Advances in Multimedia http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A IEEE 802.11e HCCA Scheduler with a Reclaiming Mechanism for Multimedia Applications Thu, 20 Mar 2014 17:45:01 +0000 http://www.hindawi.com/journals/am/2014/372693/ The QoS offered by the IEEE 802.11e reference scheduler is satisfactory in the case of Constant Bit Rate traffic streams, but not yet in the case of Variable Bit Rate traffic streams, whose variations stress its scheduling behavior. Despite the numerous proposed alternative schedulers with QoS, multimedia applications are looking for refined methods suitable to ensure service differentiation and dynamic update of protocol parameters. In this paper a scheduling algorithm, Unused Time Shifting Scheduler (UTSS), is deeply analyzed. It is designed to cooperate with a HCCA centralized real-time scheduler through the integration of a bandwidth reclaiming scheme, suitable to recover nonexhausted transmission time and assign that to the next polled stations. UTSS dynamically computes with an complexity transmission time providing an instantaneous resource overprovisioning. The theoretical analysis and the simulation results highlight that this injection of resources does not affect the admission control nor the centralized scheduler but is suitable to improve the performance of the centralized scheduler in terms of mean access delay, transmission queues length, bursts of traffic management, and packets drop rate. These positive effects are more relevant for highly variable bit rate traffic. Anna Lina Ruscelli and Gabriele Cecchetti Copyright © 2014 Anna Lina Ruscelli and Gabriele Cecchetti. All rights reserved. Salt and Pepper Noise Removal with Noise Detection and a Patch-Based Sparse Representation Thu, 13 Mar 2014 12:33:03 +0000 http://www.hindawi.com/journals/am/2014/682747/ Images may be corrupted by salt and pepper impulse noise due to noisy sensors or channel transmission errors. A denoising method by detecting noise candidates and enforcing image sparsity with a patch-based sparse representation is proposed. First, noise candidates are detected and an initial guide image is obtained via an adaptive median filtering; second, a patch-based sparse representation is learnt from this guide image; third, a weighted - regularization method is proposed to penalize the noise candidates heavier than the rest of pixels. An alternating direction minimization algorithm is derived to solve the regularization model. Experiments are conducted for 30%∼90% impulse noise levels, and the simulation results demonstrate that the proposed method outperforms total variation and Wavelet in terms of preserving edges and structural similarity to the noise-free images. Di Guo, Xiaobo Qu, Xiaofeng Du, Keshou Wu, and Xuhui Chen Copyright © 2014 Di Guo et al. All rights reserved. Macroblock Layer Rate Control Based on Structural Similarity and Mean Absolute Difference for H.264 Tue, 11 Feb 2014 00:00:00 +0000 http://www.hindawi.com/journals/am/2014/680859/ In the process of the H.264 video coding, special attention should be paid to the subjective quality of the image. This paper applies the structural similarity (SSIM) based subjective evaluation to the rate control in the H.264 coding and proposes to combine the SSIM and the mean absolute difference (MAD) to perform the macroblock layer bit allocation instead of the MAD. Experimental results show that the proposed method is correlating better with the human visual system and thus achieves better subjective image quality. Xiao Chen and Dongjue Gu Copyright © 2014 Xiao Chen and Dongjue Gu. All rights reserved. Heritage Multimedia and Children Edutainment: Assessment and Recommendations Sun, 09 Feb 2014 10:36:30 +0000 http://www.hindawi.com/journals/am/2014/579182/ Despite the rising commodification of heritage sites and practices, children engagement in their own cultures remains incredibly low, greatly endangering the future preservation of nations’ unique nonrenewable resource. Considering children’s very early engagement with cultural attitudes and identities, it is increasingly critical to develop a deeply rooted culture of responsibility and conservation from the earliest years, ensuring that children naturally feel invested in their surroundings. Unfortunately, heritage education remains largely undervalued, with most efforts relying on in-person experiences in formal cultural institutions. This paper thus aims to explore how heritage education can be redefined, using some of the most innovative virtual imaging and artificial reality technologies to at once expand access and engagement with one’s own history. Though