maskcreate - Build a mask by simple thresholding of an image

1997 Ulrik Kjems, DSP/IMM, Technical University of Denmark, uk@imm.dtu.dk
Use :
  maskcreate {-[g|s|a] thres} outputmask file1 [file2 ... filen]

Computes a mask volume 'outputmask' in BYTE format consisting of 1's where 
voxels values in all vols satisfy

      (x-min)/(max/min) > thres   AND   x > absthres

The min and max may either be slice based (-s) or global (-g). The absolute
threshold 'absthres' is specified using (-a). The 3 thresholds may be used
simultaneoulsly. Ex.

  maskcreate -g 0.1 -s 0.3 -a 100 mask vol1 vol2 vol3

All volumes have to be same size and they are converted to BYTE format 
internally.

maskcreate -h produces above information