1. A local positioning apparatus for detecting a local position of a subject capable of advancing in a direction relating to a lane in a local area based on a digital image signal representing a local image of an area in an advancing direction of said subject, said apparatus comprising: a first image signal generating means for extracting a high spatial frequency component from the digital image signal, and producing an edge signal; a contour extraction means for extracting a contour of a lane based on the edge signal, and generating road contour data; a second image signal generating means for extracting a low spatial frequency component from the digital image signal, and producing a luminance signal; a lane area extraction means for extracting the lane area based on the luminance signal and generating road region data; and a lane detection means for detecting the lane position based on the lane contour data and road region data, and producing a lane detection signal.