Dépouillements

An improved fast mode decision algorithm for intraprediction in H.264/AVC video coding / Manuel De-Frutos-López in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 709–716 Titre : An improved fast mode decision algorithm for intraprediction in H.264/AVC video coding Type de document : texte imprimé Auteurs : Manuel De-Frutos-López, Auteur ; Daniel Orellana-Quirós, Auteur ; José C. Pujol-Alcolado, Auteur Année de publication : 2012 Article en page(s) : pp. 709–716 Note générale : Electronique Langues : Anglais (eng) Mots-clés : H.264/AVC  Intra  Mode  decision  Fast  intra  mode  decision Résumé : In this article, an improved version of one of the most cited intra mode decision algorithms in H.264/AVC video coding is proposed with the aim to improve its efficiency and performance. The reference algorithm determines the interpolation/extrapolation spatial direction (mode) for achieving the best intra prediction using the Sobel gradient calculation. The proposed algorithm suggests reducing the number of gradients calculated and changing the Sobel operator to that of Roberts. In addition to this, it also proposes including the previously encoded neighboring block modes among the evaluated modes. Experimental results show that the proposed algorithm reduces the computational load of the original algorithm and substantially improves its rate-distortion performance. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001128 [article] An improved fast mode decision algorithm for intraprediction in H.264/AVC video coding [texte imprimé] / Manuel De-Frutos-López, Auteur ; Daniel Orellana-Quirós, Auteur ; José C. Pujol-Alcolado, Auteur . - 2012 . - pp. 709–716. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 709–716 Mots-clés : H.264/AVC  Intra  Mode  decision  Fast  intra  mode  decision Résumé : In this article, an improved version of one of the most cited intra mode decision algorithms in H.264/AVC video coding is proposed with the aim to improve its efficiency and performance. The reference algorithm determines the interpolation/extrapolation spatial direction (mode) for achieving the best intra prediction using the Sobel gradient calculation. The proposed algorithm suggests reducing the number of gradients calculated and changing the Sobel operator to that of Roberts. In addition to this, it also proposes including the previously encoded neighboring block modes among the evaluated modes. Experimental results show that the proposed algorithm reduces the computational load of the original algorithm and substantially improves its rate-distortion performance. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001128

Morphological dilation image coding with context weights prediction / Jiaji Wu in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 717–728 Titre : Morphological dilation image coding with context weights prediction Type de document : texte imprimé Auteurs : Jiaji Wu, Auteur ; Anand Paul, Auteur ; Yan Xing, Auteur Année de publication : 2012 Article en page(s) : pp. 717–728 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Quad-tree  coding  Morphological  dilation  Variable-length  group  test  coding  Weights  training Résumé : This paper proposes an adaptive morphological dilation image coding with context weights prediction. The new dilation method is not to use fixed models, but to decide whether a coefficient needs to be dilated or not according to the coefficient’s predicted significance degree. It includes two key dilation technologies: (1) controlling dilation process with context weights to reduce the output of insignificant coefficients and (2) using variable-length group test coding with context weights to adjust the coding order and cost as few bits as possible to present the events with large probability. Moreover, we also propose a novel context weight strategy to predict a coefficient’s significance degree more accurately, which can be used for two dilation technologies. Experimental results show that our proposed method outperforms the state of the art image coding algorithms available today. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001104 [article] Morphological dilation image coding with context weights prediction [texte imprimé] / Jiaji Wu, Auteur ; Anand Paul, Auteur ; Yan Xing, Auteur . - 2012 . - pp. 717–728. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 717–728 Mots-clés : Quad-tree  coding  Morphological  dilation  Variable-length  group  test  coding  Weights  training Résumé : This paper proposes an adaptive morphological dilation image coding with context weights prediction. The new dilation method is not to use fixed models, but to decide whether a coefficient needs to be dilated or not according to the coefficient’s predicted significance degree. It includes two key dilation technologies: (1) controlling dilation process with context weights to reduce the output of insignificant coefficients and (2) using variable-length group test coding with context weights to adjust the coding order and cost as few bits as possible to present the events with large probability. Moreover, we also propose a novel context weight strategy to predict a coefficient’s significance degree more accurately, which can be used for two dilation technologies. Experimental results show that our proposed method outperforms the state of the art image coding algorithms available today. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001104

