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Computer Graphics and Image Processing, 2003. SIBGRAPI 2003. XVI Brazilian Symposium on

Date 12-15 Oct. 2003

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Displaying Results 1 - 25 of 54
  • Effective image retrieval by shape saliences

    Publication Year: 2003, Page(s):167 - 174
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB) | HTML iconHTML

    Content-based image retrieval (CBIR) systems have been developed aiming at enabling users to search and retrieve images based on their properties such as shape, color and texture. We are concerned with shape-based image retrieval. Here, we discuss a recently proposed shape descriptor, called contour saliences, defined as the influence areas of its higher curvature points. We introduce a robust app... View full abstract»

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  • Object retrieval in image databases using image composition

    Publication Year: 2003, Page(s):159 - 166
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (358 KB) | HTML iconHTML

    We propose an algorithm of image retrieval from a partial request. In order to retrieve images containing a specific object or group of objects, we use an algorithm of inexact graph matching, adapted to adjacency graphs of regions. The number of regions representing the object can be different from an image to the other. The algorithm uses a search tree in which only similar nodes are developed. T... View full abstract»

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  • Blood vessels segmentation in nonmydriatic images using wavelets and statistical classifiers

    Publication Year: 2003, Page(s):262 - 269
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1178 KB) | HTML iconHTML

    This work describes a new framework for automatic analysis of optic fundus nonmydriatic images, focusing on the segmentation of the blood vessels by using pixel classification based on pattern recognition techniques. Each pixel is represented by a feature vector composed of color information and measurements at different scales taken from the continuous wavelet (Morlet) transform as well as from m... View full abstract»

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  • Graphic simulation for virtual prototyping with Java3D

    Publication Year: 2003, Page(s):83 - 90
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (499 KB)

    We report some issues involved in the construction of an interactive, interoperable application, whose primary purpose is to be used as a virtual mockup. This graphic tool was tailored for machine vision application prototyping, to cope with metrological settings of large part assemblies. Some relevant aspects of designing interactive 3D applications will be discussed, including an account of some... View full abstract»

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  • Automatically choosing source color images for coloring grayscale images

    Publication Year: 2003, Page(s):151 - 158
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (393 KB) | HTML iconHTML

    We introduce a methodology for adding color to grayscale images in a way that is completely automatic. Towards this goal, we build on a technique that was recently developed to transfer colors from a user-selected source image to a target grayscale image. More specifically, we eliminate the need for human intervention in the selection of the source color images, which can be regarded as a first st... View full abstract»

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  • Texture segmentation considering multiband, multiresolution and affine invariant roughness

    Publication Year: 2003, Page(s):254 - 261
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (473 KB) | HTML iconHTML

    Texture segmentation is a basic task in the process of satellite image analysis. However, texture characterization is not an easy task specially when more than one wavelength band need to be considered. Several difficulties are present, as the basic texture definition in different resolution and image scales. Consequently, some approaches are essentially empiric and should be adjusted to different... View full abstract»

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  • Creating and editing curves on subdivision surfaces

    Publication Year: 2003, Page(s):75 - 80
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (572 KB) | HTML iconHTML

    Curves on spline surfaces such as NURBS have a long tradition in 3D modeling, for instance as trimming curves or as motion paths. Now, as subdivision surfaces have become very popular, we seek a method for constructing spline-like curves on subdivision surfaces, beginning with a study of the Loop scheme. By using the natural parametrization of these surfaces, we find an appropriate construction ba... View full abstract»

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  • An approximation for normal vectors of deformable models

    Publication Year: 2003, Page(s):3 - 10
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1984 KB) | HTML iconHTML

    A physically-based deformable model proposed by Terzopoulous et al. is governed by the Lagrange's form, that establishes the relation between the dynamics of deformable models under the influence of applied forces. The net instantaneous potential energy of deformation is derived on the basis of the geometric properties, namely the first and second fundamental forms. For simplicity, the normal vect... View full abstract»

