References of "Van Droogenbroeck, Marc"
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See detailThe CINEMA Project: A Video-Based Human-Computer Interaction System for Audio-Visual Immersion
Dardenne, Renaud; Embrechts, Jean-Jacques ULg; Van Droogenbroeck, Marc ULg et al

in ERCIM News (2005), 62

Numerous studies are currently focusing on the modelling of humans and their behavior in 3D environments. The CINEMA project has similar goals but differentiates itself by aiming at enhanced interactions ... [more ▼]

Numerous studies are currently focusing on the modelling of humans and their behavior in 3D environments. The CINEMA project has similar goals but differentiates itself by aiming at enhanced interactions, the creation of mixed reality, and the creation of interactive and reactive acoustical environments. Part of the project consists in gesture recognition of a user, who is given the real-time control of auralization and audio spatialization processes. [less ▲]

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See detailMorphological erosions and openings: fast algorithms based on anchors
Van Droogenbroeck, Marc ULg; Buckley, Michael

in Journal of Mathematical Imaging and Vision (2005), 22(2-3), 121-142

Several efficient algorithms for computing erosions and openings have been proposed recently. They improve on VAN HERK's algorithm in terms of number of comparisons for large structuring elements. In this ... [more ▼]

Several efficient algorithms for computing erosions and openings have been proposed recently. They improve on VAN HERK's algorithm in terms of number of comparisons for large structuring elements. In this paper we introduce a theoretical framework of anchors that aims at a better understanding of the process involved in the computation of erosions and openings. It is shown that the knowledge of opening anchors of a signal f is sufficient to perform both the erosion and the opening of f. Then we propose an algorithm for one-dimensional erosions and openings which exploits opening anchors. This algorithm improves on the fastest algorithms available in literature by approximately 30% in terms of computation speed, for a range of structuring element sizes and image contents [less ▲]

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See detailAcquisition vidéo au moyen d'une caméra IEEE 1394
Dardenne, Renaud; Van Droogenbroeck, Marc ULg

in Linux Magazine (2005), 69

Pour l'acquisition vidéo grand public, la norme USB 1.1 est devenu le choix le plus courant en matière de standard d'interconnexion. Pour des applications à plus haut débit, les utilisateurs préfèrent ... [more ▼]

Pour l'acquisition vidéo grand public, la norme USB 1.1 est devenu le choix le plus courant en matière de standard d'interconnexion. Pour des applications à plus haut débit, les utilisateurs préfèrent recourir à des cartes d'acquisition vidéo dédiées ou à des normes d'interfaçage génériques, permettant des transferts à débit plus élevé. Cet article explique comment se servir de la norme IEEE 1394, aussi appelée FireWire ou i.Link, pour l'acquisition de séquences vidéo. [less ▲]

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See detailDesign of statistical measures for the assessment of image segmentation schemes
Van Droogenbroeck, Marc ULg; Barnich, Olivier ULg

in Lecture Notes in Computer Science (2005), 3691

Image segmentation is discussed for years in numerous papers, but assessing its quality is mainly dealt with in recent works. Quality assessment is a primary concern for anyone working towards better ... [more ▼]

Image segmentation is discussed for years in numerous papers, but assessing its quality is mainly dealt with in recent works. Quality assessment is a primary concern for anyone working towards better segmentation tools. It both helps to objectively improve segmentation techniques and to compare performances with respect to other similar algorithms. In this paper we use a statistical framework to propose statistical measures capable to describe the performances of a segmentation scheme. All the measures rely on a ground-truth segmentation map that is supposed to be known and that serves as a reference when qualifying the results of any segmentation tool. We derive the analytical expression of several transition probabilities and show how to calculate them. An important conclusion from our study, often overlooked, is that performances can be content dependent, which means that one should adapt a measure to the content of an image. [less ▲]

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See detailTechnologies du multimédia, de l'Internet et des télécommunications
Van Droogenbroeck, Marc ULg

Learning material (2004)

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See detailFaut-il chasser les marchands du temple?
Debruyne, Guido; Van Droogenbroeck, Marc ULg

Article for general public (2004)

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See detailPartial encryption of images for real-time applications
Van Droogenbroeck, Marc ULg

in Fourth IEEE Signal Processing Symposium (2004, April)

Multimedia systems mostly base security on a restricted access to services. In the context of real-time imaging applications, this model suffers several drawbacks. Applications become vulnerable to ... [more ▼]

