Nonlinear modeling of wavelet coefficients around edges
Hasan Fehmi Ates, M.T. Orchard · 2004
State of the art image coders make use of various methods to exploit intra and inter-band dependencies of wavelet coefficients in order to improve performance. While these efforts achieve considerable bitrate reduction for coding clusters of insignificant coefficients in smooth areas, most of the bitrate is spent on coding wavelet coefficients that are localized around edges in images. Recent research in literature is focused on developing new (linear or nonlinear) representations that deal with the rich and varying structures of pixel values around edges. In this paper, we use a simplified edge model to investigate the nonlinear dependencies that exist among wavelet coefficients, and introduce a nonlinear representation that is geared towards exploiting such dependencies for improved coding performance. Simulations support the relevance of the model, and we discuss our current efforts to incorporate these ideas into an actual image coder.