1. A driver assistance apparatus comprising: a camera configured to acquire an image outside of a driver's vehicle, the image being a vehicle front view image, a vehicle rear view image or a vehicle side view image; and a processor configured to detect an object in the image, determine whether a collision between the driver's vehicle and the object is expected, and provide a height control signal for a suspension of the driver's vehicle to adjust a height of an expected impacted portion of the driver's vehicle, wherein the object includes a following vehicle positioned behind the driver's vehicle, wherein the processor is configured to: provide the height control signal for lowering a rear wheel suspension of the driver's vehicle when sudden braking is performed when a collision between the driver's vehicle and the following vehicle is expected, provide a control signal for performing full-braking after a collision between the driver's vehicle and the following vehicle, and provide a height control signal for lowering a front wheel suspension of the driver's vehicle when a collision between the driver's vehicle and a preceding vehicle positioned in front of the driver's vehicle is expected after a collision between the driver's vehicle and the following vehicle, and wherein the processor is further configured to: determine an overturning situation based on whether rotation of the object about an overall-length direction greater than or equal to a reference value is sensed in the image, and provide, based on the determination of the overturning situation, the height control signal for raising left wheel suspensions or right wheel suspensions.