Signal Distribution Analyser

Command: Tools > Signal Distribution Analyser

The Signal Distribution Analyser (SDA) serves two purposes: (1) Sometimes it is advantageous to analyze the intensity distribution of a particular wavelength, mass, or spectral descriptor, and (2) the intensity distribution may be used in connection with the Mask Editor to mask certain pixels (e.g. pixels that belong to the background). In its first application the SDA is exclusively used for signal analysis; it's just a tool to improve your understanding of the signal (spectra) of the hyperspectral image.

The second way of using the SDA is mainly as a tool to decide which pixels should be masked. In order to be able to use this mode, the mask editor has to be open and at least one pixel mask has to be available and selected in the mask editor. In this case the buttons "Replace Mask", "Add to Mask", and "Subtract from Mask" are enabled.

The SDA allows to set a lower and an upper threshold in the histogram. Pixels below the lower threshold are marked in red, pixels above the upper threshold are colored in blue. In addition, the quantiles, the percentages and the absolute numbers of the red and blue pixels are displayed in a small box in the upper part of the histogram.

How To:
  1. Open the Signal Distribution Analyser (click the button or go to Tools/Signal Distribution Analyser)
  2. Select the wavelength, mass, or property to be analyzed in the upper right spectral window. This will recalculate the distribution of the selected signal.
  3. Move the threshold cursors in the histogram to set the pixel mask. The resulting mask will be displayed in the image at the left side.
  4. Additionally (if the mask editor is open), you can transfer the colored pixels to the currently active pixel mask (has to be selected in the mask editor). The colored pixels may replace the current mask, or may be added to or subtracted from the existing pixel mask.