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 Title: |
US5315406:
Screen generation for halftone screening of images using arbitrary distribution of transformed screen coordinates
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Levien, Raphael L.; McDowell, VA 24458
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| Assignee: |
None
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| Published / Filed: |
1994-05-24
/ 1991-12-10
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| Application Number: |
US1991000805278
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| IPC Code: |
Advanced:
H04N 1/405;
IPC-7:
H04N 1/40;
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| ECLA Code: |
H04N1/405C6;
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| U.S. Class: |
Current:
358/003.2;
358/466;
358/534;
Original:
358/456;
358/459;
358/466;
358/534;
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| Field of Search: |
358/400,401,429,452,455,456,457,458,465,466,75,80,296,298,77,451
101/211
H04N 140
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| Priority Number: |
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| Abstract: |
A halftone screen with precisely controlled angles and rulings, including irrational screen angles and rulings, for screening photographic images is generated by representing a desired screen pattern in an irregular or non-grid like array of screen elements. In one embodiment, a random array of screen elements is used. In another embodiment, a Poisson-disk distribution of screen elements is used to improve quality. The error between an ideal screen point and an actual screen point in the transformed UV space is calculated and used as the basis for selecting an actual screen point as having the least error between the ideal and actual screen points in UV space. The number of error calculations may be reduced by storing pointers the nearest points to each screen point in transformed UV space, and by storing a plurality of successive screen values at a given angle and screen ruling corresponding to each point in the transformed UV space.
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| Attorney, Agent or Firm: |
Jacobson, Allan ;
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| Primary / Asst. Examiners: |
Coles, Sr., Edward L.; Grant, II, Jerome
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| Maintenance Status: |
E2 Expired Check current status
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| INPADOC Legal Status: |
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| Related Applications: |
| Application Number |
Filed |
Patent |
Pub. Date |
Title |
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| US1991000768135 | 1991-09-27 |
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| US1991000753893 | 1991-09-03 |
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| Parent Case: |
This is a continuation-in-part application of U.S. patent application entitled, "SCREEN GENERATION FOR HALFTONE SCREENING OF IMAGES USING SCAN LINE SEGMENTS OF OVERSIZED SCREEN SCAN LINES", U.S. patent application Ser. No. 768,135 filed Sept. 27, 1991, which is a continuation in-part of U.S. patent application entitled, "SCREEN GENERATION FOR HALFTONE SCREENING OF IMAGES", U.S. patent application Ser. No. 753,893, filed Sept. 3, 1991.
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| Designated Country: |
DE DK FR GB
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| Family: |
Show 25 known family members
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First Claim:
Show all 44 claims |
What is claimed is:
1. In a method for generating a halftone screened image from an original image at a desired screen angle, said method including storing a screen pattern as an array of elements representing a desired spot function, transforming a point from said original image to an ideal screen point, selecting an actual screen point in said stored screen pattern array of elements to form a generated screen pattern, and screening said original image with said generated screen pattern to form said halftone screened image, the improvement comprising:
- computing an error function based on the error between said ideal screen point and actual points in said stored screen pattern array, wherein said step of computing an error function comprises computing an error vector between an actual screen point and said ideal screen point; and
- selecting said actual screen point in said stored screen pattern which produces the least said computed error function.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 11 U.S. patent(s) that reference this one
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