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A novel filter for block-based motion estimation
Noises, in the form of false motion vectors, cannot be avoided while capturing block motion vectors using block based motion estimation techniques. Similar noises are further introduced when the technique of global motion compensation is applied to obtain 'true' object motion from video sequences, where both the camera and object motions are present. We observe that the performance of the mean and the median filters in removing false motion vectors, for estimating 'true' object motion, is not satisfactory, especially when the size of the object is significantly smaller than the scene. In this paper we introduce a novel filter, named as the Mean-Accumulated-Thresholded (MAT) filter, in order to capture 'true' object motion vectors from video sequences with or without the camera motion (zoom and/or pan). Experimental results on representative standard video sequences are included to establish the superiority of our filter compared with the traditional median and mean filters
Distributed video coding for wireless video sensor networks: a review of the state-of-the-art architectures
Distributed video coding (DVC) is a relatively new video coding architecture originated from two fundamental theorems namely, Slepian–Wolf and Wyner–Ziv. Recent research developments have made DVC attractive for applications in the emerging domain of wireless video sensor networks (WVSNs). This paper reviews the state-of-the-art DVC architectures with a focus on understanding their opportunities and gaps in addressing the operational requirements and application needs of WVSNs
Motion-Compensated Coding and Frame-Rate Up-Conversion: Models and Analysis
Block-based motion estimation (ME) and compensation (MC) techniques are
widely used in modern video processing algorithms and compression systems. The
great variety of video applications and devices results in numerous compression
specifications. Specifically, there is a diversity of frame-rates and
bit-rates. In this paper, we study the effect of frame-rate and compression
bit-rate on block-based ME and MC as commonly utilized in inter-frame coding
and frame-rate up conversion (FRUC). This joint examination yields a
comprehensive foundation for comparing MC procedures in coding and FRUC. First,
the video signal is modeled as a noisy translational motion of an image. Then,
we theoretically model the motion-compensated prediction of an available and
absent frames as in coding and FRUC applications, respectively. The theoretic
MC-prediction error is further analyzed and its autocorrelation function is
calculated for coding and FRUC applications. We show a linear relation between
the variance of the MC-prediction error and temporal-distance. While the
affecting distance in MC-coding is between the predicted and reference frames,
MC-FRUC is affected by the distance between the available frames used for the
interpolation. Moreover, the dependency in temporal-distance implies an inverse
effect of the frame-rate. FRUC performance analysis considers the prediction
error variance, since it equals to the mean-squared-error of the interpolation.
However, MC-coding analysis requires the entire autocorrelation function of the
error; hence, analytic simplicity is beneficial. Therefore, we propose two
constructions of a separable autocorrelation function for prediction error in
MC-coding. We conclude by comparing our estimations with experimental results
Data compression techniques applied to high resolution high frame rate video technology
An investigation is presented of video data compression applied to microgravity space experiments using High Resolution High Frame Rate Video Technology (HHVT). An extensive survey of methods of video data compression, described in the open literature, was conducted. The survey examines compression methods employing digital computing. The results of the survey are presented. They include a description of each method and assessment of image degradation and video data parameters. An assessment is made of present and near term future technology for implementation of video data compression in high speed imaging system. Results of the assessment are discussed and summarized. The results of a study of a baseline HHVT video system, and approaches for implementation of video data compression, are presented. Case studies of three microgravity experiments are presented and specific compression techniques and implementations are recommended
Detection of dirt impairments from archived film sequences : survey and evaluations
Film dirt is the most commonly encountered artifact in archive restoration applications. Since dirt usually appears as a temporally impulsive event, motion-compensated interframe processing is widely applied for its detection. However, motion-compensated prediction requires a high degree of complexity and can be unreliable when motion estimation fails. Consequently, many techniques using spatial or spatiotemporal filtering without motion were also been proposed as alternatives. A comprehensive survey and evaluation of existing methods is presented, in which both qualitative and quantitative performances are compared in terms of accuracy, robustness, and complexity. After analyzing these algorithms and identifying their limitations, we conclude with guidance in choosing from these algorithms and promising directions for future research
Linear motor motion control using a learning feedforward controller
The design and realization of an online learning motion controller for a linear motor is presented, and its usefulness is evaluated. The controller consists of two components: (1) a model-based feedback component, and (2) a learning feedforward component. The feedback component is designed on the basis of a simple second-order linear model, which is known to have structural errors. In the design, an emphasis is placed on robustness. The learning feedforward component is a neural-network-based controller, comprised of a one-hidden-layer structure with second-order B-spline basis functions. Simulations and experimental evaluations show that, with little effort, a high-performance motion system can be obtained with this approach
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