I don't really understand your question, but is this just a display thing?
When you display the images, try setting the interpolation to NN.
On Wednesday 08 October 2008 18:45, Kevin Hill wrote:
> I am trying to get a gray matter mask for my group using a mean image of
> all subjects' mprages. I am getting a large ring around my gray matter
> mask, where there is a mm or so of gray matter than isn't captured into the
> mask. This is despite the fact that the tpm for the gray matter goes all
> the way to the edges of my group mprage. Does anyone know a way to reduce
> or completely remove this ring and ensure that all of the gray matter, to
> the very edge of the brain is included in the gray matter mask? Thank you.
> -Kevin Hill