A method of rendering a graphics image in which rendering is only carried out in a region to be changed is disclosed. In a preferred form the image includes a plurality of objects and the method comprises the steps of: determining if each object has changed so that the object is required to be displayed differently in a subsequent frame; determining a bounding region of each changed object in the subsequent frame; determining a bounding region of each changed object in a frame prior to the subsequent frame; and combining the bounding regions to form an aggregate region and rendering the image only within the aggregate region.