there have been introductory applications of this edutainment multimedia technology, it will require a multidisciplinary team to create heritage programming which is as entertaining as it is intellectually challenging for young children. With the rich resources of 3D imaging and interactive programming already at our disposal, we are well-equipped to do so, given a coordinated effort. Naif A. Haddad Copyright © 2014 Naif A. Haddad. All rights reserved. Real-Time QoS-Aware Video Streaming: A Comparative and Experimental Study Thu, 16 Jan 2014 12:49:15 +0000 http://www.hindawi.com/journals/am/2014/164940/ Due to its flexibility, scalability, real-time, and rich QoS features, Data Distribution Service (DDS) middleware provides seamless integration with high-performance, real-time, and mission-critical networks. Unlike traditional client-server communication models, DDS is based on the publish/subscribe communication model. DDS improves video streaming quality through its efficient and high-performance data delivery mechanism. This paper studies and investigates how DDS is suitable for streaming real-time full-motion video over a communication network. Experimental studies are conducted to compare video streaming using a the VLC player with the DDS overlay. Our results depict the superiority of DDS in provisioning quality video streams at the cost of low network bandwidth. The results also show that DDS is more scalable and flexible and is a promised technology for video distribution over IP networks where it uses much less bandwidth while maintaining high quality video stream delivery. Basem Al-Madani, Anas Al-Roubaiey, and Zubair A. Baig Copyright © 2014 Basem Al-Madani et al. All rights reserved. Video Pulses: User-Based Modeling of Interesting Video Segments Sun, 12 Jan 2014 16:07:47 +0000 http://www.hindawi.com/journals/am/2014/712589/ We present a user-based method that detects regions of interest within a video in order to provide video skims and video summaries. Previous research in video retrieval has focused on content-based techniques, such as pattern recognition algorithms that attempt to understand the low-level features of a video. We are proposing a pulse modeling method, which makes sense of a web video by analyzing users' Replay interactions with the video player. In particular, we have modeled the user information seeking behavior as a time series and the semantic regions as a discrete pulse of fixed width. Then, we have calculated the correlation coefficient between the dynamically detected pulses at the local maximums of the user activity signal and the pulse of reference. We have found that users' Replay activity significantly matches the important segments in information-rich and visually complex videos, such as lecture, how-to, and documentary. The proposed signal processing of user activity is complementary to previous work in content-based video retrieval and provides an additional user-based dimension for modeling the semantics of a social video on the web. Markos Avlonitis and Konstantinos Chorianopoulos Copyright © 2014 Markos Avlonitis and Konstantinos Chorianopoulos. All rights reserved. Cross-Layer Framework for Multiuser Real Time H.264/AVC Video Encoding and Transmission over Block Fading MIMO Channels Using Outage Probability Thu, 02 Jan 2014 09:47:15 +0000 http://www.hindawi.com/journals/am/2014/362196/ We present a framework for cross-layer optimized real time multiuser encoding of video using a single layer H.264/AVC and transmission over MIMO wireless channels. In the proposed cross-layer adaptation, the channel of every user is characterized by the probability density function of its channel mutual information and the performance of the H.264/AVC encoder is modeled by a rate distortion model that takes into account the channel errors. These models are used during the resource allocation of the available slots in a TDMA MIMO communication system with capacity achieving channel codes. This framework allows for adaptation to the statistics of the wireless channel and to the available resources in the system and utilization of the multiuser diversity of the transmitted video sequences. We show the effectiveness of the proposed framework for video transmission over Rayleigh MIMO block fading channels, when channel distribution information is available at the transmitter. Slavche Pejoski and Venceslav Kafedziski Copyright © 2014 Slavche Pejoski and Venceslav Kafedziski. All rights reserved. The Safeguard of Audio Collections: A Computer Science Based Approach to Quality Control—The Case of the Sound Archive of the Arena di Verona Sat, 14 Dec 2013 