This program will average together a series of files. For a given voxel location, only
non-zero measurements are averaged. Consequently, any voxel that is non-zero for any subject
will allow an estimate of the mean.
- where the following definitions apply:
- the name of the output file
- 'y' grants permission to overwrite output
- the suffix of files that store scaling factors. Each input file may have a
scaling factor file associated with it. These files should contain a single
ASCII number that represents a multiplicative factor for converting voxel
values into real world values (i.e., its units should be real world units/voxel
unit). All scaling files must have the same units.
- An equivalent scaling file will be created for your output file and will
have the same units as your input rescaling files.
- If all of your input files are scaled identically, you can use "null" as
the scaling suffix and a value of 1.0 will be automatically assigned to all
input files. Note that the output may still be rescaled.
- the name of the first input file
- the names of any additional input files
softmean mri_mean y null mr1 mr2 mr3 mr4 mr5 mr6
softmean pet_mean y .max pet1 pet2 pet3 pet4 pet5 pet6
- the files mr1, mr2, mr3, mr4, mr5 and mr6 will be averaged to create mri_mean
- The files pet1.img, pet2.img, and pet3.img, etc. will be converted to real
world values based on the values stored in pet1.max, pet2.max, and pet3.max,
etc., respectively. These real world values will then be averaged and written
out to pet_mean.img. A file pet_mean.max will store the values relating the
output voxel values to real world values.
- If you want to use a * wildcard on a UNIX based system to specify the input file
names, you should include either the .img or the .hdr suffix (e.g., pet*.hdr) but not
both. If you just end with the wildcard (e.g., pet*), each file will be loaded twice
(once as .hdr and once as .img). The final answer will be the same, but it will
take twice as long to get the answer.
- The output of this program is rescaled to optimize use of the dynamic range of voxel
values. If you use scaling-suffix files, the output scaling suffix will give a
quantitative measure of the rescaling applied.
- If you want to add files instead of averaging them, you need to
multiply the output scaling factor by the number of input files
See also: Generic error messages
Modified: December 18, 2001
© 2001 Roger P. Woods, M.D.(email@example.com)