Home Preprocessing Smoothing of Spectra  
See also: Derivatives, Spatial Filtering of Images, Maximum Noise Fraction Transform, Resampling Spectra, SmoothSpectrum, Fourier Analysis of Spectra, SmoothAllSpectra, FFT Based Filtering of Spectra


Filtering of Spectra 

The command Preprocessing > Filter > Spectral > Direct Filter provides various algorithms for smoothing noisy spectra^{(1)}:
The number of data points used for estimating the smoothed data (the smoothing window width Window Size) can be adjusted between 5 and 25 data points. Please note that the first and the last Window Size/2 data cannot be smoothed and are replaced by the nearest available smoothed value. The following graphic shows an example of the smoothing effect on a THz spectrum using a polynomial (SavitzkyGolay) filter: When calling the command Preprocessing > Smoothing > Spectral > Direct Filter the smoothing dialog is opened which allows to set up the parameters of the smoothing process and to have a preview of the results. The actual smoothing of all available spectra is performed only after clicking the "Apply" button .
