The spectral residuals matrix plot shows the spectral residual values
for each wavelength of the calibration spectrum. Large residuals indicate
a wavelength that does not contribute very well to the calibration model.
Therefore the spectral residuals matrix plot can aid the user in selecting
an optimal spectral range for a given calibration. By starting a calibration
with the full spectral range and subsequently analyzing the matrix plot,
one can eliminate less import wavelength from the calibration.
The dialog initially displays all relevant spectra. The configuration
windows on the right side of the tab enables the user to customize the
plot. The following picture shows an example residual spectra plot: