**fScan Reference Manual, Chapter 3 (KeyCmds:ImageKeys): thresholds **
===== Thresholds -- Control display thresholding features =====
**usage: mode,options K**

The interactive 'K' command is used to control all thresholding parameters. The THRESH Taskbar icons provide a graphical user interface (GUI) for the 'K' command.  For a general introduction to intensity thresholding in fScan, see [[jvs:fscan:manual:chapter1:thresholding|Thresholding Overview]].

The following summarizes how the K command is used:

  MODE: 0 K            - turn off thresholds
        1 K            - turn on thresholds
        2,flag,flag2 K - set threshold flag
              FLAG: 1 - must be >= low thresh
                    2 - must be <= high thresh
                    4 - either >= low thresh OR <= high thresh (low>high)
                    8 - only show boundaries of threshold region
                   16 - high thresh is band-width
                        must be >= low AND <= (low+high)
                   32 - threshold is flagged by low data bit or bits (see Mode=8 below)
                   64 - fill flag (?)
                  256 - adjust thresholds by tenths (default is whole units)
                  512 - adjust thresholds by hundredths
                  768 - adjust thresholds by thousandths
                 1024 - only activate thresholds within active ROI
             Note, FLAG2 lets you change only selected bits:
              FLAG2= -1 - set bits to FLAG (default)
                      0 - turn off bits in FLAG
                      1 - turn on bits in FLAG
                      2 - toggle bits in FLAG
  
        3,val,min,max K - set lower threshold values
                          Lower threshold is set to VAL
                          Allowable range for lower threshold can be
                           clamped to MIN - MAX
        4,val,min,max K - set upper threshold values
                          Upper threshold is set to VAL
                          Allowable range for upper threshold can be
                           clamped to MIN - MAX
        5,flag K         - set threshold(s) to value at cursor
            FLAG  0 - set lower threshold
                  1 - set upper threshold
                 >1 - set both thresholds:
                       Lower = intens - flag/2
                       Upper = intens + flag/2
        6,Nbits,mask,flg K
            NBITS: Number of low bits to use for mask bits (default 1)
            MASK:  Bit mask for sampling high data bits (default is -NBITS-1 )
            FLG: 1 - adjust brightness scale and threshold values
                 2 - shift if necessary, but otherwise don't clear low bits
               010 - set 1 bit for all voxels where MASK value is non-zero
               020 - set 2 bit for all voxels where MASK value is non-zero
               030 - set 3 bit for all voxels where MASK value is non-zero
        7,flg,fillval,datamask,low,high K       convert threshold to bit mask
            FLG: 1-6 - same as 2K values
                 010 - clear low bits before setting mask
                 020 - use 2 bits for mask
        8,nbits,flg K    - set bit mask to NBITS
                 FLG  0 - simply set io->maskbits to nbits (default)
                      1 - create mask of NBITS (shift data values if nec.)
                      2 - clear maskbits (before setting ON if FLG&1)
                      4 - set mask bit ON for all thresholded voxels
        9 K              - show threshold values
        K                - toggle threshold on/off

**See Also:**\\
[[jvs:fscan|fScan Home]],
[[jvs:fscan:manual|fScan Manual]],
[[jvs:fscan:manual:chapter3|KeyCmds]],
[[jvs:fscan:manual:chapter3:imagekeys|ImageKeys]],
[[jvs:fscan:manual:help|Manual Help]]