Image rounding while image view height and with in Ti.UI.SIZE.

I am beginner in titanium. May be its a simple question. can you please help me on this.
Is this possible to round an image in titanium which have not set any fixed height and width?
i just want to round image which have set height and width property as "Ti.UI.SIZE".
<ImageView height="Ti.UI.SIZE" width="Ti.UI.SIZE" image="/images/test.png" ></ImageView>