if the original data is stored as integers you might want to use
avwmaths_32R instead. All the avw tools write the output in the same
format as the input, e.g. if the input is int the output will be, too.
I suspect that this is what's causing the problems. Using the blah_32R
version of the binary will enforce writing the output as 32 bit reals.
hope this helps
On 14 Apr 2004, at 12:52, Johannes Klein wrote:
> Hello everyone,
> I'm having trouble with scaling some PET images. What I'm trying to do
> is scale them to their respective overall mean so I can calculate a
> template image for FLIRT registration.
> I masked out all values <=0 with avwmaths -thr 0 and then calculated
> mean of the remaining voxels with avwstats -M. Now, I'd like to divide
> my data by that factor to achieve scaling to the mean. When I do the
> avwmaths -div, the scaling factor (funused1?) is not adjusted, and the
> effect is quite deleterious. I've made a picture and put it to
> Is there a way to get around this issue? And what happens when I sum
> mean-scaled images up, are the individual scaling factors respected?
> I'd appreciate any comments.
Christian F. Beckmann
Oxford University Centre for Functional
Magnetic Resonance Imaging of the Brain,
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/
Phone: +44(0)1865 222782 Fax: +44(0)1865 222717