METHOD AND APPARATUS FOR PIPELINED PARALLEL RASTERIZATION

A rasterizer 10 for converting a datastream 12 which describes a page to be printed into a rasterized pagemap bitstream 13 to be sent to a printer. The rasterization is done in four stages using parallel processors in all stages except the first, and pipelining the processors between all of the stages. In the first stage 11, a scan processor 14 identifies and stores state-independent blocks 14 in the datastream. In the second stage 17, parallel block processors 22 convert the scanned blocks into stored intermediate-form data objects 20 and request preparation of often-used resources such as characters. In the third stage 23, the objects are sorted and stored by geographical region of the pagemap by parallel sort processors 24. In the fourth stage 31, the sorted objects are rasterized into pelmaps and placed in the pagemap by parallel bin processors 30. All four stages are pipelined. End-of-block markers are used in the third and fourth stages to maintain correct ordering of the objects within the final pagemap. The rasterizer uses general purpose microprocessors for all stages.