Method and apparatus for implementing accurate angle screens
US5426519A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1994 |
| Grant date | Jun 20, 1995 |
| Priority date | — |
| Expiry date | Aug 25, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/52
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The present invention is a method and apparatus for processing a color document for moire-free printing, the color document including a plurality of color separations each defined with a set of image signals representing optical density with m possible density levels, while a printer is capable of rendering density with n density levels. The invention employs a spatial resolution scaler to produce m-bit signals at a spatial resolution that is a function of the halftone screen angle, base dot pitch, and desired halftone cell size. Subsequently, the m-bit signals at the desired spatial resolution (frequency and angle) are halftoned to produce n-bit signals that are printed with a raster output scanning-type printer suitable for printing at selectively variable spots per inch in both the fast and slow scan directions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.