Page expansion and printing method incorporating halftoning and compositing

1. A page expansion and printing method for a pagewidth inkjet printer, said method comprising the steps of:

receiving a page description having a bi-level black layer and a contone CMYK (Cyan Magenta Yellow black) layer from a host and storing said page description in a memory;

decompressing the respective layers in parallel;

halftoning the contone CMYK layer to bi-level CMYK;

compositing the bi-level black layer over the bi-level CMYK layer; and

transmitting the image to a memory buffer for printing by the pagewidth printer.

2. The method of claim 1 , wherein the page description is received with the bi-level black layer compressed in an Edge Delta and Runlength (EDRL) format and the contone layer compressed in a Joint Photographic Experts Group (JPEG) format.

3. The method of claim 1 , wherein the steps of halftoning and compositing includes receiving an expanded 267 ppi CMYK contone layer and producing an expanded 1600 dpi black layer for transmission to the memory buffer.

4. The method of claim 1 , wherein the step of decompressing includes receiving an EDRL bitstream and producing a set of bi-level image lines which are scaled horizontally from a resolution of the expanded bi-level image by an integer scale factor.

5. The method of claim 1 , wherein the step of receiving a page description includes the step of receiving the page description in a FIFO buffer.