Method of and apparatus for smoothing an image having a periodic pattern
US5065255A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1990 |
| Grant date | Nov 12, 1991 |
| Priority date | — |
| Expiry date | Jun 26, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40075
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image signal representing image information containing a periodic pattern is processed before it is broken up into halftone dots. First, the image information is averaged to generate an unsharpness signal, and then the unsharpness signal is processed for edge sharpness to generate a sharpness signal. Thereafter, a halftone-dot image is generated from the sharpness signal. More specifically, the sharpness signal Sij* is generated from a first unsharpness signal Uij which is produced by averaging the image information and a second unsharpness signal Uij which is produced by averaging the first unsharpness signal Uij, according to the equation: EQU Sij*=Uij+K.multidot.(Uij-Uij) where PA1 i=1, 2, . . . n, PA1 j=1,2, . . . n, and PA1 K: sharpness parameter. The halftone-dot image thus reproduced is sharp and free of a moire pattern which would otherwise result from the periodic pattern.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.