**fScan Reference Manual, Chapter 2 (CmdLineOptions:Expr): Roimask**
===== Roimask -- =====
 **usage:  -expr roimask [ROINUM [NROIS]]**\\

Only keep region within selected Block ROI's. If multiple Block ROI's are associated with the current data set, all will be kept by default. Or you can select just a subset of the active ROI's by specifying ROINUM (how many to skip) and/or NROIS (how many to use).

**See Also:**\\
[[jvs:fscan:manual:chapter2:expression|Expression Command]],
[[jvs:fscan:manual:chapter2:expression:roifill|Roifill]], 
[[jvs:fscan:manual:chapter2:expression:roimove|Roimove]]

[[jvs:fscan|fScan Home]], 
[[jvs:fscan:manual|fScan Manual]], 
[[jvs:fscan:manual:chapter2|CmdLineOptions]],
[[jvs:fscan:manual:help|Manual Help]]