Dépouillements

On texture and image interpolation using Markov models / Shira Nemirovsky in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 139-157 Titre : On texture and image interpolation using Markov models Type de document : texte imprimé Auteurs : Shira Nemirovsky, Auteur ; Moshe Porat, Auteur Article en page(s) : pp. 139-157 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Markov  models  Wide-sense  Markov  Autocorrelation  function  Sampling  High  resolution  Low  resolution  Texture  interpolation  Fidelity  criterion  for  texture  reconstruction  Subjective  forced-choice  test Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Markov-type models characterize the correlation among neighboring pixels in an image in many image processing applications. Specifically, a wide-sense Markov model, which is defined in terms of minimum linear mean-square error estimates, is applicable to image restoration, image compression, and texture classification and segmentation. In this work, we address first-order (auto-regressive) wide-sense Markov images with a separable autocorrelation function. We explore the effect of sampling in such images on their statistical features, such as histogram and the autocorrelation function. We show that the first-order wide-sense Markov property is preserved, and use this result to prove that, under mild conditions, the histogram of images that obey this model is invariant under sampling. Furthermore, we develop relations between the statistics of the image and its sampled version, in terms of moments and generating model noise characteristics. Motivated by these results, we propose a new method for texture interpolation, based on an orthogonal decomposition model for textures. In addition, we develop a novel fidelity criterion for texture reconstruction, which is based on the decomposition of an image texture into its deterministic and stochastic components. Experiments with natural texture images, as well as a subjective forced-choice test, demonstrate the advantages of the proposed interpolation method over presently available interpolation methods, both in terms of visual appearance and in terms of our novel fidelity criterion. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] On texture and image interpolation using Markov models [texte imprimé] / Shira Nemirovsky, Auteur ; Moshe Porat, Auteur . - pp. 139-157. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 139-157 Mots-clés : Markov  models  Wide-sense  Markov  Autocorrelation  function  Sampling  High  resolution  Low  resolution  Texture  interpolation  Fidelity  criterion  for  texture  reconstruction  Subjective  forced-choice  test Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Markov-type models characterize the correlation among neighboring pixels in an image in many image processing applications. Specifically, a wide-sense Markov model, which is defined in terms of minimum linear mean-square error estimates, is applicable to image restoration, image compression, and texture classification and segmentation. In this work, we address first-order (auto-regressive) wide-sense Markov images with a separable autocorrelation function. We explore the effect of sampling in such images on their statistical features, such as histogram and the autocorrelation function. We show that the first-order wide-sense Markov property is preserved, and use this result to prove that, under mild conditions, the histogram of images that obey this model is invariant under sampling. Furthermore, we develop relations between the statistics of the image and its sampled version, in terms of moments and generating model noise characteristics. Motivated by these results, we propose a new method for texture interpolation, based on an orthogonal decomposition model for textures. In addition, we develop a novel fidelity criterion for texture reconstruction, which is based on the decomposition of an image texture into its deterministic and stochastic components. Experiments with natural texture images, as well as a subjective forced-choice test, demonstrate the advantages of the proposed interpolation method over presently available interpolation methods, both in terms of visual appearance and in terms of our novel fidelity criterion. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

Vision-based production of personalized video / D. I. Kosmopoulos in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 158-176 Titre : Vision-based production of personalized video Type de document : texte imprimé Auteurs : D. I. Kosmopoulos, Auteur ; A. Doulamis, Auteur ; A. Makris, Auteur Article en page(s) : pp. 158-176 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Human  identification  Tracking  Automated  content  production Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : In this paper we present a novel vision-based system for the automated production of personalized video souvenirs for visitors in leisure and cultural heritage venues. Visitors are visually identified and tracked through a camera network. The system produces a personalized DVD souvenir at the end of a visitor's stay allowing visitors to relive their experiences. We analyze how we identify visitors by fusing facial and body features, how we track visitors, how the tracker recovers from failures due to occlusions, as well as how we annotate and compile the final product. Our experiments demonstrate the feasibility of the proposed approach. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] Vision-based production of personalized video [texte imprimé] / D. I. Kosmopoulos, Auteur ; A. Doulamis, Auteur ; A. Makris, Auteur . - pp. 158-176. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 158-176 Mots-clés : Human  identification  Tracking  Automated  content  production Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : In this paper we present a novel vision-based system for the automated production of personalized video souvenirs for visitors in leisure and cultural heritage venues. Visitors are visually identified and tracked through a camera network. The system produces a personalized DVD souvenir at the end of a visitor's stay allowing visitors to relive their experiences. We analyze how we identify visitors by fusing facial and body features, how we track visitors, how the tracker recovers from failures due to occlusions, as well as how we annotate and compile the final product. Our experiments demonstrate the feasibility of the proposed approach. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

