define boundaries and merge two objects

I have these both segemented objects and I want to define their boundaries by drawing a perfect circle after that I want to merge these objects in one image . could you help?

Answer 1

[Image Analyst]

Assuming they both have the same number of rows and columns, you can do

maskBoth = mask1 | mask2; % Merge -- make union of the two binary images.

[Image Analyst]

You can use viscircles to draw perfect circles into the overlay above the image.