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PubMed2004

Unsupervised learning of a finite mixture model based on the Dirichlet distribution and its application.

This paper presents an unsupervised algorithm for learning a finite mixture model from multivariate data. This mixture model is based on the Dirichlet distribution, which offers high flexibility for modeling data. The proposed approach for estimating the parameters of a Dirichlet mixture is based on the maximum likelihood (ML) and Fisher scoring methods. Experimental results are presented for the following applications: estimation of artificial histograms, summarization of image databases for efficient retrieval, and human skin color modeling and its application to skin detection in multimedia databases.

Algorithms↗
PubMed2004

Locally optimum nonlinearities for DCT watermark detection.

The issue of copyright protection of digital multimedia data has attracted a lot of attention during the last decade. An efficient copyright protection method that has been gaining popularity is watermarking, i.e., the embedding of a signature in a digital document that can be detected only by its rightful owner. Watermarks are usually blindly detected using correlating structures, which would be optimal in the case of Gaussian data. However, in the case of DCT-domain image watermarking, the data is more heavy-tailed and the correlator is clearly suboptimal. Nonlinear receivers have been shown to be particularly well suited for the detection of weak signals in heavy-tailed noise, as they are locally optimal. This motivates the use of the Gaussian-tailed zero-memory nonlinearity, as well as the locally optimal Cauchy nonlinearity for the detection of watermarks in DCT transformed images. We analyze the performance of these schemes theoretically and compare it to that of the traditionally used Gaussian correlator, but also to the recently proposed generalized Gaussian detector, which outperforms the correlator. The theoretical analysis and the actual performance of these systems is assessed through experiments, which verify the theoretical analysis and also justify the use of nonlinear structures for watermark detection. The performance of the correlator and the nonlinear detectors in the presence of quantization is also analyzed, using results from dither theory, and also verified experimentally.

Algorithms↗
PubMed2005

Multipurpose image watermarking algorithm based on multistage vector quantization.

The rapid growth of digital multimedia and Internet technologies has made copyright protection, copy protection, and integrity verification three important issues in the digital world. To solve these problems, the digital watermarking technique has been presented and widely researched. Traditional watermarking algorithms are mostly based on discrete transform domains, such as the discrete cosine transform, discrete Fourier transform (DFT), and discrete wavelet transform (DWT). Most of these algorithms are good for only one purpose. Recently, some multipurpose digital watermarking methods have been presented, which can achieve the goal of content authentication and copyright protection simultaneously. However, they are based on DWT or DFT. Lately, several robust watermarking schemes based on vector quantization (VQ) have been presented, but they can only be used for copyright protection. In this paper, we present a novel multipurpose digital image watermarking method based on the multistage vector quantizer structure, which can be applied to image authentication and copyright protection. In the proposed method, the semi-fragile watermark and the robust watermark are embedded in different VQ stages using different techniques, and both of them can be extracted without the original image. Simulation results demonstrate the effectiveness of our algorithm in terms of robustness and fragility.

Algorithms↗
PubMed2005

Transform and embedded coding techniques for maximum efficiency and random accessibility in 3-D scalable compression.

This study investigates random accessibility and efficiency enhancements in highly scalable video and volumetric compression. With the advent of interactive multimedia technology, random accessibility has emerged as an increasingly important consideration in the design and optimization process. In this paper, we assess the impact that the transform, embedded coding components, and code-block configurations have on the compression efficiency and accessibility of a scalable codestream. We develop performance bounds on techniques which exploit temporal redundancy within the confines of a feed-forward compression system. We also examine their random access properties to argue the significance of motion-adaptive subband transforms. When information-theoretic measures are used to determine the potential benefits of three-dimensional (3-D) context coding, we find that most of the coding gain is attributed to code-block extension, rather than interslice context modeling itself. To gain further insight into the tradeoffs that the coding part has to offer, we run a series of simulations to determine code-block partitioning strategies which maximize reconstruction quality and space-time localization. The LIMAT framework and EBCOT coding paradigm have laid a solid foundation for further progress in the development of highly scalable 3-D compression systems.

Algorithms↗
PubMed2006

Texture characterization for joint compression and classification based on human perception in the wavelet domain.

