Systems and methods for optimizing pixel based raster trapping

摘要

Methods disclosed permit the identification of frame buffer pixels for trapping. In some embodiments, flags associated with pixels in the frame buffer may be used to provide an indication of pixels for trapping. A bit in a flag associated with a pixel may be set when the pixel is painted, if the luminosity value of the pixel does not exceed a luminosity threshold. In some embodiments, the method discloses a process for updating the value of the bit through the rasterization process. The pixel may be identified as a candidate for trapping based on the value of the at least one bit at trapping time.

主权项

1. A computer-implemented method for identifying at least one frame buffer pixel associated with at least one display list object from a display list containing a plurality of display list objects as a candidate for trapping, by associating at least one flag with the at least one frame buffer pixel, the method comprising the computer-implemented steps of:
calculating a respective value for a first bit in the at least one flag when rendering the at least one frame buffer pixel to a frame buffer for each respective display list object in the display list associated with the at least one frame buffer pixel, wherein the at least one frame buffer pixel is associated with a plurality of respective display list objects, by:
setting the first bit in the at least one flag, if a luminosity value of the at least one frame buffer pixel does not exceed a luminosity threshold and the object is opaque;resetting the first bit in the at least one flag, if the luminosity value of the at least one frame buffer pixel exceeds a luminosity threshold and the object is opaque;setting the first bit in the at least one flag, if a blended luminosity value of the at least one frame buffer pixel does not exceed a luminosity threshold and the object is non-opaque; and,resetting the first bit in the at least one flag, if the blended luminosity value of the at least one frame buffer pixel exceeds at luminosity threshold and the object is non-opaque; and identifying the at least one frame buffer pixel as a candidate for trapping, if the first bit in the flag associated with the at least one frame buffer pixel has been set.