Dépouillements

No-reference image and video quality estimation / Sheila S. Hemami in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 469–481 Titre : No-reference image and video quality estimation : Applications and human-motivated design Type de document : texte imprimé Auteurs : Sheila S. Hemami, Auteur ; Amy R. Reibman, Auteur Année de publication : 2012 Article en page(s) : pp. 469–481 Note générale : Electronique Langues : Anglais (eng) Mots-clés : No-reference  Video  quality  Quality  metrics  Quality  estimator  Applications  of  quality  metrics  Blind  quality  assessment Résumé : This paper reviews the basic background knowledge necessary to design effective no-reference (NR) quality estimators (QEs) for images and video. We describe a three-stage framework for NR QE that encompasses the range of potential use scenarios for the NR QE and allows knowledge of the human visual system to be incorporated throughout. We survey the measurement stage of the framework, considering methods that rely on bitstream, pixels, or both. By exploring both the accuracy requirements of potential uses as well as evaluation criteria to stress-test a QE, we set the stage for our community to make substantial future improvements to the challenging problem of NR quality estimation. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000688 [article] No-reference image and video quality estimation : Applications and human-motivated design [texte imprimé] / Sheila S. Hemami, Auteur ; Amy R. Reibman, Auteur . - 2012 . - pp. 469–481. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 469–481 Mots-clés : No-reference  Video  quality  Quality  metrics  Quality  estimator  Applications  of  quality  metrics  Blind  quality  assessment Résumé : This paper reviews the basic background knowledge necessary to design effective no-reference (NR) quality estimators (QEs) for images and video. We describe a three-stage framework for NR QE that encompasses the range of potential use scenarios for the NR QE and allows knowledge of the human visual system to be incorporated throughout. We survey the measurement stage of the framework, considering methods that rely on bitstream, pixels, or both. By exploring both the accuracy requirements of potential uses as well as evaluation criteria to stress-test a QE, we set the stage for our community to make substantial future improvements to the challenging problem of NR quality estimation. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000688

Perceptual-based quality assessment for audio–visual services / Junyong You in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 482–501 Titre : Perceptual-based quality assessment for audio–visual services : A survey Type de document : texte imprimé Auteurs : Junyong You, Auteur ; Ulrich Reiter, Auteur ; Miska M. Hannuksela, Auteur Année de publication : 2012 Article en page(s) : pp. 482–501 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Objective  quality  metric  Subjective  quality  assessment  HVS  Psychophysical  approach  Engineering  approach  Perception  Alignment  PEAQ  Semantic  importance Résumé : Accurate measurement of the perceived quality of audio–visual services at the end-user is becoming a crucial issue in digital applications due to the growing demand for compression and transmission of audio–visual services over communication networks. Content providers strive to offer the best quality of experience for customers linked to their different quality of service (QoS) solutions. Therefore, developing accurate, perceptual-based quality metrics is a key requirement in multimedia services. In this paper, we survey state-of-the-art signal-driven perceptual audio and video quality assessment methods independently, and investigate relevant issues in developing joint audio–visual quality metrics. Experiments with respect to subjective quality results have been conducted for analyzing and comparing the performance of the quality metrics. We consider emerging trends in audio–visual quality assessment, and propose feasible solutions for future work in perceptual-based audio–visual quality metrics. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000299 [article] Perceptual-based quality assessment for audio–visual services : A survey [texte imprimé] / Junyong You, Auteur ; Ulrich Reiter, Auteur ; Miska M. Hannuksela, Auteur . - 2012 . - pp. 482–501. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 482–501 Mots-clés : Objective  quality  metric  Subjective  quality  assessment  HVS  Psychophysical  approach  Engineering  approach  Perception  Alignment  PEAQ  Semantic  importance Résumé : Accurate measurement of the perceived quality of audio–visual services at the end-user is becoming a crucial issue in digital applications due to the growing demand for compression and transmission of audio–visual services over communication networks. Content providers strive to offer the best quality of experience for customers linked to their different quality of service (QoS) solutions. Therefore, developing accurate, perceptual-based quality metrics is a key requirement in multimedia services. In this paper, we survey state-of-the-art signal-driven perceptual audio and video quality assessment methods independently, and investigate relevant issues in developing joint audio–visual quality metrics. Experiments with respect to subjective quality results have been conducted for analyzing and comparing the performance of the quality metrics. We consider emerging trends in audio–visual quality assessment, and propose feasible solutions for future work in perceptual-based audio–visual quality metrics. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000299

