Removing components touching phase in 3d volume

Hi all

I have a 3d volume composed of tif files with three phases, namely particle phase, pore phase and a border phase. I would like to delete all particles touching the border phase. One slice looks something like this

http://imgur.com/HwJ0vZj

and I would like to remove all the particles (2) that touch the outer border (1) within the whole 3d volume.

Any help would be greatly appreciated.

thanks

Answer 1

[Sean de Wolski]

Use bwdist to get the distance from every pixel to the border (euclidean distance). Zero out any less than or equal to sqrt(2).

D = bwdist(I==phase1);
D(D<=(sqrt(2)+eps)) = 0;

Answer 2

[Sohrab Daemi]

Hi

thanks but this seems to deletes everything within the circle. I just need to delete the particles (marked as 2 in the image) that are touching the outer border (marked as 1).

thanks again