Modified wavelet coding of arbitrarily shaped objects based on extrapolation and reflection (EAR)
Jia Wang, Jun Sun, Songyu Yu · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
In this paper, we propose a modified shape adaptive discrete wavelet transform (SA DWT). In conventional SA DWT method, after several levels of decomposition, the number of coefficients that has no parent in coarser scale is usually large and uncontrollable. If a tree-structure coding method is applied to the wavelet coefficients, the coding efficiency will be decreased by these coefficients. In our proposed method the boundary of object needs to be extrapolated first and then symmetric reflection is applied. By using this kind of procedure, the number of coefficients without parent can be reduced. The proposed SA DWT is also non-expansive. We establish a modified SPIHT coding algorithm to test the new method's contribution to coding efficiency. Experiment results show that the proposed method can produce more regular LL band figure and achieve a better rate-distortion curve than that of a conventional one.