Search results for " image processing."
showing 10 items of 2265 documents
Approche multicritère pour la caractérisation des adventices par imagerie
2019
La réduction des produits phytosanitaires représente un des enjeux majeurs du secteur agricole. Les plans gouvernementaux Ecophyto, Ecophyto II et Ecophyto II+ visent à réduire fortement leurs usages et les solutions actuelles ne permettent pas d’obtenir les résultats escomptés. La détection des adventices par imagerie est un des axes de travail devant permettre cette réduction. La qualité de la discrimination cultures/adventices est fortement liée au type de méthodes utilisées, à la résolution spatiale des images et au stade de développement des plantes présentes. L'objectif de ce travail, est donc d'évaluer l’impact des différents critères pouvant être extraits depuis des images acquises …
A nonlinear derivative
2014
International audience; A nonlinear derivative is directly defined in the discrete domain. This derivative is motivated by the asymmetry of pattern in discrete signal as step or edge in 2D signal. Thanks to the special definition (in the discrete domain) of this derivative, pattern can be detected in a univocal way. This derivative is the only one able to perfectly detect and localize ideal edges in image. Beside this fundamental benefit, the derivative has the nice property to reduce noise. Ap- plications to edge detection, noise reduction and noise estimation are described and their performances are studied.
Novel weighting and resampling schemes in Population Monte Carlo
2017
International audience; In this paper we focus on novel population Monte Carlo schemes that present added flexibility and superior performance compared to the standard approach. The new schemes combine different weighting and resampling strategies to achieve more efficient performance at the cost of a reasonable computational complexity increment. Computer simulations compare the different alternatives when applied to the problem of frequency estimation in superimposed sinusoids.; Dans cet article, nous nous concentrons sur de nouveaux schémas de population Monte Carlo présentant une flexibilité et des performance supérieures par rapportàrapport`rapportà l'approche standard. Ces nouveaux sc…
Temporal Semantic Centrality for the Analysis of Communication Networks
2012
National audience; De nos jours, la compréhension des communautés en ligne devient un enjeu majeur du Web. Dans cet article nous proposons une nouvelle mesure, la Probabilité de Propagation Sémantique (SPP), qui caractérise la capacité de l'utilisateur à propager un concept sémantique à d'autres utilisateurs, d'une manière rapide et ciblée. La sémantique des messages est analysée selon une ontologie donnée. Nous utilisons cette mesure pour obtenir la Centralité Sémantique Temporelle (TSC) d'un utilisateur dans une communauté. Nous proposons et évaluons une expérimentation de cette mesure, en utilisant une ontologie et des données réelles issues du Web.
Temporal Logic To Query Semantic Graphs Using The Model Checking Method
2012
International audience; Semantic interoperability problems have found their solutions due to the use of languages and techniques from the Semantic Web. The proliferations of ontologies and meta-information have improved the understanding of information and the relevance of search engine responses. However, the construction of semantic graphs is a source of numerous errors of interpretation or modeling, and scalability remains a major problem. The processing of large semantic graphs is a limit to the use of semantics in current information systems. The work presented in this paper is part of a new research at the border of two areas: the semantic web and the model checking. This line of rese…
In Vitro Arrhythmia Generation by Mild Hypothermia - a Pitchfork Bifurcation Type Process
2015
International audience; The neurological damage after cardiac arrest (CA) constitutes a big challenge of hospital discharge. The therapeutic hypothermia (34°C-32°C) has shown its benefit to reduce cerebral oxygen demand and improve neurological outcomes after the cardiac arrest. However, it can have many adverse effects, among them the cardiac arrhythmia generation represents an important part (up to 34%, according different clinical studies). Monolayer cardiac culture is prepared with cardiomyocytes from new-born rat directly on the multi-electrodes array, which allows acquiring the extracellular potential of the culture. The temperature range is 37°C - 30°C - 37°C, representing the coolin…
Détection d'Anomalie dans les Signaux Physiologiques
2015
International audience; Les signaux physiologiques sont des séries temporelles riches en informations. Analyser ces signaux pour extraire ces informations, pour établir un diagnostic ou encore pour prédire une évolution, nécessite des outils performants et adaptés à leurs caractéristiques intrinsèques. En effet le comportement d'un système biologique dépend des variations de très nombreux paramètres, ce qui le rend alors presque imprévisible. Les méthodes issues de la théorie du chaos et de la dynamique non linéaire apportent des éléments qui permettent de comprendre ce type de comportements, et d'établir ainsi un lien qualitatif avec des modèles mathématiques bio-inspirés ou phénoménologiq…
Retrievals of soil moisture and optical depth from CAROLS
2011
International audience; We propose in this paper to evaluate a method to retrieve soil moisture (SM) and vegetation optical thickness, in areas of unknown roughness and unknown vegetation water content in view of operational applications, by using airborne Tb measurements acquired in South-West of France. Results are compared to in situ measurements, manual and automatic ones included in SMOSmania network, in the South-West of France.
Translucent medium
2013
8 pages; article in McGraw-Hill Science & Technology Encyclopedia; International audience; A medium allowing light to pass through partially or diffusely. An object cannot be seen clearly through translucent matter. In the most accepted meaning, translucency is used to describe a medium transmitting most of the light but scattering it more or less so that objects seen through it are blurry with soft contours and without details. The closer the object is to the medium the sharper its image through it. There are many examples of such media among natural or manufactured artifacts, including wax paper, milky water, colloidal and hydrogel materials, aerogels, smoke, fog, clouds, optical ceramics…
A Study on the Impact of Spectral Characteristics of Filters on Multispectral Image Acquisition
2013
International audience; In every aspect, filter design plays an important role in an image acquisition system based on a single image sensor and a colour filter array (CFA) mounted onto the sensor. Complementary CFAs are used by some colour cameras in the interest of higher sensitivity, which motivated us to employ filters of wide pass bands in the effort to adapt CFA for multispectral image acquisition. In this context, filter design has an effect on the accuracy of spectrum reconstruction in addition to other aspects. The results show that wider bandwidths in general result in more faithful spectrum reconstruction and higher signal-to-noise performance.