1. A computerized method for detecting a deviation in vertical contour of a road, the method performable by a driver assistance system mountable in a host vehicle while the host vehicle is moving, wherein the driver assistance system includes a camera operatively connectable to a processor, the method comprising: capturing a first image frame and a second image frame in the field of view of the camera; and processing image motion between respective images of the road, wherein said images of the road are derived from said first image frame and said second image frame, wherein said processing said image motion between said images of the road includes estimating the vertical contour of the road using a road surface model of the road; and computing the deviation in the vertical contour from said road surface model.