Image segmentation through combined methods: watershed transform, unsupervised distance learning and normalized cut

Research on image processing has shown that combining segmentation methods may lead to a solid approach to extract semantic information from different sort of images. Within this context, the Normalized Cut (NCut) is usually used as a final partitioning tool for graphs modeled in some chosen method. This work explores the Watershed Transform as a modeling tool, using different criteria of the hierarchical Watershed to convert an image into an adjacency graph. The Watershed is combined with an unsupervised distance learning step that redistributes the graph weights and redefines the Similarity matrix, before the final segmentation step using NCut. Adopting the Berkeley Segmentation Data Set and Benchmark as a background, our goal is to compare the results obtained for this method with previous work to validate its performance.

Ridge-based fingerprint matching using hough transform

Despite the efficacy of minutia-based fingerprint matching techniques for good-quality images captured by optical sensors, minutia-based techniques do not often perform so well on poor-quality images or fingerprint images captured by small solid-state sensors. Solid-state fingerprint sensors are being increasingly deployed in a wide range of applications for user authentication purposes. Therefore, it is necessary to develop new fingerprint-matching techniques that utilize other features to deal with fingerprint images captured by solid-state sensors. This paper presents a new fingerprint matching technique based on fingerprint ridge features. This technique was assessed on the MSU-VERIDICOM database, which consists of fingerprint impressions obtained from 160 users (4 impressions per finger) using a solid-state sensor. The combination of ridge-based matching scores computed by the proposed ridge-based technique with minutia-based matching scores leads to a reduction of the false non-match rate by approximately 1.7% at a false match rate of 0.1%. © 2005 IEEE.

Image segmentation using morphological watershed applied to cartography

Image segmentation is a process frequently used in several different areas including Cartography. Feature extraction is a very troublesome task, and successful results require more complex techniques and good quality data. The aims of this paper is to study Digital Image Processing techniques, with emphasis in Mathematical Morphology, to use Remote Sensing imagery, making image segmentation, using morphological operators, mainly the multi-scale morphological gradient operator. In the segmentation process, pre-processing operators of Mathematical Morphology were used, and the multi-scales gradient was implemented to create one of the images used as marker image. Orbital image of the Landsat satellite, sensor TM was used. The MATLAB software was used in the implementation of the routines. With the accomplishment of tests, the performance of the implemented operators was verified and carried through the analysis of the results. The extration of linear feature, using mathematical morphology techniques, can contribute in cartographic applications, as cartographic products updating. The comparison to the best result obtained was performed by means of the morphology with conventional techniques of features extraction. © Springer-Verlag 2004.

Avaliação da distribuição das forças produzidas com arco lingual removível pelo método de elementos finitos

Pós-graduação em Ciências Odontológicas - FOAR

Human face verification based on multidimensional Polynomial Powers of Sigmoid (PPS)

In this paper, we described how a multidimensional wavelet neural networks based on Polynomial Powers of Sigmoid (PPS) can be constructed, trained and applied in image processing tasks. In this sense, a novel and uniform framework for face verification is presented. The framework is based on a family of PPS wavelets,generated from linear combination of the sigmoid functions, and can be considered appearance based in that features are extracted from the face image. The feature vectors are then subjected to subspace projection of PPS-wavelet. The design of PPS-wavelet neural networks is also discussed, which is seldom reported in the literature. The Stirling Universitys face database were used to generate the results. Our method has achieved 92 % of correct detection and 5 % of false detection rate on the database.

Comparison of fracture surface and plane section analysis for ceramic grain size characterisation

A method has been developed to obtain quantitative information about grain size and shape from fractured surfaces of ceramic materials. One elaborated a routine to split intergranular and transgranular grains facets of ceramic fracture surfaces by digital image processing. A commercial ceramic (ALCOA A-16, Al2O3-1.5% of CrO) was used to test the proposed method. Microstructural measurements of grain shape and size taken from fracture surfaces have been compared through descriptive statistics of distributions, with the corresponding measurements from polished and etched surfaces. The agreement between results, with the expected bias on grain size values from fractures, obtained for both types of surfaces allowed to infer that this new technique can be used to extract the relevant microstructural information from fractured surfaces, thus minimising the time consuming steps of sample preparation. (C) 2003 Elsevier Ltd. All rights reserved.

Boundary identification criteria and geometry analysis of Al 7050 stretch zone from elevation profiles

This article describes the development of a method for analysis of the shape of the stretch zone surface based on parallax measurement theory and using digital image processing techniques. Accurate criteria for the definition of the boundaries of the stretch zone are established from profiles of fracture surfaces obtained from crack tip opening displacement tests on Al-7050 alloy samples. The elevation profiles behavior analysis is based on stretch zone width and height parameters. It is concluded that the geometry of the stretch zone profiles under plane strain conditions can be described by a semi-parabolic relationship. (C) Elsevier B.V., 1999. All rights reserved.

Fractal behavior throughout stretch zone of 15-5PH steel under elastic-plastic loading conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extended depth from focus reconstruction using NIH ImageJ plugins: Quality and resolution of elevation maps

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

3-D reconstruction by extended depth-of-field in failure analysis - Case study I: Qualitative fractographic investigation of fractured bolts in a partial valve

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sistemas distribuídos aplicados à compressão e recuperação de imagens

Digital image processing is a field that demands great processing capacity. As such it becomes relevant to implement software that is based on the distribution of the processing into several nodes divided by computers belonging to the same network. Specifically discussed in this work are distributed algorithms of compression and expansion of images using the discrete cosine transform. The results show that the savings in processing time obtained due to the parallel algorithms in comparison to its sequential equivalents is a function that depends on the resolution of the image and the complexity of the involved calculation; that is efficiency is greater the longer the processing period is in terms of the time involved for the communication between the network points.

