HEPHAESTUS Research Repository: Recent submissions

Now showing items 3001-3020 of 6637

  • Mean Normalized Retrieval Order (MNRO): a new content-based image retrieval performance measure 

    Chatzichristofis, Savvas A.; Iakovidou, Chryssanthi; Boutalis, Yiannis S.; Angelopoulou, Elli (Springer, 2014)
    The results of a content based image retrieval system can be evaluated by several performance measures, each one employing different evaluation criteria. Many of the methods used in the field of information retrieval have ...

  • Bag-of-visual-words vs global image descriptors on two-stage multimodal retrieval 

    Zagoris, Konstantinos; Chatzichristofis, Savvas A.; Arampatzis, Avi (ACM SIGIR 2011, 2011)
    The Bag-Of-Visual-Words (BOVW) paradigm is fast becoming a popular image representation for Content-Based Image Retrieval (CBIR), mainly because of its better retrieval effectiveness over global feature representations ...

  • Comparative Performance Evaluation of Image Descriptors Over IEEE 802.11b NoisyWireless Networks 

    Chatzistavros, Evaggelos; Chatzichristofis, Savvas A.; Stamatellos, Georgios; Zagoris, Konstantinos (IEEE (Computer Society), 2011)
    Abstract—In this paper we evaluate the image retrieval procedure over an IEEE 802.11b Ad Hoc network, operating in 2.4GHz, using IEEE Distributed Coordination Function CSMA/CA as the multiple access scheme. IEEE 802.11 ...

  • Fusion vs. Two-Stage for Multimodal Retrieval 

    Arampatzis, Avi; Zagoris, Konstantinos; Chatzichristofis, Savvas A. (Springer, 2011)
    We compare two methods for retrieval from multimodal collections. The first is a score-based fusion of results, retrieved visually and textually. The second is a two-stage method that visually re-ranks the top-K results ...

  • Dynamic Two-Stage Image Retrieval from Large Multimodal Databases 

    Arampatzis, Avi; Zagoris, Konstantinos; Chatzichristofis, Savvas A. (Springer-Verlag, 2011)
    Content-based image retrieval (CBIR) with global features is notoriously noisy, especially for image queries with low percentages of relevant images in a collection. Moreover, CBIR typically ranks the whole collection, ...

  • www.MMRetrieval.net: a multimodal search engine 

    Zagoris, Konstantinos; Chatzichristofis, Savvas A.; Arampatzis, Avi (Association for Computing Machinery (ACM), United States, 2010)
    We introduce an experimental search engine for multilin- gual and multimedia information, employing a holistic web interface and enabling the use of highly distributed indices. Modalities are searched in parallel, and ...

  • Accelerating Image Retrieval Using Binary Haar Wavelet Transform on the Color and Edge Directivity Descriptor 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis; Arampatzis, Avi (Institute of Electrical and Electronics Engineers (IEEE), United States, 2010)
    In this paper, a new accelerating technique for content-based image retrieval is proposed, suitable for the Color and Edge Directivity Descriptor (CEDD). To date, the experimental results presented in the literature ...

  • Automatic Image Annotation and Retrieval Using the Joint Composite Descriptor 

    Zagoris, Konstantinos; Chatzichristofis, Savvas A.; Papamarkos, Nikos; Boutalis, Yiannis (Institute of Electrical and Electronics Engineers (IEEE), United States, 2010)
    Capable tools are needed in order to successfully search and retrieve a suitable image from large image collections. Many content-based image retrieval systems employ low-level image features such as color, texture and ...

  • Content based MRSI image indexing and retrieval involving a fuzzy descriptor 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis; Karras, D. A.; Mertzios, B. G. (Institute of Electrical and Electronics Engineers (IEEE), United States, 2010)
    Magnetic resonance spectroscopic imaging (MRSI) integrates both spectroscopic and imaging methods to produce spatially localized spectra from within the sample or patient. Although MRSI is a relatively new imaging technology ...

  • Late fusion of compact composite descriptors for retrieval from heterogeneous image databases 

    Chatzichristofis, Savvas A.; Arampatzis, Avi (Association for Computing Machinery (ACM), United States, 2010)
    Compact composite descriptors (CCDs) are global image features, capturing more than one types of information at the same time in a very compact representation. Their quality has so far been evaluated in retrieval from ...

