How to fill the unclosed region?? activecontour is not working...

I want to make like below...

I try to this by using activecontour, but image don't be changed, remain same.

Image is matrix which is consist of 0 and 1

% Fill the cavity

mask = false(row, col);

mask(1:low,1:col) = true;

Image2 = activecontour(Image, mask, 400, 'edge');

what's wrong?? if activecontour is not right way, how to fill the unclosed and disorder region??

Answer 1

[Image Analyst]

To make each blob convex, use bwconvhull().