Methods for reducing visual discomfort in stereoscopic 3D: A review

This work was supported by the EPSRC Grant EP/M01469X/1, “Geometric Evaluation of Stereoscopic Video”

Attitudes of Czechs towards Individual English Accents

The dissertation is focused on the description of the distinctive phonetic and phonological aspects of the Manchester, New Zealand and Irish accents. The theoretical part contains a comprehensive description of the segmental and suprasegmental features of the above mentioned accents in contrast with British Standard/Received Pronunciation. The practical part contains the recordings of native speakers from Manchester, Dunedin, Glasgow and Newsbury. It is followed by a research conducted in the form of a questionnaire, whose answers should help to discover the Czech students' attitude towards individual accents. Key Words Manchester, New Zealand, Irish and British accent

Postoje Čechů k jednotlivým anglickým akcentům

The dissertation is focused on the description of the distinctive phonetic and phonological aspects of the Manchester, New Zealand and Irish accents. The theoretical part contains a comprehensive description of the segmental and suprasegmental features of the above mentioned accents in contrast with British Standard/Received Pronunciation. The practical part contains the recordings of native speakers from Manchester, Dunedin, Glasgow and Newsbury. It is followed by a research conducted in the form of a questionnaire, whose answers should help to discover the Czech students' attitude towards individual accents. Key Words Manchester, New Zealand, Irish and British accentsTato práce se zabývá popisem charakteristických fonetických a fonologických jevů manchesterského, novozélandského, a irského přízvuků. Teoretická část obsahuje komplexní popis segmentálních a suprasegmentálních znaků výše uvedených akcentů na pozadí standardní britské výslovnosti (RP). V praktické části se nachází ukázky manchesterské, novozélandské, irské a britské výslovnosti na nahrávkách rodilých mluvčích. Dále je vlastní výzkum pomocí dotazníků, jehož odpovědi mají sloužit k zjištění postojů českých studentů k jednotlivým přízvukům. Klíčová slova manchesterská, novozélandská, irská a britská výslovnostiKatedra anglického jazyka a literaturyFaculty of EducationPedagogická fakult

Vers la compréhension de la perception binoculaire pour l'estimation de la fatigue visuelle, l'attention visuelle et la qualité de l'expérience pour des contenus stéréoscopiques

L'avènement de la technologie 3D stéréoscopique (3DS) a produit autant d'enthousiasme que l'introduction de la télévision couleur. Contrairement à la télévision couleur 2D, la 3DS est loin d'être un processus naturel de vision puisqu'il repose sur le fait de tromper le cerveau en lui donnant des disparités qui n'existent pas dans la réalité. Par conséquent, cette vision non naturelle peut générer une fatigue visuelle et altérer la qualité, sans parler de certains phénomènes physiologiques et cognitifs peu explorés à ce jour. Cette thèse aborde l'étude de la perception binoculaire sous trois angles différents: 1- la fatiguevisuelle, 2- l'attention visuelle et, 3- la Qualité de l'Expérience (QdE). Tout d'abord, nous avons proposé un paradigme psychophysique entièrement contrôlé afin d’évaluer la fatigue visuelle et d’étudier le lien existant avec les caractéristiques visuelles les plus importantes obtenues par oculométrie. Ainsi, nous avons montré que l'accumulation de la fatigue visuelle causée par la 3DS est fortement plus élevée que celle causée par la 2D. Nous avons également proposé un modèle de prédiction de la fatigue visuelle basé sur les principales conclusions de l’étude et faisant appel aux paramètres intrinsèques dela vidéo. Une autre exploration fondamentale a été menée pour étudier l'impact de la disparité sur la perception des couleurs. Ainsi, les expériences subjectives, conduites avec des stimuli simples, ont montré la faible influence de la disparité dans ladiscrimination des couleurs. Cette importante conclusion confirme le fait que la perception de la profondeur repose non seulement sur des indices binoculaires mais aussi sur des indices monoculaires. La deuxième partie de la thèse porte sur l'étude de l'attention visuelle binoculaire et propose des modèles permettant de prédire des cartes de saillance d'une séquence 3D. L'idée repose sur l'utilisation des caractéristiques spatiotemporelles et la possibilité de prédire avec précision la profondeur à partir d’une seule vue de la paire stéréo. Par conséquent, le modèle proposé, incluant une étape de fusion optimisée, a montré de très bonnes performances en accord avec la vérité de terrain (l’attention visuelle). Enfin, les propriétés binoculaires du système visuel humain, telles que la fusion binoculaire et la rivalité, ont été exploitées conjointement avec la saillance prédite dans l’optique de proposer une mesure objective de la qualité stéréoscopique. La métrique de qualité proposée a été testée sur des bases d’images de référence et ses résultats montrent une bonne corrélation avec le jugement humain.The advent of stereoscopic 3D (S3D) technology has generated as much enthusiasm as that generated by the introduction of color television. However, unlike color 2D television, S3D is far from being a natural viewing process since it relies on fooling thebrain by giving disparities that do not exist in reality. Therefore, this unnatural viewing may generate visual fatigue and alter the quality of Experience (QoE) of a user, not to mention some little-known physiological and cognitive phenomena. This thesis tackles the investigation of the binocular perception from three different but linked angles: 1- visual fatigue/discomfort, 2- visual attention and, 3- QoE. First, we proposed a fullycontrolled psychophysical paradigm in order to measure/estimate the visual discomfort and study the existing link with the most important visual characteristics obtained by eye-tracking. Thus, we demonstrated that visual fatigue accumulation caused by watching S3D content is significantly higher than accumulation caused by 2D watching. We also proposed a model of visual fatigue prediction based on our findings and intrinsic video features. The obtained model allows predicting visual fatigue accumulation from watching an S3D sequence. Another fundamental exploration has been conducted to study the impact of disparity on color perception. Therefore, subjective experiments with simple stimuli that have mainly binocular cues, showed that disparity plays almost no role in color discrimination. This important conclusion confirms the fact that 3D perception relies not only on binocular cues but also onmonocular cues. The second part of thesis focused on studying the binocular visual attention and proposing models allowing to predict saliency maps for a S3D scene. The idea lies in the use of temporal and spatial features in addition to the possibility of accurately predict depth from a single 2D view. Therefore, the proposed model including an optimized fusion step showed very good performance in comparison to eye-tracking experiments. Finally, the binocular properties of the human visual systemsuch as binocular fusion and rivalry have been exploited together with the visual saliency for the design of an objective quality metric. The latter accounts for the level of impairments in addition to the gap between both views. The proposed metric has been tested on publicly available datasets, and its results show a good correlation with human judgment