No-reference perceptual image quality metric using gradient profiles for JPEG2000 / Luhong Liang in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 502–516 Titre : No-reference perceptual image quality metric using gradient profiles for JPEG2000 Type de document : texte imprimé Auteurs : Luhong Liang, Auteur ; Shiqi Wang, Auteur ; Jianhua Chen, Auteur Année de publication : 2012 Article en page(s) : pp. 502–516 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Blur  Ringing  Perceptual  quality  Gradient  profile  Image  compression  JPEG2000 Résumé : No-reference measurement of perceptual image quality is a crucial and challenging issue in modern image processing applications. One of the major difficulties is that some inherent features of natural images and artifacts are possibly rather ambiguous. In this paper, we tackle this problem using statistical information on image gradient profiles and propose a novel quality metric for JPEG2000 images. The key part of the metric is a histogram representing the sharpness distribution of the gradient profiles, from which a blur metric that is insensitive to inherently blurred structures in the natural image is established. Then a ringing metric is built based on ringing visibilities of regions associated with the gradient profiles. Finally, a combination model optimized through plenty of experiments is developed to predict the perceived image quality. The proposed metric achieves performance competitive with the state-of-the-art no-reference metrics on public datasets and is robust to various image contents. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000160 [article] No-reference perceptual image quality metric using gradient profiles for JPEG2000 [texte imprimé] / Luhong Liang, Auteur ; Shiqi Wang, Auteur ; Jianhua Chen, Auteur . - 2012 . - pp. 502–516. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 502–516 Mots-clés : Blur  Ringing  Perceptual  quality  Gradient  profile  Image  compression  JPEG2000 Résumé : No-reference measurement of perceptual image quality is a crucial and challenging issue in modern image processing applications. One of the major difficulties is that some inherent features of natural images and artifacts are possibly rather ambiguous. In this paper, we tackle this problem using statistical information on image gradient profiles and propose a novel quality metric for JPEG2000 images. The key part of the metric is a histogram representing the sharpness distribution of the gradient profiles, from which a blur metric that is insensitive to inherently blurred structures in the natural image is established. Then a ringing metric is built based on ringing visibilities of regions associated with the gradient profiles. Finally, a combination model optimized through plenty of experiments is developed to predict the perceived image quality. The proposed metric achieves performance competitive with the state-of-the-art no-reference metrics on public datasets and is robust to various image contents. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000160

Content-partitioned structural similarity index for image quality assessment / Chaofeng Li in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 517–526 Titre : Content-partitioned structural similarity index for image quality assessment Type de document : texte imprimé Auteurs : Chaofeng Li, Auteur ; Alan C. Bovik, Auteur Année de publication : 2012 Article en page(s) : pp. 517–526 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Four-component  image  model  Image  quality  assessment  Structural  similarity  (SSIM)  Multi-scale  structural  similarity  (MS-SSIM)  Gradient  structural  similarity  (G-SSIM) Résumé : The assessment of image quality is important in numerous image processing applications. Two prominent examples, the Structural Similarity Image (SSIM) index and Multi-scale Structural Similarity (MS-SSIM) operate under the assumption that human visual perception is highly adapted for extracting structural information from a scene. Results in large human studies have shown that these quality indices perform very well relative to other methods. However, the performance of SSIM and other Image Quality Assessment (IQA) algorithms are less effective when used to rate blurred and noisy images. We address this defect by considering a four-component image model that classifies image local regions according to edge and smoothness properties. In our approach, SSIM scores are weighted by region type, leading to modified versions of (G-)SSIM and MS-(G-)SSIM, called four-component (G-)SSIM (4-(G-)SSIM) and four-component MS-(G-)SSIM (4-MS-(G-)SSIM). Our experimental results show that our new approach provides results that are highly consistent with human subjective judgment of the quality of blurred and noisy images, and also deliver better overall performance than (G-)SSIM and MS-(G-)SSIM on the LIVE Image Quality Assessment Database. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000354 [article] Content-partitioned structural similarity index for image quality assessment [texte imprimé] / Chaofeng Li, Auteur ; Alan C. Bovik, Auteur . - 2012 . - pp. 517–526. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 517–526 Mots-clés : Four-component  image  model  Image  quality  assessment  Structural  similarity  (SSIM)  Multi-scale  structural  similarity  (MS-SSIM)  Gradient  structural  similarity  (G-SSIM) Résumé : The assessment of image quality is important in numerous image processing applications. Two prominent examples, the Structural Similarity Image (SSIM) index and Multi-scale Structural Similarity (MS-SSIM) operate under the assumption that human visual perception is highly adapted for extracting structural information from a scene. Results in large human studies have shown that these quality indices perform very well relative to other methods. However, the performance of SSIM and other Image Quality Assessment (IQA) algorithms are less effective when used to rate blurred and noisy images. We address this defect by considering a four-component image model that classifies image local regions according to edge and smoothness properties. In our approach, SSIM scores are weighted by region type, leading to modified versions of (G-)SSIM and MS-(G-)SSIM, called four-component (G-)SSIM (4-(G-)SSIM) and four-component MS-(G-)SSIM (4-MS-(G-)SSIM). Our experimental results show that our new approach provides results that are highly consistent with human subjective judgment of the quality of blurred and noisy images, and also deliver better overall performance than (G-)SSIM and MS-(G-)SSIM on the LIVE Image Quality Assessment Database. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000354

