Adaptive filtering method and apparatus for descreening scanned halftoned image representations
US6839152B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 2000 |
| Grant date | Jan 4, 2005 |
| Priority date | — |
| Expiry date | Jun 22, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40075
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An adaptive filtering method and apparatus for descreening a scanned halftoned image representation is disclosed. The apparatus includes an image input subsystem; a processing subsystem for processing halftoned image data provided by the image input subsystem; and software/firmware means operative on the processing subsystem for a) low-pass filtering a halftoned input pixel value provided by the image input subsystem to produce a low-pass filtered pixel value; b) notch-filtering the halftoned input pixel value to produce a notch-filtered pixel value; c) determining a local contrast value for the halftoned input pixel value; and d) producing a descreened output pixel value based on the low-pass filtered pixel value, the notch-filtered pixel value, or a combination of the low-pass filtered pixel value and the notch-filtered pixel value depending on the local contrast value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.