2003
Authors
Alexandre, LA; Campilho, A; Kamel, M;
Publication
PATTERN RECOGNITION AND IMAGE ANALYSIS, PROCEEDINGS
Abstract
This paper presents a model for the probability of correct classification for the Cooperative Modular Neural Network (CMNN). The model enables the estimation of the performance of the CMNN using parameters obtained from the data set. The performance estimates for the experiments presented are quite accurate (less than 1% relative difference). We compare the CMNN with a multi-layer perceptron with equal number of weights and conclude that the CMNN is preferred for complex problems. We also investigate the error introduced by one of the CMNN voting strategies.
2003
Authors
Vinhais, C; Campilho, A;
Publication
PATTERN RECOGNITION AND IMAGE ANALYSIS, PROCEEDINGS
Abstract
We present a method for detecting the axis of bilateral symmetry in a digital chest X-ray image and subsequently measuring the degree of symmetry of the image. The detection is achieved by analysing rotated-reflected digital chest X-ray images and it is posed as a global optimization problem solved with a probabilistic genetic algorithm (PGA). The global search is initially based on natural peak orientation information related to the orientation of the symmetry axis. Only a few generations of the PGA are needed to achieve convergence to all the images in the database. This method is applied directly on the intensity input image and does not require any prior segmentation.
2004
Authors
Vinhais, C; Campilho, A;
Publication
IMAGE ANALYSIS AND RECOGNITION, PT 2, PROCEEDINGS
Abstract
We propose a method for segmenting the ribcage boundary of digital postero-anterior chest X-ray images. The segmentation is achieved by first defining image landmarks: the center of the ribcage and, using polar transformation from this point, two initial points belonging to the ribcage. A bank of Gabor filters (in analogy with the simple cells present in the human visual cortex) is used to obtain an orientation edges enhanced image. In this enhanced image, an edge following, starting from the landmarks previously determined, is performed for delineating the left and right sections of the ribcage. The complete segmentation is then accomplished by connecting these sections with the top section of the ribcage, obtained by means of spline interpolation.
2004
Authors
Garcia, B; Campilho, A; Scheres, B; Campilho, A;
Publication
IMAGE ANALYSIS AND RECOGNITION, PT 2, PROCEEDINGS
Abstract
The Arabidopsis thaliana is a well defined and a suited system to study plant development at the cellular level. To follow in vivo the root meristem activity under a confocal microscope the image acquisition process was automated through a coherent observation of a fixed point of the root tip. This position information allows the microscope stage control to track the root tip. Root tip estimation is performed following two approaches: computing the root central line intersection with the contour or the maximum filtered contour curvature point. The first method fits the root border with lines, using the Radon transform and a classification procedure. The central line is defined as the line that bisects the angle between these lines. The intersection of the central line with the root contour provides an estimate for the root tip position. The second method is based on contour traversing, followed by convolution of the contour coordinates with a Gaussian kernel. Curvature is computed for this filtered contour. The maximum curvature point provides another root tip estimate. A third method, based on a Kalman estimator is used to select between the previous two outputs. The system allowed the tracking of the root meristem for more than 20 hours in several experiments.
2004
Authors
Sousa, AV; Aguiar, R; Mendonca, AM; Campilho, A;
Publication
IMAGE ANALYSIS AND RECOGNITION, PT 2, PROCEEDINGS
Abstract
This work aims at developing an automatic method for the analysis of TLC images for measuring a set of features that can be used for the characterization of the distinctive patterns that result from the separation of oligosaccharides contained in human urine. This paper describes the methods developed for the automatic detection of the lanes contained in TLC images, and for the automatic separation of bands for each detected lane. The extraction of quantitative information related with each band was accomplished with two methods: the EM expectation-maximization and nonlinear least squares trust-region algorithms. The results of these methods, as well as additional quantitative information related with each band, are also presented.
2004
Authors
Moreira, R; Mendonca, AM; Campilho, A;
Publication
IMAGE ANALYSIS AND RECOGNITION, PT 2, PROCEEDINGS
Abstract
The purpose of the research herein presented is the automatic detection of the rib borders in posterior-anterior (PA) digital chest radiographs. In a computer-aided diagnosis system, the precise location of the ribs is important as it allows reducing the false positive in the detection of abnormalities such as nodules, rib lesions and lung lesions. We adopted an edge based approach aiming at detecting the lower border of each rib. For this purpose, the rib geometric model is described as a parabola. For each rib, the upper limit is obtained using the position of the corresponding lower border.
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