enhance Lung Field in X ray image

i want to enhance shape from this image to be more smooth

to be like this shape

thanks

Answer 1

[Sajid Khan]

Use morphology such as dilation

Answer 2

[Image Analyst]

You can try imclose() to smooth your binary mask, or try activecontour (demo attached).

[Anand]

I would try activecontour with a higher smooth factor (controlled by parameter 'SmoothFactor') till you get the desired smoothness.