Object tracking and matting for A class of dynamic image-based representations

Image-based rendering (IBR) is an emerging technology for photo-realistic rendering of scenes from a collection of densely sampled images and videos. Recently, an object-based approach for a class of dynamic image-based representations called plenoptic videos was proposed. This paper proposes an automatic object tracking approach using the level-set method. Our tracking method, which utilizes both local and global features of the image sequences instead of global features exploited in previous approach, can achieve better tracking results for objects, especially with non-uniform energy distribution. Due to possible segmentation errors around object boundaries, natural matting with Bayesian approach is also incorporated into our system. Furthermore, a MPEG-4 like object-based algorithm is developed for compressing the plenoptic videos, which consist of the alpha maps, depth maps and textures of the segmented image-based objects from different video plenoptic streams. Experimental results show that satisfactory renderings can be obtained by the proposed approaches. © 2005 IEEE.published_or_final_versio

An object-based approach to plenoptic videos

This paper proposes an object-based approach to plenoptic videos, where the plenoptic video sequences are segmented into image-based rendering (IBR) objects each with its image sequence, depth map and other relevant information such as shape information. This allows desirable functionalities such as scalability of contents, error resilience, and interactivity with individual IBR objects to be supported. A portable capturing system consisting of two linear camera arrays, each hosting 6 JVC video cameras, was developed to verify the proposed approach. Rendering and compression results of real-world scenes demonstrate the usefulness and good quality of the proposed approach. © 2005 IEEE.published_or_final_versio

An object-based approach to image/video-based synthesis and processing for 3-D and multiview televisions

This paper proposes an object-based approach to a class of dynamic image-based representations called "plenoptic videos," where the plenoptic video sequences are segmented into image-based rendering (IBR) objects each with its image sequence, depth map, and other relevant information such as shape and alpha information. This allows desirable functionalities such as scalability of contents, error resilience, and interactivity with individual IBR objects to be supported. Moreover, the rendering quality in scenes with large depth variations can also be improved considerably. A portable capturing system consisting of two linear camera arrays was developed to verify the proposed approach. An important step in the object-based approach is to segment the objects in video streams into layers or IBR objects. To reduce the time for segmenting plenoptic videos under the semiautomatic technique, a new object tracking method based on the level-set method is proposed. Due to possible segmentation errors around object boundaries, natural matting with Bayesian approach is also incorporated into our system. Furthermore, extensions of conventional image processing algorithms to these IBR objects are studied and illustrated with examples. Experimental results are given to illustrate the efficiency of the tracking, matting, rendering, and processing algorithms under the proposed object-based framework. © 2009 IEEE.published_or_final_versio

On the rendering and post-processing of simplified dynamic light fields with depth information

This paper studies the rendering and post-processing of a dynamic image-based representation called the simplified dynamic light fields (SDLF) (or plenoptic videos) with depth information. The user viewpoints are limited to a camera line to simplify the capturing and compression processes. By associating each image pixel with its depth value, methods for improving the rendering quality and detecting occlusions are proposed. Due to the limited sampling at depth discontinuities, adaptive lowpass filtering is applied to the detected occluded regions near object boundaries in order to suppress the aliasing artifacts. Rendering results using computer-generated images show that considerable improvement in rendering quality even for dynamic scenes with large depth variations.published_or_final_versio

The Plenoptic videos: Capturing, Rendering and Compression

This paper presents a system for capturing and rendering a dynamic image-based representation called the plenoptic videos. It is a simplified version of light fields for dynamic environment, where user viewpoints are constrained along the camera plane of a linear array of video cameras. The system consists of a camera array of 8 Sony CCX-Z11 CCD cameras and eight Pentium 41.8 GHz computers connected together through a 100 baseT LAN. Important issues such as multiple camera calibration, real-time compression, decompression and rendering are addressed. Experimental results demonstrated the usefulness of the proposed parallel processing based system in capturing and rendering high quality dynamic image-based representation using off-the-shelf equipment, and its potential applications in visualization and immersive television systems.published_or_final_versio

