893 research outputs found

    Pyramidal Stochastic Graphlet Embedding for Document Pattern Classification

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    This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordDocument pattern classification methods using graphs have received a lot of attention because of its robust representation paradigm and rich theoretical background. However, the way of preserving and the process for delineating documents with graphs introduce noise in the rendition of underlying data, which creates instability in the graph representation. To deal with such unreliability in representation, in this paper, we propose Pyramidal Stochastic Graphlet Embedding (PSGE). Given a graph representing a document pattern, our method first computes a graph pyramid by successively reducing the base graph. Once the graph pyramid is computed, we apply Stochastic Graphlet Embedding (SGE) for each level of the pyramid and combine their embedded representation to obtain a global delineation of the original graph. The consideration of pyramid of graphs rather than just a base graph extends the representational power of the graph embedding, which reduces the instability caused due to noise and distortion. When plugged with support vector machine, our proposed PSGE has outperformed the state-of-The-art results in recognition of handwritten words as well as graphical symbols.European Union Horizon 2020Ministerio de Educación, Cultura y Deporte, SpainRamon y Cajal FellowshipCERCA Program/Generalitat de Cataluny

    Analysis and Interpretation of Graphical Documents

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    International audienceThis chapter is dedicated to the analysis and the interpretation of graphical documents, and as such, builds upon many of the topics covered in other parts of this handbook. It will therefore not focus on any of the technical issues related to graphical documents, such as low level filtering and binarization, primitive extraction and vectorization as developed in Chapters 2.1 and 5.1 or symbol recognition, for instance, as developed in Chapter 5.2. These tools are put in a broader framework and threaded together in complex pipelines to solve interpretation questions. This chapter provides an overview of how analysis strategies have contributed to constructing these pipelines, how specific domain knowledge is integrated in these analyses, and which interpretation contexts have been contributed to successful approaches

    Recognition of handwritten music scores

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    The recognition of handwritten music scores still remains an open problem. The existing approaches can only deal with very simple handwritten scores mainly because of the variability in the handwriting style and the variability in the composition of groups of music notes (i.e. compound music notes). In this work on the one hand I study the isolated symbols (i.e half-note, quarter-note, clefs, sharps) and on the other hand the compound music notes. Firstly, I will separate the isolated symbols (i.e half-notes, quarter-notes, clefs, sharps) to the compounds and I will study each one separately. The isolated symbols will be recognized with symbol recognition methods and compounds with a primitive hierarchy and syntactic rules. The method has been tested using several handwritten music scores of the CVC-MUSCIMA database and compared with a commercial Optical Music Recognition software. Given that my method is learning-free, the obtained results are promising.El reconeixement de partitures musicals manuscrites segueix sent un problema obert. Els enfocaments existents només poden reconéixer partitures manuscrites molt simples, principalment a causa de la variabilitat en l'estil d'escriptura i la variabilitat en la composició dels grups de notes musicals (p.e. els símbols musicals compostos). En aquest treball, per començar, se separaran els símbols simples (p.e blanques, negres, claus, sostinguts) dels compostos i els estudiaré per separat. Els símbols simples mitjançant mètodes de reconeixement de símbols i els compostos a partir d'una jerarquia de primitives i regles sintàctiques. El meu mètode ha estat provat utilitzant diferents partitures de música escrita a mà de la base de dades CVC-MUSCIMA i comparat amb un programari de reconeixement òptic musical comercial. Tenint en compte que el meu mètode és d'aprenentatge lliure, els resultats obtinguts són prometedors.El reconocimiento de partituras musicales manuscritas sigue siendo un problema abierto. Los enfoques existentes sólo pueden reconocer partituras manuscritas muy simples, principalmente debido a la variabilidad en el estilo de escritura y la variabilidad en la composición de los grupos de notas musicales (p.e. los símbolos musicales compuestos). En este trabajo, para empezar, se separarán los símbolos simples (p.e blancas, negras, llaves, sostenidos) de los compuestos y los estudiaré por separado. Los símbolos simples mediante métodos de reconocimiento de símbolos y los compuestos a partir de una jerarquía de primitivas y reglas sintácticas. Mi método ha sido probado utilizando diferentes partituras de música escrita a mano de la base de datos CVC-MUSCIMA y comparado con un software de reconocimiento óptico musical comercial. Teniendo en cuenta que mi método es de aprendizaje libre, los resultados obtenidos son prometedores

    Product graph-based higher order contextual similarities for inexact subgraph matching

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record Many algorithms formulate graph matching as an optimization of an objective function of pairwise quantification of nodes and edges of two graphs to be matched. Pairwise measurements usually consider local attributes but disregard contextual information involved in graph structures. We address this issue by proposing contextual similarities between pairs of nodes. This is done by considering the tensor product graph (TPG) of two graphs to be matched, where each node is an ordered pair of nodes of the operand graphs. Contextual similarities between a pair of nodes are computed by accumulating weighted walks (normalized pairwise similarities) terminating at the corresponding paired node in TPG. Once the contextual similarities are obtained, we formulate subgraph matching as a node and edge selection problem in TPG. We use contextual similarities to construct an objective function and optimize it with a linear programming approach. Since random walk formulation through TPG takes into account higher order information, it is not a surprise that we obtain more reliable similarities and better discrimination among the nodes and edges. Experimental results shown on synthetic as well as real benchmarks illustrate that higher order contextual similarities increase discriminating power and allow one to find approximate solutions to the subgraph matching problem.European Union Horizon 202

    Graphics Recognition -- from Re-engineering to Retrieval

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    Invited talk. Colloque avec actes et comité de lecture. internationale.International audienceIn this paper, we discuss how the focus in document analysis, generally speaking, and in graphics recognition more specifically, has moved from re-engineering problems to indexing and information retrieval. After a review of ongoing work on these topics, we propose some challenges for the years to come

    Hierarchical stochastic graphlet embedding for graph-based pattern recognition

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    This is the final version. Available on open access from Springer via the DOI in this recordDespite being very successful within the pattern recognition and machine learning community, graph-based methods are often unusable with many machine learning tools. This is because of the incompatibility of most of the mathematical operations in graph domain. Graph embedding has been proposed as a way to tackle these difficulties, which maps graphs to a vector space and makes the standard machine learning techniques applicable for them. However, it is well known that graph embedding techniques usually suffer from the loss of structural information. In this paper, given a graph, we consider its hierarchical structure for mapping it into a vector space. The hierarchical structure is constructed by topologically clustering the graph nodes, and considering each cluster as a node in the upper hierarchical level. Once this hierarchical structure of graph is constructed, we consider its various configurations of its parts, and use stochastic graphlet embedding (SGE) for mapping them into vector space. Broadly speaking, SGE produces a distribution of uniformly sampled low to high order graphlets as a way to embed graphs into the vector space. In what follows, the coarse-to-fine structure of a graph hierarchy and the statistics fetched through the distribution of low to high order stochastic graphlets complements each other and include important structural information with varied contexts. Altogether, these two techniques substantially cope with the usual information loss involved in graph embedding techniques, and it is not a surprise that we obtain more robust vector space embedding of graphs. This fact has been corroborated through a detailed experimental evaluation on various benchmark graph datasets, where we outperform the state-of-the-art methods.European Union Horizon 2020Ministerio de Educación, Cultura y Deporte, SpainGeneralitat de Cataluny
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