Image processing method incorporating decompression

1. A method for image processing page data representing a page to be printed, the method comprising the steps of:

respectively decompressing a bi-level black layer and a contone layer of the page data;

halftoning the decompressed contone layer to form a bi-level cyan, yellow, magenta, and black (CYMK) layer;

compositing the decompressed bi-level black layer over the bi-level CYMK layer to form a bi-level CYMK image of the page to be printed; and

carrying out processing operations for printing the CMYK image.

2. A method as claimed in claim 1 , in which the step of carrying out said processing operations includes the step of printing the CYMK image.

3. A method as claimed in claim 2 in which the step of carrying out the processing operations includes authenticating an ink cartridge from which the printed ink is supplied.

4. A method as claimed in claim 3 , in which the step of carrying out the processing operations includes counting the number of drops of ink printed by a printhead.

5. A method as claimed in claim 4 , in which the step of carrying out the processing operations includes updating a remaining drop count of the ink cartridge using the counted drops printed.

6. A method as claimed in claim 4 , wherein the step of counting involves performing respective ink drop counts for a plurality of different ink types.

7. A method as claimed in claim 1 , in which the steps of respectively decompressing the bi-level black layer and the contone layer include the step of buffering both decompressed layers.