System and method for optimising halftoning printer performance

• US 20030227463A1
• Filed: 03/21/2003
• Published: 12/11/2003
• Est. Priority Date: 03/25/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Smith, David Christopher, Puckett, Giles
• Granted Patent: US 7,286,142 B2
• Time in Patent Office: Days
• US Class Current: 345/582
• CPC Class Codes: G06T 15/30 Clipping

Abstract

A method (500) of creating an image is disclosed. The image (e.g. 200) is formed by rendering a plurality of graphical objects (e.g. 203, 204, 205) on a scanline (e.g. 301) basis, where each scanline (301) comprises at least one run of pixels (e.g. 325). The method (500) forms an array representing the graphical objects (203, 204, 205) of the image (500). The array is sorted in an order from a top-most graphical object to a bottom-most graphical object. For each scanline (301) of the image (200) and for each run of pixels (325) of the scanline (301), the array is traversed to determine objects (203, 204, 205) contributing to the run of pixels (325). If a top-most contributing object is fully opaque, then data associated with the fully opaque object is halftoned to generate the run of pixels (325). Otherwise data associated with one or more of the contributing objects is composited and the composited data is halftoned to generate the run of pixels (325).

Claims

1. A method of creating an image, said image being formed by rendering a plurality of graphical objects on a scanline basis, where each scanline comprises at least one run of pixels, said method comprising the steps of:

(I) forming an array representing said graphical objects of said image, said array being sorted in an order from a top-most graphical object to a bottom-most graphical object; and

(II) for each scanline of said image and for each run of pixels of said scanline;

(II) (i) traversing said array to determine objects contributing to said run of pixels; and

(II)(ii) compositing data associated with one or more of said contributing objects and halftoning the composited data to generate said run of pixels.

2. A method, according to claim 1, wherein step (II)(ii) includes the further sub-steps of:

(II)(ii)(a) determining if a top-most contributing object corresponding to said run of pixels is opaque; and

(II)(ii)(b) halftoning pixel data representing said top-most contributing object to generate said run of pixels, if said top-most contributing object is opaque.

3. A method according to claim 1, further comprising the step of decomposing said objects into their constituent attributes including at least one edge of a corresponding object.

6. A method according to claim 1, wherein step (II)(ii) includes the further sub-step of using previously halftoned data to generate said run of pixels.

4. A method according to claim 4, wherein step (II)(i) includes the further sub-step of traversing a further array to determine edges of objects defining said run of pixels.

5. A method according to claim 4, further comprising the step of determining a contribution of an object depending on which edges of said contributing objects are crossed by a current scanline.

7. An apparatus for creating an image, said image being formed by rendering a plurality of graphical objects on a scanline basis, where each scanline comprises at least one run of pixels, said apparatus comprising:

array forming means for forming an array representing said graphical objects of said image, said array being sorted in an order from a top-most graphical object to a bottom-most graphical object;

traversing means for traversing said array to determine objects contributing to a run of pixels of a scanline; and

compositing means for compositing data associated with one or more of said contributing objects and halftoning the composited data to generate said run of pixels.

8. The method according to claim 7, wherein said compositing means further includes:

determining means for determining if a top-most contributing object corresponding to said run of pixels is opaque; and

halftoning means for halftoning pixel data representing said top-most contributing object to generate said run of pixels, if said top-most contributing object is opaque.

9. The apparatus according to claim 7, further comprising the step of decomposing means for decomposing said objects into their constituent attributes including at least one edge of a corresponding object.

10. The apparatus according to claim 7, further comprising means for traversing a further array to determine edges of objects defining said run of pixels.

11. The apparatus according to claim 7, further comprising means for determining a contribution of an object depending on which edges of said contributing objects are crossed by a current scanline.

12. A computer program for creating an image, said image being formed by rendering a plurality of graphical objects on a scanline basis, wherein each scanline comprises at least one run of pixels, said program comprising code for executing the following steps:

(I) forming an array representing said graphical objects of said image, said array being sorted in an order from a top-most graphical object to a bottom-most graphical object; and

(II) for each scanline of said image and for each run of pixels of said scanline;

(II) (i) traversing said array to determine objects contributing to said run of pixels; and

(II)(ii) compositing data associated with one or more of said contributing objects and halftoning the composited data to generate said run of pixels.

13. A computer readable medium, having a program recorded thereon, where the program is configured for creating an image, said image being formed by rendering a plurality of graphical objects on a scanline basis, wherein each scanline comprises at least one run of pixels, said program comprising code for executing the following steps:

(I) forming an array representing said graphical objects of said image, said array being sorted in an order from a top-most graphical object to a bottom-most graphical object; and

(II) for each scanline of said image and for each run of pixels of said scanline;

(II) (i) traversing said array to determine objects contributing to said run of pixels; and

(II)(ii) compositing data associated with one or more of said contributing objects and halftoning the composited data to generate said run of pixels.