Today's multimedia applications demand sophisticated compression and classification techniques in order to store, transmit, and retrieve audio-visual information efficiently. Over the last decade, perceptually based image compression methods have been gaining importance. These methods take into account the abilities (and the limitations) of human visual perception (HVP) when performing compression. The upcoming MPEG 7 standard also addresses the need for succinct classification and indexing of visual content for efficient retrieval. However, there has been no research that has attempted to exploit the characteristics of the human visual system to perform both compression and classification jointly. One area of HVP that has unexplored potential for joint compression and classification is spatial frequency perception. Spatial frequency content that is perceived by humans can be characterized in terms of three parameters, which are: 1) magnitude; 2) phase; and 3) orientation. While the magnitude of spatial frequency content has been exploited in several existing image compression techniques, the novel contribution of this paper is its focus on the use of phase coherence for joint compression and classification in the wavelet domain. Specifically, this paper describes a human visual system-based method for measuring the degree to which an image contains coherent (perceptible) phase information, and then exploits that information to provide joint compression and classification. Simulation results that demonstrate the efficiency of this method are presented.

Algorithms↗
PubMed2006

Joint source-channel coding for wireless object-based video communications utilizing data hiding.

In recent years, joint source-channel coding for multimedia communications has gained increased popularity. However, very limited work has been conducted to address the problem of joint source-channel coding for object-based video. In this paper, we propose a data hiding scheme that improves the error resilience of object-based video by adaptively embedding the shape and motion information into the texture data. Within a rate-distortion theoretical framework, the source coding, channel coding, data embedding, and decoder error concealment are jointly optimized based on knowledge of the transmission channel conditions. Our goal is to achieve the best video quality as expressed by the minimum total expected distortion. The optimization problem is solved using Lagrangian relaxation and dynamic programming. The performance of the proposed scheme is tested using simulations of a Rayleigh-fading wireless channel, and the algorithm is implemented based on the MPEG-4 verification model. Experimental results indicate that the proposed hybrid source-channel coding scheme significantly outperforms methods without data hiding or unequal error protection.

Algorithms↗
PubMed2006

Geodesic matching of triangulated surfaces.

Recognition of images and shapes has long been the central theme of computer vision. Its importance is increasing rapidly in the field of computer graphics and multimedia communication because it is difficult to process information efficiently without its recognition. In this paper, we propose a new approach for object matching based on a global geodesic measure. The key idea behind our methodology is to represent an object by a probabilistic shape descriptor that measures the global geodesic distance between two arbitrary points on the surface of an object. In contrast to the Euclidean distance which is more suitable for linear spaces, the geodesic distance has the advantage to be able to capture the intrinsic geometric structure of the data. The matching task therefore becomes a one-dimensional comparison problem between probability distributions which is clearly much simpler than comparing three-dimensional structures. Object matching can then be carried out by an information-theoretic dissimilarity measure calculations between geodesic shape distributions, and is additionally computationally efficient and inexpensive.

Algorithms↗
PubMed2006

Piecewise parametric interpolation for temporal compression of multijoint movement trajectories.

Computer animation of sign language used by deaf individuals has been produced from 51 time-varying trajectories of the fingertips, the centers of rotation of the joints of the hands and arms, and facial landmarks. These trajectories are sampled at 1/5th the National Television Systems Committee (NTSC) video frame rate and interpolated using piecewise sequences of cubic Bezier splines. The resulting trajectories are used to control sparse, stick figure animations of sign language resulting in considerable spatiotemporal compression with intelligibility in the range of 90%. This method introduces an additional 5:1 compression in the temporal domain that has not been previously exploited, and is potentially useful in sign language telecommunication, multimedia presentations, and gesture recognition.

Arm↗
PubMed2005

New MPLS network management techniques based on adaptive learning.

The combined use of the differentiated services (DiffServ) and multiprotocol label switching (MPLS) technologies is envisioned to provide guaranteed quality of service (QoS) for multimedia traffic in IP networks, while effectively using network resources. These networks need to be managed adaptively to cope with the changing network conditions and provide satisfactory QoS. An efficient strategy is to map the traffic from different DiffServ classes of service on separate label switched paths (LSPs), which leads to distinct layers of MPLS networks corresponding to each DiffServ class. In this paper, three aspects of the management of such a layered MPLS network are discussed. In particular, an optimal technique for the setup of LSPs, capacity allocation of the LSPs and LSP routing are presented. The presented techniques are based on measurement of the network state to adapt the network configuration to changing traffic conditions.

Algorithms↗
PubMed2004

Network flow problems with fuzzy arc lengths.