10:10:50 +0000 http://www.hindawi.com/journals/am/2013/276354/ In the field of multimedia, very little attention is given to the activities involved in the preservation of audio documents. At the same time, more and more archives storing audio and video documents face the problem of obsolescing and degrading media, which could largely benefit from the instruments and the methodologies of research in multimedia. This paper presents the methodology and the results of the Italian project REVIVAL, aimed at the development of a hardware/software platform to support the active preservation of the audio collection of the Fondazione Arena di Verona, one of the finest in Europe for the operatic genre, with a special attention on protocols and tools for quality control. On the scientific side, the most significant objectives achieved by the project are (i) the setup of a working environment inside the archive, (ii) the knowledge transfer to the archival personnel, (iii) the realization of chemical analyses on magnetic tapes in collaboration with experts in the fields of materials science and chemistry, and (iv) the development of original open-source software tools. On the cultural side, the recovery, the safeguard, and the access to unique copies of unpublished live recordings of artists the calibre of Domingo and Pavarotti are of great musicological and economical value. Federica Bressan, Antonio Rodà, Sergio Canazza, Federico Fontana, and Roberta Bertani Copyright © 2013 Federica Bressan et al. All rights reserved. An Integrated New Scheme for Digital Video Stabilization Wed, 04 Dec 2013 14:20:56 +0000 http://www.hindawi.com/journals/am/2013/651650/ In many digital video applications, video sequences suffer from jerky movements between successive frames. In this paper, an integrated general-purpose stabilization method is proposed, which extracts the information from successive frames and removes the translation and rotation motions that result in undesirable effects. The scheme proposed starts with computation of the optical flow between consecutive video frames and an affine motion model is adopted in conjunction with the optical flow field obtained to estimate objects or camera motions using the Horn-Schunck algorithm. The estimated motion vectors are then used by a model-fitting filter to stabilize and smooth video sequences. Experimental results demonstrate that the proposed scheme is efficient due to its simplicity and provides good visual quality in terms of the global transformation fidelity measured by the peak-signal-noise-ratio. W. Xu, X. Lai, D. Xu, and N. A. Tsoligkas Copyright © 2013 W. Xu et al. All rights reserved. Efficient Region-of-Interest Scalable Video Coding with Adaptive Bit-Rate Control Mon, 04 Nov 2013 19:08:52 +0000 http://www.hindawi.com/journals/am/2013/281593/ This work relates to the regions-of-interest (ROI) coding that is a desirable feature in future applications based on the scalable video coding, which is an extension of the H.264/MPEG-4 AVC standard. Due to the dramatic technological progress, there is a plurality of heterogeneous devices, which can be used for viewing a variety of video content. Devices such as smartphones and tablets are mostly resource-limited devices, which make it difficult to display high-quality content. Usually, the displayed video content contains one or more ROI(s), which should be adaptively selected from the preencoded scalable video bitstream. Thus, an efficient scalable ROI video coding scheme is proposed in this work, thereby enabling the extraction of the desired regions-of-interest and the adaptive setting of the desirable ROI location, size, and resolution. In addition, an adaptive bit-rate control is provided for the region-of-interest scalable video coding. The performance of the presented techniques is demonstrated and compared with the joint scalable video model reference software (JSVM 9.19), thereby showing significant bit-rate savings as a tradeoff for the relatively low PSNR degradation. Dan Grois and Ofer Hadar Copyright © 2013 Dan Grois and Ofer Hadar. All rights reserved. Video Genre Classification Using Weighted Kernel Logistic Regression Wed, 09 Oct 2013 09:33:37 +0000 http://www.hindawi.com/journals/am/2013/653687/ Due to the widening semantic gap of videos, computational tools to classify these videos into different genre are highly needed to narrow it. Classifying videos accurately demands good representation of video data and an efficient and effective model to carry out the classification task. Kernel Logistic Regression (KLR), kernel version of logistic regression (LR), proves its efficiency as a