Motion tubes for the representation of images sequences

International audienceIn this paper, we introduce a novel way to represent an image sequence, which naturally exhibits the temporal persistence of the textures. Standardized representations have been thoroughly optimized, and getting significant improvements has become more and more difficult. As an alternative, Analysis-Synthesis (AS) coders have focused on the use of texture within a video coder. We introduce here a new AS representation of image sequences that remains close to the classic block-based representation. By tracking textures throughout the sequence, we propose to reconstruct it from a set of moving textures which we call motion tubes. A new motion model is then proposed, which allows for motion field continuities and discontinuities, by hybridizing Block Matching and a low-computational mesh-based representation. Finally, we propose a bi-predictional framework for motion tubes management

NAMA3DS1-COSPAD1: Subjective video quality assessment database on coding conditions introducing freely available high quality 3D stereoscopic sequences

Research in stereoscopic 3D coding, transmission and subjective assessment methodology depends largely on the availability of source content that can be used in cross-lab evaluations. While several studies have already been presented using proprietary content, comparisons between the studies are difficult since discrepant contents are used. Therefore in this paper, a freely available dataset of high quality Full-HD stereoscopic sequences shot with a semiprofessional 3D camera is introduced in detail. The content was designed to be suited for usage in a wide variety of applications, including high quality studies. A set of depth maps was calculated from the stereoscopic pair. As an application example, a subjective assessment has been performed using coding and spatial degradations. The Absolute Category Rating with Hidden Reference method was used. The observers were instructed to vote on video quality only. Results of this experiment are also freely available and will be presented in this paper as a first step towards objective video quality measurement for 3DTV

Subjective experiment dataset for joint development of hybrid video quality measurement algorithms

International audienceThe application area of an objective measurement algorithm for video quality is always limited by the scope of the video datasets that were used during its development and training. This is particularly true for measurements which rely solely on information available at the decoder side, for example hybrid models that analyze the bitstream and the decoded video. This paper proposes a framework which enables researchers to train, test and validate their algorithms on a large database of video sequences in such a way that the - often limited - scope of their development can be taken into consideration. A freely available video database for the development of hybrid models is described containing the network bitstreams, parsed information from these bitstreams for easy access, the decoded video sequences, and subjectively evaluated quality scores

Les tubes de mouvement : nouvelle représentation pour les séquences d'images

Within a few years only, the amount of video information transmitted across a large range of communication channels has been critically increasing. It is expected, by 2014, that IP traffic will consist, most exclusively, of video data. In mobiles, video traffic is expected to undergo an increase without precedent as well. Despite the ever-increasing throughput of modern transmission channels, these will not be able to sustain such an increase in payload. More than ever, it is essential to improve our ability to compact the video information. Research, for the past 30 years, provided numerous decorrelation tools that reduce the amount of redundancies across both spatial and temporal dimensions in image sequences. To this day, the classical video compression paradigm locally splits the images into blocks of pixels (macroblocks), and processes the temporal axis on a frame by frame basis, without any obvious continuity. Despite very high compression performances (e.g. AVC and forthcoming HEVC standards), one may still advocate the use of alternative approaches. Disruptive solutions have also been proposed, and notably offer the ability to continuously process the temporal axis. However, they often rely on complex tools (e.g. Wavelets, control grids) whose use is rather delicate in practice. This thesis investigates the viability of an alternative representation that embeds features of both classical and disruptive approaches. Its goal is to exhibit the temporal persistence of the textural information, through a time-continuous description. However, it still relies on blocks, mostly responsible for the popularity of the classical approach. Instead of re-initializing the description at each frame, it is proposed to track the evolution of initial blocks taken from a reference image. A block, and its trajectory across time and space, is called a motiontube. An image sequence is then interpreted as a set of motiontubes. Three major problems have been considered within this thesis. At first, motiontubes need to track both continuous and discontinuous displacements and deformations of individual patches of textures. Above all, it is critical for them to evolve as consistently as possible, which will require dedicated regularization mechanisms. Then, a second problem lies in the texture itself and the way it is used to synthesize images: how to handle non-registered and multi-registered areas. Finally, it is essential for a motiontube to be terminated whenever the corresponding patch of texture disappears or cannot be properly tracked any longer, which raises the problem of quality and efficiency assessment. This has a critical influence on the compactness of the representation. Results will eventually show that tubes can effectively be used to represent image sequences, and compare their performances with those of \AVC standard.En quelques années, le trafic vidéo a augmenté de manière spectaculaire sur de nombreux médias. D'ici 2014, on estime que la quasi-intégralité du trafic IP sera composée de données vidéo. De même, l'usage de la vidéo sur les téléphones mobiles aura subi une augmentation sans précédent. Or, on estime que les infrastructures réseau, malgré les progrès constants en matière de transmission, ne pourront pas supporter une telle charge. A ce titre, il est plus que jamais capital d'améliorer nos capacités à compresser les vidéos. Depuis 30 ans, la recherche travaille à l'élaboration de techniques de décorrélation, notamment afin de réduire les redondances spatiales et temporelles des séquences d'images et les compresser. A ce jour, l'approche classique est basée sur le concept de macroblocs : le contenu spatial est divisé en un ensemble de blocs. Le long de l'axe temporel, les images sont traitées une à une, sans faire apparaître de continuité évidente. Bien que cette approche soit déjà très efficace (cf. standards AVC et futur HEVC), l'emploi d'approches en rupture reste toujours envisageable. Celles-ci offrent, entre autre, la possibilité de décrire l'évolution temporelle du contenu de manière continue. Cependant, elles mettent souvent en oeuvre des outils dont l'utilisation, en pratique, est délicate. Ce travail de thèse propose une nouvelle représentation, qui combine les avantages de l'approche classique et ceux de certaines approches en rupture, puis en étudie la viabilité. On cherche à exhiber la persistance temporelle des textures, à travers une description continue le long de l'axe temporel. A l'instar de l'approche classique, la représentation proposée est basée sur des blocs. Au lieu de réinitialiser la description à chaque image, notre représentation suit l'évolution de blocs initialement repérés à un instant de référence. Ces blocs, ainsi que leur trajectoire spatio-temporelle, sont appelés tubes de mouvement. Trois problématiques sont soulevées. Tout d'abord, les tubes doivent être capable de représenter continuités et discontinuités du mouvement, ainsi que de suivre les déplacements et les déformations de patchs de texture. Des mécanismes de régularisation sont également mis en place, et s'assurent que l'évolution des tubes se fait de manière cohérente. Ensuite, la représentation doit gérer les recouvrements et les découvrements de tubes, et donc la manière dont la texture doit être synthétisée. Enfin, la problématique de vie et de mort des tubes}est probablement la plus délicate: comment détecter la disparition ou l'impossibilité de suivre un patch de texture ? Le cas échéant, le tube correspondant devra être arrêté, ceci afin de garantir une représentation aussi compacte que possible. Les résultats montreront que notre représentation est viable, et ses performances seront comparées à celles du standard AVC