Deblocking filtering method using a perceptual map / Aladine Chetouani in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 527–534 Titre : Deblocking filtering method using a perceptual map Type de document : texte imprimé Auteurs : Aladine Chetouani, Auteur ; Ghiles Mostafaoui, Auteur ; Azeddine Beghdadi, Auteur Année de publication : 2012 Article en page(s) : pp. 527–534 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Blocking  effect  Deblocking  HVS  Masking  effect Résumé : A new method of deblocking is proposed. It aims to reduce the blocking artifacts in the compressed image by analyzing their visibility. A perceptual map is obtained using some Human Visual System (HVS) characteristics. This perceptual map is used as input to a recursive filter to reduce the blocking effect. The obtained results have been compared with a very recent efficient method. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596509001222 [article] Deblocking filtering method using a perceptual map [texte imprimé] / Aladine Chetouani, Auteur ; Ghiles Mostafaoui, Auteur ; Azeddine Beghdadi, Auteur . - 2012 . - pp. 527–534. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 527–534 Mots-clés : Blocking  effect  Deblocking  HVS  Masking  effect Résumé : A new method of deblocking is proposed. It aims to reduce the blocking artifacts in the compressed image by analyzing their visibility. A perceptual map is obtained using some Human Visual System (HVS) characteristics. This perceptual map is used as input to a recursive filter to reduce the blocking effect. The obtained results have been compared with a very recent efficient method. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596509001222

Modelling of spatio–temporal interaction for video quality assessment / Quan Huynh-Thu in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 535–546 Titre : Modelling of spatio–temporal interaction for video quality assessment Type de document : texte imprimé Auteurs : Quan Huynh-Thu, Auteur ; Mohammed Ghanbari, Auteur Année de publication : 2012 Article en page(s) : pp. 535–546 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Video  Subjective  quality  Objective  model  Spatial  quality  Temporal  quality  Spatio–temporal  interaction Résumé : Video services have appeared in the recent years due to advances in video coding and convergence to IP networks. As these emerging services mature, the ability to deliver adequate quality to end-users becomes increasingly important. However, the transmission of digital video over error-prone and bandwidth-limited networks may produce spatial and temporal visual distortions in the decoded video. Both types of impairments affect the perceived video quality. In this paper, we examine the impact of spatio–temporal artefacts in video and especially how both types of errors interact to affect the overall perceived video quality. We show that the impact of the spatial quality on overall video quality is dependent on the temporal quality and vice-versa. We observe that the introduction of a degradation in one modality affects the quality perception in the other modality, and this change is larger for high-quality conditions than for low-quality conditions. The contribution of the spatial quality to the overall quality is found to be greater than the contribution of the temporal quality. Our results also indicate that low-motion talking-head content can be more negatively affected by temporal frame freezing artefacts than other general type of content with higher motion. Based on the results of a subjective experiment, we propose an objective model to predict overall video quality by integrating the contributions of a spatial quality and a temporal quality. The non-linear model shows a very high linear correlation with subjective data. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000378 [article] Modelling of spatio–temporal interaction for video quality assessment [texte imprimé] / Quan Huynh-Thu, Auteur ; Mohammed Ghanbari, Auteur . - 2012 . - pp. 535–546. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 535–546 Mots-clés : Video  Subjective  quality  Objective  model  Spatial  quality  Temporal  quality  Spatio–temporal  interaction Résumé : Video services have appeared in the recent years due to advances in video coding and convergence to IP networks. As these emerging services mature, the ability to deliver adequate quality to end-users becomes increasingly important. However, the transmission of digital video over error-prone and bandwidth-limited networks may produce spatial and temporal visual distortions in the decoded video. Both types of impairments affect the perceived video quality. In this paper, we examine the impact of spatio–temporal artefacts in video and especially how both types of errors interact to affect the overall perceived video quality. We show that the impact of the spatial quality on overall video quality is dependent on the temporal quality and vice-versa. We observe that the introduction of a degradation in one modality affects the quality perception in the other modality, and this change is larger for high-quality conditions than for low-quality conditions. The contribution of the spatial quality to the overall quality is found to be greater than the contribution of the temporal quality. Our results also indicate that low-motion talking-head content can be more negatively affected by temporal frame freezing artefacts than other general type of content with higher motion. Based on the results of a subjective experiment, we propose an objective model to predict overall video quality by integrating the contributions of a spatial quality and a temporal quality. The non-linear model shows a very high linear correlation with subjective data. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000378

