It was a dream since the invention of computers that they would be able to see and think. Though computers became faster and faster day by day, just its speed and memory were not enough to make that dream, a practical. Vision is the task of knowing the surrounding environment by processing the information in visible light. Artificial vision by perceiving and understanding an image in machines is Machine Vision or Computer Vision. Dana H Ballard and Christopher M Brown [1] have defined Computer Vision as "Enterprise of automating and integrating a wide range of processes and representations for vision perception". Computer vision systems rely on image sensors, which detect electromagnetic radiation of either visible or infra-red light. The camera includes a lens similar to lens found in eyes. Tasks such as identifying persons and their activities from an image, summarizing a video when there is no time to watch it completely, looking for accuracy in manufactured products in an industry, identification of path in an environment for movements by robots etc., make use of computer vision algorithms. Many fields of science and technology have contributed to computer vision. Different applications make use of different combination of these fields.