classifier, which can naturally provide probabilities and extend to multiclass classification problems. In this paper, Weighted Kernel Logistic Regression (WKLR) algorithm is implemented for video genre classification to obtain significant accuracy, and it shows accurate and faster good results. Ahmed A. M. Hamed, Renfa Li, Zhang Xiaoming, and Cheng Xu Copyright © 2013 Ahmed A. M. Hamed et al. All rights reserved. A Novel Model of Image Segmentation Based on Watershed Algorithm Wed, 04 Sep 2013 14:07:24 +0000 http://www.hindawi.com/journals/am/2013/120798/ A novel model of image segmentation based on watershed method is proposed in this paper. To prevent the oversegmentation of traditional watershed, our proposed algorithm has five stages. Firstly, the morphological reconstruction is applied to smooth the flat area and preserve the edge of the image. Secondly, multiscale morphological gradient is used to avoid the thickening and merging of the edges. Thirdly, for contrast enhancement, the top/bottom hat transformation is used. Fourthly, the morphological gradient of an image is modified by imposing regional minima at the location of both the internal and the external markers. Finally, a weighted function is used to combine the top/bottom hat transformation algorithm and the markers algorithm to get the new algorithm. The experimental results show the superiority of the new algorithm in terms of suppression over-segmentation. Ali Abdullah Yahya, Jieqing Tan, and Min Hu Copyright © 2013 Ali Abdullah Yahya et al. All rights reserved. Real-Time Audio-Visual Analysis for Multiperson Videoconferencing Mon, 26 Aug 2013 09:53:28 +0000 http://www.hindawi.com/journals/am/2013/175745/ We describe the design of a system consisting of several state-of-the-art real-time audio and video processing components enabling multimodal stream manipulation (e.g., automatic online editing for multiparty videoconferencing applications) in open, unconstrained environments. The underlying algorithms are designed to allow multiple people to enter, interact, and leave the observable scene with no constraints. They comprise continuous localisation of audio objects and its application for spatial audio object coding, detection, and tracking of faces, estimation of head poses and visual focus of attention, detection and localisation of verbal and paralinguistic events, and the association and fusion of these different events. Combined all together, they represent multimodal streams with audio objects and semantic video objects and provide semantic information for stream manipulation systems (like a virtual director). Various experiments have been performed to evaluate the performance of the system. The obtained results demonstrate the effectiveness of the proposed design, the various algorithms, and the benefit of fusing different modalities in this scenario. Petr Motlicek, Stefan Duffner, Danil Korchagin, Hervé Bourlard, Carl Scheffler, Jean-Marc Odobez, Giovanni Del Galdo, Markus Kallinger, and Oliver Thiergart Copyright © 2013 Petr Motlicek et al. All rights reserved. A Survey on Content Adaptation Systems towards Energy Consumption Awareness Thu, 25 Jul 2013 11:26:30 +0000 http://www.hindawi.com/journals/am/2013/871516/ The availability of heterogeneous devices has rapidly changed the way people access the World Wide Web that includes rich content applications such as video streaming, 3D games, video conferencing, and mobile TV. However, most of these devices' (i.e., mobile phone, PDA, smartphone, and tablet) capabilities differ in terms of built-in software and library (what they can display), display size (how the content appears), and battery supply (how long the content can be displayed). In order for the digital contents to fit the target device, content adaptation is required. There have been many projects focused on energy-aware-based content adaptation that have been designed with different goals and approaches. This paper reviews some of the representative content adaptation solutions that have been proposed during the last few years, in relation to energy consumption focusing on wireless multimedia streaming in mobile devices. Also, this paper categorizes the research work according to different classifications of multimedia content adaptation requirements. In addition, we discuss some energy-related challenges content adaptation systems. Mohd Norasri Ismail, Rosziati Ibrahim, and Mohd Farhan Md Fudzee Copyright © 2013 Mohd Norasri Ismail et al. All rights reserved. Superwideband Bandwidth Extension Using Normalized MDCT Coefficients for Scalable Speech and Audio Coding Mon, 08 Jul 2013 11:33:06 +0000 