Living Image 3.1

8. Spectral Unmixing
8.4 Spectral Unmixing Options
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In the spectral unmixing tools, the Options tab shows the user-modifiable parameters
in the spectral unmixing algorithm (Figure 8.3). It is recommended that you first perform
spectral unmixing using the default settings. Then, if necessary, change the option
settings and reanalyze the data.
Figure 8.3 Tool palette, spectral unmixing options
Table 8.3 Spectral unmixing options
Option Description
Constraints The constraints for unmixing the components.
Init The method for generating the initial guess of the spectrum for the
selected component. “Auto” means this is automatically
determined by the software. Alternatively, you can used a loaded
spectrum as the initial guess.
Lock The lock option determines whether the spectrum is allowed to
change. If this option is chosen, the spectrum of that component is
not updated during unmixing.
Unimod Choose this option to apply the unimodality constraint. Unimodality
forces the spectrum to have only one peak (one extremum).
however, small magnitude extrema are allowed if they are less than
the Unimod Tolerance value. This tolerance value limits the rising
slope of the second spectral peak. For example, 5% tolerance
means that the increase in magnitude of the neighboring nodes
cannot exceed 5%.