How can I extract the region enclosed by a zero level set function?

Boundary detected by a zero level set function after a finite iteration has been plotted with a syntax contour(a,[0,0],'r'); This shows the object boundary. Due to the presence of some shades, it has 3 or 4 small holes inside the boundary region. I want to extract the region enclosed by the object boundary including the hole region also. I tried to view the matrix, but cant. Now my question is is there any function available to get the xy coordinates of the object boundary.