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  • Picking and snapping for 3D input devices

    Publication Year: 2003, Page(s):140 - 147
    Cited by:  Papers (4)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (265 KB) | HTML iconHTML

    A picking mechanism (pointing and indicating) with the cursor is essential for any direct-manipulation application. The windowing systems, under whose control a direct-manipulation application runs, provide facilities that together with special utility routines allow identification of which object within the region the user is pointing at. Such picking algorithms have been widely used for selectin... View full abstract»

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  • 2-D histogram-based segmentation of postal envelopes

    Publication Year: 2003, Page(s):247 - 253
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB) | HTML iconHTML

    Mail sorting automation is yet a partially solved challenge. Due to no fixed positions of the semantic information in envelope images, part of this challenge is the automatic location of address blocks. We approach this problem by proposing a new postal envelope segmentation method based on 2D histogram clustering and watershed transform. Segmentation task consists in detecting the 2D histogram mo... View full abstract»

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  • Image feature extraction for application of biometric identification of iris - a morphological approach

    Publication Year: 2003, Page(s):391 - 398
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (462 KB) | HTML iconHTML

    We present a new approach based on morphological operators for application of biometric identification of individuals by segmentation and analysis of the iris. Algorithms based on morphological operators are developed to segment the iris region from the eye image and also to highlight chosen iris patterns. The extracted features are used to represent and characterize the iris. In order to properly... View full abstract»

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  • Design of order statistic filters from examples

    Publication Year: 2003, Page(s):222 - 229
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB) | HTML iconHTML

    Order statistic filters form a subclass of the stack filters. The design of stack filters is computationally prohibitive for relatively large windows. A possible approach to overcome this difficulty is to constrain design to a smaller class. We propose an algorithm for the design of optimal order statistic filters from training data, and show how it can also be applied to the design of optimal wei... View full abstract»

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  • The language LinF for fractal specification

    Publication Year: 2003, Page(s):67 - 74
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB) | HTML iconHTML

    We present the language LinF for L-System specification. L-Systems are formal string rewriting systems introduced in 1968 by the botanist Aristid Lindenmayer that are used to model fractal images. LinF allows the definition of three-dimensional fractals and stochastic fractals. Together with the LinF definition we present the implementation of cFLC, an OpenGL-based system that generates fractal im... View full abstract»

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  • An interaction model for scientific visualization using sound

    Publication Year: 2003, Page(s):132 - 139
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (741 KB)

    In scientific visualization, interaction tools allow users to navigate through volume and explore its features, helping information understanding. The use of sound as a data display tool (sonification) has also been shown to support information understanding and may help dealing with adding dimensions to a visual display. However, thus far the issues of data exploration tools and sonification have... View full abstract»

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  • Object segmentation in image sequences by watershed from markers: a generic approach

    Publication Year: 2003, Page(s):347 - 352
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (387 KB) | HTML iconHTML

    We propose a generic method to interactive object segmentation in image sequences. This method consists in the extension of efficient techniques of static image segmentation to image sequences by combining them to fast motion estimation techniques. The proposed method has the following characteristics: interactivity, generality, rapid response and progressive manual edition. View full abstract»

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  • RZSweep: a new hardware-assisted volume-rendering technique for regular datasets

    Publication Year: 2003, Page(s):99 - 106
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (431 KB) | HTML iconHTML

    A long-standing challenge in the field of volume rendering is to obtain high quality images in near real-time. This is particularly important for scientific datasets where highly precise results are required to ensure accurate data interpretation. We present RZSweep as a new hardware-assisted technique for volume rendering of regular datasets based on the plane-sweep paradigm. Although some resear... View full abstract»

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  • A computer vision framework for eye gaze tracking

    Publication Year: 2003, Page(s):406 - 412
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (722 KB) | HTML iconHTML

