Application of biorthogonal wavelet transform to the compression of ultraviolet-visible spectra

A wavelet transform (WT) based method was proposed to compress ultraviolet- visible (UV-vis) spectra from chemical and biochemical studies. These spect ra were first transformed into different sub-bands which contain informatio n on different scales and frequency bands. The biorthogonal filter banks (B FB) coupled with the circular (CE) or symmetric extension (SE) method were employed in the WT treatment. Differential pulse code modulation (DPCM) was applied to further reduce the storage space required for the scale coeffic ients which were generated from the WT treatment. Then, optimal bit allocat ion (OBA) procedure for data quantization coupled with variable length codi ng (VLC) was applied to these coefficients to minimize the root-mean-square difference (RMSD) between the original and reconstructed spectra. Both syn thetic and experimental spectra were used in the study. Our results show th at the performance of the proposed compression methods are better than thos e suggested in the previous studies. (C) 1999 Elsevier Science Ltd. All rig hts reserved.