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Tree adaptive wavelet coding

In this paper, a new tree-based adaptive wavelet coding method is proposed In this method, the wavelet coefficients after a full-frame-based wavelet transform are tree structured. Then these trees are further adaptively wavelet transformed according to their local properties. By using this method, the energy of images can be further concentrated on lower AC frequency coefficients, hence the coding efficiency can be greatly improved. Furthermore, as mentioned above, by using this tree-based wavelet transform, the energy is further concentrated on the top-most and/or left-most AC coefficients of the tree blocks, the AC prediction method becomes much more powerful in reducing the redundancy. As a result, the coding efficiency and the subjective quality can be highly improved. The simulation results show that the PSNR values are improved by 1 dB.