Tracking an object in a video

In the previous two recipes, we learned how to track the motion of points and pixels in an image sequence. In many applications, however, the requirement is rather to track a specific moving object in a video. An object of interest is first identified and then it must be followed over a long sequence. This is challenging because as it evolves in the scene, the image of this object will undergo many changes in appearance due to viewpoint and illumination variations, non-rigid motion, occlusion, and so on.

This recipe presents some of the object-tracking algorithms implemented in the OpenCV library. These implementations are based on a common framework, which facilitates the substitution of one method by another. Contributors have also made available a number of new methods. Note that, we have already presented a solution to the object-tracking problem in the Counting pixels with integral images recipe in Chapter 4 , Counting the Pixels with Histograms; this...