Overt visual attention for free-viewing and quality assessment tasks / O. Le Meur in Signal processing. Image communication, Vol. 25 N° 7 (Août 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 547–558 Titre : Overt visual attention for free-viewing and quality assessment tasks : Impact of the regions of interest on a video quality metric Type de document : texte imprimé Auteurs : O. Le Meur, Auteur ; A. Ninassi, Auteur ; P. Le Callet, Auteur Année de publication : 2012 Article en page(s) : pp. 547–558 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Visual  attention  Video  quality  assessment  Video  quality  metric  Free-viewing  and  quality  tasks Résumé : The aim of this study is to understand how people watch a video sequence during free-viewing and quality assessment tasks. To this end, two eye tracking experiments were carried out. The video dataset is composed of 10 original video sequences and 50 impaired video sequences (five levels of impairments obtained by a H.264 video compression). A first experiment consisted in recording eye movements in a free-viewing task. The 10 original video sequences were used. The second experiment concerned an eye tracking experiment in a context of a subjective quality assessment. Eye movements were recorded while observers judged on the quality of the 50 impaired video sequences. The comparison between gaze allocations indicates the quality task has a moderate impact on the visual attention deployment. This impact increases with the presentation number of impaired video sequences. The locations of regions of interest remain highly similar after several presentations of the same video sequence, suggesting that eye movements are still driven by the low level visual features after several viewings. In addition, the level of distortion does not significantly alter the oculomotor behavior. Finally, we modified the pooling of an objective full-reference video quality metric by adjusting the weight applied on the distortions. This adjustment depends on the visual importance (the visual importance is deduced from the eye tracking experiment realized on the impaired video sequences). We observe that a saliency-based distortion pooling does not significantly improve the performances of the video quality metric. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000561 [article] Overt visual attention for free-viewing and quality assessment tasks : Impact of the regions of interest on a video quality metric [texte imprimé] / O. Le Meur, Auteur ; A. Ninassi, Auteur ; P. Le Callet, Auteur . - 2012 . - pp. 547–558. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 7 (Août 2010) . - pp. 547–558 Mots-clés : Visual  attention  Video  quality  assessment  Video  quality  metric  Free-viewing  and  quality  tasks Résumé : The aim of this study is to understand how people watch a video sequence during free-viewing and quality assessment tasks. To this end, two eye tracking experiments were carried out. The video dataset is composed of 10 original video sequences and 50 impaired video sequences (five levels of impairments obtained by a H.264 video compression). A first experiment consisted in recording eye movements in a free-viewing task. The 10 original video sequences were used. The second experiment concerned an eye tracking experiment in a context of a subjective quality assessment. Eye movements were recorded while observers judged on the quality of the 50 impaired video sequences. The comparison between gaze allocations indicates the quality task has a moderate impact on the visual attention deployment. This impact increases with the presentation number of impaired video sequences. The locations of regions of interest remain highly similar after several presentations of the same video sequence, suggesting that eye movements are still driven by the low level visual features after several viewings. In addition, the level of distortion does not significantly alter the oculomotor behavior. Finally, we modified the pooling of an objective full-reference video quality metric by adjusting the weight applied on the distortions. This adjustment depends on the visual importance (the visual importance is deduced from the eye tracking experiment realized on the impaired video sequences). We observe that a saliency-based distortion pooling does not significantly improve the performances of the video quality metric. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000561

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