An imaging system for a vehicle includes an imaging array sensor and a control. The imaging array sensor is disposed at least partially within an exterior rearview mirror assembly that is attached at a side of a vehicle. The field of view of the imaging array sensor encompasses at least one of a rearward field of view, a sideward field of view and a forward field of view. The control may utilize edge detection in processing captured image data. Responsive at least in part to processing of captured image data by the control, the control determines an object of interest present in the field of view of the imaging array sensor. A portion of the equipped vehicle is present in the field of view of the imaging array sensor and the control may be operable to determine that the portion of the equipped vehicle is not an object of interest.