Proceedings 13th Brazilian Symposium on Computer Graphics and Image Processing (Cat. No.PR00878)

17-20 Oct. 2000

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  • Proceedings 13th Brazilian Symposium on Computer Graphics and Image Processing (Cat. No.PR00878)

    Publication Year: 2000
    Request permission for commercial reuse | PDF file iconPDF (324 KB)
    Freely Available from IEEE
  • Vascular image processing

    Publication Year: 2000, Page(s): 3
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  • Shape from shading and intensity gradient

    Publication Year: 2000, Page(s):7 - 14
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (764 KB)

    We present a novel algorithm for shape estimation, using both brightness and brightness gradient as input data. Our algorithm is an improvement of the recently introduced Green's function approach to shape-from-shading (GSFS). In GSFS, we assume that the single brightness image will be matched to a second image through a uniform disparity field, and solve for the matching image via Green's functio... View full abstract»

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  • Methodology of automatic extraction of table-form cells

    Publication Year: 2000, Page(s):15 - 21
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    The article presents a method for the automatic extraction of the contents of passive and/or active cells in forms. The approach is based on the analysis and recognition of the types of intersection of the lines that make up such cells. Very little a priori knowledge of the form is required. The performance of this approach depends on the correction module mechanisms for detection and correction o... View full abstract»

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  • Tracking facial features using Gabor wavelet networks

    Publication Year: 2000, Page(s):22 - 27
    Cited by:  Papers (6)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (729 KB)

    The work presents a method for automatic facial feature tracking in video sequences. In this method, a discrete face template is represented as a linear combination of continuous 2D odd-Gabor wavelet functions. The weights and 2D parameters (position, scale and orientation) of each wavelet are determined optimally so that the maximum amount of image information is preserved for a given number of w... View full abstract»

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  • Improved face/spl times/non-face discrimination using Fourier descriptors through feature selection

    Publication Year: 2000, Page(s):28 - 35
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (828 KB)

    This work presents a new method to discriminate face from non-face images using Fourier descriptors. The first step of our approach consists in applying a horizontal edge detection filter in the input image, followed by the extraction of a 1D signal from the computed edge map. Then we calculate the Fourier descriptors from this signal and classify the image using statistical classifiers. In order ... View full abstract»

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  • A visual attention model for tracking regions based on color correlograms

    Publication Year: 2000, Page(s):36 - 43
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (586 KB)

    The amount of information contained in a single color shot of a scene is extreme considering the variety of tasks that can be performed relying on visual data only. For the purpose of analyzing scenes dynamically, where objects come and go, one has to work under a structure of a visual attention model which prioritizes what type of visual data the system has to follow. This paper presents a novel ... View full abstract»

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  • Curvature and orientation estimation by neuronal structures

    Publication Year: 2000, Page(s):44 - 51
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1008 KB)

    The paper presents a simple model of curvature and orientation estimation by neural networks where a pair of neurons is used to approximate the partial differential operators needed for curvature and orientation estimation. The influence of neuronal morphometry in the estimation of curvature and orientation is investigated and discussed. In addition, the biological plausibility of the model is dis... View full abstract»

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  • Multiple correspondences in stereo vision under a genetic algorithm approach

    Publication Year: 2000, Page(s):52 - 59
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (682 KB)

    This paper presents a multiple point hierarchical approach to the stereo correspondence problem in computer vision. The low-level processing employs an area-and-token hybrid method to obtain, for distinctive points in one image, a set of points in the other image that are candidates for correspondence. The refinement of the set of low-level correspondences obtained is performed by a high-level N-p... View full abstract»

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  • Target search by bottom-up and top-down fuzzy information

    Publication Year: 2000, Page(s):60 - 66
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (732 KB)

    One of the basic tasks assigned to the attentional mechanism is to decide which location in the visual field we must pay attention first. An object containing a distinctive feature can attract attention in a bottom-up way. By comparing one object with the others present in the scene, bottom-up conspicuity features are used to guide attention to the most different object. Top-down hints are based o... View full abstract»

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  • Handwritten digits segmentation based on structural approach

    Publication Year: 2000, Page(s):67 - 73
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (537 KB)

    We deal with a new segmentation approach applied to unconstrained handwritten digits. The novelty of the proposed algorithm is based on the combination of two types of structural features in order to provide the best segmentation path between connected entities. This method was developed to be applied in a segmentation-based recognition system. We first present the features used to generate our ba... View full abstract»

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  • Probabilistic intensity mapping in MRI image registration

    Publication Year: 2000, Page(s):74 - 81
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (698 KB)

    In this work, we present a method which is able to relate different MR sensors with respect to intensity distortions in the output images. For the important problem of image registration, the method makes possible a principled approach to likelihood modeling or the construction of similarity metrics. Likelihood models can be used as prior knowledge of the relationship between intensities in both i... View full abstract»

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  • A boundary extraction approach based on multi-resolution methods and the T-Snakes framework

    Publication Year: 2000, Page(s):82 - 89
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (966 KB)

    We present a new approach which integrates the T-Snakes model and a multi-resolution method in a unified framework for segmentation and boundary extraction. In a first stage, a local scale property of the objects is used to define a triangulation of the image domain and a sampling (coarsest resolution) of the image field. The low resolution image is thresholded to get a 0-1 field which is processe... View full abstract»

