Traffic congestion measuring method and apparatus and image processing method and apparatus

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:
• Bn+1=Bn+η×(Xn−Bn)
• wherein Xn is a brightness level of each of picture elements forming the image taken at time tn, Bn 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 tn, Bn+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 tn+1, each of said predetermined regular intervals is equal to tn+1−tn, and η is a variable coefficient decreased in proportion as |xn−Bn| becomes large and as a level of the traffic congestion on said road is increased.