Minimization of edge effects in images using an extrapolated discrete wavelet transform
Sumit K. Nath, Éric Dubois · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2001
The discrete wavelet transform(DWT) is a tool extensively used in image processing algorithms. It can be used to decorrelate information from the original image, which can thus help in compressing the data for storage, transmission or other post-processing purposes. However, the finite nature of such images gives rise to edge artifacts in the reconstructed data. A commonly used technique to overcome this problem is a symmetric extension of the image, which can preserve zeroth order continuity in the data. This still produces undesirable edge artifacts in derivatives and subsampled versions of the image. In this paper we present an extension to Williams and Amaratunga's work of extrapolating the image data using a polynomial extrapolation technique before performing the forward or inverse DWT for biorthogonal wavelets. Comaparitive results of reconstructed data, with individual subband reconstruction as well as using the embedded zerotree coding (EZC) scheme, are also presented for both the aforementioned techniques.