Quality enhancement and assessment of 3D content on mobile using structural statistics

Sujets de thèse 2013

Intitulé de la thèse
Quality enhancement and assessment of 3D content on mobile using structural statistics
Publication du sujet sur le site de l’ABG : NON
Nature du financement : Financement institutionnel, Contrat Doctoral, Financement régional, Contrats université sur projets,)
Spécialité de doctorat : Image Signal et Automatique

Lieu de travail
FRance/Norvege
Laboratoire d’accueil : XLIM/SIC

Présentation de l’équipe de recherche
Les activités de recherche de l’équipe ICONES sont organisées autour du traitement, de la caractérisation et de l’analyse de signaux et images multi sources et multi composantes avec une spécificité concernant la couleur. Une image est le résultat d’interactions entre lumière et matière, nous tentons donc d’approfondir ces modèles physiques tout en maîtrisant les acquisitions lorsque cela est possible. Ensuite, une image ou une vidéo est un ensemble de données vectorielles, nous souhaitons le modéliser de façon optimale par des modèles mathématiques appropriés. Enfin, lorsque l’on traite une image, la finalité est souvent de la visualiser devant un observateur humain, d’où l’intérêt de le prendre en compte ainsi que son contexte. Nos spécificités reposent ainsi sur la définition d’outils mathématiques adaptés à la manipulation de données vectorielles, associée à l’introduction de paramètres physiques issus, d’une part, de modèles d’aspects des surfaces analysées, d’autre part, de modèles, du système visuel humain. De plus, notre originalité s’appuie sur la mise en place d’évaluations objectives et subjectives de la qualité, à la fois des traitements développés, mais aussi des supports de reproduction des images ou vidéos couleur, selon des conditions normalisées au sein de salles dédiées. La force et l’originalité de notre équipe repose donc sur le fait que nous travaillons sur toute la «chaîne de vie» d’une image couleur, depuis son acquisition jusqu’à l’évaluation de la qualité de son rendu, en passant par divers traitements; traitements définis de manière vectorielle et/ou sensorielle, en prenant éventuellement en compte les aspects physiques de la scène acquise.

Résumé de la thèse en français
À ce jour, il n’existe pas de méthode établie (ni subjective ni objective) pour garantir la qualité de l’expérience pour le contenu 3D sur mobile. Ce travail de thèse est orienté vers l’amélioration et l’évaluation de la qualité des contenus 3D sur des appareils mobiles (smartphone, tablette). L’objectif est de produire des algorithmes et des modèles aidant à garantir l’expérience de l’utilisateur étroitement liée à la perception.

Résumé de la thèse en anglais
To date there is no established methodology (neither subjective nor objective) to guarantee the quality of experience for 3D content on mobile. This PhD work is oriented towards quality enhancement and assessment of 3D content on Mobile devices. The aim is to produce algorithms and models helping to guarantee the user experience closely linked to perception.

Description complète du sujet de thèse
The digital era allowed the easy spread of 3D technologies in different application domains. The most appealing aspect is that stereoscopic 3D can offer viewing experience providing new sensations thanks to depth (binocular cues). Due to the challenges brought by 3D technology, the latter has yet to be widely adopted. Recently, one can notice a decrease or speed-down especially for 3DTV spread. This is mainly due to 3D-related issues that have been identified across the whole chain. At the capture side, there are no common rules for creating a stereoscopic content besides some initiatives coming from stereographers that are not always leading to unanimity. Therefore, artifacts/defects may cause symptoms to viewers like headaches, nausea and visual fatigue. At the display side, if the projected content is not adapted to the aspect ratio and display size or technology, this will result in a decrease of the user experience.
Modern mobile devices and networks are developed to be used for 3D content targeting applications such as video streaming, video-conferencing, video recording, etc. Furthermore, high dynamic range Imaging together with 3D on mobile is seen as an exciting feature towards augmented experience. However, to date there are no established methodology (neither subjective nor objective) to guarantee the quality of experience with such a content.

