**fScan Reference Manual, Chapter 2 (CmdLineOptions:Expr): Viewmask**

===== Viewmask -- Use 1 image to mask multiple slices in any 3D view =====
 **usage: -expr viewmask RefImage viewplane [maskthresh flag slice0 nslices]**\\

VIEWMASK applies a single mask image (REFIMAGE) to mask voxel values in multiple image planes along any axis (X,Y,Z).

The axis is specified by the VIEWPLANE argument as:
  * 0 - default Z axis
  * 1 - coronal
  * 2 - sagittal
  * 3 - axial

The REFIMAGE must have the same XY dimensions as the active data set in the selected VIEWPLANE.

MASKTHRESH can be used to specify the minimum "ON" value in REFIMAGE; the default is 1 (any nonzero value).

FLAG:\\
  * 0 - default; set values to zero where REFIMAGE is less than MASKTHRESH
  * 1 - invert the mask; keep values where REFIMAGE is greater than or equal to MASKTHRESH

SLICE0 and NSLICES can be used to apply the mask to only a subset of slices along the VIEWPLANE axis (default is all slices).

**See Also:**\\
[[jvs:fscan|fScan Home]], 
[[jvs:fscan:manual|fScan Manual]],
[[jvs:fscan:manual:chapter2|CmdLineOptions]], 
[[jvs:fscan:manual:chapter2:expression|Expression Command]], 
[[jvs:fscan:manual:help|Manual Help]]