1,721,100 research outputs found
Content based video sequence editing: a client server JAVA system for user assisted segmentation
No full textIn this paper we present a semiautomatic video sequence segmentation technique, where the classification of the pixels of a video sequence into two classes, (moving and still) exploits parameter tuning and region marking provided by the user. User assistance is a straightforward way to increase segmentation performance, enabling the user to add high-level information in the process. The semiautomatic system is based on a client-server architecture that allows the design of a multi platform user interface by Java language and makes the system accessible on the network. This architecture allows the segmentation process to run on high speed servers, and it is configurable to give a segmentation service on the network to users who can upload their sequences to segment and download the resulting segmentation masks
Transient signal detection using higher order moments
No full textThe asymptotic performance of transient detection based on higher order moments is theoretically derived, invoking the asymptotic normality of the decision statistics, and a detector based on the third-order absolute moment is proposed. The analysis shows that for transient duration less than half the observation window, the proposed detector outperforms the detectors based on the second- and fourth-order moments for a wide range of SNR values. Computer simulations assess the applicability of the theoretical analysis. © 1999 IEEE
Affine warping using H263 overlapped motion compensation with proper weighting coefficients
No full textBayesian depth map interpolation using edge driven Markov Random Fields
No full textIn this work we present a Bayesian interpolation procedure to perform depth map upsampling. The depth map prior is designed via an edge driven Markov Random Field. The upsampling procedure is computationally efficient and outperforms selected state of the art upsampling procedure; moreover it allows to perform depth map upsampling even without the reference high resolution luminance map. © 2012 Taylor & Francis Group
Unicast, multicast and hybrid architecture for error resilient video streaming
No full textIn this work we discuss different architectures for error resilient video streaming. The architectures exploit a resilient video coding scheme, based on out-of-band transmission of suitable redundant information, that counteracts synchronization loss between the decoder and the bitstream due to transmission errors. We investigate unicast and multicast video streaming solutions and show a power/bandwidth efficient hybrid unicast/multicast architecture. Experimental results show the decoded video quality obtained by adopting the resilient streaming architecture in the case of H.264 coding. © 2005 IEEE
Performance evaluation of estimates of high order moments: Application to time delay estimation in colored noise
No full textDans cet article nous adressons le problème de l'évaluation analytique des performances de l'estime d'un paramètre inconnu avec les statistiques d'ordre supérieur (SOS). On a évalué d'abord la matrice de covariance des cumulants estimés sur un échantillon, qu'on a obtenue avec un algorithme pour un langage de manipulation symbolique. Enfin on présente de résultats de l'analyse des performances de l'éstimateur du temps de retour employant les cumulants du quatrième ordre
An empirical model of multiview video coding efficiency for wireless multimedia sensor networks
Full text linkWe develop an empirical model of the Multiview Video Coding (MVC) performance that can be used to identify and separate situations when MVC is beneficial from cases when its use is detrimental in wireless multimedia sensor networks (WMSN). The model predicts the compression performance of MVC as a function of the correlation between cameras with overlapping fields of view. We define the common sensed area (CSA) between different views, and emphasize that it depends not only on geometrical relationships among the relative positions of different cameras, but also on various object-related phenomena, e. g., occlusions and motion, and on low-level phenomena such as variations in illumination. With these premises, we first experimentally characterize the relationship between MVC compression gain (with respect to single view video coding) and the CSA between views. Our experiments are based on the H. 264 MVC standard, and on a low-complexity estimator of the CSA that can be computed with low inter-node signaling overhead. Then, we propose a compact empirical model of the efficiency of MVC as a function of the CSA between views, and we validate the model with different multiview video sequences. Finally, we show how the model can be applied to typical scenarios in WMSN, i.e., to clustered or multi-hop topologies, and we show a few promising results of its application in the definition of cross-layer clustering and data aggregation procedures
Error resilient video coding for wireless channels
No full textThis work describes how the introduction of redundancy by means of coding constraints known at the decoder side improves the error resilience of a video communication scheme. The decoder can exploit the a priori knowledge of the constraints to verify the integrity of the decoded bitstream. If the transmission errors cause the violation of the coding constraints, the decoder detects an error and recovers the synchronization with the bitstream. The improved detection capability results in better localization of the decoded frame areas affected by transmission errors, so allowing more accurate error concealment. The adoption of coding constraints does not require any feedback channel between the decoder and the coder since the decoder can be notified of the constraints during the initial negotiation phase. The syntax of the coder output is not affected and the coded bitstream remains standard compliant. Therefore, this technique is quite general and it is well suited to many transport schemes, either packet switched or circuit switched. Furthermore, it can be easily integrated with different error resilience tools. The improvement achievable in the decoded image quality using the coding constraints is here shown in the case of H.264 coded video
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