Error-robustness of polar contour-coding
For communication using digital video, compression is mandatory because of the high bit-rate requiring a large bandwidth or storage capacity. Recent developments as well as upcoming standards like MPEG-4, use not images but so-called video objects having an arbitrary shape. The contour of this shape has to be transmitted and therefore compressed as well. In mobile video communication transmission errors and loss of data will occur and this means that the compression has to be error-robust. This paper discusses the error-robustness of a technique for contour coding using polar coordinates and the Discrete Cosine Transform (DCT). The recently proposed  polar technique transforms the Cartesian x and y contour coordinate functions to the domain of polar coordinates yielding an r and a φ function. Subsequently these functions are transformed using a DCT and quantised. We investigate the impact of not-received DCT coefficients on the reconstructed intra- and intercoded contours. When inter-coding, the contour with respect to which the current contour is coded, is composed of a weighed sum of N previous contours to reduce the impact of errors. Results show that for intercoded contours, this technique can be considered error-robust, except for errors in the header. For highly compressed intra-coded contours this is only partly so due to the high energy in most of the transmitted coefficients, which have to be well protected like the header of the contour information.
KeywordsProbability Density Function Discrete Cosine Transform Discrete Cosine Transform Coefficient Inverse Discrete Cosine Transform Contour Point
Unable to display preview. Download preview PDF.
- 1.http://mmc.et.tudelft.nl/Google Scholar
- 2.R.L.Lagendijk, J. Biemond and C.P. Quist, “Low bit rate video coding for mobile multi-media communications”, Proceedings EUSIPCO-96, 1996.Google Scholar
- 3.Shape Coding Ad Hoc Group, “Core Experiments on MPEG-4 Video Contour Coding”, MPEG-4 report, 1996.Google Scholar
- 4.W. Philips, “Adaptive coding using warped polynomials”, Proceedings ICASSP, 1996.Google Scholar
- 5.F. Marques and A. Gasull, “Partition coding using multi-grid chain code and motion compensation”, Proceedings ICIP, 1996 Google Scholar
- 6.L. Torres and M. Kunt (Eds.), “Video Coding, the second generation approach”, Kluwer Academic Publishers, 1996.Google Scholar
- 7.van Otterloo, “A contour-oriented approach to digital contour analysis”, Ph.D. Thesis, Delft University of Technology, 1988.Google Scholar
- 8.Westerink, J. Biemond and D.E. Boekee, “An Optimal Bit Allocation Algorithm for Sub-Band Coding,” ICASSP'88, (New York, U.S.A.), pp.757–760, 1988.Google Scholar
- 9.Riskin, “Optimal Bit Allocation via the Generalized BFOS Algorithm,” IEEE Trans. on Inform. Theory, vol. 37, pp 400–402, March 1991.Google Scholar
- 10.F. Bosveld, “Hierarchical Video Compression using SBC” Ph.D. Thesis, Delft University of Technology, 1996.Google Scholar
- 11.F.H.P. Spaan, R.L. Lagendijk and J. Biemond, “Shape Coding Using Polar Coordinates and the DCT”, Proceedings ICIP-97, October 1997, Vol. I, pp. 516–519.Google Scholar