Modelling and Reduction of PSNR Fluctuations in 3D Wavelet Coding

We study the effects of the quantization of the three-dimensional wavelet transform coefficients, encoded using a 3D zerotree-based compression scheme. The processing of the quantization error operated by the synthesis filter bank actually determines a modulation of the reconstruction error statistics. This effect entails a non-negligible and potentially objectionable PSNR oscillation among adjacent slices of the decoded 3D data-set, which, e.g. in the biomedical field, would typically be used jointly to reach a diagnosis. In particular, we propose a cyclostationary model of the error statistics fluctuations and an experimental validation of the model itself. Moreover some strategies to reduce such oscillation are suggested and evaluated