Patent US 5,359,666

A device and a process for judging the contour of a road by processing data from an image taken of the road by a camera. In the data processing, Hough transform is used to obtain a plurality of straight lines approximate to the edges of the road. In order to recognize the contour of a road, it is most important to recognize the edges of the road. For the recognition of a road, for example, an image taken of the road is divided into upper and lower regions. In the lower region, two straight lines are given approximate to the right and the left edges of the road. In the upper region as well, two straight lines are given approximate to the right and the left edges of the road. Then, positional relationships between the intersection of the former two straight lines and that of the latter two straight lines are compared. Based on positional relationships, it can be judged very easily whether the road is straight, curves, inclines or declines.