Thread Subject:

Boundry between image regions

I have two regions in an image (labeled with 1 and 2 respectively), and I want to find out the length of the boundary between them. I thought of applying dilation to one of them and then looking for the intersection with the second. Something like:

region1 = image == 1;
region2 = image == 2;
se = strel('disk',1,0);
extended = imdilate( region1, se );
boundry = length( find( extended && region2 )

The problem is that I need to do this for a large set of images and this procedure is slow (I guess because of the imdilate).

Does anyone has an idea on how to do this faster?

Thanks in advance!

"Michael" wrote in message <igkhfo$p76$1@fred.mathworks.com>...
> I have two regions in an image (labeled with 1 and 2 respectively), and I want to find out the length of the boundary between them. I thought of applying dilation to one of them and then looking for the intersection with the second. Something like:
>
> region1 = image == 1;
> region2 = image == 2;
> se = strel('disk',1,0);
> extended = imdilate( region1, se );
> boundry = length( find( extended && region2 )
>
> The problem is that I need to do this for a large set of images and this procedure is slow (I guess because of the imdilate).
>
> Does anyone has an idea on how to do this faster?
>
> Thanks in advance!

What about:
bwboundaries, bwperim, bwtraceboundary

Also, I would guess that your method with imdilate isn't producing the results you expect, since it would fill small concave areas.