of the hand. These results pave the way for the development of a photoplethysmography imaging setup applied at the sole of the foot for different medical applications.
关键词： photoplethysmography imaging,blood volume pulse,signal-to-noise ratio,medical applications,pixel subset
更新于2025-09-09 09:28:46
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Text embedding using image steganography in spatial domain
摘要： This paper proposed novel approach of image steganography for text embedding in spatial domain. In the proposed embedding the message is dumped into the image with reference to a random generated key, based on this key the extraction of text is done from the image. So this method is a highly secured from eavesdropping and highly complex to identify the text data in the image and retrieving the text message from the message is also a resilient process. The extraction is only possible when the key is known.
关键词： Image steganography,pixel modification,steganography in spatial domain
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Sheffield (2018.7.8-2018.7.11)] 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - New Theory for Unmixing ILL-Conditioned Hyperspectral Mixtures
摘要： Hyperspectral unmixing (HU), a blind source separation problem, aims at unambiguiously identifying the spectral signatures of the materials, as well as their abundances, from the measured hyperspectral mixtures. In real hyperspectral scenes, high correlation between the spectral signatures is commonly observed, making HU quite challenging. Although such ill-conditioning is critical for effective HU, it is often ignored in existing HU literature. To the best of our knowledge, existing preconditioning techniques, for reducing the condition number of the signature matrix, were developed based on the pure-pixel assumption, which can, however, be seriously violated in remote sensing. Under a relaxed purity assumption, with respect to the pure-pixel one, this paper proposes novel theory for unmixing ill-conditioned hyperspectral mixtures. Specifically, we exactly identify the John’s ellipsoid (i.e., the maximum ellipsoid inscribed in the convex hull of the hyperspectral data vectors) via split augmented Lagrangian shrinkage algorithm (SALSA), and transform this ellipsoid into an Euclidean ball. This transformation brings the data vectors into a new space wherein the corresponding material signature vectors form a regular simplex, which is a very strong prior information. Based on this prior, we design an HU criterion, and prove its perfect identifiability under a very mild sufficient condition. Then, we demonstrate the feasibility of realizing our criterion via non-convex optimization and guarantee a stationary point solution.
关键词： split augmented Lagrangian shrinkage algorithm,Hyperspectral unmixing,pure-pixel assumption,non-convex optimization,John’s ellipsoid
更新于2025-09-09 09:28:46
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Dual-mode phase-shifting interferometry based on iterative algorithms
摘要： Interferometry is a fundamental and powerful method for optical path difference (OPD) measurement. The application of phase shifting strategy offers interferometry great opportunities to be used to full-field measurement, such as three-dimensional imaging, physical field sensing, and surface measurement. The advantages of phase-shifting interferometry (PSI), high resolutions in both transverse and depth, derive from its temporal phase shifting operation, during which the OPD increases (or decreases) step by step regularly. However, at the same time phase shifting constitutes its main disadvantage that is the sensitivity to environmental vibration. In the phase shifting process, the OPD increment is very tiny, usually tens of nanometres, and therefore is easily disturbed by environmental unsteady factors. Due to the phase-shifting error caused by vibration, traditional phase extraction algorithms [1] are not suitable and researchers have developed many methods to minimise the effect of vibration on PSI, such as simultaneous phase shifting method [2,3] and phase-shifting error detection and compensation method [4,5]. Both the two methods require modification of the interferometer and the configuration is elaborate. Recently, general phase retrieval algorithms have been proposed to retrieve wavefront phase from interferograms with arbitrary phase shifts [6-9], predicating potential of vibration resistance. Based on the relationship that a fringe corresponds to 2π phase, general phase retrieval algorithms evaluate the phase shift by analysing interference fringes and then calculate the wavefront phase with least-squares (LS) method. Among these general phase retrieval algorithms, iterative algorithms [10-14] exhibit good performance and are appealing, because there is no restriction on the measured surfaces and less approximation in the calculation. Iterative algorithms treat the wavefront phase as an unknown, construct algebraic equations with collected phase-shifting interferograms and solve equations with iteration. However, iterative algorithms require an initial value as the starting point, and the convergence of iteration largely depends on the deviation of initial value to the actual value. Because the actual value is unknown, the vibration resistance of an iterative algorithm depends on the estimating accuracy of initial value. Usually the initial value for the iterative calculation is the preset phase shift amount. In weak vibration, the actual phase shift deviates a little from the preset value; thus the iteration converges rapidly and achieves the accurate result. Conversely, in severe vibration, the actual phase shift deviates greatly from the preset value, and thus the iteration may not converge to the accurate result and fails to calculate wavefront phase. On the other hand, an estimated wavefront phase could be input as an initial value for iterative algorithms as well [12,15]. In reference [12], because the wavefront phase is estimated with a traditional phase retrieval algorithm and contains large error, the iteration is difficult to converge to the accurate value. In reference [15], the wavefront phase is estimated from a spatial-carrier interferogram that is insensitive to vibration. However, in implementation a tilting of the measured surface is needed to introduce a spatial carrier. Thus, a transverse movement of the measured surface may occur during the tilting and consequently makes the method fail. In this paper we propose a dual-mode phase-shifting interferometry (DMPSI) to enhance the vibration resistance of iterative algorithms, which utilises binning function of the camera. The basic principle of DMPSI is estimating the wavefront phase from a series of rapidly collected interferograms and using the estimation as initial value of the iterative calculation with high-resolution interferograms. This method does not rely on the hardware of interferometers but a camera having binning function. Hence, DMPSI is applicable to any type of interferometers. We first investigate the sensitivity of a representative iterative algorithm to vibration and then detail the principle of DMPSI. Finally simulations and an experiment are presented to exhibit the effectiveness of DMPSI.
