Dear Leo,
There is no right answer.
The two different ways just average over a slightly different
spherical ROIs. However, the difference will be pretty minor
and I can't think of an example where these small differences
would matter.
All the best,
Mark
On 31 Jan 2012, at 22:08, Yiou Li wrote:
> Hi Mark,
>
> I want to use rmsdiff to measure the difference between image X1 and
> X2 in terms of affine linear transformation, to do that, I ran flirt
> to register X1 to X2, taking X2 as reference image and get the
> transformation xmat_1_to_2, now I got two slightly different number by
> running:
>
> 1. rmsdiff xmat_identity xmat_1_to_2 X2
> 2. rmsdiff xmat_1_to_2 xmat_identity X2
>
> Can you please advise which one is the correct order in this case?
>
> Thanks in advance!
> Leo
>
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