This PhD work is oriented towards quality enhancement and assessment of 3D content on Mobile devices. The aim is to produce algorithms and models helping to guarantee the user experience. Four mains steps can be highlighted in this work:
1- Identification of factors affecting 3D quality on mobile: 3D has been addressed most frequently for cinema or television but very rarely for mobile. Observation conditions are very different from conventional usage of 3D. Hence, it is important to understand intrinsic and extrinsic factors playing a role on quality. This part has to deal with the whole chain from content creation to display.
2- Perceptual model reflecting the effect of migrations on 3D perception: It has been shown in a previous work (nauge 2012) that impairments can be interpreted as migration of statistical characteristics of an image. In this part, an extension will be proposed for 3D video by taking into account spatial, temporal and inter-view migration. It will be followed by psychophysical experiments aiming at identifying links between stereo spatio-temporal migration and perception. The obtained model will introduce a new Framework for dealing with 3D content and will help in the definition of quality metrics and for compression enhancement.
3- Development of a quality evaluation procedure dedicated to 3D and based on statistical modeling of impairments: The model resulting from phase 2 will be used for the construction of a 3D video metric that can be expressed depending on the availability of the reference. Of course, a mobile database coming from an extensive subjective evaluation will be created in order to validate the metric and compare it with the state of the art.
4- the final step consists in exploiting the aforementioned results for perceptual optimization of 3D extensions of HEVC known as the next standard for video coding. One possible aspect can be the use of statistical migrations in the rate-distortion optimization process.

Objectifs scientifiques de la thèse
This PhD work is oriented towards quality enhancement and assessment of 3D content on Mobile devices. The aim is to produce algorithms and models helping to guarantee the user experience. Four mains steps can be highlighted in this work:
1- Identification of factors affecting 3D quality on mobile: 3D has been addressed most frequently for cinema or television but very rarely for mobile. Observation conditions are very different from conventional usage of 3D. Hence, it is important to understand intrinsic and extrinsic factors playing a role on quality. This part has to deal with the whole chain from content creation to display.
2- Perceptual model reflecting the effect of migrations on 3D perception: It has been shown in a previous work (nauge 2012) that impairments can be interpreted as migration of statistical characteristics of an image. In this part, an extension will be proposed for 3D video by taking into account spatial, temporal and inter-view migration. It will be followed by psychophysical experiments aiming at identifying links between stereo spatio-temporal migration and perception. The obtained model will introduce a new Framework for dealing with 3D content and will help in the definition of quality metrics and for compression enhancement.
3- Development of a quality evaluation procedure dedicated to 3D and based on statistical modeling of impairments: The model resulting from phase 2 will be used for the construction of a 3D video metric that can be expressed depending on the availability of the reference. Of course, a mobile database coming from an extensive subjective evaluation will be created in order to validate the metric and compare it with the state of the art.
4- the final step consists in exploiting the aforementioned results for perceptual optimization of 3D extensions of HEVC known as the next standard for video coding. One possible aspect can be the use of statistical migrations in the rate-distortion optimization process.

Compétences à l’issue de la thèse
– 3D quality assessment
– Image description using natural scene statistics (NSS)
– Enhancement of 3D coding

Mots clés (séparés par des virgules)
quality, 3D, mobile, natural scene statistics
Conditions restrictive de candidature (nationalité, âge, …) : NON

Modalité de dépôt de candidature
Envoyer CV, avec relevé de notes M1 et M2, et lettre de motivation au directeur de thèse.

Date limite de candidature
30 avril 2013.

Directeur de thèse
Chaker Larabi et
Adresse mail du directeur de thèse : chaker.larabi@univ-poitiers.fr
Téléphone Directeur de thèse : 05 49 49 74 94

Co-directeur de thèse
Faouzi Alaya Cheikh
Cofinancement LABEX SigmaLIM demandé : NON
Thèse pour Action transverse : NON

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