Frame layer rate control for H.264/AVC with hierarchical B-frames / Ming Li in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 177-199 Titre : Frame layer rate control for H.264/AVC with hierarchical B-frames Type de document : texte imprimé Auteurs : Ming Li, Auteur ; Yilin Chang, Auteur ; Fuzheng Yang, Auteur Article en page(s) : pp. 177-199 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Hierarchical  B-frames  Rate  control  H.264/AVC Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Hierarchical B-frames contribute to improvement of coding performance when introduced into H.264/AVC. However, the existing rate control schemes for H.264/AVC, which are mainly applied to IPPP and IBBP coding structures, cannot work efficiently for the coding structures with hierarchical B-frames. In this paper, a frame layer rate control scheme for hierarchical B-frames is proposed. Firstly, an adaptive starting quantization parameter (QP) determination method is implemented to derive the QP for the first coding frame based on the available channel bit rate and the content of the current video sequence. Then, the target bit budget for a group of pictures (GOP) is calculated based on the target bit rate and the buffer status. Afterwards, a temporal level (TL) layer rate control phase is introduced, and the GOP layer target bit budget is allocated to each TL. In the frame layer rate control phase, a method based on a rate-distortion model and the coding properties of the previous coded key frames is derived to determine the QP for the current key frame. For hierarchical B-frames, we introduce a typical weighting factor in the determination of their target bit budgets to address the features of the hierarchical coding structures. This weighting factor is calculated according to the target bit budget of the GOP layer and the knowledge obtained from the previous coded B-frames in each TL. Subsequently, the QP for coding the current B-frame is computed by a quadratic model with different model parameters for different TLs, and the computed QP is further adaptively adjusted according to the usage of the target bit budgets. After coding the current frame, an update stage, in which a threshold-based method is integrated to avoid model degradation, is invoked to update the parameters for rate control. Experimental results demonstrate that when the proposed rate control scheme is applied to the coding structure with hierarchical B-frames in H.264/AVC, the actual coding bit rates can match the target bit rates very well, and the encoding performance is also improved. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] Frame layer rate control for H.264/AVC with hierarchical B-frames [texte imprimé] / Ming Li, Auteur ; Yilin Chang, Auteur ; Fuzheng Yang, Auteur . - pp. 177-199. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 177-199 Mots-clés : Hierarchical  B-frames  Rate  control  H.264/AVC Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Hierarchical B-frames contribute to improvement of coding performance when introduced into H.264/AVC. However, the existing rate control schemes for H.264/AVC, which are mainly applied to IPPP and IBBP coding structures, cannot work efficiently for the coding structures with hierarchical B-frames. In this paper, a frame layer rate control scheme for hierarchical B-frames is proposed. Firstly, an adaptive starting quantization parameter (QP) determination method is implemented to derive the QP for the first coding frame based on the available channel bit rate and the content of the current video sequence. Then, the target bit budget for a group of pictures (GOP) is calculated based on the target bit rate and the buffer status. Afterwards, a temporal level (TL) layer rate control phase is introduced, and the GOP layer target bit budget is allocated to each TL. In the frame layer rate control phase, a method based on a rate-distortion model and the coding properties of the previous coded key frames is derived to determine the QP for the current key frame. For hierarchical B-frames, we introduce a typical weighting factor in the determination of their target bit budgets to address the features of the hierarchical coding structures. This weighting factor is calculated according to the target bit budget of the GOP layer and the knowledge obtained from the previous coded B-frames in each TL. Subsequently, the QP for coding the current B-frame is computed by a quadratic model with different model parameters for different TLs, and the computed QP is further adaptively adjusted according to the usage of the target bit budgets. After coding the current frame, an update stage, in which a threshold-based method is integrated to avoid model degradation, is invoked to update the parameters for rate control. Experimental results demonstrate that when the proposed rate control scheme is applied to the coding structure with hierarchical B-frames in H.264/AVC, the actual coding bit rates can match the target bit rates very well, and the encoding performance is also improved. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

