Abstract: In a keying system, an image of an object is gained and a plurality of the background images each of which is obtained correspondingly to a view angle of a view point in a three-dimensional space to be imaged and a view position of the view point therein are stored on a memory device. The background image from the plurality of background images stored in the memory device is selectively read according to the view angle and the view position preliminarily defined in accordance with the image of the object. A chroma-keying composition is performed between the background image and the image of the object thereby producing a composite image.