1. A method for analysis of contractile activity of the gastrointestinal (GI) tract in an in-vivo image stream, the method comprising: receiving a stream of image frames from an in-vivo imaging device; measuring a property of each image frame of a plurality of image frames of said stream; classifying said plurality of image frames into frame classifications based on the measured property, said frame classifications selected from at least turbid frames, wall frames, wrinkle pattern frames and static frames; and analyzing the properties of the classified image frames to determine contractile activity in the image stream.