background removal and return back the shape

how to do background removal after I crop the image such in this link:

http://www.flickr.com/photos/80166922@N06/8089628353/in/photostream

background removal can be used to display the contains of triangle shape and cut out noise outside the triangle. can someone explain how to do this?thank you.

Answer 1

[Image Analyst]

I'd probably start out using texture segmentation and see how it goes. I'm assuming that the background will have higher variance than the object. So you might want to use stdfilt() or entropyfilt().

[Tulips]

what should I put inside the bracket?()