The window «Spectral analysis” is designed for displaying of the spectra corresponding to the ROIs selected in the «ROIs» window.
The spectra are shown in the upper part of the window along with their legend. Click on a legend item selects the corresponding spectrum.
Different spectral bands in the visible part of the spectrum are highlighted with colors (if highlight is enabled through the options).
This window is updated on selecting a different ROI in the «ROIs» window or after relocating the selected ROI to different part of the Image in the main window.
The spectra on the plot are scaled and panned with the mouse and/or mouse wheel. Hovering mouse over the spectra opens a tooltip with the name of the spectrum, current wavelength, and the amplitude. Clicking on a spectrum (i) highlights the whole spectrum with bold line and color, (ii) sets the crosswire marker in this point of the spectrum, (iii) drops the values of this point of the spectrum to the corresponding fields of this window:
- the actual wavelength and the amplitude on the left;
- the corrected wavelength for the constructing of spectral indexes on the left;
The crosswire marker can be moved left or right with left or right arrow keys.

Shortcut menu items of the spectra plot:
- Save spectra to image… saves the image of the spectral curves as PDF, PNG, or JPG files located by default in the Working folder.
- Save spectra to Excel *.csv… saves the spectra in numeric form as Excel CSV file located by default in the Working folder.
- Save ROI to file… saves ROI to a *.roi file located by default in the Working folder.

At the bottom of the Spectral analysis window, two mode switches are located (at the left):
- Spectral range highlight;
- Show dispersion (shows the dispersion of the spectra within the ROI around their average values);

At the right, the «Fit to window» button is located (displays whole spectra by fitting them into the window) together with the field for composing of spectral indexes (holding the sample index formula). To compose a spectral index, click the desired points of spectra on the graph and complete the formula with the arithmetic operators (« + », « - », « / », « * »). The resulting formula can be copied to the corresponding field of the Calculate index by the formula window.
You can also directly enter the index formula and name in this window (use the tooltips as a guidance) and click «Compute index image». The newly computed index image shall be appended to the index image list in the «Images» window and the false-colored computed image will be overlayed on the current Image in the main window.