Introducing skip mode in distributed video coding / Stefaan Mys in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 200-213 Titre : Introducing skip mode in distributed video coding Type de document : texte imprimé Auteurs : Stefaan Mys, Auteur ; Jürgen Slowack, Auteur ; Jozef Škorupa, Auteur Article en page(s) : pp. 200-213 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Distributed  video  coding  Wyner–Ziv  coding  Skip  mode  Coding  efficiency Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Although it was proven in the 1970s already by Wyner and Ziv and Slepian and Wolf that, under certain conditions, the same rate–distortion boundaries exist for distributed video coding (DVC) systems as for traditional predicting systems, until now no practical DVC system has been developed that even comes close to the performance of state-of-the-art video codecs such as H.264/AVC in terms of rate–distortion. Some important factors for this are the lower accuracy of the motion estimation performed at the decoder, the inaccurate modeling of the correlation between the side information and the original frame, and the absence in most state-of-the-art DVC systems of anything conceptually similar to the notion of skipped macroblocks in predictive coding systems. This paper proposes an extension of a state-of-the-art transform domain residual DVC system with an implementation of skip mode. The skip mode has an impact at two different places: in the turbo decoder, more specifically the soft input, soft output (SISO) convolutional decoder, and in the puncturing of the parity bits. Results show average bitrate gains up to 39% (depending on the sequence) achieved by combining both approaches. Furthermore, a hybrid video codec is presented where the motion estimation task is shifted back to the encoder. This results in a drastic increase in encoder complexity, but also in a drastic performance gain in terms of rate–distortion, with average bitrate savings up to 60% relative to the distributed video codec. In the hybrid video codec, smaller but still important average bitrate gains are achieved by implementing skip mode: up to 24%. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] Introducing skip mode in distributed video coding [texte imprimé] / Stefaan Mys, Auteur ; Jürgen Slowack, Auteur ; Jozef Škorupa, Auteur . - pp. 200-213. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 200-213 Mots-clés : Distributed  video  coding  Wyner–Ziv  coding  Skip  mode  Coding  efficiency Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Although it was proven in the 1970s already by Wyner and Ziv and Slepian and Wolf that, under certain conditions, the same rate–distortion boundaries exist for distributed video coding (DVC) systems as for traditional predicting systems, until now no practical DVC system has been developed that even comes close to the performance of state-of-the-art video codecs such as H.264/AVC in terms of rate–distortion. Some important factors for this are the lower accuracy of the motion estimation performed at the decoder, the inaccurate modeling of the correlation between the side information and the original frame, and the absence in most state-of-the-art DVC systems of anything conceptually similar to the notion of skipped macroblocks in predictive coding systems. This paper proposes an extension of a state-of-the-art transform domain residual DVC system with an implementation of skip mode. The skip mode has an impact at two different places: in the turbo decoder, more specifically the soft input, soft output (SISO) convolutional decoder, and in the puncturing of the parity bits. Results show average bitrate gains up to 39% (depending on the sequence) achieved by combining both approaches. Furthermore, a hybrid video codec is presented where the motion estimation task is shifted back to the encoder. This results in a drastic increase in encoder complexity, but also in a drastic performance gain in terms of rate–distortion, with average bitrate savings up to 60% relative to the distributed video codec. In the hybrid video codec, smaller but still important average bitrate gains are achieved by implementing skip mode: up to 24%. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

