Computer vision is the automatic analysis of images and videos by computers in order to gain some understanding of the world. Computer vision is inspired by the capabilities of the human vision system and, when initially addressed in the 1960s and 1970s, it was thought to be a relatively straightforward problem to solve. However, the reason we think/thought that vision is easy is that we have our own visual system which makes the task seem intuitive to our conscious minds. In fact, the human visual system is very complex and even the estimates of how much of the brain is involved with visual processing vary from 25% up to more than 50%.
The first challenge facing anyone studying this subject is to convince themself that the problem is difficult. To try to illustrate the difficulty, we first show three different versions of the same image in Figure 1.1. For a computer, an image is just an array of values, such as the array shown in the left-hand image in Figure 1.1. For us, using our complex vision system, we can perceive this as a face image but only if we are shown it as a grey scale image (top right).