http://www.hindawi.com/journals/am/2013/909124/ A bandwidth extension (BWE) algorithm from wideband to superwideband (SWB) is proposed for a scalable speech/audio codec that uses modified discrete cosine transform (MDCT) coefficients as spectral parameters. The superwideband is first split into several subbands that are represented as gain parameters and normalized MDCT coefficients in the proposed BWE algorithm. We then estimate normalized MDCT coefficients of the wideband to be fetched for the superwideband and quantize the fetch indices. After that, we quantize gain parameters by using relative ratios between adjacent subbands. The proposed BWE algorithm is embedded into a standard superwideband codec, the SWB extension of G.729.1 Annex E, and its bitrate and quality are compared with those of the BWE algorithm already employed in the standard superwideband codec. It is shown from the comparison that the proposed BWE algorithm relatively reduces the bitrate by around 19% with better quality, compared to the BWE algorithm in the SWB extension of G.729.1 Annex E. Young Han Lee and Seung Ho Choi Copyright © 2013 Young Han Lee and Seung Ho Choi. All rights reserved. Admission Control Methods in IP Networks Mon, 25 Mar 2013 12:06:55 +0000 http://www.hindawi.com/journals/am/2013/918930/ Telecommunications operators and research institutions pay close attention to the issue of quality of service. The paper deals with methods of admission control in IP networks, which is only one of the subsets of quality of service. There are two large groups of AC methods: parameter-based admission control and measurement-based admission control. The core of the paper is simulation of AC methods and algorithms for topology model in MATLAB. Our simulations are mainly focused on required bandwidth and loss rates. At the end of the paper there are compared results of simulations. Erik Chromy, Marcel Jadron, and Tomas Behul Copyright © 2013 Erik Chromy et al. All rights reserved. QoE-Based Performance Evaluation for Adaptive Media Playout Systems Thu, 21 Feb 2013 09:41:26 +0000 http://www.hindawi.com/journals/am/2013/152359/ To improve the playout quality of video streaming services, several adaptive media playout (AMP) mechanisms were proposed in literature. However, all performance evaluations and comparisons for AMPs were made in terms of quality of service (QoS) metrics. As one knows, there may exist a trade-off between QoS metrics, such as buffer underflow and overflow performance. Thus, it is not sufficient to only evaluate the performance of AMPs in terms of QoS metrics. In this paper, we will evaluate and compare the performance of several AMPs from the aspect of quality of experience (QoE). Numerical results will show that some existing AMP systems do not perform better than the nonadaptive playout system from the point of view of overall QoE. Mingfu Li Copyright © 2013 Mingfu Li. All rights reserved. Multiple Feature Fusion Based on Co-Training Approach and Time Regularization for Place Classification in Wearable Video Mon, 28 Jan 2013 15:16:58 +0000 http://www.hindawi.com/journals/am/2013/175064/ The analysis of video acquired with a wearable camera is a challenge that multimedia community is facing with the proliferation of such sensors in various applications. In this paper, we focus on the problem of automatic visual place recognition in a weakly constrained environment, targeting the indexing of video streams by topological place recognition. We propose to combine several machine learning approaches in a time regularized framework for image-based place recognition indoors. The framework combines the power of multiple visual cues and integrates the temporal continuity information of video. We extend it with computationally efficient semisupervised method leveraging unlabeled video sequences for an improved indexing performance. The proposed approach was applied on challenging video corpora. Experiments on a public and a real-world video sequence databases show the gain brought by the different stages of the method. Vladislavs Dovgalecs, Rémi Mégret, and Yannick Berthoumieu Copyright © 2013 Vladislavs Dovgalecs et al. All rights reserved. Web Services in Multimedia Communication Thu, 13 Dec 2012 09:00:43 +0000 http://www.hindawi.com/journals/am/2012/129504/ Mohamed Hamdi, Nabil Tabbane, Tai-Hoon Kim, and Sajid Hussain Copyright © 2012 Mohamed Hamdi et al. All rights reserved. Optimal H.264 Scalable Video Scheduling Policies for 3G/4G Wireless Cellular and Video Sensor Networks Sun, 09 Dec 2012 08:31:10 +0000 http://www.hindawi.com/journals/am/2012/207471/ We consider the problem of optimal H.264 