SVC adaptation / Truong Cong Thang in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 214-228 Titre : SVC adaptation : standard tools and supporting methods Type de document : texte imprimé Auteurs : Truong Cong Thang, Auteur ; Jae-Gon Kim, Auteur ; Jung Won Kang, Auteur Article en page(s) : pp. 214-228 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Video  adaptation  Scalable  video  coding  MPEG-21  Quality  of  service Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Recently, scalable video coding (SVC) has emerged as a promising video format for applications of multimedia communication. An SVC bitstream can be easily truncated (adapted) in spatial, temporal, and SNR dimensions to meet various characteristics of terminals and connections. Though SVC allows simple and flexible truncation of a coded bitstream, there still need to be efficient means to support the adaptation in different scenarios. In this paper, we review standard tools and supporting methods for SVC adaptation. We point out the practical questions and accordingly describe potential solutions to these questions. The paper also discusses two key standard tools in detail, namely MPEG-21 AdaptationQoS and SVC priority_id. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] SVC adaptation : standard tools and supporting methods [texte imprimé] / Truong Cong Thang, Auteur ; Jae-Gon Kim, Auteur ; Jung Won Kang, Auteur . - pp. 214-228. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 214-228 Mots-clés : Video  adaptation  Scalable  video  coding  MPEG-21  Quality  of  service Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Recently, scalable video coding (SVC) has emerged as a promising video format for applications of multimedia communication. An SVC bitstream can be easily truncated (adapted) in spatial, temporal, and SNR dimensions to meet various characteristics of terminals and connections. Though SVC allows simple and flexible truncation of a coded bitstream, there still need to be efficient means to support the adaptation in different scenarios. In this paper, we review standard tools and supporting methods for SVC adaptation. We point out the practical questions and accordingly describe potential solutions to these questions. The paper also discusses two key standard tools in detail, namely MPEG-21 AdaptationQoS and SVC priority_id. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

Flexible forward error correction codes with application to partial media data recovery / Jari Korhonen in Signal processing. Image communication, Vol. 24 N° 3 (Mars 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 229-242 Titre : Flexible forward error correction codes with application to partial media data recovery Type de document : texte imprimé Auteurs : Jari Korhonen, Auteur ; Pascal Frossard, Auteur Article en page(s) : pp. 229-242 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Forward  error  correction  Multimedia  communications  Video  streaming Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Conventionally, linear block codes designed for packet erasure correction are targeted to recover all the lost source packets per block, when the fraction of lost data is smaller than the redundancy overhead. However, these codes fail to recover any lost packets, if the number of erasures just exceeds the limit for full recovery capability, while it can still be beneficial to recover part of the symbols. In addition, common linear block codes are not well suited for unequal error protection, since different block codes with different rates must be allocated for each priority class separately. These two problems motivate the design of more flexible forward error correction (FEC) codes for media streaming applications. We first review the performance of short and long linear block codes. Long block codes generally offer better error correction capabilities, but at the price of higher complexity and larger coding delay. Short block codes can be more appropriate in media streaming applications that require smooth performance degradation when the channel loss rate increases. We study a new class of linear block codes using sparse generator matrices that permit to optimize the performance of short block codes for partial recovery of the lost packets. In addition, the proposed codes are extended to the design of unequal erasure protection solutions. Simulations of practical video streaming scenarios demonstrate that the flexible sparse codes offer a promising solution with interesting error correction capabilities and small variance in the residual loss rate. They typically represent an effective trade-off between short block codes with limited flexibility, and long block codes with delay penalties. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] Flexible forward error correction codes with application to partial media data recovery [texte imprimé] / Jari Korhonen, Auteur ; Pascal Frossard, Auteur . - pp. 229-242. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 3 (Mars 2009) . - pp. 229-242 Mots-clés : Forward  error  correction  Multimedia  communications  Video  streaming Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Conventionally, linear block codes designed for packet erasure correction are targeted to recover all the lost source packets per block, when the fraction of lost data is smaller than the redundancy overhead. However, these codes fail to recover any lost packets, if the number of erasures just exceeds the limit for full recovery capability, while it can still be beneficial to recover part of the symbols. In addition, common linear block codes are not well suited for unequal error protection, since different block codes with different rates must be allocated for each priority class separately. These two problems motivate the design of more flexible forward error correction (FEC) codes for media streaming applications. We first review the performance of short and long linear block codes. Long block codes generally offer better error correction capabilities, but at the price of higher complexity and larger coding delay. Short block codes can be more appropriate in media streaming applications that require smooth performance degradation when the channel loss rate increases. We study a new class of linear block codes using sparse generator matrices that permit to optimize the performance of short block codes for partial recovery of the lost packets. In addition, the proposed codes are extended to the design of unequal erasure protection solutions. Simulations of practical video streaming scenarios demonstrate that the flexible sparse codes offer a promising solution with interesting error correction capabilities and small variance in the residual loss rate. They typically represent an effective trade-off between short block codes with limited flexibility, and long block codes with delay penalties. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

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