Visual attention modeling for 3D video using neural networks

International audienceVisual attention is one of the most important mechanisms in the human visual perception. Recently, its modeling becomes a principal requirement for the optimization of the image processing systems. Numerous algorithms have already been designed for 2D saliency prediction. However, only few works can be found for 3D content. In this study, we propose a saliency model for stereoscopic 3D video. This algorithm extracts information from three dimensions of content, i.e. spatial, temporal and depth. This model benefits from the properties of interest points to be close to human fixations in order to build spatial salient features. Besides, as the perception of depth relies strongly on monocular cues, our model extracts the depth salient features using the pictorial depth sources. Since weights for fusion strategy are often selected in ad-hoc manner, in this work, we suggest to use a machine learning approach. The used artificial Neural Network allows to define adaptive weights based on the eye-tracking data. The results of the proposed algorithm are tested versus ground-truth information using the state-of-the-art techniques

Study of visual fatigue/discomfort generated by S3D video using eye-tracking data

International audienc

On the comparison of visual discomfort generated by 3D and 2D content based on eye-tracking features

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Using binocular and monocular properties for the construction of a quality assessment metric for stereoscopic images

Best Paper AwardInternational audienc

A visual attention model for stereoscopic 3D images using monocular cues

International audience2D Visual saliency has been widely explored for decades. Several comprehensive and well performing models have been proposed, but they are not totally adapted to stereoscopic 3D content. To date only few tentatives of 3D saliency prediction can be found in the literature and most of them rely on binocular depth/disparity. The latter information cannot be correctly obtained in the case of asymmetric processing of the stereo-pair, exploiting the phenomenon of binocular suppression. Based on this aspect, we propose in this paper, a new saliency model for stereoscopic 3D images. The proposed model considers two features: (1) spatial feature based on the characteristics of interest points and (2) depth feature based on monocular cues. The latter feature is adapted to asymmetric content and uses occlusions for predicting depth order of the image objects. A tunable fusion strategy is proposed in order to take advantage of different modalities of combining conspicuity maps. For the needs of performance evaluation, an eye-tracking database is created using stereo-pairs with different content. The proposed model gives very good performance in comparison to the literature. The results show that the use of monocular cues outperforms the use of disparity

Spatio-temporal modeling of visual attention for stereoscopic 3D video

International audienceModeling visual attention is an important stage for the optimization of image processing systems nowadays. Several models have been already developed for 2D static and dynamic content, but only few attempts can be found for stereoscopic 3D content. In this work we propose a saliency model for stereoscopic 3D video. This model is based the fusion of three maps i.e. spatial, temporal and depth. It relies on interest point features known for being close to human visual attention. Moreover, since 3D perception is mostly based on monocular cues, depth information is obtained using a monocular model predicting the depth position of objects. Several fusion strategies have been experimented in order to determine the best match for our model. Finally, our approach has been validated using state-of-the-art metrics in comparison to attention maps obtained by eye-tracking experiments, and showed good performance