Network flow problems cover a wide range of engineering and management applications. Many streamlined solution methods have been devised for solving different types of the problems. This paper investigates the network flow problems in that the arc lengths of the network are fuzzy numbers. Based on the integer-solution property of the network flow problem, the Yager ranking indices can be calculated for the fuzzy arcs to change the fuzzy formulation of the problem to a crisp formulation. Consequently, the conventional streamlined solution methods can still be applied to find an optimal solution. This optimal solution is proved to be the same as that derived from an exhaustive comparison of all possible solutions. Two examples, one shortest path and one transshipment, discussed in some previous studies illustrate that the method proposed in this paper is able to find the optimal solution. To show that the proposed method is useful in solving real-world problems, the problem of multimedia transmission over the Internet is exemplified.

Journal Article↗
PubMedDate not supplied

A streaming-based solution for remote visualization of 3D graphics on mobile devices.

Mobile devices such as Personal Digital Assistants, Tablet PCs, and cellular phones have greatly enhanced user capability to connect to remote resources. Although a large set of applications are now available bridging the gap between desktop and mobile devices, visualization of complex 3D models is still a task hard to accomplish without specialized hardware. This paper proposes a system where a cluster of PCs, equipped with accelerated graphics cards managed by the Chromium software, is able to handle remote visualization sessions based on MPEG video streaming involving complex 3D models. The proposed framework allows mobile devices such as smart phones, Personal Digital Assistants (PDAs), and Tablet PCs to visualize objects consisting of millions of textured polygons and voxels at a frame rate of 30 fps or more depending on hardware resources at the server side and on multimedia capabilities at the client side. The server is able to concurrently manage multiple clients computing a video stream for each one; resolution and quality of each stream is tailored according to screen resolution and bandwidth of the client. The paper investigates in depth issues related to latency time, bit rate and quality of the generated stream, screen resolutions, as well as frames per second displayed.

Computer Communication Networks↗
PubMed2003

Joint persistence of transformation products in chemicals assessment: case studies and uncertainty analysis.

The joint persistence (JP) quantifies the environmental persistence of a parent compound and a selection of relevant transformation products. Here, the importance as well as the uncertainty of the JP in comparison to the persistence of the parent compound alone (primary persistence, PP) are investigated. To demonstrate the effect of transformation products on the environmental persistence of organic chemicals, three case studies of parent compounds (nonylphenol ethoxylates, perchloroethylene, atrazine) and transformation products are investigated in detail with a multimedia fate model. Comparison of the PP and JP values shows that transformation products can significantly increase the persistence. In addition to the point estimates of PP and JP, the associated uncertainties are investigated. For each of the case studies, the chemical-specific input parameters of all compounds are varied and the corresponding variance of the PP and JP is determined by Monte Carlo simulations. Interestingly, the higher number of input parameters required for the JP does not necessarily increase the uncertainty of the JP as compared to that of the PP alone. An exact mathematical expression specifying the contribution of each transformation product to the JP is given. When transformation products are grouped in different generations, it becomes discernible that the first generation increases the JP most; the later generations are of decreasing importance. Finally, the effect of incomplete knowledge of the transformation products and their properties on the JP results is discussed. For reliable JP estimates, knowledge of the first generation transformation products and their degradation rate constants is required.

Journal Article↗
PubMed2004

Pathway analysis for population-total health impacts of toxic metal emissions.

This article describes a simple model for quantifying the health impacts of toxic metal emissions. In contrast to most traditional models it calculates the expectation value of the total damage (summed over the total population and over all time) for typical emission sites, rather than "worst-case" estimates for specific sites or episodes. Such a model is needed for the evaluation of many environmental policy measures, e.g., the optimal level of pollution taxes or emission limits. Based on the methodology that has been developed by USEPA for the assessment of multimedia pathways, the equations and parameters are assembled for the assessment of As, Cd, Cr, Hg, Ni, and Pb, and some typical results are presented (the dose from seafood is not included and for Hg the results are extremely uncertain); the model is freely available on the web. The structure of the model is very simple because, as we show, if the parameters can be approximated by time-independent constants (the case for the USEPA methodology), the total impacts can be calculated with steady-state models even though the environment is never in steady state. The collective ingestion dose is found to be roughly 2 orders of magnitude larger than the collective dose via inhalation. The uncertainties are large, easily an order of magnitude, the main uncertainties arising from the parameter values of the model, in particular the transfer factors. Using linearized dose-response functions, estimates are provided for cancers due to As, Cd, Cr, and Ni as well as IQ loss due to Pb emissions in Europe.

Air Pollutants↗
PubMed2004

Pedagogical underpinnings of computer-based learning.

