IGF Descriptor

The Intensity Grid Filter (IGF) is a complex descriptor which can be highly selective for specific classes of spectra. The general principle of the IGF descriptor is to define one or more spectral templates which cover characteristic regions of a spectrum. The spectral descriptor returns the correlation of the spectral template to the pixel spectrum if the correlation is greater than 0.5 or zero otherwise. If several templates are defined within one IGF descriptor, the correlations of all templates are multiplied. This can highly increase the selectivity of an IGF descriptor.

Each template region (see bold red line in the figure below) is defined by its wavelength limits and a baseline. The baseline can be controlled by two baseline reference points which can be set independently from the wavelength limits.

Hint:

Please note that the IGF descriptor is based on the correlation of neighboring bands/lines. Thus it is less suited for spectroscopic techniques which result in line spectra whose neighboring lines might be uncorrelated (e.g. mass spectrometry, EDX, or optical emission). The IGF descriptor can be applied most successfully to techniques such as infrared, visual or Raman spectroscopy.

In order to generate an IGF descriptor you have to click the "add IGF" button in the spectral descriptor editor. This opens the IGF editor which allows to define an IGF descriptor.