Patent ID: 6188778
Filing Date: 2001-02-13
Classification: G08G

Abstract:
A traffic congestion measuring method of measuring a state of traffic congestion on the basis of a motion picture which represents a road and vehicles coming and going on said road and is formed by a series of images taken by a video camera, comprising the steps of:(a) forming a criterion brightness image which is taken by said video camera and in which the vehicle is expected to be absent;(b) detecting the vehicles represented in one of said series of images taken at a predetermined time on the basis of said criterion brightness image and the image taken at said predetermined time;(c) renewing said criterion brightness image after said step (b); and(d) repeating said steps (b) and (c) at predetermined regular intervals,said criterion brightness image being renewed in said step (c) by an equation described as follows:B.sub.n+1 =B.sub.n +.eta..times.(X.sub.n -B.sub.n)wherein X.sub.n is a brightness level of each of picture elements forming the image taken at time t.sub.n, B.sub.n is a brightness level of each of picture elements forming the criterion brightness image which is utilized for detecting the vehicles represented in the image taken at said time t.sub.n, B.sub.n+1 is a brightness level of each of picture elements forming the criterion brightness image which is utilized for detecting the vehicles represented in the image taken at time t.sub.n+1, each of said predetermined regular intervals is equal to t.sub.n+1 -t.sub.n, and .eta. is a variable coefficient decreased in proportion as .vertline.x.sub.n -B.sub.n.vertline. becomes large and as a level of the traffic congestion on said road is increased.