Halftoning method for multi-color laser printer
US5841458A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 28, 1996 |
| Grant date | Nov 24, 1998 |
| Priority date | — |
| Expiry date | May 28, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/52
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A halftoning method characterized by two nonaligned halftone screens, one for black and the other for the subtractive primary colors cyan, magenta, and yellow, produces multi-color images on a color laser printer. The black screen is the inverse of, i.e., in reverse fill order to, the subtractive primary colors screen. The halftone pattern is a vertical line screen. In a preferred embodiment, the cells are grouped on hexagonal centers and aligned along X and Y coordinate axes. The dots are grouped in the linear direction of print medium motion. The grouping of dots reduces the effect of halftone screen misregistration, and the cell alignment in X and Y results in fewer high frequency artifacts. Inverting the black screen increases the number of possible chromatic mixed colors that include black, increases color uniformity and reduces the frequency of white "holes" in the printed images.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.