I think I figures it out!
The header I was using was the header of one of the binary mask images.
I found (through experience) that if you want to write a volume with
non-discrete values, you should use the header from say a file that takes
non-discrete values (e.g. a beta file). Now the maximum difference is in
the order of 1e-7...
Hamed
On Sun, Jul 17, 2016 at 1:40 PM, hamed nili <[log in to unmask]> wrote:
> Dear all,
>
> I am using spm12 for some of my analysis. I create images in subject's
> native space and firstly want to write them as Nifti images. So I use
> spm_write_vol. It's strange that the nifti image that I write is not the
> same as the image that I feed in the function!
>
> Can anyone point out the mistake I am making or the solution they have.
> Here is the code:
>
> V = spm_vol(binaryMaskFile);% binaryMaskFile is one of the subject's
> files, e.g. their mask.nii created after the first level stats
>
> % now I change the name of the file
>
> V.fname = 'test.nii';
>
> % generate random data
>
> data = randn(96,96,72);
>
> % save it
>
> spm_write_vol(V,data);
>
> % read in the written volume and find the difference
>
> diffVol = spm_read_vols(spm_vol('test.nii')) - data;
>
> max(diffVol(:)) % I get 4.4715 in one example
>
>
>
>
