Is there a way to inverse image dilation?

I have an image in which my requirement is to select two pixels away from the boundary, but inside. For selecting n number of pixels outside, I can do it by 'imdilate' function. Is there a way to select pixels inside the boundary either using 'imdilate' or 'imerode' or some other functions?

Answer 1

[Asieh Daneshi]

Hi Jupiter,

I think you have found the answer of your question by yourself. But I leave the answer to others who may have the same question. "imerde" does what you want.

Answer 2

[Image Analyst]

One way is to use bwdist() and then threshold at 2.

edtImage = bwdist(mask);
imshow(edtImage, []);
mask = edtImage >= 2;
imshow(mask);