Avaliação de parâmetros métricos oculares pela fotografia digital da face: uso do diâmetro da íris como unidade de referência

Purpose: To evaluate reproducibility and precision of ocular measurements by digital photograph analysis, in addition to the transformation of the measures according to the individual iris diameter as an oculometric reference. Methods: Twenty-four eyes have been digitally photographed in a standardized way at two distances. Two researchers have analyzed these printed images using a caliper and these digital forms by ImageJ 1.37 (TM). Several external ocular parameters were estimated (mm and as iris diameter) and methods of measurement compared regarding their precision, agreement and correlation. Results: Caliper and digital analysis of oculometric measures provided significant agreement and correlation, nevertheless the precision of digital measures was higher. The estimates of numeric transformation from oculometric measures according to individual iris diameter resulted in great correlation to caliper measures and high agreement when compared to different distances of taking the photographs. Conclusions: Facial digital photographs allowed oculometric precise and reproducible estimates, endorsing clinical research usefulness. Using iris diameter as individual oculometric reference disclosed high reproducibility when facial photographs were taken at different distances.

Úlceras crônicas dos membros inferiores: avaliação pela fotografia digital

OBJETIVO: Avaliar o desempenho da análise de imagem digital na estimativa da área acometida pelas úlceras crônicas dos membros inferiores. MÉTODOS: Estudo prospectivo em que foram mensuradas úlceras empregando o método planimétrico clássico, utilizando desenho dos seus contornos em filme plástico transparente, medida sua área posteriormente por folha milimetrada. Esses valores foram utilizados como padrão para a comparação com a estimativa de área pelas fotografias digitais padronizadas das úlceras e dos desenhos das mesmas em filme plástico. Para criar um referencial de conversão dos pixels em milímetros, foi empregado um adesivo com tamanho conhecido, adjacente à úlcera. RESULTADOS: foram avaliadas 42 lesões em 20 pacientes portadores de úlceras crônicas de membros inferiores. As áreas das úlceras variaram de 0,24 a 101,65cm². Observou-se forte correlação entre as medidas planimétricas e as fotos das úlceras (R²=0,86 p<0,01), porém a correlação das medidas planimétricas com as fotos digitais dos desenhos das úlceras foi ainda maior (R²=0,99 p<0,01). CONCLUSÃO: A fotografia digital padronizada revelou-se método rápido, preciso e não-invasivo capaz de estimar a área afetada por úlceras. A avaliação das medidas fotográficas dos contornos das úlceras deve ser preferida em relação à análise de sua fotografia direta.

Avaliação da posição do supercílio por medidas angulares

OBJETIVO: Avaliar a posição do supercílio em diferentes idades, utilizando medidas angulares. MÉTODOS: Foram avaliados indivíduos com idade de 4 a 6 anos (Grupo de crianças) e igual ou superior a 50 anos (Grupo de idosos), separados em faixas etárias, avaliando-se a posição do supercílio por meio de imagens digitais, utilizando medidas angulares. As imagens foram tomadas em posição primária do olhar, utilizando filmadora Sony Lithium, e posteriormente transferidas para computador MacIntosh G4 e processadas pelo programa NIH 1,58. Os parâmetros analisados foram: ângulo interno, externo e vertical da cauda do supercílio. As comparações foram entre sexos, faixas etárias e lateralidade. Os resultados obtidos foram submetidos à análise estatística. RESULTADOS: A comparação das medidas angulares mostrou que houve diferença significativa na posição da cauda do supercílio entre os grupos estudados quando comparados dentro do grupo com faixa etária semelhante. Porém, comparando-se crianças e adultos, houve diferença em todos os tipos de ângulos estudados. CONCLUSÕES: A posição do supercílio avaliada por medidas angulares mostrou diferenças entre crianças e idosos, revelando associação positiva com a idade.

Dimensões palpebrais antes e após blefaroplastia superior: avaliação quantitativa

OBJETIVO: Quantificar, usando o sistema de imagem digital, medidas palpebrais antes e após a cirurgia de blefaroplastia superior. MÉTODOS: Foram avaliadas 18 pálpebras de 9 pacientes atendidas no HC da FMB - UNESP, com idade entre 40 a 75 anos, do sexo feminino, portadoras de dermatocálase. Foram obtidas fotografias das pacientes antes e após 60 dias da blefaroplastia da pálpebra superior. As imagens foram transferidas para um computador e analisadas pelo programa Scion Image Frame Grabber. Os parâmetros avaliados foram: a altura da fenda palpebral em posição primária do olhar, altura do sulco palpebral superior e o ângulo palpebral lateral antes e depois de 60 dias da realização da cirurgia de blefaroplastia superior. RESULTADOS: Após a cirurgia, houve aumento da altura da fenda palpebral e do sulco palpebral superior. Contudo, o ângulo palpebral lateral não se alterou. CONCLUSÃO: A posição palpebral se altera após a blefaroplastia e o processamento de imagens digitais possibilita quantificar estas alterações, mensurando os resultados obtidos com a cirurgia.