SHELL

threshold

#!/bin/sh

# Make image containing positive values only by thresholding at 0

fslmaths img -thr 0 img_pos 

threshold

#!/bin/sh

# Apply multiple ordered operations: 
# multiplication followed by thresholding 
# and then making the image binary

fslmaths img -mul gm_mask -thr 0.5 -bin img_gm_bin 

threshold

#!/bin/sh

# Make a 5 percent mask (default choice for fdt results).
# fdt is FSL's diffusion toolbox.
# Use following percentage (0-100) of ROBUST RANGE of 
# non-zero voxels and threshold below that percentage
# Note that larger values are more stringent

fslmaths img -thrp 5 img_5p