Multiple description coding of animated meshes / M. Oguz Bici in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 729–744 Titre : Multiple description coding of animated meshes Type de document : texte imprimé Auteurs : M. Oguz Bici, Auteur ; Gozde B. Akar, Auteur Année de publication : 2012 Article en page(s) : pp. 729–744 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Multiple  description  coding  Animated  meshes  3D  dynamic  meshes  Time  consistent  mesh  sequence  Subsampling  Scalable  coding Résumé : In this paper, we propose three novel multiple description coding (MDC) methods for reliable transmission of compressed animated meshes represented by series of 3D static meshes with same connectivity. The proposed methods trade off reconstruction quality for error resilience to provide the best expected reconstruction of 3D mesh sequence at the decoder side. The methods are based on layer duplication and partitioning of the set of vertices of a scalable coded animated mesh by either spatial or temporal subsampling. Each partitioned set is encoded separately to generate independently decodable bitstreams or so-called descriptions. In addition, the proposed MDC methods can achieve varying redundancy allocations by including a number of encoded spatial or temporal layers from the other description. The algorithms are evaluated with redundancy-rate-distortion (RRD) curves and per-frame reconstruction analysis. RRD performances show that vertex partitioning-based MDC performs better at low redundancies for especially spatially dense models. Temporal subsampling-based MDC performs better at moderate redundancies as well as low redundancies for spatially coarse models. Layer duplication-based MDC can achieve the lowest redundancies with flexible redundancy allocation capability and can be designed to achieve the smallest variance of reconstruction quality between consecutive frames. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001116 [article] Multiple description coding of animated meshes [texte imprimé] / M. Oguz Bici, Auteur ; Gozde B. Akar, Auteur . - 2012 . - pp. 729–744. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 729–744 Mots-clés : Multiple  description  coding  Animated  meshes  3D  dynamic  meshes  Time  consistent  mesh  sequence  Subsampling  Scalable  coding Résumé : In this paper, we propose three novel multiple description coding (MDC) methods for reliable transmission of compressed animated meshes represented by series of 3D static meshes with same connectivity. The proposed methods trade off reconstruction quality for error resilience to provide the best expected reconstruction of 3D mesh sequence at the decoder side. The methods are based on layer duplication and partitioning of the set of vertices of a scalable coded animated mesh by either spatial or temporal subsampling. Each partitioned set is encoded separately to generate independently decodable bitstreams or so-called descriptions. In addition, the proposed MDC methods can achieve varying redundancy allocations by including a number of encoded spatial or temporal layers from the other description. The algorithms are evaluated with redundancy-rate-distortion (RRD) curves and per-frame reconstruction analysis. RRD performances show that vertex partitioning-based MDC performs better at low redundancies for especially spatially dense models. Temporal subsampling-based MDC performs better at moderate redundancies as well as low redundancies for spatially coarse models. Layer duplication-based MDC can achieve the lowest redundancies with flexible redundancy allocation capability and can be designed to achieve the smallest variance of reconstruction quality between consecutive frames. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001116

Attention-based video streaming / Çağatay Dikici in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 745–760 Titre : Attention-based video streaming Type de document : texte imprimé Auteurs : Çağatay Dikici, Auteur ; H. Işıl Bozma, Auteur Année de publication : 2012 Article en page(s) : pp. 745–760 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Biologically  motivated  attentive  vision  Foveation  Spatio-temporal  pre-processing  Face  tracking  Neural  networks  Video  streaming Résumé : This paper considers the problem of video streaming in low bandwidth networks and presents a complete framework that is inspired by the fovea–periphery distinction of biological vision systems. First, an application specific attention function that serves to find the important small regions in a given frame is constructed a priori using a back-propagation neural network that is optimized combinatorially. Given a specific application, the respective attention function partitions each frame into foveal and periphery regions and then a spatial–temporal pre-processing algorithm encodes the foveal regions with high spatial resolution while the periphery regions are encoded with lower spatial and temporal resolution. Finally, the pre-processed video sequence is streamed using a standard streaming server. As an application, we consider the transmission of human face videos. Our experimental results indicate that even with limited amount of training, the constructed attention function is able to determine the foveal regions which have improved transmission quality while the peripheral regions have an acceptable degradation. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000998 [article] Attention-based video streaming [texte imprimé] / Çağatay Dikici, Auteur ; H. Işıl Bozma, Auteur . - 2012 . - pp. 745–760. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 745–760 Mots-clés : Biologically  motivated  attentive  vision  Foveation  Spatio-temporal  pre-processing  Face  tracking  Neural  networks  Video  streaming Résumé : This paper considers the problem of video streaming in low bandwidth networks and presents a complete framework that is inspired by the fovea–periphery distinction of biological vision systems. First, an application specific attention function that serves to find the important small regions in a given frame is constructed a priori using a back-propagation neural network that is optimized combinatorially. Given a specific application, the respective attention function partitions each frame into foveal and periphery regions and then a spatial–temporal pre-processing algorithm encodes the foveal regions with high spatial resolution while the periphery regions are encoded with lower spatial and temporal resolution. Finally, the pre-processed video sequence is streamed using a standard streaming server. As an application, we consider the transmission of human face videos. Our experimental results indicate that even with limited amount of training, the constructed attention function is able to determine the foveal regions which have improved transmission quality while the peripheral regions have an acceptable degradation. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000998

