Proceedings XIV Brazilian Symposium on Computer Graphics and Image Processing

Machine design of a signal or image operator involves estimating the optimal filter from sample data. In principle, relative to the error measure used, the optimal filter is best; however, owing to design error, the designed filter might not perform well. In general it is suboptimal. The envelope constraint involves using two humanly designed filters that form a lower and upper bound for the desig... View full abstract»

DNA chips (i.e., microarrays) biotechnology is a hybridization (i.e., DNA matching) based process that makes it possible to quantify the relative abundance of mRNA from two distinct samples by analysing their fluorescence signals. This technique requires robotic placement (i.e., spotting) of thousands of cDNAs (i.e., complementary DNA) in an array format on glass microscope slides which provide ge... View full abstract»

Oscillatory neural networks are a relatively recent approach for the problem of image segmentation. Inside of this context, the oscillator neuron of Terman-Wang is presented, which is used as base element of an oscillatory network called LEGION (Locally Excitatory Globally Inhibitory Oscillator Network). The continuous version of the LEGION network, based on a set of differential equations, presen... View full abstract»

We present a computational model to simulate the skeletal muscle deformation during muscle contraction. This model includes a detailed description of the skeletal muscle architecture, non-linear properties of muscle tissue, novel features in the active muscle constitutive equations, and geometric constraints that can be enforced through Lagrange multipliers. The proposed muscle model predicts fibr... View full abstract»

This paper describes some preliminary results of our ongoing project on digital mirror interfaces. Regular mirrors reflect ambient light from the scene towards the observer. Digital mirrors capture the ambient light with a camera, extract information about the scene, and display appropriate information to the user, combining real-time computer vision systems with realistic computer graphics. We de... View full abstract»

We propose an integrated framework in which local perception and close manipulation skills are used in conjunction with a high-level behavioral interface based on a "smart object" paradigm as support for a virtual agent to perform autonomous tasks. In our model, virtual "smart objects" encapsulate information about possible interactions between the agent and its environment, including sub-tasks de... View full abstract»

The utilization of the vision as a feedback sensor in closed-loop control schemes is of great interest, mainly due to the high density of information revealed by images. In this work, we present a method to perform road following tracking by aerial unmanned vehicles (AUV) based on visual input. Difficulties arise from the nonholonomic constraints of the AUV moving in 3D. The problems are overcome ... View full abstract»

In this paper, we propose a video watermarking technique to hide copyright information in MPEG motion vector. In this method, watermark is embedded in larger value motion vectors, and specially in the less phase angle changed component. Then, the motion vector is modified into a new bitstream from which the watermark information can be easily retrieved. From the experimental results, it indicates ... View full abstract»

We propose techniques to enhance the volumetric approach to stereo matching, with which to obtain dense disparity and detect occluded zones. The volumetric approach works on the row × column × disparity space initializing the voxels with a measure of the similarity between the stereo pair that they represent (similarity phase). In this phase, we propose a function L0 that pr... View full abstract»

The paper recalls the idea of classification trees in OCR (optical character recognition) systems and proposes a technique for the automatic design of these classification trees. The design of both the classification trees and of the classification operators are based on training from sample pairs of observed-ideal images, allowing the development of customized OCRs View full abstract»

Augmented shared workspaces are an instance of augmented reality which move the collaborative work from the desktop to the real workplace, enabling higher interaction level with coworkers and allowing implementation of advanced techniques of human-machine interfaces. In this paper, we advocate the employment of a constraint system as the document model (or program) for the implementation of augmen... View full abstract»

In this paper we discuss the use of high-level verification on handwritten numeral strings. First of all, we introduce the concept of levels of verification and present the baseline system used to carry out the experiments. Two different strategies were developed: absolute and one-to-one verifiers. A thorough error analysis is also presented in order to identify under which conditions high-level v... View full abstract»

In this paper we apply reversible integer wavelet transform to lossless compression of computerized tomography projections (sinograms). Lossy image compression methods can achieve high compression ratios, but sinograms should not loose information during compression process to not affect the image reconstruction View full abstract»

This paper proposes a new method for image denoising with edge preservation, based on image multiresolution decomposition by a redundant wavelet transform. In our approach, edges are implicitly located and preserved in the wavelet domain, while noise is filtered out. At each resolution, the coefficients associated to noise and coefficients associated to edges are modeled by Gaussians, and a shrink... View full abstract»

The objective of this work is to identify geological circular forms, impact and volcano craters using satellite images. The recognition of objects (circular forms) is the last step in a processing chain which can be described in four phases: image processing, pattern detection, pattern recognition, and identification of the targets (models). The work presents the detection of circular forms in ima... View full abstract»

In this paper we present an algorithm for estimating the rotation index of a closed loop from the number of singular points on it. On the basis of this index we also devise a procedure that guarantees to have an arbitrary loop being traced only once. Combining this procedure with a higher-order stepping algorithm, a robust intersection technique is resulted View full abstract»

Flow visualization has been an active research field for several years and streamlines have proved to be an effective representation of two-dimensional steady vector fields. Online simulation of complex dynamic systems, computed on powerful computers, become more and more common. Efficient steering of the computational process requires the analysis of simulation results in real time. Visualization... View full abstract»

This paper reports new results of a project to build virtual worlds aimed at the graphic simulation of an arena where small mobile robots can perform requested tasks while behaving according to their own motivation and reasoning. Each robot is an intelligent agent that perceives the virtual environment via a simulated vision system and reacts to translating or rotating its body by driving its own ... View full abstract»

We present a computational framework for semi-automated assessment of skeletal age based on a multi-scale image analysis approach. Through 2D digital X-ray images of the left hand, maturity indicators are searched by means of a two-step process: the user interactively indicates a point inside the middle finger, and the computational method analyzes the image intensity profile along this line, sear... View full abstract»

In order to fully achieve automated mammogram analysis one has to tackle two problems: classification of radial, circumscribed microcalcifications, and normal samples; and classification of benign, malignant, and normal samples. How to extract and select the best features from the images for classification is a very difficult task, since all of those classes are basically irregular textures with a... View full abstract»

The dual-t-snakes model plus dynamic programming (DP) techniques is an efficient methodology for boundary extraction and segmentation of 2D images. However, the original proposal of the dual-t-snakes suffers from difficulties for parameters choice and instabilities due to the normal force definition. Also, the proposed method to push a snake way from a local minimum is not efficient for noise imag... View full abstract»

The paper presents a procedure to implement an automatic system for supervised pattern recognition with an ongoing learning capability. The purpose is to continuously increase the knowledge of the system and, accordingly, to enhance its performance in classification tasks. The nearest neighbor rule is employed as the central classifier and several techniques are added to cope with the increase in ... View full abstract»

T-snake is an active contour able to adapt the initial curve to the object topology. It allows the simultaneous detection of multiple objects with holes and objects fitting one inside another. However, its results depend on an appropriate choice of internal parameters. When the initial T-snake splits, the new snakes use the same initial parameters for smoothed shapes and for small and large high c... View full abstract»