Color error diffusion with color bleed control

• US 6,977,663 B2
• Filed: 03/29/2004
• Issued: 12/20/2005
• Est. Priority Date: 03/29/2004
• Status: Active Grant

• Current Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chang, Ching-Wei
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): Blackman, Anthony J.
• Application Number:
  US10/812,750
• Publication Number:
  US 20050212816A1
• Time in Patent Office: 631 Days
• Field of Search: 358/1.9, 358/3.03, 358/3.04, 358/465, 345596-597, 345/601, 382/266, 382/167
• US Class Current: 345/596
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening

Abstract

A method for controlling color bleed in relation to a system-invoked halftone color-image process which involves and includes the practice of error diffusion. The proposed method involves (a) selecting a location in the system which is downstream therein relative to where error diffusion takes place, (b) at that location, performing diffusion-accumulated error calculation, (c) at another location in the system which is downstream from where error calculation takes place, applying error filtering to define a numerically weighted pixel-neighbor distribution pattern for such calculated accumulated error, where the numbers associated with that pattern add to a defined distribution-weight totality number, and (d) then preparing, for use in a next-pixel error-diffusion event, a chosen distribution-weight totality number which is less than the defined distribution-weight totality number.

Claims

1. An error distribution reduction method for controlling color bleed in relation to a system-invoked halftone color-image process which involves the practice of error diffusion in the context of a fixed-values output color palette, said method comprising

selecting a location in the system which is downstream therein relative both to where such error diffusion takes place, and to the location of the mentioned fixed values output color palette,

at that selected location, performing diffusion-accumulated error calculation,

at another location in the system which is downstream from where said performing takes place, applying error filtering to define a numerically weighted pixel-neighbor distribution pattern for such calculated accumulated error, where the numbers associated with that pattern add to a defined distribution-weight totality number, and

then, using an error distribution reduction number which is independent of error diffusion and filtering, preparing, for use in a next-pixel error-diffusion event, a chosen distribution-weight totality number which is less than the defined distribution-weight totality number, said preparing being performed by a predetermined numeric reduction in the distributable error which nominally results from the step of applying error filtering.

2. The method of claim 1, wherein the mentioned chosen distribution-weight totality number is 15/16 of the mentioned defined distribution-weight totality number.

3. The method of claim 1, wherein said applying is done using a Floyd and Steinberg error filter.

4. The method of claim 3, wherein the mentioned chosen distribution-weight totality number is 15/16 of the mentioned defined distribution-weight totality number.

5. The method of claim 1, wherein said applying is done using an error filter which is one of a (1) Floyd and Steinberg filter, (2) a Jarvis, Judice and Ninke filer, and (3) a Stucki filter.

6. The method of claim 1, wherein color error diffusion takes the form of vector error diffusion.

7. The method of claim 6, wherein said applying is done using an error filter which is one of a (1) Floyd and Steinberg filter, (2) a Jarvis, Judice and Ninke filter, and (3) a Stucki filter.

8. The method of claim 6, wherein the mentioned chosen distribution-weight totality number is 15/16 of the mentioned defined distribution-weight totality number.

9. The method of claim 6, wherein said applying is done using a Floyd and Steinberg error filter.

10. The method of claim 9, wherein the mentioned chosen distribution-weight totality number is 15/16 of the mentioned defined distribution-weight totality number.