Multimedia systems mostly base security on a restricted access to services. In the context of real-time imaging applications, this model suffers several drawbacks. Applications become vulnerable to password attacks and once exposed attackers have access to all the data. An alternative consists of the systematic encryption of all data. When dealing with images, this approach is inconvenient because the data needs to be processed in its entirety before users can gain any insight. As well, the decryption task requires large amounts of processing power. This presentation shows how partial encryption can match applications requirements without the overhead of full encryption. The paper rst analyzes several schemes mixing encryption and image encoding. Then we focus on a technique that implements partial encryption of images based on JPEG. The technique is built to meet two major requirements: (1) preserve the overall bitrate, and (2) remain compliant with the JPEG file format. Finally we introduce and elaborate on a new scheme that combines flexibility, multiple encryption, spatial selectivity, self sufficiency, and format compliance. We show how it could fit the needs of real-time applications. [less ▲]

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See detailPrincipes de base du fonctionnement du réseau GSM
Demoulin, Cédric; Van Droogenbroeck, Marc ULg

Article for general public (2004)

Si la téléphonie mobile se banalise aujourd'hui, on le doit à la conjonction de l'avènement du numérique, à l'accroissement des performances des semi-conducteurs et à différentes avancées technologiques ... [more ▼]

Si la téléphonie mobile se banalise aujourd'hui, on le doit à la conjonction de l'avènement du numérique, à l'accroissement des performances des semi-conducteurs et à différentes avancées technologiques. Mais le facteur déterminant fut sans doute la cristallisation autour de la norme GSM issue d'un effort soutenu de standardisation mené à l'ETSI (Organe européen de normalisation en télécommunications, créé à l'initiative du Conseil des ministres). Dans cet article, nous passerons en revue différents aspects de la technologie GSM : éléments de la couche physique, caractérisation de la partie radio, architecture du réseau, etc. Pour faciliter la lecture --il faut concéder que les acronymes abondent dans ce domaine--, un glossaire est fourni en fin d'article. [less ▲]

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See detailSegmentation by adaptive prediction and region merging
Van Droogenbroeck, Marc ULg; Talbot, Hugues

in Digital Image Computing Techniques and Applications, Volume II (2003, December)

This paper presents a segmentation technique based on prediction and adaptive region merging. While many techniques for segmentation exist, few of them are suited for the segmentation of natural images ... [more ▼]

This paper presents a segmentation technique based on prediction and adaptive region merging. While many techniques for segmentation exist, few of them are suited for the segmentation of natural images containing regular textures defined on non-rectangular segments. In this paper, we propose a description of regions based on a deconvolution algorithm whose purpose is to remove the influence of the shape on region contents. The decoupling of shape and texture information is achieved either by adapting waveforms to the segment shape, which is a time-consuming task that needs to be repeated for each segment shape, or by the extrapolation of a signal to fit a rectangular window, which is the chosen path. The deconvolution algorithm is the key of a new segmentation technique that uses extrapolation as a prediction of neighbouring regions. When the prediction of a region fits the actual content of a connected region reasonably well, both regions are merged. The segmentation process starts with an over-segmented image. It progressively merges neighbouring regions whose extrapolations fit according to an energy criterion. After each merge, the algorithm updates the values of the merging criterion for regions connected to the merged region pair. It stops when no further gain is achieved in merging regions or when mean values of adjacent regions are too different. Simulation results indicate that, although our technique is tailored for natural images containing periodic signals and flat regions, it is in fact usable for a large set of natural images. [less ▲]

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See detailNew Solutions to the Problem of Range Dependence in Bistatic STAP Radars
Lapierre, Fabian; Van Droogenbroeck, Marc ULg; Verly, Jacques ULg

in IEEE Radar Conference 2003, Proceedings (2003, May)

We address the problem of detecting slow-moving <br />targets using a space-time adaptive processing (STAP) radar. <br />The construction of optimum weights at each range implies <br />the estimation of ... [more ▼]

We address the problem of detecting slow-moving <br />targets using a space-time adaptive processing (STAP) radar. <br />The construction of optimum weights at each range implies <br />the estimation of the clutter covariance matrix. This is typically <br />done by straight averaging of neighboring data snapshots. <br />However, in bistatic configurations, these snapshots are rangedependent. <br />As a result, straight averaging results in poor performance. <br />After reviewing existing methods for handling the <br />range-dependence, we present new methods exploiting the precise <br />shape of the bistatic direction-Doppler curves. [less ▲]

