Showing papers by "Michael G. Strintzis published in 2003"
TL;DR: The proposed face recognition technique is based on the implementation of the principal component analysis algorithm and the extraction of depth and colour eigenfaces and Experimental results show significant gains attained with the addition of depth information.
196 citations
24 Nov 2003
TL;DR: The proposed approach bridges the gap between keyword-based approaches, which assume the existence of rich image captions or require manual evaluation and annotation of every image of the collection, and query-by-example approaches,Which assume that the user queries for images similar to one that already is at his disposal.
Abstract: In this paper, an image retrieval methodology suited for search in large collections of heterogeneous images is presented. The proposed approach employs a fully unsupervised segmentation algorithm to divide images into regions. Low-level features describing the color, position, size and shape of the resulting regions are extracted and are automatically mapped to appropriate intermediate-level descriptors forming a simple vocabulary termed object ontology. The object ontology is used to allow the qualitative definition of the high-level concepts the user queries for (semantic objects, each represented by a keyword) in a human-centered fashion. When querying, clearly irrelevant image regions are rejected using the intermediate-level descriptors; following that, a relevance feedback mechanism employing the low-level features is invoked to produce the final query results. The proposed approach bridges the gap between keyword-based approaches, which assume the existence of rich image captions or require manual evaluation and annotation of every image of the collection, and query-by-example approaches, which assume that the user queries for images similar to one that already is at his disposal.
195 citations
TL;DR: A novel watermarking scheme able to resist geometric attacks and to generate resistance to scaling and rotation attacks is presented, while resistance to translation is accomplished through a localization of the water marking method based on feature points of the image.
Abstract: The paper presents a novel watermarking scheme able to resist geometric attacks. The proposed method performs imperceptible watermarking of images in the spatial domain. To generate resistance to scaling and rotation attacks, two generalized Radon transformations of the image are introduced, while resistance to translation is accomplished through a localization of the watermarking method based on feature points of the image. The original image is not required for the detection process. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks including common geometric attacks.
110 citations
24 Nov 2003
TL;DR: A novel image transmission scheme for the communication of set partitioning in hierarchical trees image streams over wireless channels employs turbo codes and Reed-Solomon codes in order to deal effectively with burst errors.
Abstract: A novel image transmission scheme is proposed for the communication of SPIHT image streams over wireless channels. The proposed scheme employs turbo codes and erasure-correction codes in order to deal effectively with burst errors. An algorithm for the optimal unequal error protection of the compressed bitstream is also proposed. The resulting scheme is tested for the transmission of images over wireless channels. Experimental evaluation clearly demonstrates the superiority of the proposed scheme in comparison to well-known robust coding schemes.
49 citations
01 Dec 2003
TL;DR: A CAD-based stereo vision approach is adopted for the high-accuracy 3D measurement of holes on the surface of industrial components, which enables the system to achieve high robustness in versatile industrial environments, rapid response, and accuracy below 0.1 mm.
Abstract: This paper presents a machine vision system for the high-accuracy 3D measurement of holes on the surface of industrial components. This is a very important application for inline quality inspection in assembly plants. A CAD-based stereo vision approach is adopted. The introduction of several novel techniques enables the system to achieve high robustness in versatile industrial environments, rapid response, and accuracy below 0.1 mm. These are demonstrated by extensive experiments with synthetic and real data.
43 citations
TL;DR: This paper presents a complete system for the secure distribution of a copyrighted MPEG-1/2 video stored on a DVD-ROM disc using a combined selective watermarking and encryption method that operates in the compressed MPEG domain.
Abstract: This paper presents a complete system for the secure distribution of a copyrighted MPEG-1/2 video stored on a DVD-ROM disc. A combined selective watermarking and encryption method that operates in the compressed MPEG domain is introduced. Watermarking resistant to a number of attacks is used for copyright protection. The video quality deteriorates significantly due to encryption, thus restraining unauthorized viewers from viewing it. The video can only be viewed using the developed Secure MPEG Player, which performs real-time decryption of the encrypted video. The decryption requires a secret key that is extracted from the DVD-ROM disc in a cryptographically secure manner.
26 citations
01 Mar 2003
TL;DR: In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented and these advances will be integrated in theschEMA module-based, expandable reference system.
Abstract: The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system.
20 citations
TL;DR: A neural network is formed for the estimation of the rigid 3D motion of each object in the scene, using initially estimated 2D motion vectors corresponding to each camera view, applicable to problems occurring in multiview image sequence coding applications.
