Such processes as compression, storage and reproduction of an image mapped on a three-dimensional coordinate system such as a spherical surface or a cylindrical surface are performed suitably by mapping omnidirectional map information to a two-dimensional image such that the redundancy may be low while the amounts of information is kept equal as far as possible with minimized errors. Preferably, the image is converted into a two-dimensional image in a form determined taking the performance of the omnidirectional video image reproduction side into consideration. The technique can be utilized when mapping information which describes a corresponding relationship between the three-dimensional coordinate system of the original omnidirectional image and the mapped two-dimensional image coordinate system is produced to synthesize an omnidirectional video image from an arbitrary viewpoint direction.