A vision system for a vehicle includes a high resolution camera disposed at the vehicle windshield and having a field of view forward of the vehicle, and a low resolution sensor disposed at a forward portion of the vehicle and having a field of sensing forward of the vehicle. Responsive to processing of an output of the low resolution sensor, a control determines the presence of a hot spot forward of the vehicle. Responsive to determination of a hot spot, the control enhances processing of image data captured by the camera to determine if the hot spot is indicative of presence of a pedestrian or animal ahead of the vehicle. Responsive to determination that the hot spot is indicative of presence of a pedestrian or animal, the control generates an alert to a driver of the vehicle and/or controls a vehicle system to mitigate impact with the pedestrian or animal.