We propose a continuous blind/no-reference video quality assessment (NR-VQA) algorithm based on features extracted from the bitstream, i.e., without decoding the video. The resulting algorithm requires minimal training and adopts a simple multi-layer perceptron for score prediction. The algorithm is computationally appealing. To assess the performance of the algorithm, both the Pearson Correlation Coefficient (PCC) and the Spearman Rank Ordered Correlation Coefficient (SROCC) are computed between the predicted values and the quality scores of two databases. The proposed approach is shown to have a high correlation with human visual perception of quality.

Smartphones are more and more used by Internet users for different services such as social networks, e-commerce or email. User authentication with passwords on such devices is not user-friendly and does not offer a high security level for this task. Biometrics is becoming one popular solution to achieve this goal with the embedding of fingerprint scanners in smartphones. In this paper, we propose a new protocol combining fingerprint and behavioral biometrics to enhance the security of user authentication while preserving usability and privacy. The behavior when entering a pattern based authentication on the smartphone touch screen is considered as a fast and usable solution for users. We think the proposed multi-biometric solution offers great advantages for many applications such as e-payment in terms of security, usability and privacy. We show through experimental results the efficiency of the proposed method.

Les smartphones sont de plus en plus utilises pour differents services numeriques tels que les reseaux sociaux ou le commerce electronique. L'authentification de l'utilisateur avec des mots de passe sur ces appareils n'est pas conviviale et n'offre pas un niveau de securite eleve de l'utilisateur. La biometrie devient une solution populaire pour atteindre cet objectif avec notamment l'integration de capteurs d'empreintes digitales dans les smartphones. Dans cet article, nous proposons un nouveau protocole combinant l'empreinte digitale et une biometrie comportementale pour ameliorer la securite de l'authentification des utilisateurs tout en preservant la facilite d'usage et le respect de la vie privee. Le comportement lors de la saisie d'une authentification d'un motif sur l'ecran tactile du smartphone est considere comme une solution rapide et simple d'usage. Nous pensons que la solution proposee offre de nombreux avantages en termes de securite, d'usage et de respect de la vie privee. Nous montrons au travers des resultats experimentaux l'efficacite de la methode proposee meme en cas d'attaque.

In order to verify the identity of a cardholder user, the typing of a PIN code is usually required, but this method does not guarantee the verification result. Only biometrics is able to authenticate an user as this information is strongly related to the user. To ensure security and privacy issues (such as the protection of the biometric data), Match On Card (MOC) solutions have been proposed. This approach consists in storing the biometric user's reference and computing the verification decision in a Secure Element (SE). The purpose of this paper is to propose an evaluation platform on biometric MOC for testing its performance and security. This platform allows to perform tests given scenarios and benchmarks for comparing MOCs. We illustrate the usefulness of this platform on a commercial MOC.

The quality assessment of the acquired biometric raw data is very important as it deeply affects the performance of biometric systems and consequently their usability. Poor quality samples increase the enrolment failures, and decrease the system performance. In this paper, we present a new quality assessment metric of fingerprints. Its main originality lies in the use of a no-reference image quality metric. The proposed quality metric combines two types of parameters through a weighted sum optimized by a genetic algorithm: 1) image quality criterion and 2) pattern-based quality criteria (salient and patch-based features). B OZORTH3 matching system and the FVC2002 DB3 fingerprint database are used to clarify the benefits of the presented quality metric.

In order to evaluate authentication methods for keystroke dynamics, it is necessary to create new datasets. We present in this paper an analysis study of the factors, involved during the acquisition process, which affect the performance of keystroke-based authentication systems. More generally speaking, we are looking for the optimal keystroke data acquisition scenario which may deeply affect the performance of such systems. Results show that (1) it is better to choose passwords based on short, simple and known words; and (2) during the acquisition process of a new keystroke dynamics dataset, there is no significant preference for displaying or telling to a user the text to type.

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.

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. (C) 2010 Elsevier B.V. All rights reserved.

