Dear Sean,
I think that the problem is with the fact that you are using Analyze software. I
have this problem when I edit images in Analyze. Put simply, there is a bug in
analyze which means that when it writes out a new image, it does not write out
all the old information from the original header, including the scale factor.
This is reset at zero (or perhaps 1, I can't remember). The only way I found
around this was to edit the header of the new image that Analyze had created. I
did this outside Analyze in my unix window. You need to have saved an older
version of the image that still has the original scale factor in it. Get both
images in the same directory and type:
dbedit [old.image.hdr] 'dime.roi_scale'
The scale factor from the old image should now be written out (let's call it x).
Then type:
dbedit [new.image.hdr] 'dime.roi_scale=x'
And that will paste back the old scale factor into the new image header.
It's tedious if you have many images, I guess someone who knew a bit about it
could write some code for you to automate this, but I just do it by hand.
Hope that's of some help.
Cheers.
Alex.
> Dear SPM'ers
>
> I have a small problem regarding the scale factors of my images after
> spatial normalisation.
>
> The thing is, I have applied a user defined 12-parameter affine
> transformation to a set of
> registered image volumes using ANALYZE. After the transformations are
> complete I save them as
> AnalyzeImage7.5 .
>
> When I then look at these images in MRicro, it is clear that the true image
> intensities, i.e., the scale
> factors are all zero. This results for me in inconsistent image intensities.
> I have tried to change
> the scale factor within MRicro without much success?!
>
> Can anybody help me with this.
>
> I would be grateful if anybody could.
>
> Cheers
>
> Sean Colloby
> Research Associate
> Newcastle General Hospital
> Newcastle upon Tyne
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