| 摘要 |
PROBLEM TO BE SOLVED: To pick up an image while keeping the contrast of a white line area and a road surface area inside a tunnel further far away without saturating the sunny side traveling route white line data to pick up images even when a traveling vehicle is near the entrance of the tunnel. SOLUTION: The image of a white line on the traveling path is picked up by using a camera 1, and a tunnel detector 2 detects a tunnel candidate area while using this white line. The detected result of the tunnel entrance is outputted to an exposure controlled variable selector 7. An exposure amount calculating device 5 for the white line inputs a density value WD of the white line from a white line area detector 4 and calculates a target exposure amount value with which the density value WD of this white line picking up images at present can be near the upper limit density value of the image. When the tunnel entrance detected result is inputted, the exposure controlled variable selector 7 controls the exposure amount of the camera 1 to this target value. |
