Introduction

Video sequences are interesting because they show scenes and objects in motion. The preceding chapter introduced the tools for reading, processing, and saving videos. In this chapter, we will look at different algorithms that track the visible motion in a sequence of images. This visible or apparent motion can be caused by objects that move in different directions and at various speeds or by the motion of the camera (or a combination of both).

Tracking apparent motion is of utmost importance in many applications. It allows you to follow specific objects while they are moving in order to estimate their speed and determine where they are going. It also permits you to stabilize videos taken from handheld cameras by removing or reducing the amplitude of camera jitters. Motion estimation is also used in video coding to compress a video sequence in order to facilitate its transmission or storage. This chapter will present a few algorithms that track the motion in an image sequence...