Abstract: 3D films have become more and more popular due to their exceptional visual quality enhancement in comparison with the traditional 2D ones.However,due to the high cost in 3D film production which severely hampers its fast development,the conversion technology from 2D to 3D becomes a promising way to alleviate the problem.In this paper,the various 2D to 3D film conversion technologies are summarized.More specifically,the classical conversion approaches are first reviewed according to the four kinds of relative motion between camera and scene,then several more advanced ones are discussed,finally some promising future directions are listed.