  • Performance Study of the Most Commonly Used Image Retrieval Evaluation Methods 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis (ACTA PRESS, 2010)
    One of the most significant problems in the field of image retrieval results from the lack of a common test bed for the evaluation of the systems. So far, many of the methods used in the field of information retrieval ...

  • SPCD - SPATIAL COLOR DISTRIBUTION DESCRIPTOR - A Fuzzy Rule based Compact Composite Descriptor Appropriate for Hand Drawn Color Sketches Retrieval 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis; Lux, Mathias (SCITEPRESS, 2010)
    In this paper, a new low level feature suitable for Hand Drawn Color Sketches retrieval is presented. The proposed feature structure combines color and spatial color distribution information. The combination of these two ...

  • img(Anaktisi): A Web Content Based Image Retrieval System 

    Zagoris, Konstantinos; Chatzichristofis, Savvas A. (IEEE, 2009)
    img(Anaktisi) is a C#/.NET content base image retrieval application suitable for the web. It provides efficient retrieval services for various image databases using as a query a sample image, an image sketched by the ...

  • Multimedia Search with Noisy Modalities: Fusion and Multistage Retrieval 

    Arampatzis, Avi; Chatzichristofis, Savvas A.; Zagoris, Konstantinos (ImageClef, Wikipedia Retrieval Task, 2010)
    We report our experiences from participating to the controlled experiment of the ImageCLEF 2010 Wikipedia Retrieval task. We built an experimental search engine which combines multilingual and multi-image search, employing ...

  • Automatic summarization and annotation of videos with lack of metadata information 

    Papadopoulos, Dim P.; Kalogeiton, Vicky S.; Chatzichristofis, Savvas A.; Papamarkos, Nikos (Elsevier, 2013)
    The advances in computer and network infrastructure together with the fast evolution of multimedia data has resulted in the growth of attention to the digital video’s development. The scientific community has increased the ...

  • A Multi-Objective Exploration Strategy for Mobile Robots Under Operational Constraints 

    Amanatiadis, Angelos A.; Chatzichristofis, Savvas A.; Charalampous, Konstantinos; Doitsidis, Lefteris; Kosmatopoulos, Elias B.; Tsalides, Phillipos; Gasterato, Antonios; Roumeliotis, Stergios I. (IEEE, 2013)
    Multi-objective robot exploration constitutes one of the most challenging tasks for autonomous robots performing in various operations and different environments. However, the optimal exploration path depends heavily on ...

  • Content-based image retrieval over IEEE 802.11b noisy wireless networks 

    Chatzistavros, Evaggelos; Chatzichristofis, Savvas A.; Zagoris, Konstatinos; Stamatelos, George (Wiley, 2014)
    Mobile devices such as smartphones and tablets are widely used in everyday life to perform a variety of operations, such as e-mail exchange, connection to social media, bank/financial transactions, and so on. Moreover, ...

  • Img(Rummager): An Interactive Content Based Image Retrieval System 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis; Lux, Mathias (IEEE (Institute of Electrical and Electronics Engineers , United States), 2009)
    This paper presents an image retrieval suite called img(Rummager) which brings into effect a number of new as well as state of the art descriptors. The application can execute an image search based on a query image, either ...

  • Selection of the Proper Compact Composite Descriptor for Improving Content based Image Retrieval 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis; Lux, Mathias (ACTA Press, Canada, 2009)
    Compact Composite Descriptors (CCD) are global image features capturing both, color and texture characteristics, at the same time in a very compact representation. In this paper we propose a combination of two recently ...

  • Image Encryption using the Recursive Attributes of the eXclusive-OR Filter 

    Chatzichristofis, Savvas A.; Marques, Oge; Lux, Mathias; Boutalis, Yiannis (Springer, 2014)
    This paper describes a visual multimedia content encryption approach based on cellular automata (CA), expanding the work proposed in [4]. The presented algorithm relies on an attribute of the eXclusive-OR (XOR) filter, ...