Method of multipass printing using a plurality of halftone patterns of dots

1. A method of printing dots in an area on a page using a plurality of printing passes of a printhead over said area, comprising:

processing continuous tone data representing an image through N halftoning iterations to generate N halftone patterns of dots for said area; and

printing each individual halftone pattern of said N halftone patterns during said plurality of printing passes, with each individual halftone pattern of said N halftone patterns being printed on a different printing pass of said plurality of printing passes over said area,

wherein said processing continuous tone data includes:

distributing each continuous tone value in said continuous tone data to generate N sets of continuous tone values, wherein N corresponds to the number of said plurality of printing passes for printing said area; and

applying a halftoning algorithm individually to each set of said N sets of continuous tone values to generate said N halftone patterns of dots for said area.

2. The method of claim 1 , wherein said each continuous tone value in said continuous tone data is a number V in a range of zero to 255, and said each continuous tone value in said continuous tone data is represented in each of said N sets of continuous tone values by a value of V/N rounded to the nearest whole number, and with any remainder being added to a corresponding V/N in one of said N sets.

3. The method of claim 1 , wherein said halftoning algorithm is an error diffusion halftone algorithm.

4. A method of printing dots in an area on a page using a plurality of printing passes of a printhead over said area, comprising:

processing continuous tone data representing an image through N halftoning iterations to generate N halftone patterns of dots for said area; and

printing each individual halftone pattern of said N halftone patterns during said plurality of printing passes, with each individual halftone pattern of said N halftone patterns being printed on a different printing pass of said plurality of printing passes over said area,

wherein said processing continuous tone data includes:

assigning said continuous tone data to a first grid, said first grid defining pixel locations at a first resolution R;

spatially dividing said first grid to generate N second grids, wherein each of said N second grids contains a subset of said continuous tone data, and wherein N corresponds to the number of said plurality of printing passes for printing said area; and

applying a halftoning algorithm individually to each subset of said continuous tone data in each of said N second grids to generate said N halftone patterns of dots for said area.

5. The method of claim 4 , wherein said dividing is achieved by forming various combinations of odd and even rows, and odd and even columns, of said first grid.

6. The method of claim 4 , wherein said halftoning algorithm is an error diffusion halftone algorithm.

7. An apparatus for printing dots in an area on a page using a plurality of printing passes of a printhead over said area, comprising:

a print engine for carrying said printhead;

a halftoner mechanism that receives continuous tone data representing an image and processes said continuous tone data through N halftoning iterations to generate N halftone patterns of dots for said area; and

a formatter mechanism communicatively coupled between said halftoner mechanism and said print engine, said formatter mechanism being configured to supply each of said N halftone patterns individually to said print engine, with each individual halftone pattern of said N halftone patterns being printed on a different printing pass of said plurality of printing passes in said area,

wherein the processing of said continuous tone data includes:

distributing each continuous tone value in said continuous tone data to generate N sets of continuous tone values, wherein N corresponds to the number of said plurality of printing passes for printing said area; and

applying a halftoning algorithm individually to each set of said N sets of continuous tone values to generate said N halftone patterns of dots for said area.

8. The apparatus of claim 7 , wherein said each continuous tone value in said continuous tone data is a number V in a range of zero to 255, and said each continuous tone value in said continuous tone data is represented in each of said N sets of continuous tone values by a value of V/N rounded to the nearest whole number, and with any remainder being added to a corresponding V/N in one of said N sets.

9. The apparatus of claim 7 , wherein said halftoning algorithm is an error diffusion halftone algorithm.

10. An apparatus for printing dots in an area on a page using a plurality of printing passes of a printhead over said area, comprising:

a print engine for carrying said printhead;

a halftoner mechanism that receives continuous tone data representing an image and processes said continuous tone data through N halftoning iterations to generate N halftone patterns of dots for said area; and

a formatter mechanism communicatively coupled between said halftoner mechanism and said print engine, said formatter mechanism being configured to supply each of said N halftone patterns individually to said print engine, with each individual halftone pattern of said N halftone patterns being printed on a different printing pass of said plurality of printing passes in said area,

wherein the processing of said continuous tone data includes:

assigning said continuous tone data to a first grid, said first grid defining pixel locations at a first resolution R;

spatially dividing said first grid to generate N second grids, wherein each of said N second grids contains a subset of said continuous tone data, and wherein N corresponds to the number of said plurality of printing passes for printing said area; and

applying a halftoning algorithm individually to each subset of said continuous tone data in each of said N second grids to generate said N halftone patterns of dots for said area.

11. The apparatus of claim 10 , wherein said dividing is achieved by forming various combinations of odd and even rows, and odd and even columns, of said first grid.

12. The apparatus of claim 10 , wherein said halftoning algorithm is an error diffusion halftone algorithm.

13. A method of printing dots in an area in a page using a plurality of printing passes of a printhead over said area, comprising:

processing continuous tone data representing an image through N halftoning iterations to generate N halftone patterns of dots for said area: and

printing each individual halftone pattern of said N halftone patterns during said plurality of printing passes, with each individual halftone pattern of said N halftone patterns being printed on a different printing pass of said plurality of printing passes over said area,

wherein said processing continuous tone data includes distributing each continuous tone value in said continuous tone data to generate N sets of continuous tone values, wherein N corresponds to the number of said plurality of printing passes for printing said area and applying a halftoning algorithm individually to each set of said N sets of continuous tone values to generate said N halftone patterns of dots for said area.