Research

  • Database Schema for MPEG-7 Visual Descriptors. Encuentro de Investigación en Ingeniería de Sistemas y Computación. ENIP 2008. Universidad Nacional. Bogotá-Colombia. ISBN: 978-958-719-009-0. 2008. Best computer science paper distinction.

Abstract

“Images are retrieved from a repository using MPEG-7 visual descriptors. The MPEG-7 standard uses XML documents for storing descriptors of multimedia content. The MPEG-7 standard does not define a model for mapping XML documents into a database. However, XML documents can be considered as a database. An XML document is self-describing and portable data collection that has a data structure of a tree or a graph. An XML document collection can be semi-structured and this quality allows grouping XML documents without a schema that relate them. There are two possible database models: the Native XML and the Relational. A database model for XML documents is selected based on the purpose of information use and database requirements. In this paper, both models are described and analysed. A relational database schema is designed for mapping MPEG-7 visual descriptors into a database.”

  • MPEG-7 Service Oriented System. International Conference on Content Based Multimedia Retrieval (CBMI 2008). Queen Mary, University of London. London-UK. IEEE Catalog Number: CFP0814C. ISBN: 978-1-4244-2044-5. Library of Congress: 2008900140. 2008.

Abstract

“Multimedia content is extracted automatically using MPEG-7 visual descriptors. The MPEG-7 uses an extended XML standard for defining structural relation between descriptors allowing creation and modification of description schemes. MPEG-7 visual descriptors are numerical representations of features – such as: texture, shape and color – extracted from an image. In this paper, the MPEG-7 is conceived as a set of services for extracting and storing visual descriptors. The MPEg-7 text-annotation tool is used for semantic descriptions. Semantic descriptions are linked to images content and conceived as a service for annotating and storing. A framework using service oriented architecture for mapping semantic descriptions and MPEG-7 visual descriptors into a pure-relational model is proposed.”

  • Resource-Oriented Architecture for Managing Multimedia Content. In Proceedings of Latin American Conference of Networked and Electronic Media, Bogotá, 2009.

Abstract

“Resource-Oriented Architecture offers advantages over other web-service architectures. It is based on a simple, scalable and highly standardised application-level protocol. Multimedia content is commonly managed using the MPEG-7. The MPEG-7 is a standard for representing audiovisual information that satisfies specific requirements based on syntax, semantic and decoding. Content descriptions under MPEG-7 can be organised and characterized without ambiguity. The MPEG-7 eXperimental Model (XM) includes the best performing tools for MPEG-7 normative and non-normative elements. In this paper, multimedia content is managed using the MPEG-7 eXperimental Model functionalities and provided using web-services technology. RESTful principles are the guidelines for achieving multimedia content storage and retrieval. Quantitative evaluation of the proposed web services has shown that this approach has better performance, in term of retrieval speed and storage space.”

  • An Evaluation Methodology for Stereo Correspondence Algorithms. SciTePress Digital Library. 2012.

Abstract

“A comparison of stereo correspondence algorithms can be conducted by a quantitative evaluation of disparity maps. Among the existing evaluation methodologies, the Middlebury’s methodology is commonly used. However, the Middlebury’s methodology has shortcomings in the evaluation model and the error measure. These shortcomings may bias the evaluation results, and make a fair judgment about algorithms accuracy difficult. An alternative, the A* methodology is based on a multiobjective optimisation model that only provides a subset of algorithms with comparable accuracy. In this paper, a quantitative evaluation of disparity maps is proposed. It performs an exhaustive assessment of the entire set of algorithms. As innovative aspect, evaluation results are shown and analysed as disjoint groups of stereo correspondence algorithms with comparable accuracy. This innovation is obtained by a partitioning and grouping algorithm. On the other hand, the used error measure offers advantages over the error measure used in the Middlebury’s methodology. The experimental validation is based on the Middlebury’s test-bed and algorithms repository. The obtained results show seven groups with different accuracies. Moreover, the top-ranked stereo correspondence algorithms by the Middlebury’s methodology are not necessarily the most accurate in the proposed methodology.” co-author: Ivan Mauricio Cabezas T.

  • On the Impact of the Error Measure Selection in Evaluating Disparity Maps. World Automation Congress, 2012.

Abstract

“A quantitative evaluation methodology for disparity maps includes the selection of an error measure. Among existing measures, the percentage of bad matched pixels is commonly used. Nevertheless, it requires an error threshold. Thus, a score of zero bad matched pixels does not necessarily imply that a disparity map is free of errors. On the other hand, we have not found publications on the evaluation process where different error measures are applied. In this paper, error measures are characterised in order to provide the bases to select a measure during the evaluation process. An analysis of the impact on results of selecting different error measures on the evaluation of disparity maps is conducted based on the presented characterisation. The evaluation results showed that there is a lack of consistency on the results achieved by considering different error measures. It has an impact on interpreting the accuracy of stereo correspondence algorithms.” co-author: Ivan Mauricio Cabezas T.