This article presents a morphological, chemical, and fractal dimension study of the time evolution of aluminum AC anodization in 1 M H3PO4 solution. The morphological analysis was accomplished by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). According to SEM, ordered porous pattern was already observed after 90 s of anodization, yet AFM revealed a different surface morphology evolution. Stripes were observed on the surface at the initial stages of anodization, developing to the formation of a complete phosphate layer at an intermediate stage and finally, to a porous structure at the steady stage. The phosphate layer was observed by AFM as well as by Auger Electron Spectroscopy (AES). Nevertheless, it could not be noticed by SEM. AFM data were quantified by fractal dimension and no significant changes in terms of fractal dimension were found in the function of the anodization time.

Keywords: Fractal dimension, AFM, porous aluminum oxide

An increasing demand for sophisticated tools to characterize the integrity and functional state of vascular networks from different imaging modalities has emerged. Currently available tools are time-consuming and limited in their ability to assess the state of vascular architectures, hence there is a need for developing robust and fast computer-based techniques for extracting vessel trajectories as well as estimate their diameters. Towards this goal, we evaluate a novel technique based on the well-known Hough transform (HT) to dynamically estimate the trajectory and vessel diameter without resorting to time-consuming multiscale techniques1. Results are validated using synthetic datasets and applied on a magnetic resonance angiography (MRA) image of a human brain.

Keywords: MRA image, vessel tracking

Keywords: vessel tracking, MRA images, blood vessels

Keywords: lumen segmentation, vessel tracking, CTA, MRA

Keywords: lumen segmentation, vessel tracking, Hough transform, angiographic images, CTA, MRA

O processamento de imagens digitais pode ser aplicado como ferramenta de auxílio em diagnósticos médicos. Neste sentido, o presente trabalho mostra técnicas de análise de tomografias de crânio e tórax obtidas a partir de um fantôma antropomórfico, onde algoritmos de processamento de imagens são propostos a fim de medir as áreas das regiões de tecido ósseo, tecido mole e ar do fantôma. Em seguida uma reconstrução 3D é apresentada com o objetivo de obter o volume e visualizar essas regiões. Os parâmetros medidos mostram a robustez do método proposto por meio da comparação com valores obtidos pelo programa Voxar-3D e com valores analíticos de um fantôma virtual. Os resultados alcançados permitem a calibração de aparelhos de raios-X e constituem informações importantes para a fabricação de novos modelos antropomórficos.

Keywords: física médica, tomografia, extração de características

Keywords: Hough transform, generic form

In this paper we introduce a unique methodology to detect any conic form by using Hough transform which is an established method for shape detection. This technique works based on features extraction for each conic separately and intend to unify all type of Hough detection in only one. Once we have the conic's parameters it is possible to build an accumulator array named parameter space where the most voted set of parameters is the chosen form. To build this accumulator, a range of values is set up and each value is a real parameter candidate. The length of which cell depends on the accuracy desirable and the dimension depends on the type of conic. This transform maps points from digital space to parameters space in order to match the point of the chosen form to the form in the real image. In this way it is much easier to reconstruct the conic form whenever it is necessary and to detect a form from artificial images or handmade drawing. Although each form has one different equation and number of parameters, we realized it follows a pattern and concluded that is possible to elaborate a generic equation and a methodology to detect any conic. The use of polar coordinates makes the generic detection easier because of the rotations variety detection. In addition, the order of search is important. We observed that the detection result is better if the searching for the correct rotation is the first step. Another relevant thing is the chosen length of bins in the accumulator which really defines a better match. This paper involves analysis about each conic equation, their similarities, number of parameters and how they can be introduced by a unique expression for Hough transform.

Keywords: Feature Extraction, Geometry, Hough Transform, Conics

Hardness measurement is commonly used in industrial applications f or quality control and products conf ormity tests, because it is f ast, cheap and relatively non- destructive. Once the main error causes in hardness measurement is the indentation, this paper presents some possible approaches to measure hardness indentation automatically. It compares the use of some computer vision techniques, including Hough transf orm, to detect and analyze important parameters on the def inition of material Vickers hardness. We highlight the main problems involved in this measurement and comment the automatic possibilities to obtain accurate results.

Keywords: Vickers hardness tests, Hough transform, Measurement by image

Keywords: licence plate region, digital image

This paper presents a system developed in order to detect fails in the industrial production of pills. The main idea is based on the Hough transform methodology for quality control of drugs in circle form of predefined dimension and perfect shape. This detection occurs during the medicine industrial production to detect pills with imperfect edges.

Keywords: Hough transform, shape detection

Keywords: rugosidade, AFM, aluminum, nanoestruturas

Keywords: licence plate detection, characters region