BACKGROUND: E-learning is becoming increasingly incorporated into educational programmes. Digital materials usually require a lot of investment in terms of time, money and human resources. With advances in technology, delivery of content has much improved in terms of multimedia elements. However, often only low-level learning is achieved as a result of using these materials. AIM: The purpose of this article is to give a comprehensive overview of some of the most important issues to consider when incorporating e-learning into educational programmes. DISCUSSION: Computer-based learning has three components: hardware, software and 'underware', the pedagogy that underpins its development. The latter is the most important, as the approach adopted will influence the creation of computer-based learning materials and determine the way in which students engage with subject matter. Teachers are responsible for the quality of their courses and have a vital role in helping to develop the most appropriate electronic learning activities that will facilitate students to acquire the knowledge and skills necessary for clinical practice. Therefore, they need to have an awareness of what contributes to educationally effective, computer-based learning materials.

Computer-Assisted Instruction↗
PubMed1976

Evaluation of an integrated multi-media learning system.

Two teaching methods were compared: (1) the traditional way with textbooks, practical guidance, personal demonstration, and (2) an integrated multimedia system with text programme, slide-sound-show accompanying the experiment, and lecturer. Two samples of thirty-one students each were classified in twin groups by means of psychological tests. Both groups worked with the identical pretest/post-test and different training procedures. The integrated multi-media system produced highly significant more gain in the theoretical sphere, greater personal confidence, and lower experimental error. Furthermore positive attitude of the students towards the experiment was demonstrated. The improved performance was statistically proved by t-test and covariance analysis.

Audiovisual Aids↗
PubMed1995

Comparison of training techniques using a patient-centered approach to smoking cessation.

This study compared the use of 2 1/2-hour multimedia workshop with distribution of an algorithm on the ability of fourth-year medical students to present a stop-smoking plan to a simulated patient. Results showed that students who participated in the workshop performed statistically significantly better on the skill areas of providing information, eliciting and responding to feeling and on content areas of past experience with quitting, resources available for change and negotiating a plan. There were no significant differences in the skill area of eliciting information and the content areas of motivation to stop smoking, factors that inhibit change and problems affecting the plan. Neither of the groups performed very well. The highest number of available points obtained by both groups was in eliciting information (53% in the algorithm group and 64% in the formal training group); however, most of the values were in the range of 10%-25% of possible points. Suggested reasons for the low values may be due to the specific items rated, the teaching methods or the time needed to assimilate new skills.

Education, Medical, Undergraduate↗
PubMed2006

Impact of a communication programme on female genital cutting in eastern Nigeria.

OBJECTIVES: This study describes a female genital cutting (FGC) elimination communication programme in Enugu State and assesses its impact in changing relevant knowledge, attitudes and behavioural intentions. METHODS: The FGC programme combined a community mobilization component with targeted advocacy and mass media activities. Data for assessing the impact of the programme derived from baseline and follow-up surveys in three intervention local government areas (LGA) in Enugu State and three comparison LGAs in Ebonyi State. An ideation model of behaviour change guided the analyses of the impact of the programme on personal advocacy for FGC, perceived self-efficacy to refuse pressure to perform FGC, perceived social support for FGC discontinuation, perceived benefits of FGC, perceived health complications of FGC and intention not to perform FGC on daughters. The analytical methods include comparing change in pertinent outcome variables from baseline to follow-up in the two study states and using logistic regression on follow-up data for the intervention state to assess the link between programme exposure and the relevant outcome indicators. RESULTS: The data show that while the pertinent ideational factors and the intention not to perform FGC either worsened or remained stagnant in Ebonyi State, they improved significantly in Enugu State. The logistic regression results show that programme exposure is associated with the expected improvements in all the pertinent indicators. CONCLUSION: The multimedia communication programme has been effective in changing FGC-related attitudes and promoting the intention not to perform FGC.

Circumcision, Female↗
PubMed1996

Eco-wellness nursing: getting serious about innovation and change.

Eco-wellness nursing represents a creative, challenging and empowering approach for facilitating a sustainable future for people and their environments, focusing beyond positivistic explanations and solutions, towards a more emancipating eco-centric praxis. Underlying this approach are the principles of 'wellness', 'holism', and a 'reflexive and sustainable eco-culture'. The goal is helping people understand how to sustain their wellness, including their environments. Negotiating or brokering change from a traditional nursing model will require a revision of focus in roles, attitudes, contexts and actions of nurses. Crucial in this transformation is greater nursing independence in the private marketplace, which may involve consultancies, collaborative ventures, utilization of new technologies such as multimedia communications, and targeted nursing oriented research and development.

Diffusion of Innovation↗