Patent ID: 7714865

Claim:
A computer-implemented method of rendering an image one or more pixels at a time in scanline order, the computer comprising a processor configured to implement the method and a memory, wherein the image comprises objects described by one or more object levels, said method comprising the steps of: identifying at least one object edge, said at least one object edge intersecting a first scanline; building a compositing list for each identified object edge intersecting the first scanline that is associated with at least one active object level, wherein the compositing list comprises object levels that are active on the first scanline at the identified object edge and that contribute to at least one pixel to the image on the first scanline; caching one or more of said compositing lists of the first scanline in the memory, wherein each cached compositing list is associated with corresponding object edges of the first scanline; checking, for a current object edge intersecting a second scanline subsequent to the first scanline, whether any of the one or more cached compositing lists associated with a corresponding object edge of the first scanline is valid for the current object edge on the second scanline; retrieving an associated cached compositing list from the memory if said checking step indicates that any of the one or more cached compositing lists is valid; and rendering one or more pixels on the second scanline using the retrieved compositing list.