Tag refinement in an image folksonomy using visual similarity and tag co-occurrence statistics / Sihyoung Lee in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 761–773 Titre : Tag refinement in an image folksonomy using visual similarity and tag co-occurrence statistics Type de document : texte imprimé Auteurs : Sihyoung Lee, Auteur ; Wesley De Neve, Auteur ; Yong Man Ro, Auteur Année de publication : 2012 Article en page(s) : pp. 761–773 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Co-occurrence  Folksonomy  Recommendation  Refinement  Visual  similarity Résumé : Noisy tag assignments lower the effectiveness of multimedia applications that rely on the availability of user-supplied tags for retrieving user-contributed images for further processing. This paper discusses a novel tag refinement technique that aims at differentiating noisy tag assignments from correct tag assignments. The correctness of tag assignments is determined through the combined use of visual similarity and tag co-occurrence statistics. To verify the effectiveness of our tag refinement technique, experiments were performed with user-contributed images retrieved from Flickr. For the image set used, the proposed tag refinement technique reduces the number of noisy tag assignments with 36% (benefit), while removing 10% of the correct tag assignments (cost). In addition, our tag refinement technique increases the effectiveness of tag recommendation for non-annotated images with 45% when using the P@5 metric and with 41% when using the NDCG metric. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001098 [article] Tag refinement in an image folksonomy using visual similarity and tag co-occurrence statistics [texte imprimé] / Sihyoung Lee, Auteur ; Wesley De Neve, Auteur ; Yong Man Ro, Auteur . - 2012 . - pp. 761–773. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 761–773 Mots-clés : Co-occurrence  Folksonomy  Recommendation  Refinement  Visual  similarity Résumé : Noisy tag assignments lower the effectiveness of multimedia applications that rely on the availability of user-supplied tags for retrieving user-contributed images for further processing. This paper discusses a novel tag refinement technique that aims at differentiating noisy tag assignments from correct tag assignments. The correctness of tag assignments is determined through the combined use of visual similarity and tag co-occurrence statistics. To verify the effectiveness of our tag refinement technique, experiments were performed with user-contributed images retrieved from Flickr. For the image set used, the proposed tag refinement technique reduces the number of noisy tag assignments with 36% (benefit), while removing 10% of the correct tag assignments (cost). In addition, our tag refinement technique increases the effectiveness of tag recommendation for non-annotated images with 45% when using the P@5 metric and with 41% when using the NDCG metric. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001098

Video scene detection using graph-based representations / Ufuk Sakarya in Signal processing. Image communication, Vol. 25 N° 10 (Novembre 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 774–783 Titre : Video scene detection using graph-based representations Type de document : texte imprimé Auteurs : Ufuk Sakarya, Auteur ; Ziya Telatar, Auteur Année de publication : 2012 Article en page(s) : pp. 774–783 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Video  scene  detection  Graph-based  representation  Graph  partitioning  Dominant  sets Résumé : One of the fundamental steps in organizing videos is to parse it in smaller descriptive parts. One way of realizing this step is to obtain shot or scene information. One or more consecutive semantically correlated shots sharing the same content construct video scenes. On the other hand, video scenes are different from the shots in the sense of their boundary definitions; video scenes have semantic boundaries and shots are defined with physical boundaries. In this paper, we concentrate on developing a fast, as well as well-performed video scene detection method. Our graph partition based video scene boundary detection approach, in which multiple features extracted from the video, determines the video scene boundaries through an unsupervised clustering procedure. For each video shot to shot comparison feature, a one-dimensional signal is constructed by graph partitions obtained from the similarity matrix in a temporal interval. After each one-dimensional signal is filtered, an unsupervised clustering is conducted for finding video scene boundaries. We adopt two different graph-based approaches in a single framework in order to find video scene boundaries. The proposed graph-based video scene boundary detection method is evaluated and compared with the graph-based video scene detection method presented in literature. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001086# [article] Video scene detection using graph-based representations [texte imprimé] / Ufuk Sakarya, Auteur ; Ziya Telatar, Auteur . - 2012 . - pp. 774–783. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 10 (Novembre 2010) . - pp. 774–783 Mots-clés : Video  scene  detection  Graph-based  representation  Graph  partitioning  Dominant  sets Résumé : One of the fundamental steps in organizing videos is to parse it in smaller descriptive parts. One way of realizing this step is to obtain shot or scene information. One or more consecutive semantically correlated shots sharing the same content construct video scenes. On the other hand, video scenes are different from the shots in the sense of their boundary definitions; video scenes have semantic boundaries and shots are defined with physical boundaries. In this paper, we concentrate on developing a fast, as well as well-performed video scene detection method. Our graph partition based video scene boundary detection approach, in which multiple features extracted from the video, determines the video scene boundaries through an unsupervised clustering procedure. For each video shot to shot comparison feature, a one-dimensional signal is constructed by graph partitions obtained from the similarity matrix in a temporal interval. After each one-dimensional signal is filtered, an unsupervised clustering is conducted for finding video scene boundaries. We adopt two different graph-based approaches in a single framework in order to find video scene boundaries. The proposed graph-based video scene boundary detection method is evaluated and compared with the graph-based video scene detection method presented in literature. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510001086#

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