Dear Rick and Daniel,

Thanks for clarification and suggestion.

The linear interpolation option works better for my case. I want to simulate 2D from the 3D images.

Based on my data, when the slice of 2D is right at the 3D slice location, the voxel values are very close to each other, but not exactly the same. It seems some interpolation still happens.

"The contribution of the neighbors will be based on the fractional distances." makes sense to me. Do you have a specific equation by any chance?

" it might land somewhere with 8 neighbors" Do you mean 8 neighbor slices are always used in "3dresample" (well, except edge slices)?

Thank you for answering my tedious questions.

David