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Just to clarify, no matter what your smoothing is set at in the normalization/registration step. The warped images are not smoothed at all. The smoothing during registration/normalization is get a better match to the template, but has no effect on the smoothness of the images.

Normalization/registration is a separate step from smoothing.

Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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On Wed, Aug 28, 2013 at 12:16 PM, Watson, Christopher <[log in to unmask]> wrote:
The smoothing during registration is to better match the template, which itself is smoothed. It won't change your image resolution (except for changing it to 2x2x2 which is what the template is). So you can just skip "Smooth" after that.

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From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Lauren Hopkins [[log in to unmask]]
Sent: Wednesday, August 28, 2013 12:00 PM
To: [log in to unmask]
Subject: [SPM] Registration Error with FWHM 0

Hello everyone:

I just started using SPM this week so please forgive me if this is a stupid/obvious question.

I'm trying to preprocess functional data for eventual use in an MVPA-ish type of analysis. For this reason, when performing the registration I have set the FWHM value to "0" to avoid as much smoothing as possible during the registration step and I do not plan on using any smoothing kernal at later preprocessing steps. While I am aware that you're inevitably going to have some smoothing during registration simply due to the nature of image manipulation I want to keep it as minimal as possible for the purpose of this specific analysis. The problem is - when I set the value to 0 I get an error back saying "there is not enough overlap in the images to obtain a solution." Conceptually I THINK I get why this is happening, and setting FWHM to any non-zero value (e.g. 1) eliminates the problem. I was just wondering if there was any way around this problem - any way to get the registration to work with a FWHM of 0 (e.g. changing the separation value, etc.) or am I just stuck using a FWHM value of 1 and moving on with my life? The image origins are the same and the images are pretty well aligned.

Thanks for any help.

Lauren Hopkins