Look at Circular Hough Transform, a Java applet demonstration

http://www.markschulze.net/java/hough/index.html

Now i am able to track the red dot but the problem is that i get a cluster of red pixels so the tracked dots are not stable when i get the pixels from successive frames. I tried to find the pixel using the first red spot but that reduced the problem to a small extent. So kindly tell me how i can stabilize the dot across multiple frames.