Space-frequency quantization for a space-varying wavelet packet image coder

We introduce a new image coding algorithm which exploits the idea of space-varying wavelet packets, where the best filter bank representation is chosen from a large library. The filter bank tree representations in the library are free to vary in structure over different segments of the image, and a fast search algorithm is given. In addition we employ the idea of space-frequency quantization, which is a rate-distortion optimized extension of the zero-tree wavelet coder of Shapiro to wavelet packets. The coder thus adaptively chooses the representation to suit the image and adaptively chooses the quantization to suit the representation. We present coding results that confirm the excellent performance of the scheme