scalable video scheduling, with an objective of maximizing the end-user video quality while ensuring fairness in 3G/4G broadband wireless networks and video sensor networks. We propose a novel framework to characterize the video quality-based utility of the H.264 temporal and quality scalable video layers. Subsequently, we formulate the scalable video scheduling framework as a Markov decision process (MDP) for long-term average video utility maximization and derive the optimal index based-scalable video scheduling policies ISVP and ISVPF towards video quality maximization. Further, we extend this framework to multiuser and multisubchannel scenario of 4G wireless networks. In this context, we propose two novel schemes for long-term streaming video quality performance optimization based on maximum weight bipartite and greedy matching paradigms. Simulation results demonstrate that the proposed algorithms achieve superior end-user video experience compared to competing scheduling policies such as Proportional Fairness (PF), Linear Index Policy (LIP), Rate Starvation Age policy (RSA), and Quality Proportional Fair Policy (QPF). Vamseedhar R. Reddyvari and Aditya K. Jagannatham Copyright © 2012 Vamseedhar R. Reddyvari and Aditya K. Jagannatham. All rights reserved. Multitarget Tracking of Pedestrians in Video Sequences Based on Particle Filters Sun, 09 Dec 2012 07:54:33 +0000 http://www.hindawi.com/journals/am/2012/343724/ Video target tracking is a critical problem in the field of computer vision. Particle filters have been proven to be very useful in target tracking for nonlinear and non-Gaussian estimation problems. Although most existing algorithms are able to track targets well in controlled environments, it is often difficult to achieve automated and robust tracking of pedestrians in video sequences if there are various changes in target appearance or surrounding illumination. To surmount these difficulties, this paper presents multitarget tracking of pedestrians in video sequences based on particle filters. In order to improve the efficiency and accuracy of the detection, the algorithm firstly obtains target regions in training frames by combining the methods of background subtraction and Histogram of Oriented Gradient (HOG) and then establishes discriminative appearance model by generating patches and constructing codebooks using superpixel and Local Binary Pattern (LBP) features in those target regions. During the process of tracking, the algorithm uses the similarity between candidates and codebooks as observation likelihood function and processes severe occlusion condition to prevent drift and loss phenomenon caused by target occlusion. Experimental results demonstrate that our algorithm improves the tracking performance in complicated real scenarios. Hui Li, Shengwu Xiong, Pengfei Duan, and Xiangzhen Kong Copyright © 2012 Hui Li et al. All rights reserved. Reversible Data Hiding Using Two Marked Images Based on Adaptive Coefficient-Shifting Algorithm Tue, 04 Dec 2012 11:43:33 +0000 http://www.hindawi.com/journals/am/2012/473896/ This paper proposes a novel form of reversible data hiding using two marked images by employing the adaptive coefficient-shifting (ACS) algorithm. The proposed ACS algorithm consists of three parts: the minimum-preserved scheme, the minimum-preserved with squeezing scheme, and the base-value embedding scheme. More specifically, each input block of a host image can be encoded to two stego-blocks according to three predetermined rules by the above three schemes. Simulations validate that the proposed method not only completely recovers the host medium but also losslessly extracts the hidden message. The proposed method can handle various kinds of images without any occurrence of overflow/underflow. Moreover, the payload and peak signal-to-noise ratio (PSNR) performance of the proposed method is superior to that of the conventional invertible data hiding schemes. Furthermore, the number of shadows required by the proposed method is less than that required by the approaches which are based upon secret image sharing with reversible steganography. Ching-Yu Yang Copyright © 2012 Ching-Yu Yang. All rights reserved. Enhancing Scalability in On-Demand Video Streaming Services for P2P Systems Wed, 21 Nov 2012 15:38:53 +0000 http://www.hindawi.com/journals/am/2012/109619/ Recently, many video applications like video telephony, video conferencing, Video-on-Demand (VoD), and so forth have produced heterogeneous consumers in the Internet. In such a scenario, media servers play vital role when a large number of concurrent requests are sent by heterogeneous