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11
Efficient multiscale regularization with applications to the computation of optical flow
 IEEE Trans. Image Process
, 1994
"... AbsfruetA new approach to regularization methods for image processing is introduced and developed using as a vehicle the problem of computing dense optical flow fields in an image sequence. Standard formulations of this problem require the computationally intensive solution of an elliptic partial d ..."
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Cited by 98 (33 self)
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AbsfruetA new approach to regularization methods for image processing is introduced and developed using as a vehicle the problem of computing dense optical flow fields in an image sequence. Standard formulations of this problem require the computationally intensive solution of an elliptic partial differential equation that arises from the often used “smoothness constraint” ’yl”. regularization. The interpretation of the smoothness constraint is utilized as a “fractal prior ” to motivate regularization based on a recently introduced class of multiscale stochastic models. The solution of the new problem formulation is computed with an efficient multiscale algorithm. Experiments on several image sequences demonstrate the substantial computational savings that can be achieved due to the fact that the algorithm is noniterative and in fact has a per pixel computational complexity that is independent of image size. The new approach also has a number of other important advantages. Specifically, multiresolution flow field estimates are available, allowing great flexibility in dealing with the tradeoff between resolution and accuracy. Multiscale error covariance information is also available, which is of considerable use in assessing the accuracy of the estimates. In particular, these error statistics can be used as the basis for a rational procedure for determining the spatiallyvarying optimal reconstruction resolution. Furthermore, if there are compelling reasons to insist upon a standard smoothness constraint, our algorithm provides an excellent initialization for the iterative algorithms associated with the smoothness constraint problem formulation. Finally, the usefulness of our approach should extend to a wide variety of illposed inverse problems in which variational techniques seeking a “smooth ” solution are generally Used. I.
Motion Picture Restoration
, 1993
"... This dissertation presents algorithms for restoring some of the major corruptions observed in archived film or video material. The two principal problems of impulsive distortion (Dirt and Sparkle or Blotches) and noise degradation are considered. There is also an algorithm for suppressing the inter ..."
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Cited by 52 (9 self)
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This dissertation presents algorithms for restoring some of the major corruptions observed in archived film or video material. The two principal problems of impulsive distortion (Dirt and Sparkle or Blotches) and noise degradation are considered. There is also an algorithm for suppressing the interline jitter common in images decoded from noisy video signals. In the case of noise reduction and Blotch removal the thesis considers image sequences to be three dimensional signals involving evolution of features in time and space. This is necessary if any process presented is to show an improvement over standard twodimensional techniques. It is important to recognize that consideration of image sequences must involve an appreciation of the problems incurred by the motion of objects in the scene. The most obvious implication is that due to motion, useful three dimensional processing does not necessarily proceed in a direction `orthogonal' to the image frames. Therefore, attention is giv...
Image Processing with Multiscale Stochastic Models
, 1993
"... In this thesis, we develop image processing algorithms and applications for a particular class of multiscale stochastic models. First, we provide background on the model class, including a discussion of its relationship to wavelet transforms and the details of a twosweep algorithm for estimation. A ..."
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Cited by 29 (3 self)
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In this thesis, we develop image processing algorithms and applications for a particular class of multiscale stochastic models. First, we provide background on the model class, including a discussion of its relationship to wavelet transforms and the details of a twosweep algorithm for estimation. A multiscale model for the error process associated with this algorithm is derived. Next, we illustrate how the multiscale models can be used in the context of regularizing illposed inverse problems and demonstrate the substantial computational savings that such an approach offers. Several novel features of the approach are developed including a technique for choosing the optimal resolution at which to recover the object of interest. Next, we show that this class of models contains other widely used classes of statistical models including 1D Markov processes and 2D Markov random fields, and we propose a class of multiscale models for approximately representing Gaussian Markov random fields...
Fast BlockBased True Motion Estimation Using Distance Dependent Thresholds
"... A fast motion estimation algorithm, called distancedependent thresholding search (DTS), is presented for blockbased true motion estimation applications, and introduces the novel concept of variable distance dependent thresholds. The performance of the DTS algorithm is analysed and quantitatively c ..."
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Cited by 1 (1 self)
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A fast motion estimation algorithm, called distancedependent thresholding search (DTS), is presented for blockbased true motion estimation applications, and introduces the novel concept of variable distance dependent thresholds. The performance of the DTS algorithm is analysed and quantitatively compared with both the traditional and exhaustive fullsearch (FS) technique, and the computationally faster, nonexhaustive threestepsearch (TSS) algorithm. Experimental results show that by applying an appropriate threshold function, the DTS algorithm not only matches the speed of the TSS algorithm, but both retains a block distortion error comparable to the global minimum produced by the FS algorithm, and avoids the problem of identifying a large number of spurious motion vectors in the search process. ACM Classification: I.4 (Image processing and computer vision) 1.
