Computer-generated imagery (CGI) is using computer graphics, especially in movies. These images are used for special effects, simulation, and commercials, amongst others. Sometimes the technology is used to produce a static background, which is then merged into the image; at other times it is used to produce animations in 2D or 3D. In its broadest sense, a computer- generated image (CGI) can be defined as any image that is created with the use of a computer- based processor or program. Because computers are widely used, both in image generating and in image processing, these images are pervasive- from billboard advertisements to film productions and photography.