Video Watermarking Based on Interactive Detection of Feature Regions

International audienceVideo watermarking is very important in many areas of activity and especially in multimedia applications. Therefore, security of video stream has recently become a major concern and has attracted more and more attention in both the research and industrial domains. In this perspective, several video watermarking approaches are proposed but, based on our knowledge, there is no method which verified the compromise between invisibility and robustness against all usual attacks. In our previous work, we proposed a new video watermarking approach based on feature region generated from mosaic frame and multi-frequential embedding. This approach allowed obtaining a good invisibility and robustness against the maximum of usual attacks. In our future work, we propose to optimize the choice of the region of interest by using crowdsourcing technique. This last one is an emerging field of knowledge management that involves analyzing the behavior of users when the

Reconstruction de matrices binaires sous contraintes de voisinage

International audienceLa tomographie discrète consiste à reconstruire des objets discrets en général et les matrices binaires en particulierà partir de leurs projections dans plusieurs directions. Les problèmes en tomographie sont classés suivant le nombrede projections, le type de projections et les propriétés de matrices à reconstruire. Le problème classique de reconstructionde matrices binaires à partir de projections orthogonales est défini comme suit : étant donné deuxvecteurs H = (h1, . . . , hm) et V = (v1, . . . , vn), nous cherchons à reconstruire une matrice binaire consistante avecces projections. La projection d?une rangée (ligne ou colonne) donne le nombre de 1s dans cette rangée

A new approach of action recognition based on Motion Stable Shape (MSS) features

International audienceAction recognition is actually considered as one of the most challenging areas in computer vision domain. In this paper, we propose a new approach based on utilization of motion boundaries to generate Motion Stable Shape (MSS) features to describe human actions in videos. In fact, we have considered actions as a set of human poses. Temporal evolution of each human pose is modeled by a set of new MSS feature's. Motion stable shapes of considered poses are defined by specific regions located at the borders of movements. Our modelisation is composed of different steps. First, a volume of optical flow frames highlighting the principal motions in poses is substracted. Then, motion boundaries are computed from the previous optical flow frames. Finally, maximally Stable Extremal Regions (MSER) are applied to motion boundaries frames in order to obtain MSS features. To predict classes of different human actions, the MSS features are combined with a standard bag-of-words representation. To prove the efficiency of our developed model, we have performed a set of experiments on four datasets: Weizmann, KTH, UFC and Hollywood. Obtained experimental results show that the proposed approach significantly outperforms state-of-the-art methods

An efficient approach for video action classification based on 3d Zernike moments

International audienceAction recognition in video and still image is one of the most challenging research topics in pattern recognition and computer vision. This paper proposes a new method for video action classification based on 3D Zernike moments. These last ones aim to capturing both structural and temporal information of a time varying sequence. The originality of this approach consists to represent actions in video sequences by a three-dimension shape obtained from different silhouettes in the space-time volume. In fact, the given video is segmented in space-time volume. Then, silhouettes are extracted from obtained images of the video sequences volumes and 3D Zernike moments are computed for video, based on silhouettes volumes. Finally, least square version of SVM (LSSVM) classifier with extracted features is used to classify actions in videos. To evaluate the proposed approach, it was applied on a benchmark human action dataset. The experimentations and evaluations show efficient results in terms of action characterizations and classification. Further more, it presents several advantages such as simplicity and respect of silhouette movement progress in the video guaranteed by 3D Zernike moment

Programmation discrète pour la reconstruction de matrices convexes

International audience

Reconstructing Convex Matrices by Integer Programming Approaches

We consider the problem of reconstructing two-dimensional convex binary matrices from their row and column sums with adjacent ones. Instead of requiring the ones to occur consecutively in each row and column, we maximize the number of adjacent ones. We reformulate the problem by using integer programming and we develop approximate solutions based on linearization and convexification techniques

A robust video watermarking based on feature regions and crowdsourcing

International audienceVideo watermarking technique aims at resolving insecurity problems. Recently, many approaches have been proposed in order to satisfy the new constraints of video applications such as robustness to collusion attacks, high level of security and signature invisibility. In this paper, a new video watermarking approach based on feature regions is proposed. The originality of this approach is to use crowdsourcing technique in order to detect feature regions. First, video summary is generated. This summary is then used to detect the first type of feature regions based on crowdsourcing technique. On the other hand, mosaic is generated from original video to detect the second type of feature region browsed by the moving objects. Finally, the signature is embedded into the mosaic generated after merging these two types of feature regions using multi-frequential watermarking scheme. Experimental results have shown a high level of invisibility thanks to the efficient choice of the embedded target. Moreover, the proposed approach is robust against several attacks especially to collusion attacks

Nouvelle méthode d’évaluation de robustesse des algorithmes de tatouage vidéo : jeu d’attaque

International audienceWatermarking techniques evaluation presents a critical and very important step. In fact, with the progressive evolution of video processing and communication, many watermarking approaches are proposed and their efficiency varies from an approach to another one. This efficiency is generally evaluated based on several constraints where the most important are invisibility and robustness in front of attacks. This last one is often estimated by testing classical and simple attacks such as rotation, translation and noise add. Nevertheless, a simple watermarking technique can easily resist to this type of attacks. So, it is necessary to study the impact of other attacks which are always applied in reality such as camcording attack. The integration of these important attacks will allowed a more efficient comparison between the various proposed techniques. In this paper, a new attacking game is proposed. In this game, different marked videos will be at the disposal of a set of users who can interact to destroy the inserted mark. Indeed, a list of different attacks will be given to users who can apply a combination of several of them to the marked videos. This list will contain the most important and dangerous attacks such as camcording, color add compression. This game allowed us to evaluate our video watermarking technique. In more, based on users’ choices, we can identify the most important attacks for them.L’évaluation d’une technique de tatouage a été toujours une étape critique et importante. En effet, l’évolution progressive des outils de traitement et de communication de vidéos a fait naître de nombreuses et différentes techniques de tatouage dont l’efficacité varie d’un algorithme à un autre. Cette efficacité est toujours évaluée en se basant sur plusieurs contraintes dont les plus importantes sont l’invisibilité et la robustesse face aux attaques. Cette dernière est souvent évaluée en testant des attaques classiques et simples telles que la compression, la rotation, la translation et l’ajout de bruit. Des techniques simples de tatouage peuvent résister à des attaques simples sans pour autant être robustes aux attaques observées dans le monde réel comme le "Camcording" d’un contenu vidéo. En situation réelle, un utilisateur mal intentionné (ou un pirate) va filmer illégalement un contenu projeté, recadrer l’image, transcoder le contenu obtenu. La question que nous nous posons est l’évaluation de méthodes de tatouage dans ce type de contexte. Dans le cadre de l’élaboration d’un nouveau protocole d’évaluation de techniques de tatouage vidéo, nous proposons, dans ce papier, un jeu d’attaques de vidéos tatouées mis à disposition d’un ensemble d’utilisateurs qui vont interagir afin de détruire la marque qui a été insérée. Ceci sera réalisé en leur fournissant une liste d’attaques qu’ils peuvent librement appliquer et combiner à ces vidéos tatouées. Cette liste va comprendre les attaques les plus importantes et réelles que peut subir une vidéo telles que le camcording, la déformation, l’ajout de couleur et la compression. Ce jeu nous a permis non seulement d’évaluer n’importe quel algorithme de tatouage vidéo, mais surtout, d’identifier, à partir de l’étude de choix des utilisateurs les attaques les plus importantes pour eux