Hybrid imaging system

• US 5,838,462 A
• Filed: 04/01/1996
• Issued: 11/17/1998
• Est. Priority Date: 04/01/1996
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Ebner, Fritz F., Chan, Tse-Kee
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): LEE, CHEUKFAN
• Application Number:
  US08/625,324
• Time in Patent Office: 960 Days
• Field of Search: 358/457, 358/456, 358/535, 358/534, 358/536, 358/465, 358/466, 358/298, 358/533, 358/429, 358/460, 358/459, 358/501, 358/401, 382/270, 382/272, 395/106, 395/117, 395/109
• US Class Current: 358/3.23
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening

Abstract

A hybrid system for digitally screening black and white and/or color images using a number of imaging techniques is disclosed. Cyan, yellow, magenta and black color separation may be processed according to the same or different methods according to gray levels or other factors, in order to optimize output print quality. A hybrid ordered matrix dot rendering system may be employed in part as an optimized screen technique in a variety of circumstances

Claims

1. A method of processing a digitized image including a plurality of pixels with the digitized image being processed on a pixel-by-pixel basis to obtain a halftoned output, comprising:

a) providing a hybrid matrix function defining M×

N submatrices with each of the M×

N submatrices including like P×

Q submatrix sections, wherein each submatrix section is activatable;

b) applying an activation order to each submatrix such that each submatrix section is turned on according to a preselected order;

c) applying a stochastic function for selective activation of the submatrix sections in each M×

N submatrix such that all like submatrix sections in all submatrices in the hybrid matrix function are turned on before a next set of like submatrix sections in the preselected order are turned on; and

d) applying the hybrid matrix function with at least one activated section to the digitized image to obtain the halftoned output.

2. The method of claim 1, wherein M=N and P=Q.

3. The method of claim 1, wherein M=128, N=128, P=2 and Q=2.

4. The method of claim 1, wherein the output is a printed sheet.

5. The method of claim 1, wherein the output is a color image.

6. The method of claim 1, wherein the hybrid matrix functions is successively applied to a plurality of color planes to produce a colored halftone output.

7. The method of claim 1, wherein the stochastic function include a step in which a luminance of the halftoned output is measured and the stochastic function is modified to optimize image quality.

8. The method of claim 7, wherein a luminance curve is generated and an inverted luminance curve is generated according to the measured luminance output, said luminance curve and said inverted luminance curve being summed so as to linearize a luminance factor of the halftoned output.

9. The method of claim 1, wherein the digitized image is processed at a predetermined range of gray levels.

10. The method of claim 9, wherein the digitized image is partially processed by a quad dot imaging function at a second predetermined range of gray levels.

11. The method of claim 9, wherein the digitized image is partially processed by an error diffusion imaging system at a second predetermined range of gray levels.

12. The method of claim 9, wherein the digitized image includes at least a first color plane and a second color plane, and wherein the first color plane is processed with the hybrid matrix function and the second color plane is processed with a second imaging function.

13. A method of processing a digitized image including a plurality of pixels with the digitized image being processed on a pixel-by-pixel basis to obtain a halftoned output, comprising:

a) providing a hybrid matrix function defining M×

N submatrices with each of the M×

N submatrices including like P×

Q submatrix sections, wherein each submatrix section is activatable;

b) applying an activation order to each submatrix such that each submatrix section is turned on according to a preselected order;

c) applying a stochastic function for selective activation of the submatrix sections in each M×

N submatrix such that all like submatrix sections in all submatrices in the hybrid matrix function are turned on before a next set of like submatrix sections in the preselected order are turned on wherein a set of DC output levels are generated from the stochastic function and placed in a plurality of buffer locations, and wherein the DC levels in the buffer locations are used to optimize halftone output repeatability; and

d) applying the hybrid matrix function with at least one activated section to the digitized image to obtain the halftoned output.

14. The method of claim 13, wherein the repeatability of the DC levels in the plurality of buffer locations are verified by an automated loop program.