1. A method for identifying edge pixels in a rendered image that consists of a plurality of tiles, each of the plurality of tiles consisting of a plurality of pixels, the method comprising: accessing data to determine whether a selected tile in the plurality of tiles is fully compressed; identifying the selected tile as including only non-edge pixels responsive to a determination that the selected tile is fully compressed; and identifying the selected tile as including one or more edge pixels responsive to a determination that the selected tile is not fully compressed.