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See detailNew methods for handling the range dependence of the clutter spectrum in non-sidelooking monostatic STAP radars
Lapierre, Fabian; Van Droogenbroeck, Marc ULg; Verly, Jacques ULg

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2003), Proceedings, Volume 5 (2003, April)

We address the problem of detecting slow-moving targets using a non-sideloking monostatic space-time adaptive processing (STAP) radar. The construction of optimum weights at each range implies the ... [more ▼]

We address the problem of detecting slow-moving targets using a non-sideloking monostatic space-time adaptive processing (STAP) radar. The construction of optimum weights at each range implies the estimation of the clutter covariance matrix. This is typically done by straight averaging of neighboring data snapshots. The range-dependence of these snapshots generally results in poor performance. We present two new methods that handle the rangedependence by exploiting the geometry of the direction-Doppler curves. [less ▲]

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See detailAlgorithms for mathematical morphology
Van Droogenbroeck, Marc ULg

Scientific conference (2002, November 08)

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See detailSelective encryption of uncompressed and compressed images
Van Droogenbroeck, Marc ULg

Scientific conference (2002, November 06)

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See detailÉtude de la paradiaphonie (NEXT) au sein de câbles composés de paires torsadées
Vanderheyden, Benoît ULg; Van Droogenbroeck, Marc ULg

Report (2002)

Le réseau téléphonique est constitué d’une succession de câbles mis bout à bout et interconnectés au droit des répartiteurs. Cette hétérogénéité de câblage n’est guère favorable pour la réduction des ... [more ▼]

Le réseau téléphonique est constitué d’une succession de câbles mis bout à bout et interconnectés au droit des répartiteurs. Cette hétérogénéité de câblage n’est guère favorable pour la réduction des interférences entre signaux véhiculés sur les différentes paires. Un opérateur de télécommunications doit également tenir compte de la longue période définie pour l’amortissement comptable d’un réseau câblé, ce qui fait que les câbles risquent fort de n’être remplacés qu’en cas de panne ou d’insuffisance manifeste des performances. Le dégroupage de la boucle locale intervenu récemment complique encore la donne, car un opérateur historique comme Belgacom doit autoriser l’accès direct à la paire d’un abonné au bénéfice d’un opérateur alternatif. Ce dernier aura pour objectif d’offrir des services à haute valeur ajoutée et donc, techniquement, consommateur d’une plus large bande passante et générateur de plus d’interférence. Face à ces difficultés opérationnelles, les opérateurs et les organismes de normalisation ont défini des gabarits régissant le niveau de puissance pour tout signal émis sur une paire. À partir de ces gabarits et en fonction de son réseau, un opérateur pourra déterminer les caractéristiques des câbles à acquérir de manière à permettre la co-existence soit de signaux de même densité spectrale mais avec un haut taux de remplissage du câble, soit de signaux fort différents. Cette étude se concentre sur plusieurs points relatifs à la paradiaphonie au sein de câbles composés de paires torsadées. Dans un premier temps, nous aborderons la délicate question de la modélisation des phénomènes de paradiaphonie entre paires composant un même câble. Cette étude fournira le point de départ des développements relatifs à la fabrication de câbles de type S-Z et des effets de diaphonie dus à la distribution des paires dans le plan transversal. [less ▲]

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See detailTechniques for a selective encryption of uncompressed and compressed images
Van Droogenbroeck, Marc ULg; Benedett, Raphaël

in ACIVS Advanced Concepts for Intelligent Vision Systems, Proceedings (2002, September)

This paper describes several techniques to encrypt uncompressed and compressed images. We first present the aims of image encryption. In the usual ways to encryption, all the information is encrypted. But ... [more ▼]

This paper describes several techniques to encrypt uncompressed and compressed images. We first present the aims of image encryption. In the usual ways to encryption, all the information is encrypted. But this is not mandatory. In this paper we follow the principles of a technique initially proposed by MAPLES et al. [1] and encrypt only a part of the image content in order to be able to visualize the encrypted images, although not with full precision. This concept leads to techniques that can simultaneously provide security functions and an overall visual check which might be suitable in some applications like, for example, searching through a shared image database. The principle of selective encryption is first applied to uncompressed images. Then we propose a simple technique applicable to the particular case of JPEG images. This technique is proven not to interfere with the decoding process in the sense that it achieves a constant bit rate and that bitstreams remain compliant to the JPEG specifications. Then we develop a scheme called multiple selective encryption, discuss its properties and conclude. [less ▲]

Detailed reference viewed: 248 (7 ULg)