How to extract a circular ROI from an image?

[T-shirt]

I want to use "IMAQ Extract" function to extract ROI from an image,but it can only extract a rectangular ROI.I want to use this tools to extract and adjust a ROI when the VI is runing,who can help me modify the VI,thank you very much!

[AnalogKid2DigitalMan]

Is this of any assistance?

http://forums.ni.com/ni/board/message?board.id=200&thread.id=20514&view=by_date_ascending&page=1

-AK2DM