3.5. Spectral Signature Plot

The window Spectral Signature Plot includes several functions for displaying spectral signature values as a function of wavelength (defined in the Band set). Signatures can be added to the Spectral Signature Plot through the SCP dock.

Overlapping signatures (belonging to different classes or macroclasses) are highlighted in orange in the table Signature list; the overlapping check is performed considering MC ID or C ID according to the setting Use checkbox MC ID checkbox C ID in Classification. Overlapping signatures sharing the same ID are not highlighted.


Spectral Signature Plot

3.5.1. Signature list

The Signature list is a table that includes the spectral signatures added from the SCP dock.



MC Name


C Name


checkbox field; if checked, the spectral signature is displayed in the plot

signature Macroclass ID

signature Macroclass Name

signature Class ID

signature Class Name

signature color; also, the combination MC ID-C ID is displayed in case of overlap with other signatures

The following tools are available.

Tool symbol and name



remove highlighted signatures from this list


add highlighted spectral signatures to ROI & Signature list


calculate the spectral distances of spectral signatures displayed in the plot; distances are reported in the tab Spectral distances Plot

Left click and hold inside the plot to move the view of the plot. Use the mouse wheel to zoom in and out the view of the plot. Right click and hold inside the plot to zoom in a specific area of the plot. Legend inside the plot can be moved using the mouse.

The following tools are available.

Tool symbol and name



automatically fit the plot to data


save the plot image to file (available formats are .jpg, .png, and .pdf)

checkbox Plot value range

if checked, plot the value range for each signature with a semi-transparent area

checkbox Band lines

if checked, display a vertical line for each band (center wavelength)

checkbox Grid

if checked, display a grid

Max characters input_number

set the maximum length of text in the legend

x y

display x y coordinates of mouse cursor inside the plot


Spectral Signature: Example of plot Signature details

Display the details about spectral signatures (i.e. Wavelength, Values, and Standard deviation). In case of signatures calculated from ROIs, the ROI size (number of pixels) is also displayed.


Spectral Signature: Example of signature details Spectral distances

Display spectral distances of signatures (see Signature list), which are useful for assessing ROI separability (see Spectral Distance).

The following spectral distances are calculated :

Values are displayed in red if signatures are particularly similar.


Spectral Signature: Example of spectral distances