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Preprocessing With focus on NIR

Preprocessing With focus on NIR. Åsmund Rinnan , Frans van den Berg, Rasmus Bro, Søren Balling Engelsen, Lars Nørgaard , Jonas Thygesen. Introduction Techniques Summary. Introduction. How often is it used? When is it used? What methods are used? Why is it used?

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Preprocessing With focus on NIR

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  1. PreprocessingWith focus on NIR Åsmund Rinnan , Frans van den Berg, Rasmus Bro, Søren Balling Engelsen, Lars Nørgaard , Jonas Thygesen

  2. Introduction Techniques Summary Introduction • How often is it used? • When is it used? • What methods are used? • Why is it used? • NIR is a measurement technique “screaming” for preprocessing

  3. Introduction Techniques Summary IntroductionNIR Fructose Glucose 0 50 75 100 50 25

  4. Correction of light scatter MSC/ ISC PMSC EMSC/ EISC SNV Derivation Norris&Williams Savitsky&Golay Baseline-correction Normalization Detrend Use of reference values O-PLS OSC OS SIS Introduction Techniques Summary IntroductionTechniques

  5. Introduction Techniques Summary IntroductionWhy Baseline with a slope/ curve Nonlinearity A “fat” baseline

  6. Introduction Techniques Summary ISC MSC • Offset • Normalization Raw spectrum Reference • P Geladi, D MacDougal, H Martens (1985): Linearization and scatter correction for near-infrared reflectance spectra of meat, Applied Spectroscopy, 39, 491-500

  7. Introduction Techniques Summary MSC/ ISC • Offset • Normalization

  8. Introduction Techniques Summary EISC • Offset • Baseline • Normalization • H. Martens and 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 • H Martens, JP Nielsen, SB Engelsen (2003): Light scattering and light absorbance separated by extended multiplicative signal correction. The application to near-infrared transmission analysis of powder mixtures, Analytical chemistry, 75, 394-404 • DK Pedersen, H Martens, JP Nielsen, SB Engelsen (2002): Near-Infrared Absorption and Scattering Separated by Extended Inverse Signal Correction (EISC): Analysis of Near-Infrared Transmittance Spectra of Single Wheat, Applied Spectroscopy, 56, 1206-1214 • Thennadil, SN, Martin, EB (2005): Empirical preprocessing methods and their impact on NIR calibrations - a simulation study, Journal of Chemometrics, 19, 77-89

  9. Introduction Techniques Summary EMSC(w/ 2. degree & wavelength) • Offset • Baseline • Normalization

  10. Introduction Techniques Summary PxSC • Offset • Baseline • Normalization X = EM EI M I • Isaksson, T.; Kowalski, B. R. (1993): Piece-wise multiplicative scatter correction applied to Near-Infrared diffuse transmittance data from meat products, Applied Spectroscopy, 47, 702-09

  11. Introduction Techniques Summary PMSC(window size = 35) • Offset • Normalization

  12. Introduction Techniques Summary SNV • Offset • Normalization • 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

  13. Introduction Techniques Summary SNV vs MSC MSC SNV

  14. Introduction Techniques Summary Detrend • Offset • Baseline • 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

  15. Introduction Techniques Summary DerivationSavitsky-Golay • Offset • Baseline • A Savitsky, MJE Golay (1964): Smoothing and differentiation of data by simplified least squares procedures, Analytical Chemistry, 36 (8), 1627-1639 • P.A. Gorry (1990): General Least-Squares smoothing and differentiation by the convolution (Savitsky-Golay) method, Analytical Chemistry, 62, 570-573

  16. Introduction Techniques Summary DerivationSavitsky-Golay • Offset • Baseline

  17. Introduction Techniques Summary DerivationSavitsky-Golay • Offset • Baseline

  18. Introduction Techniques Summary DerivationNorris-Williams • Offset • Baseline • Normalization • Norris, KH (1983): in Food Research and Data Analysis (Eds: Martens H and Russwurm H Jr), Applied Science, London, 95-114 • Norris KH, Williams PC (1984): Optimization of mathematical treatments of raw near-infrared signal in the measurement of protein in hard red spring wheat: I. Influence of particle size, Cereal Chemistry, 61, 158-165

  19. Introduction Techniques Summary DerivationNorris-Williams • Offset • Baseline • Normalization

  20. Introduction Techniques Summary DerivationNorris-Williams • Offset • Baseline • Normalization

  21. Introduction Techniques Summary Preprocessing • PMSC: Sensitivite to window size • EMSC: Small effect on baseline  Detrend is better • MSC and SNV are practical the same • Savitsky-Golay is more robust than Norris-Williams

  22. Introduction Techniques Summary Preprocessing

  23. Thanks for the attention www.models.life.ku.dk

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