Patent ID: 7613326

Claim:
A method of discriminating between road markings of at least two colours, comprising the steps of: (a) providing a monochrome camera for viewing road markings through a filter positioned between said road markings and said camera, said filter extending generally transversely to the road markings and having at least two sections, the filter sections providing a first colour response in a first area of a field of view of said camera and a second colour response in a second area of said field of view of said camera; (b) capturing an image of at least one road marking with the monochrome camera provided in step (a), said captured road marking image extending generally along the length of the road marking from said first area of said camera field of view into said second area of said camera field of view; (c) determining a change in intensity of said captured image of said road marking between said first and second areas in said field of view; and (d) utilizing the change in intensity of said captured road marking image to discriminate between at least two colours.