1. An image transformation method, for an image display device, the method comprising: obtaining a 2 dimensional (2D) image and a corresponding depth image; according to the depth image and N gain values GM W , performing a motion process on the 2D image to obtain N motion images, wherein a pixel motion value in each of the motion images varies with the corresponding gain value GM W , N and w are positive integers, and 1≦w≦N; respectively performing an interpolation process on the motion images to obtain a plurality of corresponding view images; and performing a synthesis process on the view images to obtain a 3D image.