A three-dimensional compression scheme based on wavelet transform

In this paper, a three-dimensional (3-D) compression method based on separable wavelet transform is discussed in detail. The most commonly used digital modalities generate multiple slices in a single examination, which are normally anatomically or physiologically correlated to each other. 3-D wavelet compression methods can achieve more efficient compression by exploring the correlation between slices; The first step is based on a separable 3-D wavelet transform. Considering the difference between pixel distances within a slice and those between slices, one biorthogonal Antoninin filter bank is applied within two-dimensional slices and a second biorthogonal Villa4 filter bank on the slice direction. Then, S+P transform is applied in the lo ur-resolution wavelet components and an optimal quantizer is presented after analysis of the quantization noise. We use an optimal bit allocation algorithm, which, instead of eliminating the coefficients of high-resolution components in smooth areas, minimizes the system reconstruction distortion at a given bit-rate. Finally, to remain high coding efficiency and adapt to different properties of each component, a comprehensive entropy coding method is proposed, in which arithmetic coding method is applied in high-resolution components and adaptive Huffman coding method in low-resolution components. Our experimental results are evaluated by several image measures and our 3-D wavelet compression scheme is proved to be more efficient than 2-D wavelet compression.