Motion Analysis and Estimation using Multiresolution Affine Models
, 1998
"... Motion analysis is central to many applications where timevarying image data are involved, such as robotics and multimedia systems. This thesis describes a new motion analysis framework using multiresolution affine models. Traditional approaches using local translational models lack sufficient flex ..."
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Motion analysis is central to many applications where timevarying image data are involved, such as robotics and multimedia systems. This thesis describes a new motion analysis framework using multiresolution affine models. Traditional approaches using local translational models lack sufficient flexibility to derive robust and concise descriptions of motion, since they are only valid over small local regions. Affine models, however, provide a closer approximation to regional motion variation, hence allowing for larger analysis windows to be employed, leading to greater robustness and conciseness. The new framework is applied to the motion estimation and tracking problems. The estimator employs an affine model of local motion and the model parameters are estimated using generalised correlation, implemented efficiently in the frequency domain. A multiresolution framework allows the approach to adapt to the data by varying the analysis window size. Regions where the motion has high spatia...
Temporal Redundancy Reduction Using a Motion Model Hierarchy and Tracking for Image Sequence Coding
"... This paper introduces an improved variable size block based motion estimation algorithm relying on a hierarchy of motion representations. The most efficient of the latter is chosen through an evaluation constraint which models the total bit rate. The proposed coding technique exploits the concepts o ..."
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This paper introduces an improved variable size block based motion estimation algorithm relying on a hierarchy of motion representations. The most efficient of the latter is chosen through an evaluation constraint which models the total bit rate. The proposed coding technique exploits the concepts of temporal tracking and localization of the displaced frame difference energy. Moreover, only the smallest regions of the latter are coded and transmitted. Simulations show a significant improvement of the performances. 1 Introduction In recent years, there has been a growing interest in image data compression, related to the emergence of high definition television (HDTV) and video conference. Classically, image coding techniques reduce the temporal redundancy thanks to motion estimation and compensation methods, the latter relying on a translation model of the motion vectors. An example of such a technique is given by MPEGII [1] which is based on a block matching motion estimation algorit...
Fast Motion Estimation with Search Center Prediction
 Optical Engineering  The Journal of SPIE
, 2001
"... This paper presents a new block based motion estimation algorithm that employs motion vector prediction to locate an initial search point, which is called a search center, and an outward spiral search pattern with motion vector refinement, to speed up the motion estimation process. It is found that ..."
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This paper presents a new block based motion estimation algorithm that employs motion vector prediction to locate an initial search point, which is called a search center, and an outward spiral search pattern with motion vector refinement, to speed up the motion estimation process. It is found that the proposed algorithm is only slightly slower than Cross Search (CS), but has PSNR very close to that of Full Search (FS).
Displacement Estimation for Image Predictive Coding and Frame . . .
"... We present and investigate methods of displacement vector estimation, which can be used in predictive image coding or motionadaptive frame interpolative coding. In both cases, a differential approach is adopted. This means that the displacement vector estimation is based on the measurement of the ..."
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We present and investigate methods of displacement vector estimation, which can be used in predictive image coding or motionadaptive frame interpolative coding. In both cases, a differential approach is adopted. This means that the displacement vector estimation is based on the measurement of the spatiotemporal gradient of the image sequence. In the case of predictive coding the motion estimator is composed of three parts. The first is a spatial predictor of the displacement vector, which is based on a spatial autoregressive relation of the velocity field. The coefficients of this relation are made intensitydependent. The presence of discontinuities inherent to the motion and to the instabilities of the estimation algorithm makes necessary a stage of detection of all type of discontinuities. Finally, an a posteriori estimator achieves the task of displacement vector estimation. This last stage is of iterative form. The application of this algorithm in a very noisy image sequence has permitted to obtain a gain of about 40% in the absolute value of the difference with the predicted displacement vector and 65% with the estimated one after two iterations. The same structure of displacement field estimation can be used to make a frame interpolation motionadaptive.
RegionBased Segmentation of Generic Video Scenes Indexing
"... Abstract — In this work we develop an object extraction method and propose efficient algorithms for object motion characterization. The set of proposed tools serves as a basis for development of objectbased functionalities for manipulation of video content. The estimators by different algorithms are ..."
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Abstract — In this work we develop an object extraction method and propose efficient algorithms for object motion characterization. The set of proposed tools serves as a basis for development of objectbased functionalities for manipulation of video content. The estimators by different algorithms are compared in terms of quality and performance and tested on real video sequences. The proposed method will be useful for the latest standards of encoding and description of multimedia content – MPEG4 and MPEG7.
A Novel Filter for BlockBased Object Motion Estimation
"... and other research outputs A novel filter for blockbased motion estimation ..."
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and other research outputs A novel filter for blockbased motion estimation