Leonardo Torres

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This paper presents a technique for reducing speckle in Polarimetric Synthetic Aperture Radar (PolSAR) imagery using Nonlocal Means and a statistical test based on stochastic divergences. The main objective is to select homogeneous pixels in the filtering area through statistical tests between distributions. This proposal uses the complex Wishart model to(More)
BACKGROUND Nasal foreign bodies (NFBs) are a common occurrence, particularly in children between 2 and 4 years old. Many techniques have been developed to remove NFBs, though intranasal batteries, in particular, possess characteristics such as round shape, smooth surface, and limited visibility that make attempts at removal significantly more difficult. In(More)
This paper presents a new approach for filter design based on stochastic distances and tests between distributions. A window is defined around each pixel, samples are compared and only those which pass a goodness-of-fit test are used to compute the filtered value. The technique is applied to intensity Synthetic Aperture Radar (SAR) data, using the Gamma(More)
This paper presents a new approach for filter design based on stochastic distances and tests between distributions. A window is defined around each pixel, overlapping samples are compared and only those which pass a goodnessof-fit test are used to compute the filtered value. The technique is applied to intensity SAR data with homogeneous regions using the(More)
This study evaluates the usage of Stochastic Distances Nonlocal Means (SDNLM) speckle filter in an image from Brazilian Amazon. The objective is to evaluate whether the noise reduction improves land cover and change classification. Results obtained from filtered images were compared with those obtained from unfiltered images and images filtered using Gamma(More)
Previous studies have demonstrated that free radicals are formed under hypoxic conditions in newborn piglet brain. To test the hypothesis that the cyclooxygenase pathway serves as a source of free radical generation during hypoxia studies were performed on 24 piglets divided into four groups. Six saline (group 3) and six indomethacin treated (group 4) were(More)
This paper presents two approaches for filter design based on stochastic distances for intensity speckle reduction. A window is defined around each pixel, overlapping samples are compared and only those which pass a goodness-of-fit test are used to compute the filtered value. The tests stem from stochastic divergences within the Information Theory(More)
Polarimetric Synthetic Aperture Radar (PolSAR) images are establishing as an important source of information in remote sensing applications. The most complete format this type of imaging produces consists of complex-valued Hermitian matrices in every image coordinate and, as such, their visualization is challenging. They also suffer from speckle noise which(More)
Polarimetric Synthetic Aperture Radar (PolSAR) is having an increasingly positive impact in the Remote Sensing community since the launch of the first practical fully polarimetric sensor, AIRSAR, in 1985. The availability and relevance of these data makes it important to offer users state-of-the-art techniques for PolSAR image processing and analysis. One(More)