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 receives the captured image, which comprises an image data set representative of the exterior scene. The control may apply an edge detection algorithm to a reduced image data set of the image data set. The reduced image data set is representative of a target zone of the captured image. The control may be operable to process the reduced image data set more than other image data, which are representative of areas of the captured image outside of the target zone, to detect objects present within the target zone. The imaging system may be associated with a side object detection system, a lane change assist system, a lane departure warning system and/or the like.