Vehicle extraction using spatial differentiation and subtraction
Masao Takatoo, Tadaaki Kitamura, Yoshiki Kobayashi · Systems and Computers in Japan · 1998
In this paper we propose a method, which is executable on today's commercially available image processors, for extracting vehicles. The method is summarized as follows: (1) First, the method generates an initial background image by extracting a background region using logical OR operations among sequentially inputted and subtracted images. (2) Second, on the basis of the change ratio of the brightness of visible road surface, the method dynamically updates the background image by estimating brightness of road surface regions hidden by vehicles. (3) Finally, the method extracts the vehicles using images subtracted by the background image and spatially differentiated images. In preliminary experiments we obtained a good background image by updating it with moving shadows, even under bad conditions at dusk. Furthermore, we had good accuracy in traffic flow measurements, with more than a 95% recognition rate of vehicles and only 3% overdetection. We confirmed the effectiveness of the method by the above evaluation experiments. © 1998 Scripta Technica, Syst Comp Jpn, 29(7): 21–32, 1998