A method and system for effecting a transformation of video image on a video screen applicable to a system for producing a special visual effect on, e.g., a television screen, in which a two-dimensional address plane is defined within a memory area, input video image is stored within the memory area, a cylinder shaped virtual image is placed on the address plane, a part of the address plane is wound on the cylinder shaped image, and when the cylinder shaped image is displaced along a predetermined direction on the address plane with a radius of a circle in vertical section thereof being varied with time, the address plane can be viewed as if it were turned over. If the input address data within the memory area is read out on the basis of output address data indicating the above-described displacement of the address plane, the output video image on the video screen can be viewed therethrough as if the video image were being turned over.