The visual attention deployment in a visual scene is contingent upon a number of factors. The relationship between the observer's attention and the visual quality of the scene is investigated in this paper: can a video artifact disturb the observer's attention? To answer this question, two experiments have been conducted. First, eye-movements of human observers were recorded, while they watched ten video clips of natural scenes under a free-viewing task. These clips were more or less impaired by a video encoding scheme (H.264/AVC). The second experiment relies on the subjective rating of the quality of the video clips. A quality score was then assigned to each clip, indicating the extent to which the impairments were visible. The standardized method double stimulus impairment scale (DSIS) was used, meaning that each observer viewed the original clip followed by its impaired version. Both experimental results have conjointly been analyzed. Our results suggest that video artifacts have no influence on the deployment of visual attention, even though these artifacts have been judged by observers as at least annoying.

The temporal distortions such as flickering, jerkiness, and mosquito noise play a fundamental part in video quality assessment. A temporal distortion is commonly defined as the temporal evolution, or fluctuation, of the spatial distortion on a particular area which corresponds to the image of a specific object in the scene. Perception of spatial distortions over time can be largely modified by their temporal changes, such as increase or decrease in the distortions, or as periodic changes in the distortions. In this paper, we have designed a perceptual full reference video quality assessment metric by focusing on the temporal evolutions of the spatial distortions. As the perception of the temporal distortions is closely linked to the visual attention mechanisms, we have chosen to first evaluate the temporal distortion at eye fixation level. In this short-term temporal pooling, the video sequence is divided into spatio-temporal segments in which the spatio-temporal distortions are evaluated, resulting in spatio-temporal distortion maps. Afterwards, the global quality score of the whole video sequence is obtained by the long-term temporal pooling in which the spatio-temporal maps are spatially and temporally pooled. Consistent improvement over objective existing video quality assessment methods is observed. Our validation has been realized with a dataset built from video sequences of various contents.

The present invention relates to a version of method for selecting a document. A user enters an identifier of a multimedia document to its receptor connected to at least one communication network, and launched a search query to receive versions of at least part of this document. The receiver then receives a plurality of versions of the document. Each received version is analyzed by a plurality of evaluation modules for calculating an evaluation value for each received version of a determined criterion. The receiver selects for each of the evaluation modules a document version whose evaluation is the best for this test and displays the version identifiers have the best ratings for each criterion. The user can easily select to reproduce the version that best meets a criterion. The invention also relates to a receiver implementing the method.

Cette etude traite de l'evaluation locale des distorsions perceptuelles, de l'evaluation globale de la qualite visuelle, et de l'influence de l'attention visuelle en evaluation de qualite. Afin d'evaluer localement les distorsions dans les images, nous avons simplifie un modele existant du systeme visuel humain en utilisant la transformee en ondelettes et nous avons propose une meilleure modelisation des effets de masquage par la prise en compte du masquage semi-local. A partir de ces modeles, nous avons concu et valide des metriques de qualite d'images. Pour les videos, nous avons concu une methode d'evaluation locale des distorsions temporelles reposant sur un cumul temporel court terme des distorsions spatiales. Celui-ci simule l'evaluation des distorsions via des mecanismes de selection de l'attention visuelle. Une metrique de qualite s'appuyant sur cette methode a ete concue et validee. Celle-ci est basee sur un cumul temporel long terme incorporant un comportement asymetrique et un effet de saturation perceptuelle. L'influence de l'attention visuelle sur l'evaluation de la qualite a ete analysee a partir des donnees issues de tests oculometriques realises sur des images et sur des videos, en exploration libre et en tâche de qualite. Les resultats ont confirme, entre autres, l'influence de la tâche de qualite sur le deploiement de l'attention visuelle. L'impact de l'attention visuelle sur l'evaluation objective de la qualite a egalement ete etudie en utilisant l'information de saillance reelle. Nous avons montre qu'une simple ponderation lineaire des distorsions par l'attention visuelle ne permettait pas d'ameliorer clairement les performances des metriques de qualite.

T}he invention is a method for assessing image quality value of a distorted image with respect to a reference image. {T}he method comprises the following steps: computing, for each pixel of the distorted image, at least one quality level with respect to the reference image; adding, for the distorted image, the quality levels associated to each pixel by weighting them by a weight depending on a perceptual interest of the pixel in order to get the image quality value, the weight being lower for a pixel of high perceptual interest.