1. A method of generating a disparity map for an image sequence displayable on a screen defining a screen plane, wherein the image sequence includes a stereoscopically viewable first object perceivable by a viewer on an image plane different to the screen plane, the stereoscopically viewable object comprising a first image viewable by a viewer's eye and a second image viewable by the viewer's other eye, the method comprising: performing a first edge pixel detection process on the first image frame to identify edges within the first image frame; identifying a feature pixel of the first image from the detected edges; generating a block of pixels including the feature pixel, performing block matching on a search region of the second image using the block of pixels from the first image frame, wherein the block of pixels generated from the first frame is correlated against the search region; and generating a disparity map by identifying a relative displacement of the feature pixel of the first image frame from a corresponding feature pixel in the second image frame.