Introduction

Vision allows humans to perceive and understand the world surrounding them. Computer vision aims to duplicate the effect of human vision by electronically perceiving and understanding an image. Giving computers the ability to see is not an easy task — we live in a three-dimensional (3D) world, and when computers try to analyse objects in 3D space, available visual sensors (e.g. TV cameras) usually give two-dimensional (2D) images, and this projection to a lower number of dimensions incurs an enormous loss of information. Dynamic scenes such as those to which we are accustomed, with moving objects or a moving camera, make computer vision even more complicated.