Perhaps someone's already working on these questions from last week, but in case it's fallen through the cracks...

Summary:

1. -delta and -x_thresh: Qualitatively, what do they do. What range of numbers is useful (maybe relative to particular voxel size?) and what effect does adjustment in each direction have?

2. Edges: Qualitatively, what does 3dvolreg do with the edges of the volume (or the box defined with -edging)? How is it that the edges of the box don't become the most salient feature for alignment?

3. Weight: If using the -weight option, what range of values are expected in the weighting brik? If not using that option, is there a way to extract the weighting values employed by default by 3dvolreg?

4. Docs caution that algorithm is good for a couple of voxels or couple of degrees of misalignment -- is there further quantification of ability to register larger misalignments?

5. 3dvolreg help: Looks to me like the -help info is mis-edited, see details in my message of last week.

Thanks,

Graham