dilation of specific objects

I am wondering if it is possible to perform dilation on a part of the image. Basically after converting the image to binary I have a number of objects. By using regionprops I have their area. Can I perform dilation only for those whose area<x using imdilate. If not imdilate is there a way I can do that? Thanx.

Answer 1

[Nathan Greco]

First, I would label regions in your image:

   bwl = bwlabel(img,8);

Area of regions:

   a = regionprops(img,'area');
   a = {a.Area}; %turn into cell array

Create a mask for what you want to be dilated:

   xarea = 10;
   idx = find(cellfun(@(x)x<xarea,a));
   bwl2 = sum(reshape(cell2mat(arrayfun(@(x)x==bwl,idx,'un',0)),size(img,1),size(img,2),[]),3);

Dilate the mask:

   bwl2 = bwmorph(bwl2,'dilate',1);

And finally, apply this dilated mask back to the original bw image:

   img = img | bwl2;

[Image Analyst]

Yikes! For a simpler way to extract the indicated region, you might use ismember:

bw12 = ismember(bwl, idx) > 0;

instead of that complicated sum() expression.

[Mahalakshmi]

Thanx :).. It worked :) :)..