users. Moreover, the server and distributed client systems participating in the Internet communication have to provide suitable resources to heterogeneous users to meet their requirements satisfactorily. The challenges in providing suitable resources are to analyze the user service pattern, bandwidth and buffer availability, nature of applications used, and Quality of Service (QoS) requirements for the heterogeneous users. Therefore, it is necessary to provide suitable techniques to handle these challenges. In this paper, we propose a framework for peer-to-peer- (P2P-) based VoD service in order to provide effective video streaming. It consists of four functional modules, namely, Quality Preserving Multivariate Video Model (QPMVM) for efficient server management, tracker for efficient peer management, heuristic-based content distribution, and light weight incentivized sharing mechanism. The first two of these modules are confined to a single entity of the framework while the other two are distributed across entities. Experimental results show that the proposed framework avoids overloading the server, increases the number of clients served, and does not compromise on QoS, irrespective of the fact that the expected framework is slightly reduced. R. Arockia Xavier Annie, P. Yogesh, and A. Kannan Copyright © 2012 R. Arockia Xavier Annie et al. All rights reserved. A Novel Anonymous Proxy Signature Scheme Wed, 05 Sep 2012 13:43:31 +0000 http://www.hindawi.com/journals/am/2012/427961/ Recently, several studies about proxy signature schemes have been conducted. In 2009, Yu et al. proposed an anonymous proxy signature scheme attempting to protect the proxy signer's privacy from outsiders. They claimed that their scheme can make the proxy signer anonymous. However, based on our research, we determined that this was not the case and the proxy signer's privacy was not anonymous. Hence, in this paper, we propose a new anonymous proxy signature scheme that truly makes the proxy signer anonymous while making it more secure and efficient when compared with Yu et al.'s scheme. Our proxy signature scheme consists of two contributions. First, we mainly use random numbers and bilinear pairings to attain the anonymous property. Secondly, we increase the security and efficiency of our proxy in the design. Jue-Sam Chou Copyright © 2012 Jue-Sam Chou. All rights reserved. Color Image Quality Assessment Based on CIEDE2000 Thu, 30 Aug 2012 11:18:07 +0000 http://www.hindawi.com/journals/am/2012/273723/ Combining the color difference formula of CIEDE2000 and the printing industry standard for visual verification, we present an objective color image quality assessment method correlated with subjective vision perception. An objective score conformed to subjective perception (OSCSP) Q was proposed to directly reflect the subjective visual perception. In addition, we present a general method to calibrate correction factors of color difference formula under real experimental conditions. Our experiment results show that the present DE2000-based metric can be consistent with human visual system in general application environment. Yang Yang, Jun Ming, and Nenghai Yu Copyright © 2012 Yang Yang et al. All rights reserved. Mining Local Specialties for Travelers by Leveraging Structured and Unstructured Data Sun, 26 Aug 2012 10:00:42 +0000 http://www.hindawi.com/journals/am/2012/987124/ Recently, many local review websites such as Yelp are emerging, which have greatly facilitated people's daily life such as cuisine hunting. However they failed to meet travelers' demands because travelers are more concerned about a city's local specialties instead of the city's high ranked restaurants. To solve this problem, this paper presents a local specialty mining algorithm, which utilizes both the structured data from local review websites and the unstructured user-generated content (UGC) from community Q&A websites, and travelogues. The proposed algorithm extracts dish names from local review data to build a document for each city, and applies tfidf weighting algorithm on these documents to rank dishes. Dish-city correlations are calculated from unstructured UGC, and combined with the tfidf ranking score to discover local specialties. Finally, duplicates in the local specialty mining results are merged. A recommendation service is built to present local specialties to travelers, along with specialties' associated restaurants, Q&A threads, and travelogues. Experiments on a large data set show that the proposed algorithm can achieve a good performance, and compared to using local review data alone, leveraging unstructured UGC can boost the