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Pre-processing of NIR

Pre-processing of NIR. Åsmund Rinnan. Introduction NIR. Fructose. Glucose. 25 50 75. 75 50 25. Introduction NIR. Baseline with a slope/ curve. Nonlinearity. Fructose. Glucose. 25 50 75. 75 50 25. A “fat” baseline. Reference dependent O-PLS OSC OS SIS.

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Pre-processing of NIR

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  1. Pre-processing of NIR Åsmund Rinnan

  2. IntroductionNIR Fructose Glucose 25 50 75 75 50 25

  3. IntroductionNIR Baseline with a slope/ curve Nonlinearity Fructose Glucose 25 50 75 75 50 25 A “fat” baseline

  4. Reference dependent O-PLS OSC OS SIS Reference independent MSC/ ISC EMSC/ EISC SNV Detrend Normalization Savitzky-Golay Norris-Williams Finite difference IntroductionTechniques

  5. Correction of light scatter MSC EMSC Detrend SNV Derivation Finite difference Savitzky-Golay IntroductionTechniques

  6. Effect of pre-processingBefore Specular effect

  7. Effect of pre-processingAfter

  8. MSC Raw Reference

  9. MSC Raw Reference

  10. MSC Raw spectrum b = Slope a = Intercept Reference • P Geladi, D MacDougal, H Martens (1985): Linearization and scatter correction for near-infrared reflectance spectra of meat, Applied Spectroscopy, 39, 491-500

  11. MSC

  12. Extended MSC Wavelength correction Slope & Intercept Known spectra = Detrend = Basic MSC • H. Martens, E. Stark (1991): Extended multiplicative signal correction and spectral interference subtraction: new preprocessing methods for near infrared spectroscopy, Journal of Pharmaceutical and Biomedicinal Analysis, 9, 625-635

  13. Extended MSC Calculated The correction Step 1: Step 2: • H. Martens, E. Stark (1991): Extended multiplicative signal correction and spectral interference subtraction: new preprocessing methods for near infrared spectroscopy, Journal of Pharmaceutical and Biomedicinal Analysis, 9, 625-635

  14. Extended MSCSummary X X • Parameter setting • Parameter setting • Paraemter setting MSC Detrend

  15. SNV • R.J. Barnes, M.S. Dhanoa, S.J. Lister (1989): Standard Normal Variate Transformation and De-trending of Near-Infrared Diffuse Reflectance Spectra, Applied Spectroscopy, 43, 772-777

  16. SNV vs MSC MSC SNV

  17. SNV vs. MSCClassificafication of barley

  18. SNV vs. MSC MSC Reference needed Outlier sensitive Only similar spectra No normalization SNV Normalization No reference

  19. Derivation

  20. DerivationFinite difference

  21. Savitzky-Golay vs.Finite difference

  22. DerivationSavitzky-Golay • A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures, Analytical Chemistry, 36 (8), 1627-1639

  23. DerivationSavitzky-Golay Smoothing 11 9 7 5 3 • A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures, Analytical Chemistry, 36 (8), 1627-1639

  24. DerivationSavitzky-Golay Smoothing Polynomial 7 4 2 5 3 1 • A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures, Analytical Chemistry, 36 (8), 1627-1639

  25. DerivationSavitzky-Golay 7 point smoothing 15 point smoothing 2nd order derivative

  26. Run the following for near to optimal results MSC with Only 1st order reference correction or SNV 1st order reference correction and 2nd order wavelength correction Only 2nd order wavelength correction Savitzky-Golay derivation with 2nd order polynomial smoothing 7 points smoothing for the 1st derivative 9 points smoothing for the 2nd derivative SummaryPre-processing of NIR

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