AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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rob risinger
December 01, 2004 12:25PM
Weighting, as implemented, is designed to minimize variance of intra-brain voxels over extra-brain noise. However during the 3dVolreg process motion vectors are created based on signal variance. A given voxel's variance is weighted based upon a blurred mask. I understand from above that this mask normally consists of all voxel's whose signal is greater than 97.5% of the max of the base image. The -weight flag allows us to specify a different mask, but that mask appears to undergo the same thresholding and blurring.

Is there a way to specify the distribution of the weighting function such that we can incorporate more of the variance of the outer brain voxels and less weighting for center brain voxels (r-squared dependence for example) in 3dvolreg?

rob risinger

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3D registration

Marleine June 04, 2003 09:16AM

Re: 3D registration

bob cox June 04, 2003 11:24AM

Re: 3D registration

rob risinger December 01, 2004 12:25PM