Patent ID: 7345782

Claim:
A method of supporting transparency in a printer, said method comprising: receiving a plurality of commands corresponding to a page to be printed in a page description language, said plurality of commands specifying a plurality of raster operations, wherein said plurality of raster operations use one or more of a source, a paint and a destination as operands to generate a bit map representing an image portion and store said bit map at a destination, said plurality of commands further specifying whether transparency is effective for said source if said raster operation includes a source and said paint if said raster operation includes a paint, said image portion containing a plurality of points; interpreting said plurality of commands in said page description language into a corresponding display list describing objects to be printed, said interpreting including for each of said plurality of raster operations generating a data mask having a bit for each point of said image portion of said corresponding raster operation, said bit having a first digital value indicating said corresponding point of said image portion should equal said destination or a second digital value indicating said corresponding point of said image portion should equal a result of said raster operation; and rendering said display list into a bit map for the page, said rendering including generating said bit map based on a result of said plurality of raster operations or said destination according to said corresponding data mask.