a Preview of the Future of Portugal in the Political Turmoil of the First Republic

UID/ELT/04097/2013 UID/ELT/04097/2016 UID/ELT/04097/2019 UIDB/04097/2020publishersversionpublishe

Hierarchical motion estimation for side information creation in Wyner-Ziv video coding

Recently, several video coding solutions based on the distributed source coding paradigm have appeared in the literature. Among them, Wyner-Ziv video coding schemes enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill requirements of emerging applications such as visual sensor networks and wireless surveillance. To achieve a performance comparable to the predictive video coding solutions, it is necessary to increase the quality of the side information, this means the estimation of the original frame created at the decoder. In this paper, a hierarchical motion estimation (HME) technique using different scales and increasingly smaller block sizes is proposed to generate a more reliable estimation of the motion field. The HME technique is integrated in a well known motion compensated frame interpolation framework responsible for the creation of the side information in a Wyner-Ziv video decoder. The proposed technique enables to achieve improvements in the rate-distortion (RD) performance up to 7 dB when compared to H.263+ Intra and 3 dB when compared to H.264/AVC Intra

Tool for 3D analysis and segmentation of retinal layers in volumetric SD-OCT images

With the development of optical coherence tomography in the spectral domain (SD-OCT), it is now possible to quickly acquire large volumes of images. Typically analyzed by a specialist, the processing of the images is quite slow, consisting on the manual marking of features of interest in the retina, including the determination of the position and thickness of its different layers. This process is not consistent, the results are dependent on the clinician perception and do not take advantage of the technology, since the volumetric information that it currently provides is ignored. Therefore is of medical and technological interest to make a three-dimensional and automatic processing of images resulting from OCT technology. Only then we will be able to collect all the information that these images can give us and thus improve the diagnosis and early detection of eye pathologies. In addition to the 3D analysis, it is also important to develop visualization tools for the 3D data. This thesis proposes to apply 3D graphical processing methods to SD-OCT retinal images, in order to segment retinal layers. Also, to analyze the 3D retinal images and the segmentation results, a visualization interface that allows displaying images in 3D and from different perspectives is proposed. The work was based on the use of the Medical Imaging Interaction Toolkit (MITK), which includes other open-source toolkits. For this study a public database of SD-OCT retinal images will be used, containing about 360 volumetric images of healthy and pathological subjects. The software prototype allows the user to interact with the images, apply 3D filters for segmentation and noise reduction and render the volume. The detection of three surfaces of the retina is achieved through intensity-based edge detection methods with a mean error in the overall retina thickness of 3.72 0.3 pixels

Coding mode decision algorithm for binary descriptor coding

In visual sensor networks, local feature descriptors can be computed at the sensing nodes, which work collaboratively on the data obtained to make an efficient visual analysis. In fact, with a minimal amount of computational effort, the detection and extraction of local features, such as binary descriptors, can provide a reliable and compact image representation. In this paper, it is proposed to extract and code binary descriptors to meet the energy and bandwidth constraints at each sensing node. The major contribution is a binary descriptor coding technique that exploits the correlation using two different coding modes: Intra, which exploits the correlation between the elements that compose a descriptor; and Inter, which exploits the correlation between descriptors of the same image. The experimental results show bitrate savings up to 35% without any impact in the performance efficiency of the image retrieval task. © 2014 EURASIP

Halitosis and the pH variation with four mouthwashes

Poster apresentado no XXV Congresso da Ordem dos Médicos Dentistas, 10-12 Novembro 2016. Porto, PortugalSob uma licença CC-BY-NC - http://creativecommons.org/licenses/by-nc/4.0/Introduction: It is estimated that the prevalence of halitosis, varies between 2-44% at world population. It is suggested that the oral pH value is an important factor on the oral microbiota composition which has impact in gaseous breath constitution (2).The aim of this study was to compare the effect of four mouthwashes on salivary pH values, over time.N/