Current Issue : July - September Volume : 2013 Issue Number : 3 Articles : 4 Articles
The analysis of video acquired with a wearable camera is a challenge that multimedia community is facing with the proliferation\r\nof such sensors in various applications. In this paper, we focus on the problem of automatic visual place recognition in a weakly\r\nconstrained environment, targeting the indexing of video streams by topological place recognition.We propose to combine several\r\nmachine learning approaches in a time regularized framework for image-based place recognition indoors.Theframework combines\r\nthe power of multiple visual cues and integrates the temporal continuity information of video. We extend it with computationally\r\nefficient semisupervised method leveraging unlabeled video sequences for an improved indexing performance. The proposed\r\napproach was applied on challenging video corpora. Experiments on a public and a real-world video sequence databases show\r\nthe gain brought by the different stages of the method....
Video target tracking is a critical problem in the field of computer vision. Particle filters have been proven to be very useful in\r\ntarget tracking for nonlinear and non-Gaussian estimation problems. Although most existing algorithms are able to track targets\r\nwell in controlled environments, it is often difficult to achieve automated and robust tracking of pedestrians in video sequences\r\nif there are various changes in target appearance or surrounding illumination. To surmount these difficulties, this paper presents\r\nmultitarget tracking of pedestrians in video sequences based on particle filters. In order to improve the efficiency and accuracy of\r\nthe detection, the algorithm firstly obtains target regions in training frames by combining the methods of background subtraction\r\nand Histogram of Oriented Gradient (HOG) and then establishes discriminative appearance model by generating patches and\r\nconstructing codebooks using superpixel and Local Binary Pattern (LBP) features in those target regions. During the process of\r\ntracking, the algorithm uses the similarity between candidates and codebooks as observation likelihood function and processes\r\nsevere occlusion condition to prevent drift and loss phenomenon caused by target occlusion. Experimental results demonstrate\r\nthat our algorithm improves the tracking performance in complicated real scenarios....
To improve the playout quality of video streaming services, several adaptive media playout (AMP) mechanisms were proposed in\r\nliterature.However, all performance evaluations and comparisons forAMPs weremade in terms of quality of service (QoS) metrics.\r\nAs one knows, there may exist a trade-off between QoS metrics, such as buffer underflow and overflow performance. Thus, it is\r\nnot sufficient to only evaluate the performance of AMPs in terms of QoS metrics. In this paper, we will evaluate and compare the\r\nperformance of several AMPs from the aspect of quality of experience (QoE). Numerical results will show that some existing AMP\r\nsystems do not perform better than the nonadaptive playout system from the point of view of overall QoE....
This paper proposes a novel formof reversible data hiding using two marked images by employing the adaptive coefficient-shifting\r\n(ACS) algorithm. The proposed ACS algorithm consists of three parts: the minimum-preserved scheme, the minimum-preserved\r\nwith squeezing scheme, and the base-value embedding scheme.More specifically, each input block of a host image can be encoded\r\nto two stego-blocks according to three predetermined rules by the above three schemes. Simulations validate that the proposed\r\nmethod not only completely recovers the host medium but also losslessly extracts the hidden message. The proposed method\r\ncan handle various kinds of images without any occurrence of overflow/underflow. Moreover, the payload and peak signal-tonoise\r\nratio (PSNR) performance of the proposed method is superior to that of the conventional invertible data hiding schemes.\r\nFurthermore, the number of shadows required by the proposed method is less than that required by the approaches which are\r\nbased upon secret image sharing with reversible steganography....
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