Wavelet based compression and denoising of optical tomography data

Two methods based on wavelet/wavelet packet expansion to denoise and compre ss optical tomography data containing scattered noise are presented, In the first, the wavelet expansion coefficients of noisy data are shrunk using a soft threshold. In the second, the data are expanded into a wavelet packet tree upon which a best basis search is done. The resulting coefficients ar e truncated on the basis of energy content. It can be seen that the first m ethod results in efficient denoising of experimental data when scattering p article density in the medium surrounding the object was up to 12.0 x 10(6) per cm(3). This method achieves a compression ratio of approximate to 8:1. The wavelet packet based method resulted in a compression of up to 11:1 an d also exhibited reasonable noise reduction capability. Tomographic reconst ructions obtained from denoised data are presented. (C) 1999 Published by E lsevier Science B.V. All rights reserved,