    Eye gaze tracking (EGT) allows us to estimate the direction of gaze and the point of regard. This technique has been successfully used as a pointing device in computer interfaces for people with disabilities, but significant technological advances are still required to make EGT appropriate to be used in general computer interfaces. In order to improve the EGT technology, a testbed where new device... View full abstract»

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  • Area fractions by linear analysis of intensity level histograms

    Publication Year: 2003, Page(s):238 - 244
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (359 KB) | HTML iconHTML

    Linear analysis of intensity level histograms is proposed as a method to determine the area fractions of homogeneous components of images. The area fractions are the coefficients of the respective histograms in the linear combination that best fits the histogram of the entire image. This method can be applied whenever the components can be identified by their individual histograms which must be li... View full abstract»

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  • Quantized features for gesture recognition using high speed vision camera

    Publication Year: 2003, Page(s):383 - 390
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (330 KB) | HTML iconHTML

    In addition to speech, gestures have been considered as a means of interacting with a computer as naturally as possible. Like speech, gestures can be acquired and recognized using hidden Markov models (HMMs), but there are several problems that must be overcome. We propose solutions to two of these problems: the feature extraction and the HMMs training. First, the acquisition is done by means of a... View full abstract»

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  • Informed embedding for multibit watermarking

    Publication Year: 2003, Page(s):214 - 221
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (424 KB) | HTML iconHTML

    We propose a practical blind detection multibit watermarking system. The proposed system is analogous to code division multiplexing in spread spectrum communications. Performance improvements with respect to existing multibit systems are obtained by means of informed embedding. With informed embedding we exploit perceptual modelling by using a wavelet-based multiplicative mask and exploit the digi... View full abstract»

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  • A non-self-intersection Douglas-Peucker algorithm

    Publication Year: 2003, Page(s):60 - 66
    Cited by:  Papers (6)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB) | HTML iconHTML

    The classical Douglas-Peucker line-simplification algorithm is recognized as the one that delivers the best perceptual representations of the original lines. It is used extensively for both computer graphics and geographic information systems. There are two variants of this algorithm, the original O(nm) method, where n denotes the number of input vertices and m the number of output segments, that ... View full abstract»

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  • Image inpainting and denoising by nonlinear partial differential equations

    Publication Year: 2003, Page(s):287 - 293
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (489 KB) | HTML iconHTML

    A new approach is presented for recovering shapes from noisy and damaged images as well as the filling in of missing information or the removal of objects from an image. The procedure allows for the denoising and inpainting of images simultaneously. The denoising is performed by the smoothing equation working inside and outside of the inpainting domain but in completely different ways. Inside the ... View full abstract»

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  • Multiscale detection of linear features in speckled imagery

    Publication Year: 2003, Page(s):371 - 375
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (733 KB) | HTML iconHTML

    We are concerned with multiscale extraction of linear features in speckled images. The methodology combines the a trous algorithm, Hough transform and the line detectors D1 and D2. The noisy image is decomposed into several scales by applying a redundant discrete wavelet algorithm (a trous) and the detectors D1 and D2 extract in each scale the straight lines. An associative symmetrical sum is used... View full abstract»

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  • A sketch-based collaborative design system

    Publication Year: 2003, Page(s):125 - 131
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (647 KB) | HTML iconHTML

    We present a system for collaborative conceptual design that allows users potentially located in geographically distant areas to cooperate by sketching, exploring and modifying their ideas interactively, with immediate visual feedback. The system supports several modeling primitives and can be easily extended with user-defined objects. We introduce the notions of animated and sketchy billboards. A... View full abstract»

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  • Robust multiview range image registration

    Publication Year: 2003, Page(s):307 - 314
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB) | HTML iconHTML

    We present a new method for precise registration of multiple range images with low overlap based on enhanced genetic algorithms (GAs). The proposed method minimizes the alignment error within the common overlap area among a set of views, which is computed by a novel robust evaluation metric, called the surface interpenetration measure. Because they search in a space of transformations, GAs are cap... View full abstract»

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