Now showing items 21-40 of 1054

    • A morphological approach for segmentation and tracking of human faces 

      Marqués Acosta, Fernando; Vilaplana Besler, Verónica (Barcelona, 2000)
      Conference lecture
      Open Access
      A new technique for segmenting and tracking human faces in video sequences is presented. The technique relies on morphological tools such as using connected operators to extract the connected component that more likely ...
    • A near-optimum mac protocol based on the distributed queueing random access protocol (dqrap) for a cdma mobile communication system 

      Alonso Zárate, Luis Gonzaga; Agustí Comes, Ramon; Sallent Roig, José Oriol (2000-09)
      Article
      Open Access
      This paper presents and analyses a new near– optimum random access protocol. The proposed access scheme is suitable for a CDMA environment and minimises the total number of spreading codes needed to achieve a certain ...
    • A new approach to active contours for tracking 

      Pardàs Feliu, Montse; Sayrol Clols, Elisa (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      This paper addresses the application of active contours or snakes for robust tracking of contours. Conventional snake approaches to tracking initialize the current frame snake with the snake obtained in the previous frame ...
    • A new approach to texture coding using stochastic vector quantization 

      Gimeno, D; Torres Urgell, Lluís; Casas Pla, Josep Ramon (IEEE Computer Society, 1994)
      Conference report
      Open Access
      A new method for texture coding which combines 2-D linear prediction and stochastic vector quantization is presented in this paper. To encode a texture, a linear predictor is computed first. Next, a codebook following the ...
    • A new positive time-frequency distribution 

      Rodríguez Fonollosa, Javier; Nikias, C L (1994)
      Conference report
      Open Access
      This article studies the formulation of new members of the Cohen-Posch (1985) class of positive time-frequency energy distributions. Members of this class are always positive functionals and satisfy the marginal constraints. ...
    • A non-extensive maximum entropy based regularization method for bad conditioned inverse problems 

      Rebollo-Neira, L; Fernández Rubio, Juan Antonio; Plastino, A (1998-08)
      Article
      Restricted access - publisher's policy
      A regularization method based on the non-extensive maximum entropy principle is devised. Special emphasis is given to the q=1/2 case. We show that, when the residual principle is considered as constraint, the q=1/2 generalized ...
    • A novel ekf-based recovery in ds scheme for ds/cdma systems tracking code delay 

      Díaz Romero, M. del Pilar; Agustí Comes, Ramon (1997-04)
      Article
      Restricted access - publisher's policy
      Classical delay-lock loops (DLL) have beenwidely considered for code synchronization purposes inDS/CDMA systems, although they have not been devised foroperation when channel fading is present. This paper describes a new ...
    • A novel methodology for measuring coherent homowavelength crosstalk in an optical signal supervisory system 

      Rafel Porti, Alberto; Prat Gomà, Josep Joan; Sales Zaragozá, Vicente (Optical Society of America, 1999)
      Conference report
      Open Access
      We present a novel, easy, and cost-effective methodology that allows an optical signal supervisory system the detection, isolation, and measurement of the coherent homowavelength crosstalk within an optical node. It also ...
    • A polynomial rooting approach for synchronization in multipath channels using antenna arrays 

      Seco Granados, Gonzalo; Swindlehurst, A K; Fernández Rubio, Juan Antonio (2000-08)
      Article
      Open Access
      The estimation of the delay of a known training signal received by an antenna array in a multipath channel is addressed. The effect of the co-channel interference is taken into account by including a term with unknown ...
    • A probabilistic method for blind multiuser detection using array observations 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (IEEE, 1997)
      Conference report
      Open Access
      In this paper, a blind algorithm for detecting active users in a DS-CDMA system is presented. This probabilistic algorithm relies on the theory of hidden Markov models (HMM) and is completely blind in the sense that no ...
    • A proposal for dependent optimization in scalabale region-based coding systems 

      Morros, R; Marqués Acosta, Fernando (Institute of Electrical and Electronics Engineers (IEEE), 1999)
      Conference report
      Open Access
      We address in this paper the problem of optimal coding in the framework of region-based video coding systems, with a special stress on content-based functionalities. We present a coding system that can provide scaled layers ...
    • A radio channel emulator for WCDMA, based on the hidden Markov model (HMM) 

      Umbert Juliana, Anna; Díaz Romero, M. del Pilar (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      One of the main development and research subjects within the telecommunications area activity is the 3G mobile systems standardisation. The radio access is, of course, the main trouble in mobile systems, so it is important ...
    • A real time emulator of the UMTS lower layers for the wineglass demonstrator 

      Gelonch Bosch, Antonio José; Revés Ballesté, Xavier; Umbert Juliana, Anna; Ferrús Ferré, Ramón Antonio; Casadevall Palacio, Fernando José (European Commission, 2000)
      Conference report
      Open Access
      In this paper, a general description of the main features of a Real Time Emulator, which emulates the lower layers of the UMTS Radio Access system, is presented. For the physical layer, the emulation model is based on the ...
    • A reduced-complexity and asymptotically efficient time-delay estimator 

      Seco Granados, Gonzalo; Swindlehurst, A L; Fernández Rubio, Juan Antonio; Astély, D (ICASSP, 2000)
      Conference report
      Open Access
      This paper considers the problem of estimating the time delays of multiple replicas of a known signal received by an array of antennas. Under the assumptions that the noise and co-channel interference (CCI) are spatially ...
    • A region-based subband coding scheme 

      Casas Pla, Josep Ramon; Torres Urgell, Lluís (1997-07)
      Article
      Restricted access - publisher's policy
      This paper describes a region-based subband coding scheme intended for efficient representation of the visual information contained in image regions of arbitrary shape. QMF filters are separately applied inside each region ...
    • A robust motion estimation and segmentation approach to represent moving images with layers 

      Torres Urgell, Lluís; García Luque, David; MATES, A (IEEE COMPUTER SOCIETY, 1997)
      Conference report
      Open Access
      The paper provides a robust representation of moving images based on layers. To that goal, we have designed efficient motion estimation and segmentation techniques by affine model fitting suitable for the construction of ...
    • A second opinion approach for speech recognition verification 

      Hernández-Ábrego, G; Mariño Acebal, José Bernardo (M,I, Torres & A. Sanfeliu / AERFAI, 1999)
      Conference report
      Open Access
      In order to improve the reliability of speech recognition results, a verifying system, that takes profit of the information given from an alternative recognition step is proposed. The alternative results are considered as ...
    • A segmentation algorithm based on acoustical features using a self organizing neural network. 

      Monte Moreno, Enrique (. EUROSPEECH, 1993)
      Conference report
      Open Access
      In this paper we investigate the use of a self-organizing map in an acoustic segmentation task. The aim is to obtain a limited number of acoustic classes and to segment whenever a change in the class between two adjacent ...
    • A segmentation-based coding system allowing manipulation of objects (sesame) 

      Marqués Acosta, Fernando; Salembier Clairon, Philippe Jean; Pardàs Feliu, Montse; Marcotegui Iturmendi, Beatriz (IEEE, 1996)
      Conference report
      Open Access
      We present a coding scheme that achieves, for each image in the sequence, the best segmentation in terms of rate-distortion theory. It is obtained from a set of initial regions and a set of available coding techniques. The ...
    • A self organizing feature map based on the fisher discriminant 

      Monte Moreno, Enrique (1994)
      Conference report
      Open Access
      In this paper we propose a modification of the Self Organising map, where we is train the units using a transformation related to the Fisher Discriminant, in order to maximise the discrimination between units. The algorithm ...