Fig. 1. Process of baseline fitting by cubic spline smoothing combined with discrete state transformation algorithm (DSTAspline)

Fig. 2. Estimated results for simulated spectrum and the comparison among airPLS, IAsLS, AWSF and DSTAspline. (a) Estimated baseline and corrected Raman spectrum by DSTAspline; (b) comparison among airPLS, IAsLS, AWSF 　and DSTAspline

Fig. 3. Estimated results for noise spectrum and the comparison among airPLS, IAsLS, AWSF and DSTAspline. (a) Baseline correction for noise spectrum by DSTAspline; (b) comparison among airPLS, IAsLS, AWSF and DSTAspline

Fig. 4. Applications of the proposed baseline correction method to rhodamine B and tricyclazole. (a) Rhodamine B; (b) tricyclazole

Fig. 5. Comparison among airPLS, IAsLS, AWSF and DSTAspline baseline correction methods for Raman spectra of rhodamine B and tricyclazole. (a) Rhodamine B; (b) tricyclazole

Fig. 6. Original and corrected Raman spectra of peanut oil adulterated with rapeseed oil by the proposed DSTAspline baseline correction method. (a) Original Raman spectra; (b) corrected Raman spectra

Fig. 7. Correlation between actual and predicted values of peanut oil adulteration of rapeseed oil based on PLSR and the proposed baseline correction method. (a) No baseline correction; (b) DSTAspline baseline correction