An imaging system for a vehicle includes an imaging sensor and a control. The imaging sensor is operable to capture an image of a scene occurring exteriorly of the vehicle. The control is responsive to the imaging sensor. The imaging system may be associated with a side object detection system, a lane change assist system, a lane departure warning system, a monitoring system, a passive steering system and/or the like. The control may be operable to process a reduced image data set more than other image data, which are representative of areas of the captured image outside of a target zone, to detect objects present within the target zone.