Algorithms for super-resolution of images based on Sparse Representation and Manifolds

lmage super-resolution is defined as a class of techniques that enhance the spatial resolution of images. Super-resolution methods can be subdivided in single and multi image methods. This thesis focuses on developing algorithms based on mathematical theories for single image super­ resolution problems. lndeed, in arder to estimate an output image, we adopta mixed approach: i.e., we use both a dictionary of patches with sparsity constraints (typical of learning-based methods) and regularization terms (typical of reconstruction-based methods). Although the existing methods already per- form well, they do not take into account the geometry of the data to: regularize the solution, cluster data samples (samples are often clustered using algorithms with the Euclidean distance as a dissimilarity metric), learn dictionaries (they are often learned using PCA or K-SVD). Thus, state-of-the-art methods still suffer from shortcomings. In this work, we proposed three new methods to overcome these deficiencies. First, we developed SE-ASDS (a structure tensor based regularization term) in arder to improve the sharpness of edges. SE-ASDS achieves much better results than many state-of-the- art algorithms. Then, we proposed AGNN and GOC algorithms for determining a local subset of training samples from which a good local model can be computed for recon- structing a given input test sample, where we take into account the underlying geometry of the data. AGNN and GOC methods outperform spectral clustering, soft clustering, and geodesic distance based subset selection in most settings. Next, we proposed aSOB strategy which takes into account the geometry of the data and the dictionary size. The aSOB strategy outperforms both PCA and PGA methods. Finally, we combine all our methods in a unique algorithm, named G2SR. Our proposed G2SR algorithm shows better visual and quantitative results when compared to the results of state-of-the-art methods.

Educação bilíngue para surdos : um estudo acerca de práticas de letramento crítico com alunos surdos usuários da Língua Brasileira de Sinais

At a time when the issue of the inclusion of hearing-impaired students in regular schools has been discussed, it becomes necessary to reflect upon the relevance of a recurrent educational process in schools specialized in education for the hearing-impaired: the bilingual schools. Such institutions, still scarce in Brazil, offer an oriented and specialized education to hearing-impaired children and adolescents, since they have the Brazilian Sign Language as a language of instruction in all subjects, and the Portuguese written language as an additional language, which gives them the bilingual status. This research aims to investigate how the practices developed in my Portuguese classes in a bilingual school have contributed to the development of student‟s literacy, specifically the Critical Literacy (STREET, 1985, 1990, 1998), in two classes of hearing-impaired students enrolled in the final grades of elementary school. It is a qualitative, ethnographic research, which uses the triangulation system for analyzing data: (i) the pedagogical sequences; (ii) the students‟ activities and (iii) the teacher‟s and students‟ written accounts registered as field notes. Through the intersection of the data, this work evaluates whether students have achieved some level of Critical Literacy, and what kind of collaboration and/or activity is relevant during this process. This research is justified by the need to evaluate practices at bilingual schools that, although supported by current law in Brazil, are still a minority whose work is still not acknowledged or valued. The results show that activities using real texts of different genres can contribute to the development of Critical Literacy, and also to dynamic classes, with discussions about relevant topics to society in Sign Language. Also, activities that encourage students to do research and that provide to the hearing-impaired student, the understanding of the real usefulness of Portuguese as an instrument for the social inclusion of the hearing-impaired providing opportunities for them to change their social position can collaborate to this process.

Múltiplos fluxos ópticos e o processamento atentivo da informação visual

The environment in which we live in, we constantly deal with a huge amount of dynamic information, thus, attention is an indispensable cognitive resource that allows an effective selection of stimuli for our survival. From this, investigating how we process our encouragement in movements and how the attention spreads into a space to serve more than one stimuli simultanously is something very important. The behavioural urgence hipothesis suggests that the encouragement in a movement of approaching shows a certain priority in the process related to objects which are in a movement away, but there are researches that point out that it might not happen in an attentive phase, but instead as a priorization of motor response. There are also many controversies found in researches about attentive focalization, in which some studies suggest that the focus of attention would work in a similar manner to a zoom lens, while some searches indicate that the focus of attention could be shared to answer some stimuli in non contiguous regions. This study tried to investigate through two experiments the effect of attentive priorization by encouragement in movements and how the attention is spread with distractors stimuli. The first experiment investigated if the amount of moving flows really influenced in the process of information. The results indicate an effect of priorization of the flows guided in relation to aleatory ones and also from the unique flow due to dual flow. The second experiment investigated how the distribution of attention is in a space with the use of flows as an exogenous cue. The results indicate that the focus of attention works as the one suggested in the zoom lens model.