Browsing NUP Academic Publications - Ακαδημαϊκές Δημοσιεύσεις ΠΝΠ by Author "Chatzichristofis, Savvas A."

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  • 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 ...

  • Accurate Image Retrieval Based on Compact Composite Descriptors and Relevance Feedback Information 

    Chatzichristofis, Savvas A.; Zagoris, Konstantinos; Boutalis, Yiannis S.; Papamarkos, Nikos (World Scientific Publishing Company, 2010)
    In this paper a new set of descriptors appropriate for image indexing and retrieval is proposed. The proposed descriptors address the tremendously increased need for e±cient content-based image retrieval (CBIR) in many ...

  • 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 ...

  • 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 ...

  • Autonomous Navigation of Teams of Unmanned Aerial or Underwater Vehicles for Exploration of Unknown Static & Dynamic Environments 

    Kapoutsis, A. Ch.; Chatzichristofis, Savvas A.; Doitsidis, L.; Borges de Sousa, Joao; Kosmatopoulos, E. B. (MED’13, 2013)
    In this paper, we present a new approach that is able to efficiently and fully-autonomously navigate a team of Unmanned Aerial or Underwater Vehicles (UAUV’s) when deployed in exploration of unknown static and dynamic ...

  • 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 ...

  • CEDD: Color and Edge Directivity Descriptor: A Compact Descriptor for Image Indexing and Retrieval 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis (Springer-Verlag, 2008)
    This paper deals with a new low level feature that is extracted from the images and can be used for indexing and retrieval. This feature is called “Color and Edge Directivity Descriptor” and incorporates color and texture ...

  • Cellular Automata Ants 

    Bitsakidis, Nikolaos P.; Dourvas, Nikolaos I.; Chatzichristofis, Savvas A.; Sirakoulis, Georgios Ch. (Springer, 2017)
    During the last decades much attention was given to bio-inspired techniques able to successfully handle really complex algorithmic problems. As such Ant Colony Optimization (ACO) algorithms have been introduced as a ...

  • Co.Vi.Wo.: Color Visual Words Based on Non-Predefined Size Codebooks 

    Chatzichristofis, Savvas A.; Iakovidou, Chryssanthi; Boutalis, Yiannis; Marques, Oge (IEEE, 2012)
    Due to the rapid development of information technology and the continuously increasing number of available multimedia data, the task of retrieving information based on visual content has become a popular subject of scientific ...

  • Color and Edge Directivity Descriptor on GPGPU 

    Iakovidou, Chrysanthi; Bampis, L.; Chatzichristofis, Savvas A.; Boutalis, Yiannis; Amanatiadis, A. (IEEE (Computer Society), 2015)
    Image indexing refers to describing the visual multimedia content of a medium, using high level textual information or/and low level descriptors. In most cases, images and videos are associated with noisy and incomplete ...

  • Combining Color and Spatial Color Distribution Information in a Fuzzy Rule Based Compact Composite Descriptor 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis S.; Lux, Mathias (Springer, 2011)
    In this paper, a novel low level feature for content based image retrieval is presented. The proposed feature structure combines color and spatial color distribution information. The combination of these two features in ...

  • CoMo: A Compact Composite Moment-Based Descriptor for Image Retrieval 

    Vassou, Sotiris A.; Anagnostopoulos, Nektarios; Amanatiadis, Angelos; Christodoulou, Klitos; Chatzichristofis, Savvas A. (ACM, 2017-06-19)
    Low level features play a vital role in image retrieval. Image moments can effectively represent global information of image content while being invariant under translation, rotation, and scaling. This paper briefly presents ...

  • CoMo: a scale and rotation invariant compact composite moment-based descriptor for image retrieval 

    Vassou, S. A.; Anagnostopoulos, N.; Amanatiadis, A.; Chatzichristofis, Savvas A.; Christodoulou, Klitos (Springer International Publishing, 2018-03-01)
    Low level features play a significant role in image retrieval. Image moments can effectively represent global information of image content while being invariant under translation, rotation, and scaling. This paper presents ...

  • 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 ...

  • Composite description based on Salient Contours and Color information for CBIR tasks 

    Iakovidou, C.; Anagnostopoulos, N.; Lux, M.; Christodoulou, Klitos; Boutalis, Y.; Chatzichristofis, Savvas A. (Institute of Electrical and Electronics Engineers (IEEE), 2019)
    This paper introduces a novel image descriptor for content based image retrieval tasks that integrates contour and color information into a compact vector. Loosely inspired by the human visual system and its mechanisms in ...

  • Computer Vision Meets Educational Robotics 

    Sophokleous, Aphrodite; Christodoulou, Panayiotis; Doitsidis, Lefteris; Chatzichristofis, Savvas A. (MDPI, 2021)
    Educational robotics has gained a lot of attention in the past few years in K-12 education. Prior studies have shown enough shreds of evidence and highlight the benefits of educational robotics as being effective in providing ...

  • Content Based Image Retrieval Using Visual-Words Distribution Entropy 

    Chatzichristofis, Savvas A.; Iakovidou, Chrysanthi; Boutalis, Yiannis (Springer, 2011)
    Bag-of-visual-words (BOVW) is a representation of images which is built using a large set of local features. To date, the experimental results presented in the literature have shown that this approach achieves high retrieval ...

  • 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 ...

  • Content based radiology image retrieval using a fuzzy rule based scalable composite descriptor 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis (Springer Nature, 2009)
    The rapid advances made in the field of radiology, the increased frequency in which oncological diseases appear, as well as the demand for prevailing medical checks, led to the creation of a large database of radiology ...

  • Content based radiology image retrieval using a fuzzy rule based scalable composite descriptor 

    Chatzichristofis, Savvas A.; Boutalis, Yiannis S. (2010)
    The rapid advances made in the field of radiology, the increased frequency in which oncological diseases appear, as well as the demand for regular medical checks, led to the creation of a large database of radiology ...