Relatório de estágio: Novadelta Comércio de Cafés España, SAU

O presente relatório enquadra-se no estágio curricular do Mestrado em Auditoria Empresarial e Pública ministrado pelo Instituto Superior de Contabilidade e Administração de Coimbra. O estágio teve lugar na empresa Novadelta Comercio de Cafés España, S.A.U, no Departamento de Contabilidade, tendo decorrido entre 2 de maio e 30 de outubro de 2012. As atividades do estágio visaram fundamentalmente percecionar de que forma a contabilidade é executada nesta organização, em particular no que respeita aos processos que envolvem pagamentos e recebimentos, bem como os procedimentos de controlo interno nas diversas áreas do negócio, mormente os relativos à informação financeira. Os procedimentos de controlo interno relativos à informação financeira (contabilidade) existentes nesta Empresa são de extrema importância, porque permitem que os utilizadores da informação financeira tenham maior confiança nas suas demonstrações financeiras. O controlo existente em cada área de atividade assume-se como um ponto forte para a Empresa, contribuindo para que o contacto direto com clientes, fornecedores e outras entidades seja assente na confiança, honestidade e amizade. Por outro lado, permite responder melhor à exigência de qualidade dos serviços. O estágio na Novadelta Espanha foi muito gratificante, na medida em que foi possível pôr em prática os conhecimentos teóricos adquiridos ao nível da contabilidade e controlo interno, bem como o desenvolvimento de novas competências, a autonomia no desenvolvimento das tarefas nessas áreas, adaptação a novos ambientes e fomentar o relacionamento interpessoal e intercultural

Mechanical Activation of Al-Oxyhydroxide Minerals – Physicochemical Changes, Reactivity and Relevance to Bayer Process

Overview of our research on ‘structure and reactivity’ of gibbsite and boehmite under varied conditions of mechanical activation, e.g. milling energy and presence of a second phase is presented. Bulk and surface changes induced in the solids by milling are characterized in terms of morphology, particle size distribution, specific surface area and nature of porosity, crystallite size and zeta potential. Results on enhanced amorphisation of gibbsite in presence of a second phase (quartz, hematite etc), changes in zeta potential of gibbsite due to loss of texture during milling and anomalous decrease in surface area of boehmite during milling are reported. Reactivity of the activated solids in sodium hydroxide and variation in thermal transformation temperatures is correlated with physicochemical characteristics of the samples and plausible explanation for the observed correlations presented. Significance of the results with specific reference to bauxite and alumina processing in Bayer process is highlighted

Modulation of microglia by Wolfberry on the survival of retinal ganglion cells in a rat ocular hypertension model

The active component of Wolfberry (Lycium barbarum), lycium barbarum polysaccharides (LBP), has been shown to be neuroprotective to retinal ganglion cells (RGCs) against ocular hypertension (OH). Aiming to study whether this neuroprotection is mediated via modulating immune cells in the retina, we used multiphoton confocal microscopy to investigate morphological changes of microglia in whole-mounted retinas. Retinas under OH displayed slightly activated microglia. One to 100 mg/kg LBP exerted the best neuroprotection and elicited moderately activated microglia in the inner retina with ramified appearance but thicker and focally enlarged processes. Intravitreous injection of lipopolysaccharide decreased the survival of RGCs at 4 weeks, and the activated microglia exhibited amoeboid appearance as fully activated phenotype. When activation of microglia was attenuated by intravitreous injection of macrophage/microglia inhibitory factor, protective effect of 10 mg/kg LBP was attenuated. The results implicated that neuroprotective effects of LBP were partly due to modulating the activation of microglia

A fresh look at the evolution and diversification of photochemical reaction centers

In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments. I show, for example, that the protein folds at the C-terminus of the D1 and D2 subunits of Photosystem II, which are essential for the coordination of the water-oxidizing complex, were already in place in the most ancestral Type II reaction center subunit. I then evaluate the evolution of reaction centers in the context of the rise and expansion of the different groups of bacteria based on recent large-scale phylogenetic analyses. I find that the Heliobacteriaceae family of Firmicutes appears to be the earliest branching of the known groups of phototrophic bacteria; however, the origin of photochemical reaction centers and chlorophyll synthesis cannot be placed in this group. Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria. Finally, I argue that the discrepancies among the phylogenies of the reaction center proteins, chlorophyll synthesis enzymes, and the species tree of bacteria are best explained if both types of photochemical reaction centers evolved before the diversification of the known phyla of phototrophic bacteria. The primordial phototrophic ancestor must have had both Type I and Type II reaction centers