Showing results 81 to 100 of 113
  Comparison of methods for handling the range-dependence of the clutter ridge for monostatic and bistatic STAP radars; Van Droogenbroeck, Marc  ; Verly, Jacques Poster (2002, December) Detailed reference viewed: 21 (5 ULg)Algorithms for mathematical morphologyVan Droogenbroeck, Marc Scientific conference (2002, November 08) Detailed reference viewed: 21 (0 ULg)Selective encryption of uncompressed and compressed imagesVan Droogenbroeck, Marc Scientific conference (2002, November 06) Detailed reference viewed: 13 (0 ULg) Étude de la paradiaphonie (NEXT) au sein de câbles composés de paires torsadéesVanderheyden, Benoît ; Van Droogenbroeck, Marc 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 ▲] Detailed reference viewed: 22 (0 ULg)Techniques for a selective encryption of uncompressed and compressed imagesVan Droogenbroeck, Marc ; 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: 208 (7 ULg)Algorithms for openings of binary and label images with rectangular structuring elementsVan Droogenbroeck, Marc in Talbot, Hugues; Beare, Richard (Eds.) International Symposium on Mathematical morphology (ISMM) (2002, April) Two new families of algorithms for computing openings of binary and label images are presented in this paper. The first family of algorithms is based on an horizontal scan, and a vertical scan that takes ... [more ▼] Two new families of algorithms for computing openings of binary and label images are presented in this paper. The first family of algorithms is based on an horizontal scan, and a vertical scan that takes the result of the horizontal scan as input. With the results of these two scans it is possible to compute an opening with respect to a rectangle of any size. The second family of algorithms is based on the construction of an exhaustive list of rectangles included in an object. Rectangles of this list all have a maximal extension, i.e. no larger rectangle included in a region contains them. The opening then results from filling the output image with rectangles larger than the structuring element. After a description of the algorithms we provide a comparison of several algorithms in terms of computation time efficiency. The comparison shows that some of the new algorithms advantageously compete with existing algorithms. [less ▲] Detailed reference viewed: 32 (5 ULg)An entropy based technique for information embedding in imagesVan Droogenbroeck, Marc ; in IEEE Signal Processing Symposium, Proceedings (2002, March) Many information hiding techniques have recently been analyzed as they could help manage part of the digital rights. Among the general framework of information hiding, the focus has been put on ... [more ▼] Many information hiding techniques have recently been analyzed as they could help manage part of the digital rights. Among the general framework of information hiding, the focus has been put on steganography and on watermarking techniques. This paper proposes an entropy based technique for data embedding in images with a specific target, sometimes referred to as feature location: inclusion of a maximum amount of information instead of robustness against attacks. After an introduction, we analyze the error that results from a modification of the least significant bits. Then we describe our embedding technique. Finally we examine the upper bound of information that can be embedded in the least significant bits by means of our technique and we conclude. [less ▲] Detailed reference viewed: 23 (1 ULg)Xlim3D: Un logiciel de traitement d'imageVan Droogenbroeck, Marc Report (2002) Mode d'emploi et descriptif du logiciel Xlim3D Detailed reference viewed: 9 (0 ULg)MPEG: Standards for Digital Video MPEG Activities in BelgiumVan Droogenbroeck, Marc in Revue HF (2002), 2 Detailed reference viewed: 9 (1 ULg)Bluetooth: technologie et potentiel industrielVan Droogenbroeck, Marc ; Report (2002) Présentation du potentiel industriel de la norme Bluetooth Detailed reference viewed: 15 (0 ULg)Le futur des télécommunicationsVan Droogenbroeck, Marc Conference given outside the academic context (2001) Detailed reference viewed: 18 (0 ULg)Acquisition et traitement de l'imageVan Droogenbroeck, Marc Learning material (2001) Detailed reference viewed: 168 (16 ULg)La télévision numérique aujourd'hui et demainVan Droogenbroeck, Marc Learning material (2001) Detailed reference viewed: 18 (3 ULg) Étude relative au plan de fréquences en Communauté Française de Belgique; ; Van Droogenbroeck, Marc Report (1999) Detailed reference viewed: 8 (0 ULg)Data networks integration; ; Van Droogenbroeck, Marc in 37th European Telecommunications Congress, Volume 17 (1998, August) This paper discusses the role of data networks integration on an asynchronous transfer mode (ATM) core and compares the advantages achieved by the usage of ATM with those given by emerging technologies ... [more ▼] This paper discusses the role of data networks integration on an asynchronous transfer mode (ATM) core and compares the advantages achieved by the usage of ATM with those given by emerging technologies such Internet protocol (IP) over synchronous digital hierarchy (SDH) (giga-routers). [less ▲] Detailed reference viewed: 43 (2 ULg)Connection-oriented vs. connectionless communicationsVan Droogenbroeck, Marc Conference given outside the academic context (1997) Detailed reference viewed: 32 (0 ULg)Narrowband versus broadband for tele-education : a critical evaluation; Van Droogenbroeck, Marc ; in International Conference on Technology Supported Learning, Proceedings (1996, November) Detailed reference viewed: 22 (4 ULg)Fast Computation of morphological operations with arbitrary structuring elementsVan Droogenbroeck, Marc ; in Pattern Recognition Letters (1996), 17(14), 1451-1460 Detailed reference viewed: 27 (2 ULg)A methodology for image segmentation based on the spectral content of regionsVan Droogenbroeck, Marc in Workshop on Nonlinear Signal and Image Processing, Proceedings (1995, June) Detailed reference viewed: 24 (1 ULg) |
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