2AFC evaluation of Fourier watermarked images/documents

Subjective database available at : http://www.polytech.univ-nantes.fr/autrusseau-f/DFTWmking/#subjectiv

Les tubes de mouvement (nouvelle représentation pour les séquences d'images)

D'ici 2014, on estime que les réseaux ne pourront pas supporter l'augmentation du trafic vidéo: il nous faut améliorer nos capacités de compression. Classiquement, les images sont traitées une à une, et divisées en blocs. Cette approche est simple et efficace, mais l'emploi d'alternatives reste envisageable, notamment pour décrire l'évolution temporelle du contenu de manière continue. Cette thèse propose une nouvelle représentation, qui combine certains avantages de l'approche classique et d'approches en rupture. Elle exhibe la persistance temporelle des textures: au lieu de réinitialiser la représentation à chaque image, elle suit l'évolution de blocs de texture. Ces blocs, et leur trajectoire temporelle, sont appelés tubes de mouvement. Trois problématiques sont soulevées: la modélisation du déplacement et de la déformation des tubes; leurs recouvrements et découvrements; et leur vie et mort. Les résultats montrent que la représentation est viable, et la comparent au standard H.264.By 2014, it is expected that networks will not be able to sustain the increase in video traffic: there is a need for better compression schemes. Usually, images are processed one by one, and split into blocks. This approach is simple and effective, but alternatives also need to be considered, notably to describe the temporal content in a continuous fashion. This thesis proposes a new representation, that combines some advantages of both classical and disruptive approaches. It exhibits the temporal persistence of the textures: instead of reinitializing the representation for each image, it tracks the evolution of blocs of textures. These blocks, along with their temporal trajectories, are called motion tubes. Three issues are raised: how to model the displacements and the deformations of the tubes, the fact that tubes may overlap of introduce unreconstructed areas, and their life and death. Results show that the representation est viable, and compare it to H.264 standard.RENNES-INSA (352382210) / SudocSudocFranceF

Cover Page 1) Title of the paper: PERCEPTUAL DFT WATERMARKING WITH IMPROVED DETECTION AND ROBUSTNESS TO GEOMETRICAL DISTORTIONS

title = {Perceptual DFT watermarking with improved detection and robustness to geometrical distortions}, journal = {Accepted for publication in IEEE Transactions o

Visual Comfort and Fatigue in Stereoscopy

International audienceThis chapter provides an overview of visual fatigue and discomfort, both in terms of the mechanisms involved in the human visual system (HVS) and in terms of 3D content and processing technologies. It begins by defining the notions of fatigue and discomfort. A section provides an overview of cognitive and optical manifestations of fatigue and discomfort. Another section is devoted to different sources of visual fatigue and discomfort, in connection with binocular vision. The chapter considers the problems posed by 3D technologies and content. The whole of the 3D chain, from capture to viewing, via data representation, compression, transmission and display, requires careful mastery in order to limit stereoscopic faults and reproduce content in a suitable manner. The best compromise should be obtained between the quantity or intensity of 3D effects and the level of visual fatigue and discomfort experienced by the majority of people

Mechanical behavior of a chromium coating on a zirconium alloy substrate at room temperature

International audienc