Luis Urbano
Universidad Simón Bolívar, Electronical Engineering, Faculty Member
The search for methods to analyze signals, aimed at obtaining the attributes related to the physical properties that generate these signals, has always been a topic of interest to engineers and mathematicians. One of the most widely used... more
The search for methods to analyze signals, aimed at obtaining the attributes related to the physical properties that generate these signals, has always been a topic of interest to engineers and mathematicians. One of the most widely used techniques has been representing the signals in the time domain; frequency domain analysis or Fourier analysis complements this information. However for non-stationary signals another tool is needed. This produced the idea of a new signal representation using other basis functions to obtain a better time-frequency resolution compromise. This was defined as the wavelet transform. Also, in recent years, the theory of perfect reconstruction filter banks has been impulsed by the search of methods that optimize the storing and transmision of information. This paper introduces the waveet transform and perfect reconstruction filter bandks basics concepts and presents their relationships. This connection makes it possible to present a wavelet transform meth...
Research Interests: Mathematics and Revista
Abstract— Navigation systems have allowed a significant increase in effectiveness in a large number of high risk surgical procedures. These systems have experienced a prominent progress in the last 20 years thanks to advances in various... more
Abstract— Navigation systems have allowed a significant increase in effectiveness in a large number of high risk surgical procedures. These systems have experienced a prominent progress in the last 20 years thanks to advances in various image processing techniques. In this paper, we present a review of different technological aspects present in surgical navigation systems. In the first part its presents some historical background followed by the basics of this type of system. In the second part are shown some technological development such as common imaging modalities, different image registration procedures and tracking mechanisms for spatial location. The purpose of this paper is to provide an introduction to the people who are new into the field of surgical navigation systems. The growing development in devices and tracking techniques, computer systems and algorithmic efficiency used in surgical navigation will allow increasingly implementation of more accurate and versatile syst...
A basic area of research in digital video processing is the frame to frame low level motion estimation of image sequences. The motion information obtained is usually displayed as a 2-D distribution of displacement vectors, called the... more
A basic area of research in digital video processing is the frame to frame low level motion estimation of image sequences. The motion information obtained is usually displayed as a 2-D distribution of displacement vectors, called the optical flow field or image flow. How to use that information, in order to precisely estimate the location of objects in the scene, remains a relevant and very hard problem in computer vision. In previous schemes, the discontinuities appearing in the motion field have been studied in order to use them to discriminate between the various objects in the scene. In this work, the polar form of the image flow representation is used to enable a new approach to the handling of motion field discontinuities in dynamic scene analysis
Research Interests:
The motion information obtained from a sequence of time-varying two-dimensional images gives fundamental clues about the three-dimensional structure of the observed scene. For many vision systems, the main task is to extract that... more
The motion information obtained from a sequence of time-varying two-dimensional images gives fundamental clues about the three-dimensional structure of the observed scene. For many vision systems, the main task is to extract that information. The authors present a quantitative and qualitative analysis of the 2D motion field obtained applying optical flow algorithms (with either global or local conditions), and pel-recursive algorithms to image sequences (using real and synthetic data). Special emphasis is placed on assessing the performance of both techniques in scene segmentation. The experiments were carried out in two stages: the first one consisted of a qualitative analysis of the results of the motion field estimation process for a known motion field; the second one was the quantitative evaluation of the applicability of the results to scene segmentation, pondering sensitivity and specificity as figures of merit. The results are presented and discussed
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ABSTRACT Time-Frequency Representations (TFRs) are useful tools for frequency-domain analysis of non-stationary signals. However, there is not a single TFR that can be considered optimum for all kinds of signals. This has motivated the... more
ABSTRACT Time-Frequency Representations (TFRs) are useful tools for frequency-domain analysis of non-stationary signals. However, there is not a single TFR that can be considered optimum for all kinds of signals. This has motivated the appearance of a general optimiza-tion ...
Research Interests:
Absfracf. A technique of Image Sequence Compression, whose application domain is Medicine, is proposed in this work. It is an adaptation of the Walker-Rao scheme to an interpolation environment which preserves its fundamental advantage:... more
Absfracf. A technique of Image Sequence Compression, whose application domain is Medicine, is proposed in this work. It is an adaptation of the Walker-Rao scheme to an interpolation environment which preserves its fundamental advantage: the recursive motion estimation ...
Research Interests:
Rev. Tec. Ing. Univ. Zulia. Vol. 21, № 2, 107-123, 1998 Wavelet transform and filter banks theory relationship« A revision Trina Adrián de Pérez, Margarita Juanatey, Luis Urbano and Rafael Banchs Grupo de Procesamiento de Señales,... more
Rev. Tec. Ing. Univ. Zulia. Vol. 21, № 2, 107-123, 1998 Wavelet transform and filter banks theory relationship« A revision Trina Adrián de Pérez, Margarita Juanatey, Luis Urbano and Rafael Banchs Grupo de Procesamiento de Señales, Departamento de Electrónica y Circuitos ...
Research Interests:
Page 1. 3-Dimensional Medical Image Compression : A first approach to the Application of the ADCT-ISO Luis Urbano Grupo de Bioingenieria y Bioffsica Aplicada Universidad Simon Bolivar, Apartado 89000, Caracas 1080A, Venezuela ...
Research Interests:
Miguel Castro INSERM U642, Rennes F-35000, France Université de Rennes 1, LTSI, Rennes F-35042, France GBBA, University Simón Bolívar, Caracas, Venezuela e-mail: Miguel.Castro@univ-rennes1.fr ... Cemil Göksu and Pascal Haigron INSERM... more
Miguel Castro INSERM U642, Rennes F-35000, France Université de Rennes 1, LTSI, Rennes F-35042, France GBBA, University Simón Bolívar, Caracas, Venezuela e-mail: Miguel.Castro@univ-rennes1.fr ... Cemil Göksu and Pascal Haigron INSERM U642, ...