fScan Reference Manual, Chapter 2 (CmdLineOptions): mask
usage: -mask [maskname] [flag masklevel] [refname]
Specify a binary mask for the current data set based on its own intensity values, or based on values in a reference data set. If REFNAME is an image window, it will be used to generate a new IOMASK for the current active dataset. If REFNAME is not specified, the current active dataset will be used to set its own mask.
If MASKNAME is specified, the mask will be stored as a new byte image data set with that name. Pixel values are either 0 or 1.
Note: The new data set is independent of storing the mask within the current data set (see FLAG 4).
The FLAG argument is used to specify mask options: