1,183 research outputs found
Combining local regularity estimation and total variation optimization for scale-free texture segmentation
Texture segmentation constitutes a standard image processing task, crucial to
many applications. The present contribution focuses on the particular subset of
scale-free textures and its originality resides in the combination of three key
ingredients: First, texture characterization relies on the concept of local
regularity ; Second, estimation of local regularity is based on new multiscale
quantities referred to as wavelet leaders ; Third, segmentation from local
regularity faces a fundamental bias variance trade-off: In nature, local
regularity estimation shows high variability that impairs the detection of
changes, while a posteriori smoothing of regularity estimates precludes from
locating correctly changes. Instead, the present contribution proposes several
variational problem formulations based on total variation and proximal
resolutions that effectively circumvent this trade-off. Estimation and
segmentation performance for the proposed procedures are quantified and
compared on synthetic as well as on real-world textures
Mathematics and Digital Signal Processing
Modern computer technology has opened up new opportunities for the development of digital signal processing methods. The applications of digital signal processing have expanded significantly and today include audio and speech processing, sonar, radar, and other sensor array processing, spectral density estimation, statistical signal processing, digital image processing, signal processing for telecommunications, control systems, biomedical engineering, and seismology, among others. This Special Issue is aimed at wide coverage of the problems of digital signal processing, from mathematical modeling to the implementation of problem-oriented systems. The basis of digital signal processing is digital filtering. Wavelet analysis implements multiscale signal processing and is used to solve applied problems of de-noising and compression. Processing of visual information, including image and video processing and pattern recognition, is actively used in robotic systems and industrial processes control today. Improving digital signal processing circuits and developing new signal processing systems can improve the technical characteristics of many digital devices. The development of new methods of artificial intelligence, including artificial neural networks and brain-computer interfaces, opens up new prospects for the creation of smart technology. This Special Issue contains the latest technological developments in mathematics and digital signal processing. The stated results are of interest to researchers in the field of applied mathematics and developers of modern digital signal processing systems
Modeling and rendering for development of a virtual bone surgery system
A virtual bone surgery system is developed to provide the potential of a realistic, safe, and controllable environment for surgical education. It can be used for training in orthopedic surgery, as well as for planning and rehearsal of bone surgery procedures...Using the developed system, the user can perform virtual bone surgery by simultaneously seeing bone material removal through a graphic display device, feeling the force via a haptic deice, and hearing the sound of tool-bone interaction --Abstract, page iii
Parameter optimization for local polynomial approximation based intersection confidence interval filter using genetic algorithm: an application for brain MRI image de-noising
Magnetic resonance imaging (MRI) is extensively exploited for more accuratepathological changes as well as diagnosis. Conversely, MRI suffers from variousshortcomings such as ambient noise from the environment, acquisition noise from theequipment, the presence of background tissue, breathing motion, body fat, etc.Consequently, noise reduction is critical as diverse types of the generated noise limit the efficiency of the medical image diagnosis. Local polynomial approximation basedintersection confidence interval (LPA-ICI) filter is one of the effective de-noising filters.This filter requires an adjustment of the ICI parameters for efficient window size selection.From the wide range of ICI parametric values, finding out the best set of tunes values is itselfan optimization problem. The present study proposed a novel technique for parameteroptimization of LPA-ICI filter using genetic algorithm (GA) for brain MR imagesde-noising. The experimental results proved that the proposed method outperforms theLPA-ICI method for de-noising in terms of various performance metrics for different noisevariance levels. Obtained results reports that the ICI parameter values depend on the noisevariance and the concerned under test image
Motion-resilient Heart Rate Monitoring with In-ear Microphones
With the soaring adoption of in-ear wearables, the research community has
started investigating suitable in-ear heart rate (HR) detection systems. HR is
a key physiological marker of cardiovascular health and physical fitness.
Continuous and reliable HR monitoring with wearable devices has therefore
gained increasing attention in recent years. Existing HR detection systems in
wearables mainly rely on photoplethysmography (PPG) sensors, however, these are
notorious for poor performance in the presence of human motion. In this work,
leveraging the occlusion effect that can enhance low-frequency bone-conducted
sounds in the ear canal, we investigate for the first time \textit{in-ear
audio-based motion-resilient} HR monitoring. We first collected the HR-induced
sound in the ear canal leveraging an in-ear microphone under stationary and
three different activities (i.e., walking, running, and speaking). Then, we
devise a novel deep learning based motion artefact (MA) mitigation framework to
denoise the in-ear audio signals, followed by an HR estimation algorithm to
extract HR. With data collected from 20 subjects over four activities, we
demonstrate that hEARt, our end-to-end approach, achieves a mean absolute error
(MAE) of 5.466.50BPM, 12.349.24BPM, 14.2210.69BPM and
15.4411.43BPM for stationary, walking, running and speaking, respectively,
opening the door to a new non-invasive and affordable HR monitoring with usable
performance for daily activities. Not only does the performance hEARt
outperform that of previous in-ear HR monitoring work, but is comparable (and
even better whenever full-body motion is concerned) to that reported by in-ear
PPG works
Communication dans le bruit : perception de sa propre voix et rehaussement de la parole
La communication dans le bruit est un problĂšme de tous les jours pour les travailleurs qui oeuvrent dans des environnements industriels bruyants. Un grand nombre de travailleurs se plaignent du fait que leurs protecteurs auditifs les empĂȘchent de communiquer facilement avec leurs collĂšgues. Ils ont alors tendance Ă retirer leurs protecteurs et mettent ainsi leur audition Ă risque. Ce problĂšme de communication est en fait double : les protecteurs modifient Ă la fois la perception de la propre voix du porteur, ainsi que la comprĂ©hension de la parole des autres personnes. Cette double problĂ©matique est considĂ©rĂ©e dans le cadre de cette thĂšse.
