Fig. 1. Principle diagram of wavelet de-noising

Fig. 2. Flow chart of wavelet de-noising

Fig. 3. Flow chart of spike removal algorithm

Fig. 4. Flow chart of baseline correction

Fig. 5. Comparison between spectral signal and wavelet signal. (a) Single spectrum peak; (b) mult-spectrum peaks

Fig. 6. Comparison of denoising effects of simulated spectral signals

Fig. 7. Contrast map of simulated de-noising spectral signal. (a) Initial signal; (b) signal with noise; (c) hard thresholding denoising; (d) soft thresholding denoising; (e) Savitzky-Golay denoising; (f) DTD denoising

Fig. 8. Map of spectral signal with baseline. (a) Initial signal; (b) signal with linear baseline; (c) signal with Gaussian baseline; (d) signal with polynomial baseline; (e) signal with exponential baseline; (f) signal with sigmoidal baseline

Fig. 9. inVia confocal micro Raman spectrometer

Fig. 10. Principle diagram of spectral imaging

Fig. 11. Sample slide

Fig. 12. Comparison of denoising results for measured data. (a) Initial signal; (b) hard thresholding denoising; (c) soft thresholding denoising; (d) Savitzky-Golay denoising; (e) DTD denoising

Fig. 13. Measured spectral signal. (a) Initial signal; (b) corrected signal by WFPSI algorithm