EVALUATION OF MESH-BASED MOTION ESTIMATION IN H.263-LIKE CODERS

Citation
Y. Wang et J. Ostermann, EVALUATION OF MESH-BASED MOTION ESTIMATION IN H.263-LIKE CODERS, IEEE transactions on circuits and systems for video technology, 8(3), 1998, pp. 243-252
Citations number
22
Categorie Soggetti
Engineering, Eletrical & Electronic
ISSN journal
10518215
Volume
8
Issue
3
Year of publication
1998
Pages
243 - 252
Database
ISI
SICI code
1051-8215(1998)8:3<243:EOMMEI>2.0.ZU;2-Y
Abstract
In this paper, we present two mesh-based motion estimation algorithms, and evaluate their performance when incorporated in an H.263-like blo ck-based video coder. Both algorithms compute nodal motions in a hiera rchical manner. Within each hierarchy level, the first algorithm (HMMA ) minimizes the prediction error in the four elements surrounding each node, where the prediction is accomplished by a bilinear mapping. The optimal solution Is obtained by a full search within a range defined by the topology of the mesh. The second algorithm (HBMA) minimizes the error in a block surrounding each node, assuming the motion in the bl ock is constant. In both cases, bilinear mapping is used for motion-co mpensated prediction based on nodal displacements. The two algorithms are compared with an exhaustive block-matching algorithm (EBMA) by eva luating their performances in temporal prediction and in an H.263/TMN4 coder. For prediction only, the HMMA and HBMA algorithms yield visual ly more satisfactory results, even though the PSNR's of predicted imag es are on average lower. The coded images also have lower PSNR's at si milar bit rates. The coding artifacts are different: while the block-b ased method leads to more severe block distortions, the mesh-based met hod experiences some warping artifacts. The HMMA algorithm outperforms HBMA slightly for certain sequences at the expense of higher computat ional complexity.