Abstract: Multiview image sequence processing has been the focus of considerable attention in recent literature. This paper presents an efficient technique for object-based rigid and non-rigid 3D motion estimation, applicable to problems occurring in multiview image sequence coding applications. More specifically, a neural network is formed for the estimation of the rigid 3D motion of each object in the scene, using initially estimated 2D motion vectors corresponding to each camera view. Non-linear error minimization techniques are adopted for neural network weight update. Furthermore, a novel technique is also proposed for the estimation of the local non-rigid deformations, based on the multiview camera geometry. Experimental results using both stereoscopic and trinocular camera setups illustrate and evaluate the proposed scheme.
12 citations
TL;DR: A novel Authoring tool fully exploiting the object-based coding and 3D synthetic functionalities of the MPEG-4 standard is described, based upon an open and modular architecture able to progress with MPEG- 4 versions and it is easily adaptable to newly emerging better and higher-level authoring and image sequence analysis features.
Abstract: An Authoring tool for the MPEG-4 multimedia standard integrated with image sequence analysis algorithms is described. MPEG-4 offers numerous capabilities and is expected to be the future standard for multimedia applications. However, the implementation of these capabilities requires a complex authoring process, employing many different competencies from image sequence analysis and encoding of audio/visual/BIFS to the implementation of different delivery scenarios: local access on CD/DVD-ROM, Internet, or broadcast. However powerful the technologies underlying multimedia computing are, the success of these systems depends on their ease of authoring. In this paper, a novel Authoring tool fully exploiting the object-based coding and 3D synthetic functionalities of the MPEG-4 standard is described. It is based upon an open and modular architecture able to progress with MPEG-4 versions and it is easily adaptable to newly emerging better and higher-level authoring and image sequence analysis features.
10 citations
TL;DR: In this article, a region classification algorithm and a spatial adaptive filtering are proposed to alleviate the blocking artifacts that usually occur in JPEG coded images especially at low bit rates, and the proposed algorithm consists of two stages: first, the AC coefficients are estimated based on their observed probability distribution and secondly, a postprocessing scheme is applied for blockiness removal.
10 citations
01 Jan 2003
TL;DR: Experimental results on known sequences demonstrate the efficiency of the proposed approach and reveal the potential of employing it in content-based applications such as objectbased video indexing and retrieval.
Abstract: In this paper, a novel algorithm for the real-time, unsupervised segmentation of image sequences in the compressed domain is proposed. The algorithm utilizes the motion information present in the compressed stream in the form of P-frame forward motion vectors, as well as basic color information in the form of DC coefficients present in I-frames. An iterative rejection scheme based on the bilinear motion model is used for performing foreground/background segmentation. Further examining the temporal consistency of the output of iterative rejection, clustering to connected regions and performing region tracking, results to foreground spatiotemporal objects being formed. Background segmentation to spatiotemporal objects is also performed. Experimental results on known sequences demonstrate the efficiency of the proposed approach and reveal the potential of employing it in content-based applications such as objectbased video indexing and retrieval.
01 Jan 2003
TL;DR: The error-resilient structure of the stream endows the proposed systems with the capability to localize and discard the corrupted portion of the transmitted information and thus, attain superior reconstruction quality.
Abstract: Error-resilient techniques are proposed for the efficient transmission of still images and video over unreliable channels. The proposed techniques are applied in conjunction with multiresolution decomposition of images or video frames. The resulting coders produce scalable bitstreams which can deliver very good quality over a variety of different bandwidths. The error-resilient structure of the stream endows the proposed systems with the capability to localize and discard the corrupted portion of the transmitted information and thus, attain superior reconstruction quality. When combined with forward error correction, the resulting streams are shown to yield very good performance in terms of error resilience and reconstruction quality.
01 Jan 2003
TL;DR: The proposed watermarking scheme operates directly in the domain of MPEG-1 system streams and MPEG-2 program streams (multiplexed streams) and is suitable for the copyright protection of video content.
Abstract: In this chapter, a new technique for the watermarking of MPEG-1 and MPEG-2 compressed video streams is proposed. The watermarking scheme operates directly in the domain of MPEG-1 system streams and MPEG-2 program streams (multiplexed streams). Perceptual models are used during the embedding process in order to preserve video quality. The watermark is embedded in the compressed domain and is detected without the use of the original video sequence. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks. The resulting watermarking system is very fast and reliable, and is suitable for the copyright protection of video content.