Method of printing a compressed image having bi-level black contone data layers

1. A method of printing a compressed image, the method comprising the steps of:

receiving the image, having a bi-level black data layer and a continuous tone (contone) CMYK data layer, from an image host;

expanding the image by decompressing the two data layers in parallel;

halftoning the contone CMYK data layer into bi-level CMYK data layer;

compositing the bi-level black data layer over the bi-level CMYK data layer to form a composited bi-level CMYK image;

separating the color planes of the composited bi-level CMYK image, and separating each color plane into even and odd pixels;

storing the odd and even pixels of each color plane in respective odd and even FIFOs for each color; and

printing the composited bi-level CMYK image with a pagewidth printhead onto a print medium.

2. The method of claim 1 , wherein the step of receiving the image includes receiving the bi-level black data layer compressed in an Edge Delta and Runlength (EDRL) compression format.

3. The method of claim 2 , wherein the step of expanding includes decoding of entropy coded EDRL codewords in an input bitstream according to a predetermined decoding table.

4. The method of claim 1 , wherein the step of receiving the image includes receiving the contone layer in a Joint Photographic Experts Group (JPEG) compression format.

5. The method of claim 4 , wherein the step of expanding includes decoding a JPEG bitstream with a decoder according to 8 parallel pixel First-In-First-Out (FIFO) registers to deliver an output in the form of 8×8 pixel blocks.

6. The method of claim 1 , wherein the steps are sequentially performed by a print controller using a number of First-In-First-Out (FIFO) registers.

7. The method of claim 1 , wherein the step of receiving the image includes receiving the image at a constant data rate.