A method is proposed for automatically obtaining depth. information from a 2-D motion image, so as to create an image for a 3-D display. Further, methods are proposed for selecting appropriate frames for the calculation of the depth information, or discontinuing the calculation, and for conducting image., processing using the depth information. Examples of various types of image processing can be listed as including the creation of a viewfinder image seen from a different point, natural scaling operations to an image area, and separation of a desired image area. First, a motion information of an object on a screen is extracted by block matching or the like. Second, the actual movement of the object in the 3-D world is calculated. Since the viewfinder image is a projection of a 3-D space, it is possible to obtain the original 3-D movement of the object, based on the movements of a plurality of representative points through an inverse transformation, the representative points being provided in the viewfinder image. Resultantly, 3-D coordinates of this object are identified, so that depth information of the object is obtained. Afterwards, a parallax is calculated based on the depth information, so as to create right and left eye images from the input viewfinder image. Alternatively, image processing, such as separation of an object having a depth within a predetermined range, is carried out based on the depth information.