Antialiased imaging with improved pixel supersampling

Abstract

An image processing system is described that receives polygonal image data at the direction of a processor and develops antialiased image data for display on a raster scanned display. In particular, the image system includes a scan convertor for converting the polygonal image data into pixel data, which includes pixel screen coordinates and at least one color value for each polygon covered pixel of the pixel data and a supersample coverage mask indicating an extent of polygon coverage within each polygon covered pixel. The image system also includes a raster system having at least one image processor for receiving the pixel data for each pixel, for developing a region mask based on the supersample coverage mask, and for storing the color value in association with the region mask as anitialiased display data in an image memory in communication with the image processor based on the pixel screen coordinates. The region mask indicates one or more, geographical regions of supersamples within each pixel covered by one or more polygons and indicates a color value stored in the image memory to be assigned to the supersamples in a region. This requires only a single color value for supersamples within a region of a covered pixel to be stored in the image memory. The image system can also be configured to develop and store Z-values, alpha values, stencil values, and texture values for each pixel for storage in the image memory in association with the region mask.