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  • Towards 3D reconstruction of endoscope images using shape from shading

    Publication Year: 2000, Page(s):90 - 96
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (579 KB)

    The 3D reconstruction problem from a single endoscope image of a smooth object is studied in the context of the shape from shading methods and considering a single light source at the camera projection center. Based on a curve expansion shape from shading algorithm, a spherical projection model for the endoscope camera and a dichromatic model for the surface reflectance, an approach to solve pract... View full abstract»

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  • Brazilian bank check handwritten legal amount recognition

    Publication Year: 2000, Page(s):97 - 104
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (742 KB)

    This paper presents a system that is being developed for the recognition of the handwritten legal amount in Brazilian bank checks. Our strategy used to approach the handwritten legal amount recognition problem puts on evidence the keywords: "mil", "reals/real", "centavos/centavo" which are almost always present in each amount. The recognizer, based on hidden markov models, does a global word analy... View full abstract»

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  • An off-line signature verification system using hidden Markov model and cross-validation

    Publication Year: 2000, Page(s):105 - 112
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (577 KB)

    The main objective is to present an off-line signature verification system. It is basically divided into three parts. The first demonstrates a pre-processing process, a segmentation process and a feature extraction process, in which the main aim is to obtain the maximum performance quality of the process of verification of random falsifications, in the false acceptance and false rejection concept.... View full abstract»

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  • Recognition of handwritten dates on bank checks using an HMM approach

    Publication Year: 2000, Page(s):113 - 120
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (577 KB)

    The article presents the first results of our system applied to the automatic recognition of handwritten dates on Brazilian bank checks. Considering the omni-writer context, we detail our recognition module dedicated to processing the month field. This module is based on the combination of holistic and analytical approaches with a fixed lexicon. Both approaches operate with a single explicit segme... View full abstract»

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  • Variable resolution 4-k meshes

    Publication Year: 2000, Page(s):123 - 130
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (725 KB)

    We introduce variable resolution 4-k meshes, a powerful structure for the representation of geometric objects at multiple levels of detail. It combines most properties of other related descriptions with several advantages, such as more flexibility and greater expressive power. The main unique feature of the 4-k mesh structure lies in its variable resolution capability, which is crucial for adaptiv... View full abstract»

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  • Semi-regular 4-8 refinement and box spline surfaces

    Publication Year: 2000, Page(s):131 - 138
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (746 KB)

    We introduce a new mesh refinement method for subdivision surfaces. It generates a semiregular 3-direction hierarchical structure from control meshes representing 2D manifolds of arbitrary topology. The main advantage of this structure is that it allows the extraction of conforming variable-resolution meshes based on spatially varying adaptation functions. We also present a smoothing method design... View full abstract»

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  • Robust approximation of offsets and bisectors of plane curves

    Publication Year: 2000, Page(s):139 - 145
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (578 KB)

    Most methods for computing offsets and bisectors of parametric curves are based on a local formulation of the distance to a curve. As a consequence, the computed objects may contain spurious parts and components, and have to be trimmed. We approach these problems as global optimization problems, and solve them using interval arithmetic, thus generating robust approximations that need not be trimme... View full abstract»

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  • Fast customization of geometric models

    Publication Year: 2000, Page(s):146 - 151
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (755 KB)

    We present a technique for customization of geometric models of animals based on pictures. The object to be customized is divided into a set of hierarchically related local coordinate systems which allow for independent transformations of different body parts. A picture of the desired result is used as a visual aid to drive the customization process. We show the results of applying this technique ... View full abstract»

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  • On estimating local geometric properties of intersection curves

    Publication Year: 2000, Page(s):152 - 159
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (799 KB)

    The paper presents a simple and robust algorithm for estimating the local geometric properties of intersection curves, namely the tangent, normal, binormal, curvature and torsion vectors at any point. In addition, two new marching directions that make use of these properties are given. View full abstract»

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  • An estimation theoretic approach to 3D image interpolation

    Publication Year: 2000, Page(s):163 - 169
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (652 KB)

    The paper presents a new approach to image 3D interpolation using Bayesian estimation theory. Two methods are presented, depending on the used a priori information. The approach is applied to the interpolation of X-ray images from the solar atmosphere taken at different depths, as well as RMN tomographic images of a tomato. View full abstract»

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  • Directional analysis of images with Gabor wavelets

    Publication Year: 2000, Page(s):170 - 177
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1073 KB)

    The paper presents a new scheme for analysis of linear directional components in images by using a multiresolution representation based on Gabor wavelets. A dictionary of Gabor filters with varying tuning frequency and orientation, specifically designed in order to reduce the redundancy in the wavelet-based representation, is applied to the given image. The filter responses for different scales an... View full abstract»

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  • Stochastic texture image retrieval and similarity matching

    Publication Year: 2000, Page(s):178 - 184
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (777 KB)

    Stochastic texture images representing various foil materials (like polymer sheets, nonwoven textiles and paper) provide important information about these materials, and are frequently utilized in industry. It is often difficult to objectively measure the similarity among those images, or to discriminate images of different types of materials. This work proposes a new multi-resolution method for t... View full abstract»

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