To provide a technology capable of adjusting the contrast of a picked-up image to the most suitable state for recognizing an object on a road included in the picked-up image.

By taking into consideration a portion of a road 14 where an object such as the other vehicle or a fallen object is extremely liable to exist, and a white line 13 drawn on the road 14 along a vehicle lane (road 14), and by adjusting the contrast of a top view image tF so that the contrast between the portion of the white line 13 and the portion of the road 14 is particularly accentuated, a boundary between the portion of the road 14 and the object becomes extremely clear when the object is included on the top of the road 14; the contrast of the top view image tF can be adjusted to the most suitable state for recognizing the object on the road 14 included in the top view image tF. Thus, by processing the top view image tF whose contrast has been adjusted to the most suitable state for object recognition by image processing, the object on the road 14 can surely be recognized.