Threshold

Threshold

Purpose

This utility applies a threshold to a volume or image, you can define a density band and binarize the output. If this volume is coming from a phantom and you have the distance map and labels for it you may impose distance conditions and formulate a problem as complex asGive me a binary volume of those background voxels with density between 0.5 and 0.8 which are at a distance smaller than 4 voxels from the feature

Usage

$ threshold ...

Parameters

• __OR__ Input file
• __OR__ Output volume
• `` Remove all those values whose absolute value is below this threshold
• `` You can give both thresholds (-below and -above) and only those values in the band are kept
• `` You can give both thresholds (-below and -above) and only those values in the band are kept
• `` You may want the output to be binary

-substitute <old_val> <new_val> [-accuracy <accuracy=0>]

• -substitute [old val] [new val] -accuracy [accuracy0>] = This option allows you to substitute a value by another. The accuracy is optional, if not given an exact match is required for substitution. However, if it is different from 0 then if the value in the matrix is closer thanaccuracy to the old value, then it is substituted

If you use a distance condition, too:

• `` This volumes are created by Evaluate
• `` Select from the threshold condition only those which also meet the distance condition, again a distance band can be given. Remember that inside the features distances are negative. These distances refer to the distance from one voxel to the nearest feature border.

Examples and Notes

The complex question:

$ threshold -i art0001.vol -o binart0001.vol -below 0.5 -above 0.8 -binarize -distance art0001_eval_distance.vol \
-label art0001_eval_label.vol -dmin 0 -dmax 4

Binarizing a volume for all values greater than 0.5, leave the result in the input volume

$ threshold -i art0001.vol -below 0.5 -binarize 

--Main.AlfredoSolano - 22 Jan 2007