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MPEG4 and RateDistortionBased ShapeCoding Techniques
 PROCEEDINGS OF THE IEEE
, 1998
"... In this paper, we address the problem of the efficient encoding of object boundaries. This problem is becoming increasingly important in applications such as contentbased storage and retrieval, studio and television postproduction, and mobile multimedia applications. The MPEG4 visual standard will ..."
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Cited by 53 (9 self)
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In this paper, we address the problem of the efficient encoding of object boundaries. This problem is becoming increasingly important in applications such as contentbased storage and retrieval, studio and television postproduction, and mobile multimedia applications. The MPEG4 visual standard will allow the transmission of arbitrarily shaped video objects. The techniques developed for shape coding within the MPEG4 standardization effort are described and compared first. A framework for the representation of shapes using their contours is presented next. Such representations are achieved using curves of various orders, and they are optimal in the ratedistortion sense. Last, conclusions are drawn
An Optimal Polygonal Boundary Encoding Scheme in the Rate Distortion Sense
, 1998
"... In this paper, we present fast and efficient methods for the lossy encoding of object boundaries which are given as 8connect chain codes. We approximate the boundary by a polygon and consider the problem of finding the polygon which leads to the smallest distortion for a given number of bits. We al ..."
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Cited by 26 (8 self)
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In this paper, we present fast and efficient methods for the lossy encoding of object boundaries which are given as 8connect chain codes. We approximate the boundary by a polygon and consider the problem of finding the polygon which leads to the smallest distortion for a given number of bits. We also address the dual problem of finding the polygon which leads to the smallest bit rate for a given distortion. We consider two different classes of distortion measures. The first class is based on the maximum operator and the second class is based on the summation operator. For the first class, we derive a fast and optimal scheme which is based on a shortest path algorithm for a weighted directed acyclic graph. For the second class we propose a solution approach which is based on the Lagrange multiplier method, which uses the above mentioned shortest path algorithm. Since the Lagrange multiplier method can only find solutions on the convex hull of the operational rate distortion function, w...
An efficient boundary encoding scheme using BSpline Curves which is optimal in the ratedistortion sense
, 1997
"... A major problem in object oriented video coding is the efficient encoding of object boundaries. In this paper, we present an efficient method for the lossy encoding of object boundaries which are given as 8connect chain codes. We approximate a boundary by a second order Bspline curve and consider ..."
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Cited by 3 (3 self)
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A major problem in object oriented video coding is the efficient encoding of object boundaries. In this paper, we present an efficient method for the lossy encoding of object boundaries which are given as 8connect chain codes. We approximate a boundary by a second order Bspline curve and consider the problem of finding the curve with the lowest bit rate for a given distortion. The presented scheme is optimal, efficient and offers complete control over the tradeoff between bitrate and distortion. It is an extension of the approaches in (1, 2, 3, 4, 5), where we used polygons to approximate a boundary. The main reason for using curves rather than polygons is that curves have a more natural appearance than polygons. Finally we present results of the proposed scheme using objects boundaries in different shapes and sizes.
Geometric Shape Distortion Tolerance Towards Inside
"... this paper, is based on pure motion information keeping the framework of model compliance and model failure regions of [12]. However, the object hierarchy is reverted so as to proceed from smaller objects to larger ones, thus allowing a more exible segmentation which is closer to the optimum partiti ..."
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this paper, is based on pure motion information keeping the framework of model compliance and model failure regions of [12]. However, the object hierarchy is reverted so as to proceed from smaller objects to larger ones, thus allowing a more exible segmentation which is closer to the optimum partition and which is applicable to a more general class of image sequences. The bottomup scheme is superior to the topdown approachin that a) object detail can be controlled at any resolution level, b) the chance of missing small but semantically relevant objects, suchaseyes and mouth in videophony is minimized, c) the scheme is independent of the scene content. On the contrary the topdown scheme can miss semantically important details and it is too much oriented towards headandshoulder scenes. The proposed scheme is based on region growing and region merges with reestimation of the motion parameters after a joint operation
Signal Processing: Image Communication 15 (2000) 729}766 A quadratic motionbased objectoriented video codec �
, 1997
"... A novel motionbased objectoriented codec for video transmission at very low bitrates is proposed. The object motion is modeled by quadratic transform with coe$cients estimated via a nonlinear quasiNewton method. The segmentation problem is put forward as a constrained optimization problem which ..."
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A novel motionbased objectoriented codec for video transmission at very low bitrates is proposed. The object motion is modeled by quadratic transform with coe$cients estimated via a nonlinear quasiNewton method. The segmentation problem is put forward as a constrained optimization problem which interacts with the motion estimation process in the course of region growing. A contextbased shape coding method which takes into account the image synthesis error as well as the geometric distortion, is also proposed. Quantitative and subjective performance results of the codec on various test sequences illustrate the superior performance of the method. � 2000 Elsevier Science B.V. All rights reserved. Keywords: Objectoriented video coding; Motion segmentation; Region growing; Quadratic transform; Shape polygonization