Method and apparatus for generating digital, angled halftone screens using pixel candidate lists and screen angle correction to prevent moire patterns
US5124803A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 25, 1991 |
| Grant date | Jun 23, 1992 |
| Priority date | — |
| Expiry date | Feb 25, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4058
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In digital halftone color printing, low spatial frequency patterning can occur due to the interaction of the overlapping angled halftone screens. The moire patterning can be minimized by automatically constructing digital haltone angled screens from screen tiles which are designed to minimize the low spatial frequency patterning. The screen tile boundaries are generated in response to selected integers which, together with the number of screen dots along a side of the tile in the direction of screen pitch measurement, determine the a limit on the magnitude of screen angle error. Based upon these values, each pixel within the tile boundary is associated with one of the screen dots of the image. Typically, the pixels are added to potential candidate lists from which they can be selected for inclusion within a particular screen dot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.