mining performance a lot, especially in large cities. Kai Jiang, Like Liu, Rong Xiao, and Nenghai Yu Copyright © 2012 Kai Jiang et al. All rights reserved. Distortion-Based Slice Level Prioritization for Real-Time Video over QoS-Enabled Wireless Networks Thu, 23 Aug 2012 14:11:09 +0000 http://www.hindawi.com/journals/am/2012/319785/ This paper presents a prioritization scheme based on an analysis of the impact on objective video quality when dropping individual slices from coded video streams. It is shown that giving higher-priority classified packets preference in accessing the wireless media results in considerable quality gain (up to 3 dB in tests) over the case when no prioritization is applied. The proposed scheme is demonstrated for an IEEE 802.11e quality-of-service- (QoS-) enabled wireless LAN. Though more complex prioritization systems are possible, the proposed scheme is crafted for mobile interactive or user-to-user video services and is simply implemented within the Main or the Baseline profiles of an H.264 codec. Ismail A. Ali, Martin Fleury, and Mohammed Ghanbari Copyright © 2012 Ismail A. Ali et al. All rights reserved. Protecting H.264/AVC Data-Partitioned Video Streams over Broadband WiMAX Thu, 23 Aug 2012 12:06:00 +0000 http://www.hindawi.com/journals/am/2012/129517/ Broadband wireless technology, though aimed at video services, also poses a potential threat to video services, as wireless channels are prone to error bursts. In this paper, an adaptive, application-layer Forward Error Correction (FEC) scheme protects H.264/AVC data-partitioned video. Data partitioning is the division of a compressed video stream into partitions of differing decoding importance. The paper determines whether equal error protection (EEP) through FEC of all partition types or unequal error protection (UEP) of the more important partition type is preferable. The paper finds that, though UEP offers a small reduction in bitrate, if EEP is employed, there are significant gains (several dBs) in video quality. Overhead from using EEP rather than UEP was found to be around 1% of the overall bitrate. Given that data partitioning already reduces errors through packet size reduction and differentiation of coding data, EEP with data partitioning is a practical means of protecting user-based video streaming. The gain from employing EEP is shown to be higher quality video to the user, which will result in a greater take-up of video services. The results have implications for other forms of prioritized video streaming. Laith Al-Jobouri, Martin Fleury, and Mohammed Ghanbari Copyright © 2012 Laith Al-Jobouri et al. All rights reserved. A Design Method of Saturation Test Image Based on CIEDE2000 Thu, 16 Aug 2012 09:44:37 +0000 http://www.hindawi.com/journals/am/2012/513963/ In order to generate color test image consistent with human perception in aspect of saturation, lightness, and hue of image, we propose a saturation test image design method based on CIEDE2000 color difference formula. This method exploits the subjective saturation parameter C′ of CIEDE2000 to get a series of test images with different saturation but same lightness and hue. It is found experimentally that the vision perception has linear relationship with the saturation parameter C′. This kind of saturation test image has various applications, such as in the checking of color masking effect in visual experiments and the testing of the visual effects of image similarity component. Yang Yang, Jun Ming, and Nenghai Yu Copyright © 2012 Yang Yang et al. All rights reserved. Division-Free Multiquantization Scheme for Modern Video Codecs Thu, 09 Aug 2012 14:21:51 +0000 http://www.hindawi.com/journals/am/2012/302893/ The current trend of digital convergence leads to the need of the video encoder/decoder (codec) that should support multiple video standards on a single platform as it is expensive to use dedicated video codec chip for each standard. The paper presents a high performance circuit shared architecture that can perform the quantization of five popular video codecs such as H.264/AVC, AVS, VC-1, MPEG-2/4, and JPEG. The proposed quantizer architecture is completely division-free as the division operation is replaced by shift and addition operations for all the standards. The design is implemented on FPGA and later synthesized in CMOS 0.18 m technology. The results show that the proposed design satisfies the requirement of all five codecs with a maximum decoding capability of 60 fps at 187 MHz on Xilinx FPGA platform for 1080 p HD video. Mousumi Das, Atahar Mostafa, and Khan Wahid Copyright © 2012 Mousumi Das et al. All rights reserved.