find the neighbor region

I have two binary image, A and B ( A and B are same size but have different object). There are many regions in each image. Now I want to find the neighbor of any regions in A. I use imdilate - dilation function in matlab. Because after dilation the regions of A will be increase so this may be connected with a region in B. I will add the region of B to A and continue to do it. I will stop when we can't add any region of B to A.

I don't know how to code this ? can you help me. thank you so much ? will it take a lot of time to calculate?

Answer 1

[Image Analyst]

So basically you want to keep growing A until it completely engulfs B. I'm not sure why/where this would be useful. But anyway, you can do this (pseudocode)

AorB = A; % Initialize
while true
  if sum(A(:)) == sum(AorB(:))
    break;   % B is completely within A
  end
  A = imdilate(A, true(3)); % Grow A by one layer
  AorB = A | B; % "OR" the growing A with the constant B image.
end

Basically keep growing until adding B to the growing A will not add any more pixels and the sizes are the same.

[Image Analyst]

Actually, you may be able to quit before A completely engulfs B, as long as all B are "connected" to A. Is that what you want? If that's true, label the image

[L, blobCount] = bwlabel(A);

and stop when blobCount = 1:

while true
  A = imdilate(A, true(3)); % Grow A by one layer
  AorB = A | B; % "OR" the growing A with the constant B image.
  [L, blobCount] = bwlabel(AorB);
  if blobCount == 1
      break;
  end
end

It will keep growing until all blobs in B are attached to A, then quit. It will not keep growing to engulf all blobs in B like the first code did. I think this is more like what you described.