determine shape smoothness/roughness

I am trying to do a small program to differentiate a smooth shape from a rough shape, the left image is a smooth shape and the right one is the rough shape,

any ideas?

Answer 1

[Image Analyst]

Usually I use the circularity which is perimeter^2 / (4*pi*Area). This will be higher for blobs with more tortuous borders. You could also use solidity, as returned from regionprops().

[Image Analyst]

See my Image Segmentation Tutorial if you need to learn how to use regionprops(). >http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862>

[George]

the perimeter can get from regionprops() as well or there is another equation to get it?

[Image Analyst]

Yes, you can get perimeter and area from regionprops(), as well as lots of other things.