Image compression with adaptive Haar-Walsh tilings
Maj Lindberg, Lars F. Villemoes · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
We perform adaptive joint space and frequency tilings including all levels in the Haar-Walsh wavelet packet tree for 2D signals. The method gives surprisingly good results in terms of nonlinear approximation. The visual quality of the compressed images with this method is the same as the quality using twice the number of coefficients for wavelets and standard wavelet packets when Haar filters are used. When all levels are allowed the cost for description of the location of the winning coefficients is not negligible. A tiling information vector is introduced for description of the chosen basis and the original image can be easily and quickly reconstructed using this information. For image compression, this tilting information vector is compressed to only those nodes which correspond to kept coefficients, and this makes the adaptive scheme competitive.