1. An image transmission apparatus for transmitting multiple image frames, comprising: an outline extraction processor configured, based on image data representing a plurality of image frames, to extract an outline of a specific-type image element in each of the image frames and to create outline data for each of the image frames; a selector configured to select selected data for each of the image frames, the selected data for each image frame being either the image data representing said image frame or the outline data created for said image frame; and a transmission module configured to transmit the selected data for each image frame to an external receiving device, wherein the selector determines, for each image frame, whether a scene change has occurred or not, selects the image data representing said image frame if a scene change has occurred, and selects the outline data created for said image frame if a scene change has not occurred; and wherein the selector determines, for each image frame, whether a scene change has occurred or not based on a change in a direction of an outline vector indicating a direction of an outline in said image frame.