关键词： Surface measurement,Phase-shifting interferometry,Pixel binning,Iterative algorithms
更新于2025-09-09 09:28:46
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Geometry optimization of a barrel silicon pixelated tracker
摘要： We have studied optimization of the design of a barrel-shaped pixelated tracker for given spatial boundaries. The optimization includes choice of number of layers and layer spacing. Focusing on tracking performance only, momentum resolution is chosen as the (cid:12)gure of merit. The layer spacing is studied based on Gluckstern’s method and a numerical geometry scan of all possible tracker layouts. A formula to give the optimal geometry for curvature measurement is derived in the case of negligible multiple scattering to deal with trajectories of very high momentum particles. The result is validated by a numerical scan method, which could also be implemented with any track (cid:12)tting algorithm involving material e(cid:11)ects, to search for the optimal layer spacing and to determine the total number of layers for the momentum range of interest under the same magnetic (cid:12)eld. The geometry optimization of an inner silicon pixel tracker proposed for BESIII is also studied by using a numerical scan and these results are compared with Geant4-based simulations.
关键词： least squares,numerical scan,BESIII silicon pixel tracker,optimal spacing,kalman (cid:12)lter initialization,tracker geometry optimization
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Moving Target Detection and Tracking Based on Pyramid Lucas-Kanade Optical Flow
摘要： In order to enable the optical flow to track larger and faster moving targets, pyramid Lucas-Kanade optical flow method is used to detect and track moving targets. First, detecting the corners which is easy to track, in order to improve the tracking accuracy, detected corners and then calculate the sub-pixel corner, and then the video in each frame of the image layered in the image pyramid to calculate the optical flow at the top corner, use the next pyramid as the starting point of the pyramid and repeat this process until the bottom pyramid image, which can overcome the Lucas-Kanade optical flow method cannot track faster and larger movements the shortcomings, to achieve the tracking of moving goals.
关键词： pyramid Lucas-Kanade optical flow,corner detection,sub-pixel corner,target tracking
更新于2025-09-09 09:28:46
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A New Probabilistic Representation of Color Image Pixels and Its Applications
摘要： This paper proposes a novel probabilistic representation of color image pixels (PRCI) and investigates its applications to similarity construction in motion estimation and image segmentation problems. The PRCI explores the mixture representation of the input image(s) as prior information and describes a given color pixel in terms of its membership in the mixture. Such representation greatly simplifies the estimation of the probability density function from limited observations and allows us to derive a new probabilistic pixel-wise similarity measure based on the continuous domain Bhattacharyya coefficient. This yields a convenient expression of the similarity measure in terms of the pixel memberships. Furthermore, this pixel-wise similarity is extended to measure the similarity between two image regions. The usefulness of the proposed pixel/region-wise similarities is demonstrated by incorporating them respectively in a dense image descriptor-based multi-layered motion estimation problem and an unsupervised image segmentation problem. Experimental results show that i) the integration of the proposed pixel-wise similarity in dense image-descriptor construction yields improved peak signal to noise ratio performance and higher tracking accuracy in the multi-layered motion estimation problem, and ii) the proposed similarity measures give the best performance in terms of all quantitative measurements in the unsupervised superpixel-based image segmentation of the MSRC and BSD300 datasets.
关键词： Pixel-wise similarity,registration,Region-wise similarity,Image matching,and segmentation,Image descriptors,Probabilistic color representation
更新于2025-09-09 09:28:46
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Performance of CMOS pixel sensor prototypes in ams H35 and aH18 technology for the ATLAS ITk upgrade
摘要： Pixel sensors based on commercial high-voltage CMOS processes are an exciting technology that is considered as an option for the outer layer of the ATLAS inner tracker upgrade at the High Luminosity LHC. Here, charged particles are detected using deep n-wells as sensor diodes with the depleted region extending into the silicon bulk. Both analog and digital readout electronics can be added to achieve different levels of integration up to a fully monolithic sensor. Small scale prototypes using the ams CMOS technology have previously demonstrated that it can achieve the required radiation tolerance of 1015 neq∕cm2 and detection efficiencies above 99.5%. Recently, large area prototypes, comparable in size to a full sensor, have been produced that include most features required towards a final design: the H35demo prototype produced in ams H35 technology that supports both external and integrated readout and the monolithic ATLASPix1 pre-production design produced in ams aH18 technology. Both chips are based on large fill-factor pixel designs, but differ in readout structure. Performance results for H35DEMO with capacitively-coupled external readout and first results for the monolithic ATLASPix1 are shown.
关键词： HV-MAPS,Silicon pixel sensor,Monolithic active pixel sensor,High luminosity LHC,ATLAS ITk upgrade,CMOS
更新于2025-09-04 15:30:14
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Dose and Single Event Effects on a Color CMOS Camera for Space Exploration
摘要： This paper focuses on the radiation-induced dose and single event effects on a color CMOS camera designed for space missions. Gamma-ray and protons are used to evaluate the tolerance against cumulative dose effects. The dark current of the image sensor is the main parameter impacted by dose effects. Heavy ions testing is performed to evaluate single event effects. SEU, SEFI and SEL have been observed and mitigation techniques were proposed for specific space missions.
关键词： Total Ionizing Dose (TID),Microlens,CMOS Image Sensor (CIS),Single Event Effects (SEE),Displacement Damage Dose (DDD),Pinned Photodiode (PPD),Active Pixel Sensor (APS),Monolithic Active Pixel Sensor (MAPS),Camera,Color filter,Random Telegraph Signal (RTS)
更新于2025-09-04 15:30:14