La modification de la perception de la propre voix du porteur des protecteurs est en partie due Ă lâeffet dâocclusion qui se produit lorsque le conduit auditif est occlus par un bouchon dâoreille. Cet effet dâocclusion se traduit essentiellement par une amĂ©lioration de la perception des sons de basses frĂ©quences internes Ă lâĂȘtre humain (bruits physiologiques), et par une modification de la perception de la propre voix de la personne. Dans le but de mieux comprendre ce phĂ©nomĂšne, suite Ă une Ă©tude approfondie de ce qui se trouve dĂ©jĂ dans la littĂ©rature, une nouvelle mĂ©thode pour quantifier lâeffet dâocclusion a Ă©tĂ© dĂ©veloppĂ©e. Au lieu dâexciter la boite crĂąnienne du sujet au moyen dâun pot vibrant ou de faire parler le sujet, comme il se fait classiquement dans la littĂ©rature, il a Ă©tĂ© dĂ©cidĂ© dâexciter la cavitĂ© buccale des sujets au moyen dâune onde sonore. LâexpĂ©rience a Ă©tĂ© conçue de telle maniĂšre que lâonde sonore qui excite la cavitĂ© buccale nâexcite pas lâoreille externe ou le reste du corps directement. La dĂ©termination des seuils auditifs en oreilles ouvertes et occluses a ainsi permis de quantifier un effet dâocclusion subjectif pour une onde sonore dans le conduit buccal. Ces rĂ©sultats ainsi que les autres quantifications dâeffet dâocclusion prĂ©sentĂ©es dans la littĂ©rature ont permis de mieux comprendre le phĂ©nomĂšne de lâeffet dâocclusion et dâĂ©valuer lâinfluence des diffĂ©rents chemins de transmission entre la source sonore et lâoreille interne.
La comprĂ©hension de la parole des autres personnes est altĂ©rĂ©e Ă la fois par le fort niveau sonore prĂ©sent dans les environnements industriels bruyants et par lâattĂ©nuation du signal de parole due aux protecteurs auditifs. Une possibilitĂ© envisageable pour remĂ©dier Ă ce problĂšme est de dĂ©bruiter le signal de parole puis de le transmettre sous le protecteur auditif. De nombreuses techniques de dÂŽebruitage existent et sont utilisĂ©es notamment pour dĂ©bruiter la parole en tĂ©lĂ©communication. Dans le cadre de cette thĂšse, le dĂ©bruitage par seuillage dâondelettes est considĂ©rĂ©. Une premiĂšre Ă©tude des techniques âclassiquesâ de dĂ©bruitage par ondelettes est rĂ©alisĂ©e afin dâĂ©valuer leurs performances dans un environnement industriel bruyant. Ainsi les signaux de paroles testĂ©s sont altĂ©rĂ©s par des bruits industriels selon une large de gamme de rapports signal Ă bruit. Les signaux dĂ©bruitĂ©s sont Ă©valuĂ©s au moyen de quatre critĂšres. Une importante base de donnĂ©es est ainsi obtenue et est analysĂ©e au moyen dâun algorithme de sĂ©lection conçue spĂ©cifiquement pour cette tĂąche. Cette premiĂšre Ă©tude a permis de mettre en Ă©vidence lâinfluence des diffĂšrents paramĂȘtres du dĂ©bruitage par ondelettes sur la qualitĂ© de celui-ci et ainsi de dĂ©terminer la mĂ©thode âclassiqueâ qui permet dâobtenir les meilleures performances en terme de qualitĂ© de dĂ©bruitage. Cette premiĂšre Ă©tude a Ă©galement permis de donner des guides pour la conception dâune nouvelle loi de seuillage adaptĂ©e au dĂ©bruitage de la parole par ondelettes dans un environnement industriel bruitĂ©. Cette nouvelle loi de seuillage est prĂ©sentĂ©e et Ă©valuĂ©e dans le cadre dâune deuxiĂšme Ă©tude. Ses performances se sont avĂ©rĂ©es supĂ©rieures Ă la mĂ©thode âclassiqueâ mise en Ă©vidence dans la premiĂšre Ă©tude pour des signaux de parole dont le rapport signal Ă bruit est compris entre â10 dB et 15 dB
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ReSCon '09, Research Student Conference: Book of Abstracts
The second SED Research Student Conference (ReSCon2009) was hosted over three days, 22-24 June 2009, in the Lecture Centre at Brunel University. The conference consisted of technical presentations, a poster session and social events. The abstracts and presentations were the result of ongoing research by postgraduate research students from the School of Engineering and Design at Brunel University. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School
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