1. An apparatus for generating an image file for use in a stereographic display, comprising: one or more processors; a memory storing program code configured to execute on said one or more processors, said code comprising: a file obtaining code which obtains a main image file in which a main stereographic image is recorded and a sub-image file in which a sub-stereographic image is recorded; image composing code which generates a first synthetic stereographic image by reconstructing the sub-stereographic image to conform to the main stereographic image and synthesizing the reconstructed sub-stereographic image with the main stereographic image, and generates a second synthetic stereographic image by reconstructing the main stereographic image to conform to the sub-stereographic image and synthesizing the reconstructed main stereographic image with the sub-stereographic image; and a file generating code which generates a file of a predetermined format including the first and second synthetic stereographic images.